U-Pb Geochronology of the Karoo Large Igneous Province, South Africa

9725131 Encarnaci n Flood玄武岩代表着大量(数百万立方千米)的岩浆侵位在大陆地壳上。卡鲁和费拉尔(分别位于非洲和南极洲)的洪水玄武岩省是一系列洪水玄武岩省中最古老和最大的一个，这些洪水玄武岩省标志着冈瓦那超大陆的解体。虽然费拉尔和卡鲁省南部似乎是同步部署的，而且间隔很短(大约100万年)，但北部卡鲁省的时间和持续时间受到的限制很小。卡鲁岩浆省的北部是在一个短暂的时期内侵位的，它们与南部的省是同步的吗？早期碱性岩浆作用与主导的拉斑玄武岩岩浆作用以及北方晚期流纹岩事件的时间关系是什么？是否有更年轻的岩浆事件可能与非洲和南极洲的最后破裂和海底扩张有关？这些问题的答案涉及到这个大型火成岩省的岩浆演化、它与地幔热异常(柱？)、岩石圈伸展和大陆解体的关系，并可能为洪水玄武岩事件与大灭绝之间的关系提供洞察。该项目旨在通过获取卡鲁省各种样本的准确年龄限制来解决这些问题。AU1

9725131 Encarnaci n Flood basalts represent voluminous (millions of cubic km) amounts of magma that were emplaced on continental crust. AU1 The combined Karoo and Ferrar (in Africa and Antarctica, respectively) flood basalt province is the oldest and largest of a series of flood basalt provinces that punctuated the breakup of the Gondwana supercontinent. Although the Ferrar and the southern part of the Karoo province appear to have been emplaced synchronously, and over a short interval (in about 1 million years) the timing and duration of the northern Karoo province is poorly constrained. Were the northern parts of the Karoo magmatic province emplaced over a brief period, and were they synchronous with the southern province? What is the timing of early alkaline magmatism in relation to the dominant tholeiitic magmatism, and the later rhyolitic events in the north? Are there any younger magmatic events that may be associated with final rupture of Africa and Antarctica and seafloor spreading? Answers to these questions bear on the magmatic evolution of this large igneous province, its relationship to mantle thermal anomalies (plumes?), lithospheric extension, and continental breakup, and may provide insight to the relationship between flood basalt events and mass extinctions. This project aims to approach these issues by obtaining precise age constraints on a variety of samples in the Karoo province. AU1