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  • 1.
    Abbott, Benjamin
    et al.
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    Baranov, Viktor
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany.
    Mendoza-Lera, Clara
    Ctr LyonVilleurbanne, UR MALY, Irstea, F-69616 Villeurbanne, France.
    Nikolakopoulou, Myrto
    Naturalea, Barcelona, Spain.
    Harjung, Astrid
    Univ Barcelona, E-08007 Barcelona, Spain.
    Kolbe, Tamara
    Univ Rennes 1, CNRS, OSURGeosci Rennes, UMR 6118, F-35014 Rennes, France.
    Balasubramanian, Mukundh
    BioSistemika Ltd, Ljubljana, Slovenia.
    Vaessen, Timothy N
    CEAB CSIC, Girona, Spain.
    Ciocca, Francesco
    Silixa, Elstree, England.
    Campeau, Audrey
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Romeijn, Paul
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Antonelli, Marta
    LIST, Esch Sur Alzette, Luxembourg.
    Goncalves, José
    Natl Inst Biol, Ljubljana, Slovenia.
    Datry, Thibault
    Ctr LyonVilleurbanne, UR MALY, Irstea, F-69616 Villeurbanne, France.
    Laverman, Anniet
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    de Dreuzý, Jean-Raynald
    Univ Rennes 1, CNRS, OSURGeosci Rennes, UMR 6118, F-35014 Rennes, France.
    David, Hannah M.
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Krause, Stefan
    Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England.
    Oldham, Carolyn
    Univ Western Australia, Civil Environm & Min Engn, Perth, WA, Australia.
    Pinay, Gilles
    Univ Rennes 1, OSUR, CNRS, ECOBIO,UMR 6553, Rennes, France.
    Using multi-tracer inference to move beyond single-catchment ecohydrology2016In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 160, p. 19-42Article in journal (Refereed)
    Abstract [en]

    Protecting or restoring aquatic ecosystems in the face of growing anthropogenic pressures requires an understanding of hydrological and biogeochemical functioning across multiple spatial and temporal scales. Recent technological and methodological advances have vastly increased the number and diversity of hydrological, biogeochemical, and ecological tracers available, providing potentially powerful tools to improve understanding of fundamental problems in ecohydrology, notably: 1. Identifying spatially explicit flowpaths, 2. Quantifying water residence time, and 3. Quantifying and localizing biogeochemical transformation. In this review, we synthesize the history of hydrological and biogeochemical theory, summarize modem tracer methods, and discuss how improved understanding of flowpath, residence time, and biogeochemical transformation can help ecohydrology move beyond description of site-specific heterogeneity. We focus on using multiple tracers with contrasting characteristics (crossing proxies) to infer ecosystem functioning across multiple scales. Specifically, we present how crossed proxies could test recent ecohydrological theory, combining the concepts of hotspots and hot moments with the Damkohler number in what we call the HotDam framework.

  • 2.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics. University of Gävle, Sweden .
    Improving gravimetric-isostatic models of crustal depth by correcting for non-isostatic effects and using CRUST2.02013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 117, p. 29-39Article in journal (Refereed)
    Abstract [en]

    The principle of isostasy is important in different fields of geosciences. Using an isostatic hypothesis for estimating the crustal thickness suffers from the more or less incomplete isostatic model and that the observed gravity anomaly is not only generated by the topographic/isostatic signal but also by non-isostatic effects (NIEs). In most applications of isostatic models the NIEs are disregarded. In this paper, we study how some isostatic models related with Vening Meinez's isostatic hypothesis can be improved by considering the NIE. The isostatic gravity anomaly needs a correction for the NIEs, which varies from as much as 494 mGal to -308 mGal. The result shows that by adding this correction the global crustal thickness estimate improves about 50% with respect to the global model CRUST2.0, i.e. the root mean square differences of the crustal thickness of the best Vening Meinesz type and CRUST2.0 models are 6.9 and 3.2 km before and after improvement, respectively. As a result, a new global model of crustal thickness using Vening Meinesz and CRUST2.0 models is generated. A comparison with an independent African crustal depth model shows an improvement of the new model by 6.8 km vs. CRUST2.0 (i.e. rms differences of 3.0 and 9.8 km, respectively). A comparison between oceanic lithosphere age and the NIEs is discussed in this study, too. One application of this study can be to improve crustal depth in areas where CRUST2.0 data are sparse and bad and to densify the resolution vs. the CRUST2.0 model. Other applications can be used to infer the viscosity of the mantle from the NIEs signal to study various locations around the Earth for understanding complete, over- and under-compensations of the topography.

  • 3.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E.
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Improving gravimetric–isostatic models of crustal depth by correcting for non-isostatic effects and using CRUST2.02013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 117, p. 29-39Article, review/survey (Refereed)
    Abstract [en]

    The principle of isostasy is important in different fields of geosciences. Using an isostatic hypothesis for estimating the crustal thickness suffers from the more or less incomplete isostatic model and that the observed gravity anomaly is not only generated by the topographic/isostatic signal but also by non-isostatic effects (NIEs). In most applications of isostatic models the NIEs are disregarded. In this paper, we study how some isostatic models related with Vening Meinez's isostatic hypothesis can be improved by considering the NIE. The isostatic gravity anomaly needs a correction for the NIEs, which varies from as much as 494 mGal to − 308 mGal. The result shows that by adding this correction the global crustal thickness estimate improves about 50% with respect to the global model CRUST2.0, i.e. the root mean square differences of the crustal thickness of the best Vening Meinesz type and CRUST2.0 models are 6.9 and 3.2 km before and after improvement, respectively. As a result, a new global model of crustal thickness using Vening Meinesz and CRUST2.0 models is generated. A comparison with an independent African crustal depth model shows an improvement of the new model by 6.8 km vs. CRUST2.0 (i.e. rms differences of 3.0 and 9.8 km, respectively). A comparison between oceanic lithosphere age and the NIEs is discussed in this study, too. One application of this study can be to improve crustal depth in areas where CRUST2.0 data are sparse and bad and to densify the resolution vs. the CRUST2.0 model. Other applications can be used to infer the viscosity of the mantle from the NIEs signal to study various locations around the Earth for understanding complete, over- and under-compensations of the topography.

  • 4.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University of Gävle, Sweden .
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Tenzer, Robert
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    A new Fennoscandian crustal thickness model based on CRUST1. 0 and a gravimetric–isostatic approach2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 145, p. 132-145Article, review/survey (Refereed)
    Abstract [en]

    In this paper a new gravimetric–isostatic crustal thickness model (VMM14_FEN) is estimated for Fennoscandia. The main motivation is to investigate the relations between geological and geophysical properties, the Moho depth and crust–mantle density contrast at the crust–mantle discontinuity. For this purpose the Bouguer gravity disturbance data is corrected in two main ways namely for the gravitational contributions of mass density variation due to the different layers of the Earth's crust such as ice and sediments, as well as for the gravitational contribution from deeper masses below the crust. This second correction (for non-isostatic effects) is necessary because in general the crust is not in complete isostatic equilibrium and the observed gravity data are not only generated by the topographic/isostatic masses but also from those in the deep Earth interior. The correction for non-isostatic effects is mainly attributed to unmodeled mantle and core boundary density heterogeneities. These corrections are determined using the recent seismic crustal thickness model CRUST1.0. We compare our modeling results with previous studies in the area and test the fitness. The comparison with the external Moho model EuCRUST-07 shows a 3.3 km RMS agreement for the Moho depth in Fennoscandia. We also illustrate how the above corrections improve the Moho depth estimation. Finally, the signatures of geological structures and isostatic equilibrium are studied using VMM14_FEN, showing how main geological unit structures attribute in isostatic balance by affecting the Moho geometry. The main geological features are also discussed in the context of the complete and incomplete isostatic equilibrium.

  • 5.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. KTH.
    Sjöberg, Lars E.
    KTH.
    Tenzer, Robert
    Wuhan University, China.
    Abrehdary, Majid
    KTH.
    A new Fennoscandian crustal thickness model based on CRUST1.0 and a gravimetric-isostatic approach2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 145, p. 132-145Article, review/survey (Refereed)
    Abstract [en]

    In this paper a new gravimetric-isostatic crustal thickness model (VMM14_FEN) is estimated for Fennoscandia. The main motivation is to investigate the relations between geological and geophysical properties, the Moho depth and crust-mantle density contrast at the crust-mantle discontinuity. For this purpose the Bouguer gravity disturbance data is corrected in two main ways namely for the gravitational contributions of mass density variation due to the different layers of the Earth's crust such as ice and sediments, as well as for the gravitational contribution from deeper masses below the crust. This second correction (for non-isostatic effects) is necessary because in general the crust is not in complete isostatic equilibrium and the observed gravity data are not only generated by the topographic/isostatic masses but also from those in the deep Earth interior. The correction for non-isostatic effects is mainly attributed to unmodeled mantle and core boundary density heterogeneities. These corrections are determined using the recent seismic crustal thickness model CRUST1.0. We compare our modeling results with previous studies in the area and test the fitness. The comparison with the external Moho model EuCRUST-07 shows a 3.3. km RMS agreement for the Moho depth in Fennoscandia. We also illustrate how the above corrections improve the Moho depth estimation. Finally, the signatures of geological structures and isostatic equilibrium are studied using VMM14_FEN, showing how main geological unit structures attribute in isostatic balance by affecting the Moho geometry. The main geological features are also discussed in the context of the complete and incomplete isostatic equilibrium. 

