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

南非卡鲁大火成岩省 U-Pb 地质年代学

• 批准号: 9725131
• 负责人: John Encarnacion
• 金额: $ 5.47万
• 依托单位: Saint Louis University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725131&HistoricalAwards=false
• 关键词: Pb; Geochronology; Karoo; Large; Igneous

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

9725131恩卡纳奇洪水玄武岩代表了大陆地壳上大量（数百万立方千米）的岩浆。合并的卡鲁和费拉（分别位于非洲和南极洲）洪水玄武岩省是一系列洪水玄武岩省中最古老和最大的，这些洪水玄武岩省打断了冈瓦纳超大陆的分裂。尽管费拉尔和卡鲁省的南部似乎是同步就位的，而且在很短的时间间隔（大约100万年）内，卡鲁省北部的时间和持续时间很难确定。卡鲁岩浆省的北部是在一个短暂的时期内形成的吗？它们与南部省份是同步的吗？早期碱性岩浆活动的时间与北方主导的拉斑岩浆活动和晚期流纹岩活动的时间有什么关系？是否有任何更年轻的岩浆事件可能与非洲和南极洲的最终破裂和海底扩张有关？这些问题的答案关系到这个大火成岩省的岩浆演化，它与地幔热异常（羽流？）、岩石圈伸展和大陆分裂的关系，并可能为洪水玄武岩事件和大灭绝之间的关系提供见解。该项目旨在通过获得卡鲁省各种样本的精确年龄限制来解决这些问题。AU1