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

[9814313]在过去的115年里，东印度洋海底的很大一部分是由来自凯尔盖伦地幔柱的岩浆形成的。这项研究的总体目标是利用这些火山记录来了解凯尔盖伦地幔柱的起源和演化。这是一个重要的目标，因为源自地幔柱的岩浆提供了地幔中发生的物理和化学过程的信息，而这些信息是无法从与板块分裂和收敛相关的火山活动研究中获得的。具体来说，地幔柱提供了地幔中对流过程的信息，以及地壳长期再循环到地幔中的影响。克格伦羽流特别重要，因为：(a)它的寿命很长；(b)与羽流有关的火山活动的所有方面都可供研究；例如，一个非常大的火成岩省（凯尔盖伦高原）通常与羽流的形成有关，一个长长的火山热点轨迹（Ninetyeast Ridge）是印度板块在羽流上快速向北迁移时形成的，以及一个位于南极板块的最近活跃的大型海洋岛屿（凯尔盖伦群岛）；(c)与该地幔柱相关的熔岩具有明显的地球化学特征，反映地壳向深部地幔的再循环；(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扩散到印度洋软流圈，从而形成了目前活跃的印度洋海底扩张中心喷发的玄武岩的独特地球化学特征；(e)克尔格伦高原南部中白垩世构造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。为了解与克格伦羽有关的40 My火山活动的来源和演化，将获得克格伦群岛和克格伦高原北部海底的火成岩地球化学和年龄资料。

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.