  • 6. Baker, Paul A.
    et al.
    Fritz, Sherilyn C.
    Dick, Christopher W.
    Eckert, Andrew J.
    Horton, Brian K.
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Ribas, Camila C.
    Garzione, Carmala N.
    Battisti, David S.
    The emerging field of geogenomics: Constraining geological problems with genetic data2014In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 135, p. 38-47Article in journal (Refereed)
    Abstract [en]

    The development of a genomics-derived discipline within geology is timely, as a result of major advances in acquiring and processing geologically relevant genetic data. This paper articulates the emerging field of geogenomics, which involves the use of large-scale genetic data to constrain geological hypotheses. The paper introduces geogenomics and discusses how hypotheses can be addressed through collaboration between geologists and evolutionary biologists. As an example, geogenomic methods are applied to evaluate competing hypotheses regarding the timing of the Andean uplift, the closure of the Isthmus of Panama, the onset of trans-Amazon drainage, and Quaternary climate variation in the Neotropics.

  • 7. Betts, Marissa, J.
    et al.
    Paterson, John, R.
    Jacquet, Sarah, M.
    Andrew, Anita S.
    Hall, Philip A.
    Jago, James, B.
    Jagodzinski, Elisabeth A.
    Preiss, Wolfgang V.
    Crowley, James L.
    Brougham, Tom
    Mathewson, Ciaran P.
    Garcia-Bellido, Diego C.
    Topper, Timothy, P.
    Skovsted, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Brock, Glenn, A.
    Early Cambrian chronostratigraphy and geochronology of South Australia2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 185, p. 498-543Article in journal (Refereed)
    Abstract [en]

    The most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio- and geo-events. Here we present the first regional, high-resolution shelly fossil biostratigraphy integrated with δ13C chemostratigraphy (and corresponding δ18O data) from the traditional lower Cambrian (Terreneuvian and provisional Cambrian Series 2) of South Australia. The global ZHUCE, SHICE, positive excursions II and III and the CARE are captured in lower Cambrian successions from the Arrowie and Stansbury basins. The South Australian shelly fossil biostratigraphy has a consistent relationship with the δ13C results, bolstering interpretation, identification and correlation of the excursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgei zones, and the CARE straddles the boundary between the M. etheridgei and Dailyatia odyssei zones, peaking in the lower parts of the latter zone. New CA-TIMS zircon dates from the upper Hawker Group and Billy Creek Formation provide geochronologic calibration points for the upper D. odyssei Zone and corresponding chemostratigraphic curve, embedding the lower Cambrian successions from South Australia into a global chronostratigraphic context. This multi-proxy investigation demonstrates the power of integrated methods for developing regional biostratigraphic schemes and facilitating robust global correlation of lower Cambrian successions from South Australia (part of East Gondwana) with coeval terranes on other Cambrian palaeocontinents, including South and North China, Siberia, Laurentia, Avalonia and West Gondwana.

  • 8. Bozkurt, S.
    et al.
    Lucisano, M.
    Moreno, Luis
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Neretnieks, Ivars
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Peat as a potential analogue for the long-term evolution in landfills2001In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 53, no 02-jan, p. 95-147Article, review/survey (Refereed)
    Abstract [en]

    A survey of the existing studies on peat and its decomposition processes is presented with the aim to characterise the long-term behaviour of peat accumulating systems. The chemical and physical characteristics of peat together with its accumulation and decay processes have been analysed. Peat is an acidic mixture of dead and decomposed. mainly vegetable, matter formed in boggy areas; it is the youngest and least altered component of the combustible rocks and is characterised by the lowest content of fixed carbon and the highest content of volatile constituents. Peat is formed by degeneration processes under exclusion of atmospheric oxygen by the action of water; the speed of formation depends upon the climatic and environmental conditions. In most peatlands two layers can be characterised: the aerobic acrotelm and the anaerobic catotelm, their relative importance being controlled mainly by the position of the water table. In the acrotelm the aerobic processes are responsible for the loss of up to 90% of the original mass, Degeneration in the acidic and anaerobic catotelm is still imperfectly characterised even though the catotelm is the real site of peat accumulation. Most of the recent literature considers peat as composed of easily degradable compounds, e.g. polysaccharides. and recalcitrant matter (lignin and complex aromatics). The lone-term destiny of peat has not been sufficiently characterised: although in a large majority of cases it seems probable that peat decomposes completely (even though slowly) provided that it is given a sufficiently long residence rime in the catotelm, some cases can still be interpreted as examples of simple accumulation. The rates of influx of oxygen and hence the degradation of organic matter into both saturated and partially saturated peat have been estimated. The depletion rate is about 4500 g m(-1) year(-1) for partially saturated peat. The average depletion rate of the peat for this case will then be such that it will take on the order of 5 to 50 years to degrade half of the organics in a 10 cm partially saturated layer. For the water-saturated case the depletion rate varies between 8 and 12 g m(-2) year(-1), which is considerably lower than in the partially saturated region. The models used to analyse the field and laboratory data on generation, diffusion and emission of methane and carbon dioxide indicate that laboratory data and field observations agree reasonably well. It is suggested that peat-accumulating ecosystems may be valuable natural analogues for the study of the long-term destiny of industrial and municipal solid wastes. Accurate studies of active mires together with an ad hoc review of the existing literature give valuable insights in this problem. Peatlands might then be considered as organic waste deposition experiments lasting up to several thousands years.

  • 9. Brown, D.
    et al.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Ayala, C.
    Tryggvason, Ari
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Bea, F.
    Alvarez-Marron, J.
    Carbonell, R.
    Seward, D.
    Glasmacher, U.
    Puchkov, V.
    Perez-Estaun, A.
    Mountain building processes during continent-continent collision in the Uralides2008In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, ISSN 0012-8252, Vol. 89, no 3-4, p. 177-195Article in journal (Refereed)
    Abstract [en]

    Since the early 1990's the Paleozoic Uralide Orogen of Russia has been the target of a significant research initiative as part of EUROPROBE and GEODE, both European Science Foundation programmes. One of the main objectives of these research programmes was the determination of the tectonic processes that went into the formation of the orogen. In this review paper we focus on the Late Paleozoic continent-continent collision that took place between Laurussia and Kazakhstania. Research in the Uralides was concentrated around two deep seismic profiles crossing the orogen. These were accompanied by geological, geophysical, geochronological, geochemical, and low-temperature thermochronological studies. The seismic profiles demonstrate that the Uralides has an overall bivergent structural architecture, but with significantly different reflectivity characteristics from one tectonic zone to another. The integration of other types of data sets with the seismic data allows us to interpret what tectonic processes where responsible for the formation of the structural architecture, and when they were active. On the basis of these data, we suggest that the changes in the crustal-scale structural architecture indicate that there was significant partitioning of tectonothermal conditions and deformation from zone to zone across major fault systems, and between the lower and upper crust. Also, a number of the structural features revealed in the bivergent architecture of the orogen formed either in the Neoproterozoic or in the Paleozoic, prior to continent-continent collision. From the end of continent-continent collision to the present, low-temperature thermochronology suggests that the evolution of the Uralides has been dominated by erosion and slow exhumation. Despite some evidence for more recent topographic uplift, it has so far proven difficult to quantify it.

