DOI: 10.5194/cp-14-441-2018
Scopus记录号: 2-s2.0-85045266981
论文题名: Salinity changes and anoxia resulting from enhanced run-off during the late Permian global warming and mass extinction event
作者: Van Soelen E.E. ; Twitchett R.J. ; Kürschner W.M.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2018
卷: 14, 期: 4 起始页码: 441
结束页码: 453
语种: 英语
Scopus关键词: Acritarcha
英文摘要: The late Permian biotic crisis had a major impact on marine and terrestrial environments. Rising CO2 levels following Siberian Trap volcanic activity were likely responsible for expanding marine anoxia and elevated water temperatures. This study focuses on one of the stratigraphically most expanded Permian-Triassic records known, from Jameson Land, East Greenland. High-resolution sampling allows for a detailed reconstruction of the changing environmental conditions during the extinction event and the development of anoxic water conditions. Since very little is known about how salinity was affected during the extinction event, we especially focus on the aquatic palynomorphs and infer changes in salinity from changes in the assemblage and morphology. The start of the extinction event, here defined by a peak in spore : pollen, indicating disturbance and vegetation destruction in the terrestrial environment, postdates a negative excursion in the total organic carbon, but predates the development of anoxia in the basin. Based on the newest estimations for sedimentation rates, the marine and terrestrial ecosystem collapse took between 1.6 and 8 kyr, a much shorter interval than previously estimated. The palynofacies and palynomorph records show that the environmental changes can be explained by enhanced run-off and increased primary productivity and water column stratification. A lowering in salinity is supported by changes in the acritarch morphology. The length of the processes of the acritarchs becomes shorter during the extinction event and we propose that these changes are evidence for a reduction in salinity in the shallow marine setting of the study site. This inference is supported by changes in acritarch distribution, which suggest a change in palaeoenvironment from open marine conditions before the start of the extinction event to more nearshore conditions during and after the crisis. In a period of sea-level rise, such a reduction in salinity can only be explained by increased run-off. High amounts of both terrestrial and marine organic fragments in the first anoxic layers suggest that high run-off, increased nutrient availability, possibly in combination with soil erosion, are responsible for the development of anoxia in the basin. Enhanced run-off could result from changes in the hydrological cycle during the late Permian extinction event, which is a likely consequence of global warming. In addition, vegetation destruction and soil erosion may also have resulted in enhanced run-off. Salinity stratification could potentially explain the development of anoxia in other shallow marine sites. The input of freshwater and related changes in coastal salinity could also have implications for the interpretation of oxygen isotope records and seawater temperature reconstructions at some sites. © Author(s) 2018. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109578
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: University of Oslo, Department of Geosciences, P.O. Box 1047, Blindern, Oslo, 0316, Norway; Natural History Museum, Earth Sciences Department, London, SW7 5BD, United Kingdom
Recommended Citation:
Van Soelen E.E.,Twitchett R.J.,Kürschner W.M.. Salinity changes and anoxia resulting from enhanced run-off during the late Permian global warming and mass extinction event[J]. Climate of the Past,2018-01-01,14(4)