REU: Evolution of the Kerguelen Plume: Studies of Mafic Rocks From the Northern Kerguelen Plateau

在过去的115年里，东印度洋海底的很大一部分是由科尔盖伦地幔热柱产生的岩浆形成的。这项研究的总体目标是利用这一火山记录来了解科尔盖伦地幔热柱的起源和演化。这是一个重要的目标，因为地幔热柱产生的岩浆提供了有关地幔中发生的物理和化学过程的信息，这些信息是通过研究与板块发散和汇聚有关的火山作用而得不到的。具体地说，地幔热柱提供了关于地幔对流过程的信息，以及地壳长期循环进入地幔的影响。克尔盖伦羽流特别重要，因为：(A)它是长寿的；(B)与羽流有关的火山活动的方方面面都可供研究；即，一个通常与羽流形成有关的非常大的火成岩省(克尔盖伦高原)，一个漫长的火山热点轨迹(尼尼特比恩海脊)，它是印度板块在羽流上方迅速向北迁移时形成的，以及位于南极板块上的一个最近活跃的大型海洋岛屿(科尔盖伦群岛)；(C)与该羽流有关的熔岩具有独特的地球化学特征，反映了地壳向地幔深处的再循环；(D)在新形成的相对较小的印度洋上形成的大火成岩省可能使这些羽流地球化学特征得以扩散到印度洋软流圈，从而形成印度洋目前活跃的海底扩张中心喷发的玄武岩的独特地球化学特征；(E)南克尔盖伦高原白垩纪中期形成所反映的高岩浆通量可能对地球水圈/大气系统产生了重大影响。将获得科尔盖伦群岛和海底科尔盖伦高原北部火成岩的地球化学和年龄数据，以了解与科尔盖伦羽流有关的40My火山的来源和演化。

9814313FreyOver the past 115 My a significant fraction of the eastern Indian Ocean seafloor was formed by magmas derived from the Kerguelen mantle plume. The overall goal of this research is to use this volcanic record to understand the origin and evolution of the Kerguelen mantle plume. This is an important objective because magmas derived from mantle plumes provide information about physical and chemical processes occurring in the earth's mantle that cannot be obtained from study of volcanism associated with diverging and converging plates. Specifically, mantle plumes provide information about convection processes in the mantle, and the effects of long-term recycling of crust into the mantle. The Kerguelen Plume is particularly important because: (a) it is long-lived; (b) all aspects of plume-related volcanism are accessible for study; i.e., a very large igneous province (Kerguelen Plateau) which is commonly associated with plume initiation, a long hotspot track of volcanoes (Ninetyeast Ridge) which formed as the Indian plate migrated rapidly northwards over the plume, and a large, recently active oceanic island (Kerguelen Archipelago) located on the Antarctic Plate; (c) lavas associated with this plume have a distinctive geochemical signature which reflect recycling of crust into the deep mantle; (d) formation of the large igneous province in the newly formed relatively small Indian Ocean may have enabled dispersal of these plume geochemical characteristics into the Indian Ocean asthenosphere, thereby creating the distinctive geochemical characteristics of basalts erupted at currently active seafloor spreading centers in the Indian Ocean; and (e) the high magma flux reflected by the mid-Cretaceous formation of the Southern Kerguelen Plateau may have significantly affected the earth's hydrosphere/atmosphere system. Geochemical and age data for igneous rocks from the Kerguelen Archipelago and submarine Northern Kerguelen Plateau will be obtained in order to understand the source and evolution of the 40 My volcanism related to the Kerguelen Plume.