  • 10. Brown, D.
    et al.
    Spadea, P.
    Puchkov, V.
    Alvarez-Marron, J.
    Herrington, R.
    Willner, A.P.
    Hetzel, R.
    Gorozhanina, Y.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. Geofysik.
    Arc-continent collision in the Southern Urals2006In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 79, no 3-4, p. 261-287Article in journal (Refereed)
    Abstract [en]

    The Southern Urals of Russia contain what is arguably one of the best-preserved examples of an arc–continent collision in anyPaleozoic orogen. The arc–continent collision history recorded in the rocks of the Southern Urals began in the Early Devonian withthe onset of intra-oceanic subduction and the formation of the Magnitogorsk Arc and ended with its collision with the margin ofBaltica during the Late Devonian. The Baltica margin consisted of a basement that was composed predominantly of rocks ofArchean and Proterozoic age that, by the time of arc–continent collision, was overlain by Cambrian, Ordovician, Silurian, andDevonian sediments interpreted to have been deposited in rift-related grabens on the continental slope and rise, and on the shallowmarine platform. The Magnitogorsk Arc consists of Early to Late Devonian island arc volcanic rocks and overlying volcaniclasticsediments. Arc–continent collision led to the development of an accretionary complex that includes shallowly and deeplysubducted continental margin rocks, ophiolite fragments, and sediments that were deposited in a foreland-basin setting. Thegeochemistry of the Magnitogorsk Arc volcanic rocks, the structure of the arc–continent collision accretionary complex and theforearc, the high-pressure rocks beneath and along the suture zone, the mafic and ultramafic ophiolitic material, and the syn-tectonic sediments show that the Paleozoic tectonic processes recorded in the Southern Urals can be favorably compared with thosein currently active settings such as the west Pacific.© 2006 Elsevier B.V. All rights reserved.

  • 11. Carracedo, Juan Carlos
    et al.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Zaczek, Kirsten
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Rodriguez-Gonzales, Alejandro
    Soler, Vincente
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    The 2011-2012 submarine eruption off El Hierro, Canary Islands: New lessons in oceanic island growth and volcanic crisis management2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 150, p. 168-200Article in journal (Refereed)
    Abstract [en]

    Forty years after the eruption of the Teneguía volcano on La Palma, 1971, the last volcanic event in the Canary Islands, a submarine eruption took place in 2011 off-shore El Hierro, the smallest and youngest island of the archipelago. In this paper, we review the periods of seismic unrest leading up to the 2011–2012 El Hierro eruption, the timeline of eruptive events, the erupted products, the wider societal impacts, and the insights garnered for our understanding of ocean island growth mechanisms and hazard management. Seismic precursors allowed early detection of magmatic activity and prediction of the approximate location of the eruption. White coloured “floating stones” (“xeno-pumice”) were described within the first few days of the events, the origin of which were hotly debated because of their potential implications for the character of the eruption. Due to epistemic uncertainty derived from delayed flow of scientific information and equivocal interpretations of the “floating stones”, the El Hierro 2011–2012 events were characterised by cautious civil protection measures, which greatly impacted on the residents' lives and on the island's economy. We therefore summarise the scientific lessons learned from this most recent Canary Island eruption and discuss how emergency managers might cope with similar situations of uncertainty during future eruptive events in the region.

  • 12. Chandler, Benjamin M. P.
    et al.
    Lovell, Harold
    Boston, Clare M.
    Lukas, Sven
    Barr, Iestyn D.
    Örn Benediktsson, Ívar
    Benn, Douglas I.
    Clark, Chris D.
    Darvill, Christopher M.
    Evans, David J. A.
    Ewertowski, Marek W.
    Loibl, David
    Margold, Martin
    Otto, Jan-Christoph
    Roberts, David H.
    Stokes, Chris R.
    Storrar, Robert D.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Glacial geomorphological mapping: A review of approaches and frameworks for best practice2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 185, p. 806-846Article, review/survey (Refereed)
    Abstract [en]

    Geomorphological mapping is a well-established method for examining earth surface processes and landscape evolution in a range of environmental contexts. In glacial research, it provides crucial data for a wide range of process-oriented studies and palaeoglaciological reconstructions; in the latter case providing an essential geomorphological framework for establishing glacial chronologies. In recent decades, there have been significant developments in remote sensing and Geographical Information Systems (GIS), with a plethora of high quality remotely-sensed datasets now (often freely) available. Most recently, the emergence of unmanned aerial vehicle (UAV) technology has allowed sub-decimetre scale aerial images and Digital Elevation Models (DEMs) to be obtained. Traditional field mapping methods still have an important role in glacial geomorphology, particularly in cirque glacier, valley glacier and icefield/ice-cap outlet settings. Field mapping is also used in ice sheet settings, but often takes the form of necessarily highly-selective ground-truthing of remote mapping. Given the increasing abundance of datasets and methods available for mapping, effective approaches are necessary to enable assimilation of data and ensure robustness. This paper provides a review and assessment of the various glacial geomorphological methods and datasets currently available, with a focus on their applicability in particular glacial settings. We distinguish two overarching 'work streams' that recognise the different approaches typically used in mapping landforms produced by ice masses of different sizes: (i) mapping of ice sheet geomorphological imprints using a combined remote sensing approach, with some field checking (where feasible); and (ii) mapping of alpine and plateau-style ice mass (cirque glacier, valley glacier, icefield and ice-cap) geomorphological imprints using remote sensing and considerable field mapping. Key challenges to accurate and robust geomorphological mapping are highlighted, often necessitating compromises and pragmatic solutions. The importance of combining multiple datasets and/or mapping approaches is emphasised, akin to multi-proxy approaches used in many Earth Science disciplines. Based on our review, we provide idealised frameworks and general recommendations to ensure best practice in future studies and aid in accuracy assessment, comparison, and integration of geomorphological data. These will be of particular value where geomorphological data are incorporated in large compilations and subsequently used for palaeoglaciological reconstructions. Finally, we stress that robust interpretations of glacial landforms and landscapes invariably requires additional chronological and/or sedimentological evidence, and that such data should ideally be collected as part of a holistic assessment of the overall glacier system.

  • 13.
    Christoffersson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Statistics.
    Husebye, Eystein S.
    Seismic tomographic mapping of the Earth's interior: back to basics revisiting the ACH inversion2011In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 106, no 3-4, p. 293-306Article, review/survey (Refereed)
    Abstract [en]

    It is now more than 35 years since our original work on seismic tomography commenced in June 1974 upon Keiiti Aki's arrival at Kjeller near Oslo. It was published by Aki et al. (1977) and has found wide-spread applications in numerous studies of the Earth's interior from crust to core and in addition triggered many theoretical ones as well. In those times, computer technologies were rather crude and this hampered our tomographic research. In particular, we were somewhat unhappy about both our Generalized Inverse (GI) and the Stochastic Inverse (SI) solutions because of the former being too bumpy and the latter involving vertical smoothing. These problems remain in evidence also in recent studies as will be demonstrated in this review work. We start with re-examining the ACH-original work and then introduce Gauss-Markov (GM) filtering offsetting the defects of both the generalized and stochastic inverses. We highlight the relative merits of our novel inversion method by real tests on the original Norsar P-residuals and the corresponding 5 layered lithosphere model using synthetic velocity anomalies. Then we repeated the original inversion experiment adding the GM solution. The outcome was that the original SI solution was useless; GI too bumpy while the GM solution was appealing both computationally and in the context of geotectonic interpretation. We found that alternative inversion procedures like those forwarded by Backus and Gilbert (1968) and by Pijpers and Thompson (1992), the latter for helioseismology, were not applicable. The reason is that our unknowns are relative velocity anomalies within separate model layers and thus violate basic assumptions in the mentioned procedures. We also discuss source and structure parameter separation and the recent 'double difference' approach in tomography based on local earthquake data.

  • 14.
    Greenwood, Sarah L.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Clason, Caroline C.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Helanow, Christian
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Margold, Martin
    Stockholm University, Faculty of Science, Department of Physical Geography. Durham University, UK.
    Theoretical, contemporary observational and palaeo-perspectives on ice sheet hydrology: Processes and products2016In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 155, p. 1-27Article in journal (Refereed)
    Abstract [en]

    Meltwater drainage through ice sheets has recently been a key focus of glaciological research due to its influence on the dynamics of ice sheets in a warming climate. However, the processes, topologies and products of ice sheet hydrology are some of the least understood components of both past and modem ice sheets. This is to some extent a result of a disconnect between the fields of theoretical, contemporary observational and palaeo-glaciology that each approach ice sheet hydrology from a different perspective and with different research objectives. With an increasing realisation of the potential of using the past to inform on the future of contemporary ice sheets, bridging the gaps in the understanding of ice sheet hydrology has become paramount. Here, we review the current state of knowledge about ice sheet hydrology from the perspectives of theoretical, observational and palaeo-glaciology. We then explore and discuss some of the key questions in understanding and interpretation between these research fields, including: 1) disagreement between the palaeo-record, glaciological theory and contemporary observations in the operational extent of channelised subglacial drainage and the topology of drainage systems; 2) uncertainty over the magnitude and frequency of drainage events associated with geomorphic activity; and 3) contrasts in scale between the three fields of research, both in a spatial and temporal context The main concluding points are that modem observations, modelling experiments and inferences from the palaeo-record indicate that drainage topologies may comprise a multiplicity of forms in an amalgam of drainage modes occurring in different contexts and at different scales. Drainage under high pressure appears to dominate at ice sheet scale and might in some cases be considered efficient; the sustainability of a particular drainage mode is governed primarily by the stability of discharge. To gain better understanding of meltwater drainage under thick ice, determining what drainage topologies are reached under high pressure conditions is of primary importance. Our review attests that the interconnectivity between research sub-disciplines in progressing the field is essential, both in interpreting the palaeo-record and in developing physical understanding of glacial hydrological processes and systems.

