COLLABORATIVE RESEARCH: Calibrating the Cryogenian in the Yukon

合作研究：校准育空地区的低温期Francis MacDonald.1148499，哈佛大学; Mark Schmitz.1148058，博伊西州立大学摘要雪球地球假说激发了新元古代地质学的广泛兴趣;然而，由于全球冰川作用的时间、持续时间和启动机制的不确定性，该假说仍然存在争议。与以前的和初步的研究，我们已经表明，在育空地区的Sturtian冰川沉积物的年龄是无法区分的年龄的富兰克林大火成岩省（LIP），这是侵位在劳伦蒂亚东部边缘，在热带地区，在一个理想的位置被化学风化。这很有趣，因为玄武岩比一般大陆地壳更耐候，有人提出雪球地球事件是由耐候性的增加和随之而来的二氧化碳消耗量的增加引发的。然而，富兰克林LIP上的年龄范围和误差条仍然太大，无法确定火山活动是长期的还是短暂的，以及冰川作用是否发生在火山活动的主要脉冲期间，之前或之后。在拟议的研究中，PI打算利用岩浆锆石的高分辨率U-Pb ID-TIMS测年和冰川沉积物周围碎屑锆石的LA-ICPMS测年来限制育空地区的Sturtian冰川作用和富兰克林LIP的时间和持续时间。

COLLABORATIVE RESEARCH: Calibrating the Cryogenian in the YukonFrancis MacDonald.1148499, Harvard University; Mark Schmitz.1148058, Boise State UniversityABSTRACTThe Snowball Earth hypothesis has galvanized broad interest in Neoproterozoic geology; however, the hypothesis remains controversial largely due to uncertainty about the timing, duration, and initiation mechanism of global glaciation. With previous and preliminary studies, we have demonstrated that the age of Sturtian glacial deposits in the Yukon is indistinguishable from the age of the Franklin large igneous province (LIP), which was emplaced on the eastern margin of Laurentia, in the tropics, in an ideal position for being chemically weathered. This is intriguing, because basalt is more weatherable than average continental crust, and it has been proposed that Snowball Earth events were initiated by an increase in weatherbility and a concomitant increase in CO2 consumption. However, the age range and error bars on the Franklin LIP are still too large to determine if the volcanism was long- or short-lived, and if the glaciation occurred during, before or after the main pulse of volcanism. With the proposed research PIs intend to constrain the timing and duration of the Sturtian glaciation and the Franklin LIP in the Yukon with high resolution U-Pb ID-TIMS dating of magmatic zircons and LA-ICPMS dating of detrital zircons that bracket the glacial deposits.