Paleoenvironments and geochemistry across a continuous Permian-Triassic boundary section at Bukk Mountains,Hungary  

作　　者：M.E.Brookfield J.C.Williams A.G.Stebbins 

机构地区：[1]School for the Environment,University of Massachusetts,Boston,MA 02125,USA [2]School of Earth Sciencec,The Ohio State University,Columbus,OH 43210,USA

出　　处：《Geoscience Frontiers》2021年第3期214-233,共20页地学前缘（英文版）

基　　金：funding of geochemical analyses at the Environmental Analytical Facility at University of Massachusetts at Boston(NSF Award#09-42371,DBI:MRI-RI2,to Robyn Hannigan and Alan Christian);support by the National Science Foundation Graduate Research Fellowship(DGE13491356104);the UMass Boston Chancellor's Distinguished Doctoral Fellowship。

摘　　要：The Bálvány North Permian-Triassic boundary sediments were deposited on a carbonate platform in the tropical part of the western Paleo Tethys ocean.The overall elemental geochemistry of the detailed two-metre-thick section across the boundary that we studied shows that the clastic content of the sediments came from dominantly silica-rich continental sources though with some more silica-poor inputs in the uppermost Permian and lowest Triassic limestones as shown by Ni/Al and Nb/Ta ratios.These inputs bracket,but do not coincide with,the main extinctions and associated C,O and S changes.Increased aridity at the Permian-Triassic boundary with increased wind abrasion of suitable Ti-bearing heavy minerals accounts for both the high Ti/Al and Ti/Zr ratios.Various geochemical redox proxies suggest mainly oxic depositional conditions,with episodes of anoxia,but with little systematic variation across the Permian-Triassic extinction boundary.The lack of consistent element geochemical changes across the Permian-Triassic boundary occur not only in adjacent shallower-water marine sections,and in other marine sections along the SW Tethys margin such as the Salt Range sections in Pakistan,but also in deeper shelf and oceanic sections,and in non-marine African and European continental sediments.In the absence of significant changes in physical environments,chemical changes in the atmosphere and oceans,reflected in various isotopic changes,drove the Permian-Triassic extinctions.

关 键 词：PERMIAN-TRIASSIC BOUNDARY PALEOENVIRONMENTS GEOCHEMISTRY Hungary Bukk 

分 类 号：P512.2[天文地球—地质学] P59