  • 15. He, Minhui
    et al.
    Yang, Bao
    Bräuning, Achim
    Rossi, Sergio
    Charpentier Ljungqvist, Fredrik
    Stockholm University, Faculty of Humanities, Department of History. University of Cambridge, United Kingdom.
    Shishov, Vladimir
    Grießinger, Jussi
    Wang, Jianglin
    Liu, Jingjing
    Qin, Chun
    Recent advances in dendroclimatology in China2019In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 194, p. 521-535Article, review/survey (Refereed)
    Abstract [en]

    Considerable progress has been made in dendroclimatological research in China during the period 2000-2017, including a significant increase in the spatial coverage of tree-ring chronologies developed for paleoclimatic research. New tree-ring sampling sites have been established across the Tibetan Plateau, as well as the north-eastern and sub-tropical eastern parts of China. Most of the studies use coniferous trees, although different plant functional types (e.g., broadleaf species and shrubs) have also been increasingly investigated. Tree-ring chronologies longer than 600 years, however, are mostly found on the Tibetan Plateau, with the longest one extending back to 2637 BCE (before Common Era). Most tree-ring records in the eastern parts of China are < 400 years long. Tree-ring width is the most commonly studied parameter, although stable isotope ratios and wood density data have also been obtained for specific sites. Stable oxygen isotope data frequently shares a common hydroclimate signal, whereas the climate or environmental signals remain inconsistent for the few available stable carbon isotope records. In general, tree-ring width-based temperature reconstructions originate from higher elevation sites (i.e., treeline) compared to hydroclimate reconstructions. Precipitation or drought reconstructions are mainly obtained from regions with an annual precipitation of < 800 mm. Most of the tree-ring reconstructions are based on individual site or local-scale chronologies, although a limited number of regional-scale and field reconstructions have been produced. The most prominent identified characteristics of the recent advances in dendroclimatological research for China have manifested in aspects such as an expanded network of sampling sites, improved climate reconstruction methodology, and improved uncertainty estimations in the latter. Furthermore, the traditional statistical-based tree growth climate relationships have been supplemented by monitoring and modeling approaches. Based on the progress from 2000 to 2017, and on the research potential of the country in this field, we expect additional widening of the dendroclimatological investigations in China during the coming years.

  • 16. Landing, Ed
    et al.
    Geyer, Gerd
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Brasier, Martin D.
    Bowring, Samuel A.
    Cambrian Evolutionary Radiation: Context, correlation, and chronostratigraphy-Overcoming deficiencies of the first appearance datum (FAD) concept2013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 123, p. 133-172Article in journal (Refereed)
    Abstract [en]

    Use of the first appearance datum (FAD) of a fossil to define a global chronostratigraphic unit's base can lead to intractable correlation and stability problems. FADs are diachronous-they reflect species' evolutionary history, dispersal, biofacies, preservation, collection, and taxonomy. The Cambrian Evolutionary Radiation is characterised by diachronous FADs, biofacies controls, and provincialism of taxa and ecological communities that confound a stable Lower Cambrian chronostratigraphy. Cambrian series and stage definitions require greater attention to assemblage zone successions and non-biostratigraphic, particularly carbon isotope, correlation techniques such as those that define the Ediacaran System base. A redefined, basal Cambrian Trichophycus pedum Assemblage Zone lies above the highest Ediacaran-type biotas (vendobionts, putative metazoans, and calcareous problematica such as Cloudina) and the basal Asteridium tornatumComasphaeridium velvetum Zone (acritarchs). This definition and the likely close correspondence of evolutionary origin and local FAD of T. pedum preserves the Fortune Head, Newfoundland, GSSP of the Cambrian base and allows the presence of sub-Cambrian, branched ichnofossils. The sub-Tommotian-equivalent base of Stage 2 (a suggested "Laolinian Stage") should be defined by the l'/L4/ZHUCE delta C-13 positive peak, bracketed by the lower ranges of Watsonella crosbyi and Aldanella attleborensis (molluscs) and the Skiagia omata-Fimbrioglomerella membranacea Zone (acritarchs). The W. crosbyi and A. attleborensis FADs cannot define a Stage 2 base as they are diachronous even in the Newfoundland "type" W. crosbyi Zone. The Series 2 base cannot be based on a species' FAD owing to the provincialism of skeletalised metazoans in the Terreneuvian-Series 2 boundary interval and global heterochrony of the oldest trilobites. A Series 2 and Stage 3 (a suggested "Lenaldanian Series" and "Zhurinslcyan Stage," new) GSSP base is proposed at the Siberian lower Atdabanian delta C-13 IV peak-which correlates into South China, Avalonia, and Morocco and assigns the oldest trilobites to the terminal Terreneuvian Series. 

  • 17.
    Ledin, Maria
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Accumulation of metals by microorganisms: processes and importance for soil systems2000In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 51, no 1-4, p. 1-31Article in journal (Refereed)
    Abstract [en]

    Metal accumulation by solid substances can counteract metal mobilization in the environment if the solid substance is immobile. Microorganisms have a high surface area-to-volume ratio because of their small size and therefore provide a large contact area that can interact with metals in the surrounding environment. Microbial metal accumulation has received much attention in the last years due to the potential use of microorganisms for cleaning metal-polluted water. However, considerably less attention has been paid to the role of microorganisms for metal mobility in soil even though the same processes may occur there. Therefore, this paper highlights this area. The different accumulation processes that microorganisms perform are analyzed and their potential significance in soil systems is discussed.

    Different kinds of mechanisms can be involved in the accumulation of metals by microorganisms, e.g. adsorption, precipitation, complexation and active transport into the cell. Physicochemical parameters like pH and ionic composition, as well as biological factors are of importance for the magnitude of accumulation. Often large amounts of metals can be accumulated with varying specificity, and microorganisms may provide nucleation sites for mineral formation.

    Several studies of microbial metal accumulation have been made with different methods and aims. Most of these studies concern single-component systems with one organism at a time. Data from accumulation experiments with pure cultures of microorganisms have been used to model the overall metal retention in soil. A further development is experimental model systems using various solid soil components in salt medium.

    Microbial metal accumulation is difficult to study in situ, but some experimental methods have been applied as tools for studying real soil systems, e.g. litter bags buried in soil containing microorganisms, a method where discs with microorganisms have been put onto agar plates with soil extracts, and comparison of sterilized and non-sterilized soils or soils with or without nutrient amendment.

    Different aspects of microbial metal accumulation are emphasized with the different methods applied. Single-component systems have the advantage of providing excellent information of the metal binding properties of microorganisms but cannot directly be applied to metal behavior in the heterogenous systems that real soils constitute. Studies focused on the behavior of metals in real soils can, in contrast, provide information on the overall metal distribution but less insight into the processes involved. Obviously, a combination of approaches is needed to describe metal distribution and mobility in polluted soil such as areas around mines. Different kinds of multi-component systems as well as modelling may bridge the gap between these two types of studies. Several experimental methods, complementary to each other and designed to allow for comparison, may emphasize different aspects of metal accumulation and should therefore be considered.

    To summarize, there are studies that indicate that microorganisms may also accumulate metals in soil and that the amounts may be considerable. However, much work remains to be done, with the focus of microorganisms in soil. It is also important to put microbial metal accumulation in relation to other microbial processes in soil, which can influence metal mobility, to determine the overall influence of soil microorganisms on metal mobility, and to be able to quantify these processes.

