裂谷
地质学
泛滥玄武岩
地幔柱
地幔(地质学)
玄武岩
裂谷带
岩石圈
火山
羽流
地球化学
地盾火山
前寒武纪
劳伦蒂娅
岩浆房
岩石学
岩浆
古生物学
熔岩
构造学
火山作用
古生代
物理
热力学
作者
Prasanna Mahesh Gunawardana,R. Moucha,Tyrone O. Rooney,Seth Stein,Carol A. Stein
出处
期刊:Geology
[Geological Society of America]
日期:2022-07-18
卷期号:50 (10): 1125-1129
被引量:1
摘要
Abstract The Midcontinent Rift of North America is a ca. 1.1 Ga, 3000-km-long failed rift that nearly split the Precambrian continent of Laurentia. Unlike most continental rifts, which are filled with a mixture of volcanic rocks and sediments, the Midcontinent Rift contains a large volume of flood basalts that were emplaced during both syn- and post-rift stages. Consequently, the Midcontinent Rift, which comprises the Keweenaw large igneous province, is the most significant positive anomaly on gravity maps of central North America. We investigated the mantle conditions required to produce this large volume of flood basalt and the observed two main stages of emplacement. To explore whether these magma volumes required a plume or, instead, could have resulted from the increased ambient mantle temperatures expected for the Neoproterozoic, we used a geodynamic model for a range of ambient mantle and plume temperatures under different scenarios of lithospheric extension. The most favorable scenario for the generation of both syn-rift and post-rift lavas combines a plume with excess temperatures between 175 and 225 °C introduced during the syn-rift phase and ambient mantle potential temperatures between 1393 and 1443 °C, with an initial lithospheric thickness not exceeding 150 km for 3 mm/yr extension rates.
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