The Record of Antarctic Environment Preserved in Deep Sea Sediments: Critical Times of Climate Change

摘要本奖项支持南极地区白垩纪晚期和古新世、始新世晚期和渐新世早期以及上新世早期重要气候变化时期的古气候变率研究。初步数据表明，南极洲的马斯特里赫特时期和可能的古新世时期的环境足够干燥，足以产生足够的尘埃，形成环绕该大陆的沉积物的重要组成部分。这项研究将确定这种半干旱气候是否以及何时在南极洲存在，以及何时被更湿润的环境所取代。向河流和半深海主导的侵蚀过程的转变可能有助于解释南极腹地冰川的初始形成。在始新世/渐新世界线时期，变化的沉积物积累速率以及半深海和浮冰物质的相对比例将提供有关南极冰盖何时形成的信息，从而有效地切断了南大洋河流沉积物的供应。最后，在上新世早期，冰盖结构的任何重大变化都应该很容易从伴随的陆源沉积性质和速率的变化中观察到。为了实现这些目标，本项目将研究南大洋深海沉积物的陆源成分。这些材料包含了南极环境和沉积搬运过程的双重记录。矿物颗粒提取、粒度分析、磁性结构测定、地球化学表征和通量计算等技术已被证明可用于解释古气候和古海洋条件，这些技术将在该项目中应用，以揭示南极大陆环境变化的历史。

Rea OPP 9527067 Abstract This award supports a project to define the paleoclimatic variability during times of important climate change on Antarctica, in the latest Cretaceous and Paleocene, late Eocene and early Oligocene, and the early Pliocene. Preliminary data suggest that the Maastrichtian and possibly Paleocene environment of Antarctica was dry enough to permit generation of sufficient dust to form an important component of the sediments surrounding the continent. This research will determine if and when this semi-arid climate did exist on Antarctica and when it was superseded by more moist conditions. The transition to fluvial and hemipelagic dominated erosional processes may shed light on the initial formation of glaciers in the Antarctic hinterland. At the time of the Eocene/Oligocene boundary, changing sediment accumulation rates and the relative proportions of hemipelagic and ice-rafted material will provide information on when the Antarctic ice sheet became well-established, effectively shutting off the supply of fluvial sediment to the Southern Ocean. And finally, any significant change in the ice sheet configuration during the early Pliocene should be readily observable in the concomitant changes in the nature and rates of terrigenous sedimentation. To accomplish these goals, this project will examine the terrigenous component of deep sea sediments of the Southern Ocean. These materials contain a dual record of the environment of Antarctica and of the sedimentary transport processes. Techniques of mineral grain extraction, grain-size analysis, magnetic fabric determination, geochemical characterization, and flux calculation, all of which have proven diagnostic in the interpretation of paleoclimatic and paleoceanographic conditions, will be applied within this project to unravel the history of environmental change on the Antarctic continent.