  • 18. Loisel, Julie
    et al.
    van Bellen, Simon
    Pelletier, Luc
    Talbot, Julie
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm Univ, Dept Phys Geog, Stockholm, Sweden.
    Karran, Daniel
    Yu, Zicheng
    Nichols, Jonathan
    Holmquist, James
    Insights and issues with estimating northern peatland carbon stocks and fluxes since the Last Glacial Maximum2017In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 165, p. 59-80Article, review/survey (Refereed)
    Abstract [en]

    In this review paper, we identify and address key uncertainties related to four local and global controls of Holocene northern peatland carbon stocks and fluxes. First, we provide up-to-date estimates of the current northern peatland area (3.2 M km(2)) and propose a novel approach to reconstruct changes in the northern peatland area over time (Section 2). Second, we review the key methods and models that have been used to quantify total carbon stocks and methane emissions over time at the hemispheric scale, and offer new research directions to improve these calculations (Section 3). Our main proposed improvement relates to allocating different carbon stock and emission values for each of the two dominant vegetation assemblages (sedge and brown moss-dominated vs. Sphagnum-dominated peat). Third, we discuss and quantify the importance of basin heterogeneity in estimating peat volume at the local scale (Section 4.1). We also highlight the importance of age model selection when reconstructing carbon accumulation rates from a peat core (Section 4.2). Lastly, we introduce the role of biogeomorphological agents such as beaver activity in controlling carbon dynamics (Section 5.1) and review the newest research related to permafrost thaw (Section 5.2) and peat fire (Section 5.3) under climate change. Overall, this review summarizes new information from a broad range of peat-carbon studies, provides novel analysis of hemispheric-scale paleo datasets, and proposes new insights on how to translate peat-core data into carbon fluxes. It also identifies critical data gaps and research priorities, and many ways to consider and address them.

  • 19.
    Marchant, Rob
    et al.
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Richer, Suzi
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England;Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    Boles, Oliver
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Capitani, Claudia
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Courtney Mustaphi, Colin
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, Archaeology. Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Lane, Paul
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, Archaeology. Univ Witwatersrand, Sch Geog Archaeol & Environm Studies, Johannesburg, South Africa.
    Prendergast, Mary E.
    St Louis Univ, Dept Anthropol, Ave Valle 34, Madrid 28003, Spain.
    Stump, Daryl.
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    De Cort, Gijs
    Royal Museum Cent Africa, Dept Earth Sci, Leuvensesteenweg 13, B-3080 Tervuren, Belgium;Univ Ghent, Dept Biol, Limnol Unit, KL Ledeganckstr 35, B-9000 Ghent, Belgium.
    Kaplan, Jed O.
    ARVE Res SARL, Pully, Switzerland;Max Planck Inst Sci Human Hist, Dept Archaeol, Kahlaische Str 10, D-07745 Jena, Germany.
    Phelps, Leanne
    Univ Lausanne, Inst Earth Surface Dynam, CH-1015 Lausanne, Switzerland.
    Kay, Andrea
    Univ Lausanne, Inst Earth Surface Dynam, CH-1015 Lausanne, Switzerland.
    Olago, Dan
    Univ Nairobi, Inst Climate Change & Adaptat, Nairobi, Kenya.
    Petek, Nik
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, African and Comparative Archaeology.
    Platts, Philip J.
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England;Univ York, Dept Biol, York Y010 5DD, N Yorkshire, England.
    Punwong, Paramita
    Mahidol Univ, Fac Environm & Resource Studies, Salaya 73170, Nakhon Pathom, Thailand.
    Widgren, Mats
    Stockholm Univ, Dept Human Geog, SE-10691 Stockholm, Sweden.
    Wynne-Jones, Stephanie
    Univ South Africa, Dept Anthropol & Archaeol, UNISA, POB 392, Pretoria, South Africa.
    Ferro-Vazquez, Cruz
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    Benard, Jacquiline
    Kenya Wildlife Serv, Shimba Hills, Nairobi, Kenya.
    Boivin, Nicole
    Max Planck Inst Sci Human Hist, Dept Archaeol, Kahlaische Str 10, D-07745 Jena, Germany.
    Crowther, Alison
    Max Planck Inst Sci Human Hist, Dept Archaeol, Kahlaische Str 10, D-07745 Jena, Germany;Univ Queensland, Sch Social Sci, Brisbane, Qld 4072, Australia.
    Cuni-Sanchez, Aida
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Deere, Nicolas J.
    Univ Kent, Sch Anthropol & Conservat, DICE, Marlowe Bldg, Canterbury CT2 7NR, Kent, England.
    Ekblom, Anneli
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, Archaeology.
    Farmer, Jennifer
    Univ Aberdeen, Sch Biol Sci, Aberdeen AB24 3FX, Scotland;Carbon Fdn East Africa, POB 70480 Lubowa Estate, Kampala, Uganda.
    Finch, Jemma
    Univ KwaZulu Natal, Sch Agr Earth & Environm Sci, Discipline Geog, Private Bag X01, ZA-3201 Scottsville, South Africa.
    Fuller, Dorian
    UCL, Inst Archaeol, 31-34 Gordon Sq, London WC1H OPY, England.
    Gaillard-Lemdahl, Marie-Jose
    Linnaeus Univ, Dept Biol & Environm Sci, S-35195 Vaxjo, Sweden.
    Gillson, Lindsey
    Univ Cape Town, Plant Conservat Unit, Private Bag X3, ZA-7701 Cape Town, South Africa;Univ Cape Town, Bot Dept, Private Bag X3, ZA-7701 Cape Town, South Africa.
    Githumbi, Esther
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Kabora, Tabitha
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    Kariuki, Rebecca
    Univ York, Environm Dept, York Inst Trop Ecosyst, York YO10 5NG, N Yorkshire, England.
    Kinyanjui, Rahab
    Natl Museums Kenya, Palynol & Palaeobot Sect, Dept Earth Sci, POB 40658, Nairobi 00100, Kenya.
    Kyazike, Elizabeth
    Lang, Carol
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    Lejju, Julius
    Mbarara Univ Sci & Technol, Dept Biol, POB 1410, Mbarara, Uganda.
    Morrison, Kathleen D.
    Univ Penn, Dept Anthropol, 3260 South St, Philadelphia, PA 19104 USA.
    Muiruri, Veronica
    Natl Museums Kenya, Palynol & Palaeobot Sect, Dept Earth Sci, POB 40658, Nairobi 00100, Kenya.
    Mumbi, Cassian
    Tanzania Wildlife Res Inst TAWIRI, Arusha, Tanzania.
    Muthoni, Rebecca
    Natl Museums Kenya, Palynol & Palaeobot Sect, Dept Earth Sci, POB 40658, Nairobi 00100, Kenya.
    Muzuka, Alfred
    Nelson Mandela African Inst Sci & Technol, Dept Water Resources & Environm Sci & Engn, Arusha, Tanzania.
    Ndiema, Emmanuel
    Natl Museums Kenya, Archaeol Sect, POB 40658, Nairobi 00100, Kenya.
    Nzabandora, Chantal Kabonyi
    Univ Officielle Bukavu, Bukavu, DEM REP CONGO.
    Onjala, Isaya
    Kyambogo Univ, Dept Hist & Archaeol, Kampala, Uganda.
    Schrijver, Annemiek Pas
    Stockholm Univ, Dept Human Geog, SE-10691 Stockholm, Sweden.
    Rucina, Stephen
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England;Natl Museums Kenya, Palynol & Palaeobot Sect, Dept Earth Sci, POB 40658, Nairobi 00100, Kenya.
    Shoemaker, Anna
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, Archaeology.
    Thornton-Barnett, Senna
    Univ York, Dept Archaeol, Kings Manor, York YO1 7EP, N Yorkshire, England.
    van der Plas, Geert
    Univ Ghent, Dept Biol, Limnol Unit, KL Ledeganckstr 35, B-9000 Ghent, Belgium.
    Watson, Elizabeth E.
    Kyambogo Univ, Dept Hist & Archaeol, Kampala, Uganda;Univ Cambridge, Dept Geog, Downing Pl, Cambridge CB2 3EN, England.
    Williamson, David
    IRD, United Nations Ave,POB 30677, Nairobi 00100, Kenya.
    Wright, David
    Seoul Natl Univ, Dept Archaeol & Art Hist, 1 Gwanak Ro, Seoul 08826, South Korea.
    Drivers and trajectories of land cover change in East Africa: Human and environmental interactions from 6000 years ago to present2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 178, p. 322-378Article in journal (Refereed)
    Abstract [en]

    East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region. Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.

