COLLABORATIVE RESEARCH: Calibrating the Cryogenian in the Yukon

合作研究：yukoncryogenian的校准。1148499，哈佛大学；【摘要】雪球地球假说引起了人们对新元古代地质学的广泛兴趣；然而，由于对全球冰川作用的时间、持续时间和开始机制的不确定性，这一假设仍然存在争议。根据先前和初步的研究，我们已经证明育空地区斯图特冰川沉积物的年龄与富兰克林大火成岩省（LIP）的年龄无法区分，后者位于热带地区劳伦西亚东部边缘，处于化学风化的理想位置。这很有趣，因为玄武岩比一般的大陆地壳更耐候性，并且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的增加引起的。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，以及冰川作用是发生在火山活动主脉冲期间、之前还是之后。在这项研究中，PIs计划通过对岩浆锆石进行高分辨率U-Pb ID-TIMS测年和对冰川沉积物上的碎屑锆石进行LA-ICPMS测年，来确定育空地区斯图亚特冰期和富兰克林冰期的时间和持续时间。

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.