Antarctic Ice Sheet Response to Global Pliocene Warmth

目前对南极横贯山脉冰川历史的解释允许对上新世南极气候和相关冰响应的两种截然相反的观点。一种基于半石化的天狼星地层的观点认为，东南极洲会出现大面积的冰盖崩塌和温暖（2-5摄氏度）的海洋洪水，而北法格斯在附近生长。另一种基于同位素定年的未固结上新世漂移的相反观点认为，在亚南极气候条件下，扩大的冰盖覆盖了山脉。这项调查旨在提高我们对横贯南极山脉上新世冰川历史的理解，以调和这些相互矛盾的假设。野外区域位于干谷，所有上新世冰川形态特征和沉积单元与附近火山的灰烬一起发生。这些灰烬将通过单晶激光聚变40Ar/39Ar测年的新技术产生精确的上新世年表。由此得出的冰川史和构造史应能澄清上新世气候和冰盖响应之间存在的冲突。这将阐明全球气候系统（特别是2.4 Ma附近）的长期机制，及其对海平面上升、深海氧同位素波动和南极对全球上新世变暖的响应的影响。

Current interpretations of glacial history in the Transantarctic Mountains permit two vastly opposing views of Pliocene Antarctic climate and associated ice response. One view, based on the semi-lithified Sirius Formation, calls for extensive ice-sheet collapse and warm (2-5 degrees C) marine flooding in East Antarctica, with Northfagus growing nearby. A contrasting view, based on isotopically dated unconsolidated Pliocene drifts, calls for mountain overriding by an expanded ice sheet under subantarctic climatic conditions. This investigation is designed to improve our understanding of Pliocene glacial history of the Transantarctic Mountains in order to reconcile these conflicting hypotheses. Field areas are in the Dry Valleys where all Pliocene glacial morphologic features and sedimentary units occur together with ashes from nearby volcanoes. These ashes will produce a precise Pliocene chronology by the new technology of laser fusion 40Ar/39Ar dating of single crystals. The resulting glacial and tectonic history should clarify existing conflicts of Pliocene climate and ice-sheet response. This will clarify the long-term mechanics of the global climate system (particularly near 2.4 Ma), and its effect on eustatic sea level, deep-sea oxygen isotope fluctuations, and the Antarctic response to global Pliocene warmth.