  • 20.
    Marchant, Rob
    et al.
    Univ York, UK.
    Richer, Suzi
    Univ York, UK.
    Boles, Oliver
    Univ York, UK.
    Capitani, Claudia
    Univ York, UK.
    Courtney-Mustaphi, Colin J.
    Univ York, UK;Uppsala University.
    Lane, Paul
    Uppsala University;Univ Witwatersrand, South Africa.
    Prendergast, Mary E.
    St Louis Univ, Spain.
    Stump, Daryl.
    Univ York, UK.
    De Cort, Gijs
    Royal Museum Cent Africa, Belgium;Univ Ghent, Belgium.
    Kaplan, Jed O.
    ARVE Res SARL, Switzerland;Max Planck Inst Sci Human Hist, Germany.
    Phelps, Leanne
    Univ Lausanne, Switzerland.
    Kay, Andrea
    Univ Lausanne, Switzerland.
    Olago, Dan
    Univ Nairobi, Kenya.
    Petek, Nik
    Uppsala University.
    Platts, Philip J.
    Univ York, UK.
    Punwong, Paramita
    Mahidol Univ, Thailand.
    Widgren, Mats
    Stockholm University.
    Wynne-Jones, Stephanie
    Univ South Africa, South Africa.
    Ferro-Vazquez, Cruz
    Univ York, UK.
    Benard, Jacquiline
    Kenya Wildlife Serv, Kenya.
    Boivin, Nicole
    Max Planck Inst Sci Human Hist, Germany.
    Crowther, Alison
    Max Planck Inst Sci Human Hist, Germany;Univ Queensland, Australia.
    Cuni-Sanchez, Aida
    Univ York, UK.
    Deere, Nicolas J.
    Univ Kent, UK.
    Ekblom, Anneli
    Uppsala University.
    Farmer, Jennifer
    Univ Aberdeen, UK;Carbon Fdn East Africa, Uganda.
    Finch, Jemma
    Univ KwaZulu Natal, South Africa.
    Fuller, Dorian
    UCL, UK.
    Gaillard-Lemdahl, Marie-José
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Gillson, Lindsey
    Univ Cape Town, South Africa;Univ Cape Town, South Africa.
    Githumbi, Esther
    Univ York, UK.
    Kabora, Tabitha
    Univ York, UK.
    Kariuki, Rebecca
    Univ York, UK.
    Kinyanjui, Rahab
    Natl Museums Kenya, Kenya.
    Kyazike, Elizabeth
    Lang, Carol
    Univ York, UK.
    Lejju, Julius
    Mbarara Univ Sci & Technol, Uganda.
    Morrison, Kathleen D.
    Univ Penn, USA.
    Muiruri, Veronica
    Natl Museums Kenya, Kenya.
    Mumbi, Cassian
    Tanzania Wildlife Res Inst TAWIRI, Tanzania.
    Muthoni, Rebecca
    Natl Museums Kenya, Kenya.
    Muzuka, Alfred
    Nelson Mandela African Inst Sci & Technol, Tanzania.
    Ndiema, Emmanuel
    Natl Museums Kenya, Kenya.
    Nzabandora, Chantal Kabonyi
    Univ Officielle Bukavu, Democratic Republic of the Congo.
    Onjala, Isaya
    Kyambogo Univ, Uganda.
    Schrijver, Annemiek Pas
    Stockholm University.
    Rucina, Stephen
    Univ York, UK;Natl Museums Kenya, Kenya.
    Shoemaker, Anna
    Uppsala University.
    Thornton-Barnett, Senna
    Univ York, UK.
    van der Plas, Geert
    Univ Ghent, Belgium.
    Watson, Elizabeth E.
    Kyambogo Univ, Uganda;Univ Cambridge, UK.
    Williamson, David
    IRD, Kenya.
    Wright, David
    Seoul Natl Univ, South Korea.
    Drivers and trajectories of land cover change in East Africa: Human and environmental interactions from 6000 years ago to present2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 178, p. 322-378Article in journal (Refereed)
    Abstract [en]

    East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region. Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.

  • 21. Marchant, Rob
    et al.
    Widgren, Mats
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Pas Schrijver, Annemiek
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Wright, David
    Drivers and trajectories of land cover change in East Africa: Human and environmental interactions from 6000 years ago to present2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 178, p. 322-378Article in journal (Refereed)
    Abstract [en]

    East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region.

    Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.

  • 22. Marcé, Rafael
    et al.
    Obrador, Biel
    Gómez-Gener, Lluís
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Catalan, Nuria
    Koschorreck, Matthias
    Arce, María Isabel
    Singer, Gabriel
    von Schiller, Daniel
    Emissions from dry inland waters are a blind spot in the global carbon cycle2019In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 188, p. 240-248Article, review/survey (Refereed)
    Abstract [en]

    A large part of the world's inland waters, including streams, rivers, ponds, lakes and reservoirs is subject to occasional, recurrent or even permanent drying. Moreover, the occurrence and intensity of drying events are increasing in many areas of the world because of climate change, water abstraction, and land use alteration. Yet, information on the gaseous carbon (C) fluxes from dry inland waters is scarce, thus precluding a comprehensive assessment of C emissions including all, also intermittently dry, inland waters. Here, we review current knowledge on gaseous C fluxes from lotic (streams and rivers) and lentic (ponds, lakes, and reservoirs) inland waters during dry phases and the response to rewetting, considering controls and sources as well as implications of including 'dry' fluxes for local and global scale estimates. Moreover, knowledge gaps and research needs are discussed. Our conservative estimates indicate that adding emissions from dry inland waters to current global estimates of CO2 emissions from inland waters could result in an increase of 0.22 Pg C year(-1), or similar to 10% of total fluxes. We outline the necessary conceptual understanding to successfully include dry phases in a more complete picture of inland water C emissions and identify potential implications for global C cycle feedbacks.

  • 23. Markovic, Slobodan B.
    et al.
    Stevens, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Kukla, George J.
    Hambach, Ulrich
    Fitzsimmons, Kathryn E.
    Gibbard, Phil
    Buggle, Bjoern
    Zech, Michael
    Guo, Zhengtang
    Hao, Qingzhen
    Wu, Haibin
    Dhand, Ken O'Hara
    Smalley, Ian J.
    Ujvari, Gabor
    Suemegi, Pal
    Timar-Gabor, Alida
    Veres, Daniel
    Sirocko, Frank
    Vasiljevic, Djordjije A.
    Jary, Zdzislaw
    Svensson, Anderss
    Jovic, Vidojko
    Lehmkuhl, Frank
    Kovacs, Janos
    Svircev, Zorica
    Danube loess stratigraphy - Towards a pan-European loess stratigraphic model2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 148, p. 228-258Article in journal (Refereed)
    Abstract [en]

    The Danube River drainage basin is the second largest river catchment in Europe and contains a significant and extensive region of thick loess deposits that preserve a record of a wide variety of recent and past environments. Indeed, the Danube River and tributaries may themselves be responsible for the transportation of large volumes of silt that ultimately drive loess formation in the middle and lower reaches of this large catchment However, this vast loess province lacks a unified stratigraphic scheme. European loess research started in the late 17th century in the Danube Basin with the work of Count Luigi Ferdinand Marsigli. Since that time numerous investigations provided the basis for the pioneering stratigraphic framework proposed initially by Kukla (1970, 1977) in his correlations of loess with deep-sea sediments. Loess-palaeosol sequences in the middle and lower reaches of the Danube River basin were a key part of this framework and contain some of the longest and most complete continental climate records in Europe, covering more than the last million years. However, the very size of the Danube loess belt and the large number of countries it covers presents a major limiting factor in developing a unified approach that enables continental scale analysis of the deposits. Local loess-palaeosol stratigraphic schemes have been defined separately in different countries and the difficulties in correlating such schemes, which often change significantly with advances in age-dating, have limited the number of basin-wide studies. A unified basin-wide stratigraphic model would greatly alleviate these difficulties and facilitate research into the wider significance of these loess records. Therefore we review the existing stratigraphic schemes and define a new Danube Basin wide loess stratigraphy based around a synthetic type section of the Mosorin and Stari Slankamen sites in Serbia. We present a detailed comparison with the sedimentological and palaeoclimatic records preserved in sediments of the Chinese Loess Plateau, with the oxygen isotope records from deep-sea sediments, and with classic European Pleistocene stratigraphic subdivisions. The hierarchy of Danubian stratigraphic units is determined by climatically controlled environmental shifts, in a similar way to the Chinese loess stratigraphic scheme. A new unified Danube loess stratigraphic model has a number of advantages, including preventing confusion resulting from the use of multiple national schemes, a more transparent basis, and the potential to set Pleistocene palaeoenvironmental changes recorded in the Danube catchment area into a global context. The use of a very simple labelling system based on the well-established Chinese loess scheme facilitates interpretation of palaeoenvironmental information reported from the Danube Basin loess sites in a wider more accessible context that can be readily correlated world-wide. This stratigraphic approach also provides, for the first time, an appropriate framework for the development of an integrated, pan-European and potentially pan-Eurasian loess stratigraphic scheme.

