Antarctic Ice Sheet Response to Global Pliocene Warmth

目前对横贯北极山脉的冰川历史的解释允许关于上新世南极气候和相关冰川反应的两种截然不同的观点。一种基于半岩化的天狼星地层的观点认为，南极东部将出现大范围冰盖坍塌和温暖(2-5摄氏度)的海洋洪水，诺斯法格斯火山在附近生长。一种截然不同的观点，基于上新世未巩固的同位素年代漂移，呼吁在亚南极气候条件下，山脉被扩大的冰盖盖过。这项调查旨在提高我们对横贯北极山脉的上新世冰川历史的理解，以调和这些相互矛盾的假说。野外区域位于干燥的山谷中，所有上新世冰川地貌特征和沉积单元都与附近火山的火山灰一起出现在那里。这些火山灰将通过激光熔融单晶40Ar/39Ar测年新技术产生精确的上新世年代。由此产生的冰川和构造历史应该澄清上新世气候和冰盖反应的现有冲突。这将阐明全球气候系统的长期机制(特别是在2.4 Ma附近)及其对海平面、深海氧同位素波动的影响，以及南极对全球上新世变暖的反应。

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.