US-South Africa Cooperative Research: Event Stratigraphy across the Permo-Triassic Boundary in the Karoo Basin

该奖项支持华盛顿大学地质科学系彼得·沃德和南非开普敦博物馆罗杰·史密斯的合作研究项目。该项目名为“跨越卡鲁盆地二叠纪-三叠纪边界的事件地层学”，将研究南非2.5亿年前二叠纪-三叠纪边界的大型脊椎动物灭绝记录和稳定同位素组成的变化。从两个陆地二叠纪-三叠纪边界遗址（Bethulie和Lootsberg Pass）获得的新的生物地层学、化学地层学和磁地层学结果，对南非卡鲁地区二叠纪末期大灭绝的速度和严重程度有了新的认识。南非地质调查局之前的研究表明，陆生脊椎动物的大灭绝在卡鲁是灾难性的，超过三分之二的物种在二叠纪的顶端消失了。灭绝事件的持续时间可以通过校准二叠纪卡鲁盆地积聚20米河流沉积物所需的时间来估计。这可能超过1万年，不到10万年。二叠纪/三叠纪大灭绝事件的一个被认为的原因是短暂的热脉冲，可能是由海洋翻转引起的二氧化碳流入大气，加上西伯利亚圈闭的排放造成的。拟议中的美国-南非合作研究将通过生产大量新的化石材料和一套用于同位素分析的碳酸盐样品来改进这些估计。新的化石信息将使我们对这一地区的灭绝速度作出更精确的估计。该项目由国际项目司和地球科学司联合支持。

This award supports a cooperative research project between Peter Ward, Department of Geological Sciences, University of Washington, and Roger Smith, South African Museum, Cape Town, South Africa. The project, which is entitled "Event Stratigraphy across the Permo-Triassic Boundary in the Karoo Basin," will examine the record of large vertebrate animal extinctions and changes in stable isotope composition across the 250 million year old Permian-Triassic boundary in South Africa. New biostratigraphic, chemostratigraphic, and magnetostratigraphic results obtained from two terrestrial Permo-Triassic boundary sites (Bethulie and Lootsberg Pass) yield new insight into the tempo and severity of the mass extinction ending the Permian Period in the Karoo region of South Africa. Previous work by the Geological Survey of South Africa has demonstrated that the mass extinction among terrestrial vertebrates was catastrophic in the Karoo, with over two-thirds of all species disappearing at the top of the Permian. The duration of the extinction event can be estimated by calibrating the time necessary to accumulate 20m of fluvial sediments in the Permian Karoo basin. This probably is more than 10,000 and less than 100,000 years. A suggested cause of the Permo/Triassic mass extinction event was a short-lived heat pulse, probably produced by a flux of carbon dioxide into the atmosphere caused by oceanic overturn, combined with emissions from the Siberian Traps. The proposed US-South African collaborative research will refine these estimates by producing a wealth of new fossil material and a suite of carbonate samples to be used for isotopic analysis. The new fossil information will allow a much more precise estimate of the rates of extinction in this region. The project is supported jointly by the Division of International Programs and the Division of Earth Sciences.