  • 24.
    Qvarnström, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Niedzwiedzki, Grzegorz
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Zigaite, Zivile
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Evolution and Developmental Biology.
    Vertebrate coprolites (fossil faeces): An underexplored Konservat-Lagerstatte2016In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 162, p. 44-57Article, review/survey (Refereed)
    Abstract [en]

    Fossilized soft tissues of animals (e.g. muscles, hair and feathers) are valuable sources of palaeobiological information, but a poor preservation potential makes them undesirably scarce in the fossil record. The aim of this review is to summarize main findings, current progress and the analytical constraints of detecting fossilized soft tissues in coprolites from, mainly, freshwater and terrestrial carnivorous vertebrates. We conclude that soft-tissue inclusions in coprolites are sources of two important lines of information: the fossils can be put in a direct palaeoecological context, and characters of extinct taxa are more likely preserved in the phosphate-rich taphonomic microenvironment of coprolites than elsewhere. As a result, it is possible to unravel the deep-time origins of host-parasite relations, to understand ancient trophic food webs and detect new soft-tissue characters of different animal groups. Examples of the latter include muscle tissues from a tyrannosaurid prey, tapeworm eggs (including a developing embryo) in a Permian shark coprolite, as well as hair from multituberculates and, probably, from stem-mammals (Therapsids). Additionally, the use of coprolites in an archaeological context is briefly reviewed with focus on key aspects that may become implemented in studies of pre-Quaternary specimens as well. In summary, there is a wide range of information that can be extracted from coprolites, which has not yet been fully explored in palaeontological studies.

  • 25.
    Stevens, Thomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Thomas, David S. G.
    Armitage, Simon J.
    Lunn, Hannah R.
    Lu, Huayu
    Reinterpreting climate proxy records from late Quaternary Chinese loess: A detailed OSL investigation2007In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 80, no 1-2, p. 111-136Article in journal (Refereed)
  • 26. Strauss, Jens
    et al.
    Schirrmeister, Lutz
    Grosse, Guido
    Fortier, Daniel
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Knoblauch, Christian
    Romanovsky, Vladimir
    Schädel, Christina
    Schneider von Deimling, Thomas
    Schuur, Edward A. G.
    Shmelev, Denis
    Ulrich, Mathias
    Veremeeva, Alexandra
    Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability2017In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 172, p. 75-86Article in journal (Refereed)
    Abstract [en]

    Permafrost is a distinct feature of the terrestrial Arctic and is vulnerable to climate warming. Permafrost degrades in different ways, including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features. Pleistocene ice-rich permafrost with syngenetic ice-wedges, termed Yedoma deposits, are widespread in Siberia, Alaska, and Yukon, Canada and may be especially prone to rapid-thaw processes. Freeze-locked organic matter in such deposits can be re-mobilized on short time-scales and contribute to a carbon-cycle climate feedback. Here we synthesize the characteristics and vulnerability of Yedoma deposits by synthesizing studies on the Yedoma origin and the associated organic carbon pool. We suggest that Yedoma deposits accumulated under periglacial weathering, transport, and deposition dynamics in non-glaciated regions during the late Pleistocene until the beginning of late glacial warming. The deposits formed due to a combination of aeolian, colluvial, nival, and alluvial deposition and simultaneous ground ice accumulation. We found up to 130 gigatons organic carbon in Yedoma, parts of which are well-preserved and available for fast decomposition after thaw. Based on incubation experiments, up to 10% of the Yedoma carbon is considered especially decomposable and may be released upon thaw. The substantial amount of ground ice in Yedoma makes it highly vulnerable to disturbances such as thermokarst and thermo-erosion processes. Mobilization of permafrost carbon is expected to increase under future climate warming. Our synthesis results underline the need of accounting for Yedoma carbon stocks in next generation Earth-System-Models for a more complete representation of the permafrost-carbon feedback.

  • 27.
    Talbot, Chris
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pohjola, Veijo
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Subaerial salt extrusions in Iran as analogues of ice sheets, streams and glaciers2009In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 97, no 1-4, p. 155-183Article, review/survey (Refereed)
    Abstract [en]

    Ice (H20) and salt (halite, NaCl) share many physical properties and resemble each other in hand specimens and subaerial gravity-driven flows. However, while most significant bodies of ice accumulate in cold highlands and gravity-spread where and soon after they form, most significant bodies of salt accumulate in tropical marine basins and have to be buried by > 1 km of other rocks before they flow. Buried salt is driven by differential loading into various categories of piercing structures known as diapirs. Many diapirs extrude onto the surface as sheets of allochthonous (out of place) salt. Thousands of sheets of allochthonous salt have been interpreted in over 35 basins worldwide in the last 25 years, mainly in the toes of passive continental margins and in orogenic belts where some are > 103 km2 in area. Most former salt sheets are now submarine or subsurface but several active examples are beautifully exposed in Iran. These were compared to ice glaciers soon after they were introduced to western science, a comparison that has been neglected since. Here we update this analogy and use modern understanding of flowing ice and salt to examine the similarities and differences that might be mutually beneficial to both fields of study as well as to extraterrestrial scientists.

    The profiles, internal structures and fabrics in flowing bodies of ice and salt are sensitive gauges of the histories of their budgets of supply and loss. However, whereas snow merely compacts where it accumulates, salt sheets are fed from below by already deformed salt. When salt diapirs first emerge on land they extrude domes that mature to the profiles of viscous fountains that often feed glacier-like flows known as namakiers. After locally exhausting their deep source layers, salt fountains spread to the profiles of viscous droplets normal for ice caps.

    Ice typically deforms at > 80% (usually > 90%) of its absolute melting temperature while most salt deforms at < 50% of its homologous temperature; as a result, grain shape fabrics in salt are clearer and have longer strain memories than in ice. Foliations in deformed salt map streamlines aid in the understanding of how internal folds develop. Salt sheets seldom erode their channels like flowing ice and internal debris accumulates on their tops rather than their bases. An ice sheet floats on water but as salt is twice the density of ice; rain that falls onto the top surface of namakiers tends to stay there. Both glaciers and namakiers surge but the association between surges and changes in boundary conditions are much clearer for namakiers than glaciers. Because the rate of delivery of land ice to the oceans is such an important control on sea level, we end by considering how the implications of surging salt converge on recent glaciological findings about changes in boundary conditions other than their bases.

  • 28.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Lessons from the first 100 minimum strain ellipsoids constrained in gneisses deformed at high metamorphic grade2014In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 138, p. 231-267Article in journal (Refereed)
    Abstract [en]

    The Talbot 1970 method for constraining minimum strain ellipsoids has recently been updated by a computational approach and theory that can automatically constrain more complete strain ellipsoids with sufficient data. It is thus worth appreciating the lessons learned from the 100 minimum strain ellipsoids constrained mainly in gneisses deformed at high metamorphic grades published over the last four decades. In essence, the method measures the strikes and dips of either competent or incompetent active single layers with shortened or extended deformation structures (on scales of <1 m) imparted by inhomogeneous strains to constrain ellipsoids on larger scales. The data reviewed here describe the homogeneous strains of similar to 100 localities (1-200 m(2)) in 16 districts (10-similar to 200 km(2)) in 8 gneiss regions (1-200 km(2)). Relating these ellipsoids to the natural reference frames provided by structures on intervening and larger scales allows study of the dynamics of deformation geology rather than merely structural geology. Several limitations expected on (outdated) theoretical grounds were overcome so that treating deformation fields as paths on a variety of deformation plots allowed recognition of multiple deformations, rotations, volume changes and even the distinction of contemporary pure and simple shears. By restricting measurements to single layers with length/thickness ratios >10, the competence contrast between the markers and their country rocks does not affect the ellipsoids - but can be seen to affect the structures that develop on intervening and larger scales.

  • 29.
    Tewari, Rajni
    et al.
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Ram- Awatar, Ram-
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Pandita, Sundeep
    Department of Geology, University of Jammu, Jammu-180006, India.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Agnihotri, Deepa
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Pillai, Suresh
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Singh, Vartika
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Kumar, Kamlesh
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Bhat, Ghulam
    Directorate of Geology and Mining, Jammu and Kashmir Government, Srinagar, India.
    The Permian-Triassic palynological transition in the Guryul Ravine section, Kashmir, India: implications for Tethyan – Gondwanan correlations2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 149, p. 53-66Article in journal (Refereed)
    Abstract [en]

    This first palynological study of the Permian–Triassic succession in the Guryul Ravine, Kashmir, India, reveals impoverished latest Permian spore-pollen assemblages in the uppermost Zewan Formation, a rich palynoassemblage from the basal Khunamuh Formation characteristic of the Permian–Triassic transition zone and depleted Triassic assemblages from higher in the Khunamuh Formation. The collective assemblages can be broadly correlated to the Densipollenites magnicorpus and Klausipollenites decipiens palynozones of peninsular India and to palynofloras spanning the Permian–Triassic boundary elsewhere in Gondwana. Generally, low spore-pollen yields and poor preservational quality of the studied assemblages hinder more precise correlations and are inferred to be a function of an offshore marine depositional setting on the margin of the Neotethys Ocean, and thermal alteration associated with Cenozoic collisional tectonism between India and Asia.

