COLLABORATIVE RESEARCH: EAGER: Evaluating the Larsen basin's suitability for testing the Cretaceous Glaciation Hypothesis

学术价值：最近的地球化学、层序地层学以及对来自几个大陆边缘和海洋盆地的海相地层的综合调查表明，在白垩纪和早古近纪的部分时期，南极洲可能存在短暂的冰盖。然而，这一时期的大气二氧化碳估计是现代水平的四倍之多。在这样的温室条件下，南极冰盖的存在意味着我们目前对地球的理解？应该重新考虑美国的气候系统，特别是南极冰川和冰川消退的解释阈值。本研究拟将南极半岛东部Larsen盆地白垩系沉积物的数量和物源与半岛及邻近地区潜在沉积物源地体的出土年代学和组成进行比较。新的露头地层分析和改进了放射性同位素方法的年龄模型将被整合在一起，以确定在关键年代地层表面之间流入拉森盆地的碎屑沉积物的数量。石英砂和粉砂颗粒的微观结构分析有助于确定拉森盆地碎屑沉积物是否来源于冰川风化。这些初步结果将检验提出的方法的可行性，以评估有争议的白垩纪南极冰川假说。更广泛的影响：拟议的工作将部分支持南卡罗来纳大学的博士，硕士和三名本科生。pi将通过志愿者演讲活动和视频和播客的开发来宣传这项工作。它们还承诺迅速公布结果并及时向档案提交数据。Larsen盆地年龄模型的发展和完善，将有利于古生物学、古气候和生物地理学的研究。海绿石K-Ar和Rb-Sr计时器的开发可能是拟议研究直接范围之外的重要成果。

Intellectual Merit: Recent geochemical, sequence stratigraphic, and integrated investigations of marine strata from several continental margins and ocean basins suggest that ephemeral ice sheets may have existed on Antarctica during parts of the Cretaceous and early Paleogene. However, atmospheric carbon dioxide estimates for this time are as much as four times modern levels. With such greenhouse conditions, the presence of Antarctic ice sheets would imply that our current understanding of Earth?s climate system, and specifically the interpreted thresholds of Antarctic glaciation and deglaciation should be reconsidered. The proposed research will compare the quantity and provenance of Cretaceous sediments in the Larsen basin of the eastern Antarctic Peninsula with the exhumation chronology and composition of potential sediment source terranes on the peninsula and in adjacent regions. New outcrop stratigraphic analyses with improvements in the age models from radioisotopic approaches will be integrated to determine the amount of detrital sediment fluxed to the Larsen basin between key chronostratigraphic surfaces. Microtextural analysis of quartz sand and silt grains will help determine whether the Larsen basin detrital sediment originated from glacial weathering. These preliminary results will test the viability of the proposed approach to assess the controversial Cretaceous Antarctic glaciation hypothesis.Broader impacts: The proposed work will partially support a PhD, a MSc, and three undergraduate students at the University of South Carolina. The PIs will publicize this work through volunteer speaking engagements and the development of videos and podcasts. They also commit to prompt publication of the results and timely submission of data to archives. The development/improvement of the Larsen basin age model will benefit ongoing research in paleobiology, paleoclimate and biogeography. Development of the glauconite K-Ar and Rb-Sr chronometers could be an important outcome beyond the direct scope of the proposed research.