  • 30.
    Topper, Timothy P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Strotz, Luke C.
    Holmer, Lars E.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Caron, Jean-Bernard
    Survival on a soft seafloor: life strategies of brachiopods from the Cambrian Burgess Shale2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 151, p. 266-287Article, review/survey (Refereed)
    Abstract [en]

    Abstract Understanding the structure of benthic communities in the Cambrian remains a major challenge. Direct evidence for species interrelationships is rare and therefore past ecological interactions typically cannot be reconstructed with great accuracy. Here we reveal the community patterns and modes of life of brachiopods – one of the most important filter-feeding groups of Cambrian ecosystems – from the Cambrian Burgess Shale LagerstÀtte. Burgess Shale brachiopods attached to a range of hard substrates, including skeletal debris, conspecific brachiopods and enigmatic tubes, with an overwhelming preference for attachment on the demosponge Pirania muricata. The dominance of P. muricata as a substrate choice – even in bedding assemblages where P. muricata individuals are rare – and similarities to the gregarious attachment strategies of extant brachiopod species suggests that brachiopods larvae in the Burgess Shale community selected their attachment substrates. The distribution of brachiopod taxa is also intricately linked with the presence of suitable hard substrates, with species declining in bedding assemblages where their preferred hard substrates are absent. In addition, brachiopods in the Burgess Shale community are predominantly low epifaunal tierers and do not exploit niches high in the water column, despite the presence of suitable attachment sites. Our analysis of tiering height versus host height indicates that there is no selection by brachiopod larvae in regard to the height of attachment and individuals attached at the first point of contact with the selected substrate. Through comparisons with the ‘early’ Cambrian Chengjiang Biota, we confirm that by the ‘middle’ Cambrian (Series 3, Stage 5) brachiopods had already developed a range of attachment strategies similar to some modern brachiopod populations. Our results provide significant insight into the ecological constraints and adaptability of brachiopods in the earliest animal communities of the Cambrian.

  • 31. Turnewitsch, Robert
    et al.
    Falahat, Saeed
    Stockholm University, Faculty of Science, Department of Meteorology .
    Nycander, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Dale, Andrew
    Scott, Robert B.
    University of Texas Austin, USA.
    Furnival, Darran
    Deep-sea fluid and sediment dynamics-Influence of hill- to seamount-scale seafloor topography2013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 127, p. 203-241Article in journal (Refereed)
    Abstract [en]

    Deep-sea sediments play a central role in a wide range of subject areas. A number of important controls on the formation of sedimentary deposits have been studied. However, to date, the impact of submarine landscape geometry as a possible control has received comparatively little attention. This seems to be particularly true for intermediate-scale topographic features such as abyssal hills, knolls and seamounts that can be found in many regions of the global seafloor: recent estimates suggest that in the deep open oceans, away from continental margins, there might be as many as similar to 25 x 10(6) abyssal hills, knolls and seamounts. Despite this large number very little is known about how they influence environmental complexity and patchiness, biogeochemical fluxes and the formation of sedimentary records. This paper reviews the currently known types of fluid-flow interactions with abyssal hills, knolls and seamounts that could potentially influence the way sediments are formed. The main types of relevant flow components are: quasi-steady to eddying background flow; internal lee and near-inertial waves; barotropic and baroclinic tides; and seamount-trapped waves. Previous studies looking into systematic links between fluid dynamics and sediments at hills, knolls and seamounts are reviewed. Finally, a case study is presented which aims to combine our current knowledge and investigate whether a given combination of recent fluid-flow components leaves a detectable imprint in the recent sediments on and around a short seamount. The main conclusions and implications are as follows. (1) Topographically generated flow-field geometries that are composed of a number of different prevailing fluid-flow components can be reflected and detected in properties of the underlying sediments. (2) Tidal and other higher-frequency (lee-wave, near-inertial) components of deep-ocean currents can be essential for locally driving total current velocities across threshold values for non-deposition/erosion/resuspension of freshly deposited deep-sea sediments. Moreover, there is evidence suggesting that not only maximum current speeds but also intensities of higher-frequency (tidal and/or (near-)inertial) current-direction variability might control sediment dynamics and sediment formation. This relativises the view that current speed is the main, or even only, controlling factor for sediment dynamics and sediment formation. (3) When it comes to the reconstruction of paleo-flows, these findings imply that certain sedimentary records may well reveal more about variability in the higher-frequency flow components than about variability in the basin-scale net flow component that often is the focus of paleoceanographic studies. (4) Single-core paleo-records from hill-, seamount- or similarly controlled sediment deposits may be biased due to the asymmetry of flow fields around these topographic features. To arrive at unbiased paleo-records for non-fluid-dynamic parameters, the influence of the flow-field geometry would have to be removed from the record first (5) It seems the mechanistic understanding of hill- and seamount-related flow/topography interactions and their links to sediment dynamics is approaching a level that may (a) facilitate improved interpretation of topographically controlled sedimentary paleo-records, (b) help fill in the knowledge gap that exists for functional deep-sea biodiversity at intermediate space scales, and (c) improve predictive capabilities for exploration of economically relevant iron-manganese (Fe-Mn) crusts on seamounts.

  • 32. Zillén, Lovisa
    et al.
    Conley, Daniel J.
    Andrén, Thomas
    Södertörn University, School of Life Sciences.
    Andrén, Elinor
    Södertörn University, School of Life Sciences.
    Björck, Svante
    Past occurrences of hypoxia in the Baltic Sea and the role of climate variability, environmental change and human impact2008In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 91, p. 77-92Article in journal (Refereed)
    Abstract [en]

    The hypoxic zone in the Baltic Sea has increased in area about four times since 1960 and widespread oxygen deficiency has severely reduced macro benthic communities below the halocline in the Baltic Proper and the Gulf of Finland, which in turn has affected food chain dynamics, fish habitats and fisheries in the entire Baltic Sea. The cause of increased hypoxia is believed to be enhanced eutrophication through increased anthropogenic input of nutrients, such as nitrogen and phosphorus. However, the spatial variability of hypoxia on long time-scales is poorly known: and so are the driving mechanisms. We review the occurrence of hypoxia in modern time (last c. 50ᅵyears), modern historical time (AD 1950-1800) and during the more distant past (the last c. 10ᅵ000ᅵyears) and explore the role of climate variability, environmental change and human impact. We present a compilation of proxy records of hypoxia (laminated sediments) based on long sediment cores from the Baltic Sea. The cumulated results show that the deeper depressions of the Baltic Sea have experienced intermittent hypoxia during most of the Holocene and that regular laminations started to form c. 8500-7800ᅵcal. yr BP ago, in association with the formation of a permanent halocline at the transition between the Early Littorina Sea and the Littorina Sea s. str. Laminated sediments were deposited during three main periods (i.e. between c. 8000-4000, 2000-800ᅵcal. yr BP and subsequent to AD 1800) which overlap the Holocene Thermal Maximum (c. 9000-5000ᅵcal. yr BP), the Medieval Warm Period (c. AD 750-1200) and the modern historical period (AD 1800 to present) and coincide with intervals of high surface salinity (at least during the Littorina s. str.) and high total organic carbon content. This study implies that there may be a correlation between climate variability in the past and the state of the marine environment, where milder and dryer periods with less freshwater run-off correspond to increased salinities and higher accumulation of organic carbon resulting in amplified hypoxia and enlarged distribution of laminated sediments. We suggest that hydrology changes in the drainage area on long time-scales have, as well as the inflow of saltier North Sea waters, controlled the deep oxic conditions in the Baltic Sea and that such changes have followed the general Holocene climate development in Northwest Europe. Increased hypoxia during the Medieval Warm Period also correlates with large-scale changes in land use that occurred in much of the Baltic Sea watershed during the early-medieval expansion. We suggest that hypoxia during this period in the Baltic Sea was not only caused by climate, but increased human impact was most likely an additional trigger. Large areas of the Baltic Sea have experienced intermittent hypoxic from at least AD 1900 with laminated sediments present in the Gotland Basin in the Baltic Proper since then and up to present time. This period coincides with the industrial revolution in Northwestern Europe which started around AD 1850, when population grew, cutting of drainage ditches intensified, and agricultural and forest industry expanded extensively.

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