Andean Delamination Events: Geochemical Tests

构造增厚区下岩石圈拆沉的证据包括与大量壳源性岩浆活动同时发生的快速隆升，有时还伴有幔源性玄武岩。安第斯山脉中部的两个地方似乎是研究与分层有关的岩浆岩的良好候选者：1)晚第三纪的阿根廷普纳高原，2)智利额科迪勒拉晚古生代-三叠纪的冈瓦纳边缘。本项目将利用同位素质量示踪剂和微量元素压力-温度指标，结合地质和地球物理约束条件，对这两个地区的剥离假说进行检验和修正，并对剥离的安第斯岩石圈物质进行表征，研究其与南半球地幔非均质性的关系。

Evidence for delamination of the lower lithosphere under regions of tectonic thickening includes rapid uplift coincident with the onset of voluminous crustally-derived magmatism, sometimes accompanied by mantle-derived basalt. Two localities in the central Andes appear to be good candidates to study magmatic rocks associated with delamination: 1) the Argentine Puna Plateau in the late tertiary, and 2) the Gondwana margin in the late Paleozoic-Triassic in the Chilean Frontal Cordillera. This project is to use isotopic mass tracers and trace element pressure-temperature indicators, along with geologic and geophysical constraints, to test and modify the delamination hypothesis in these two regions, as well as to characterize the delaminated Andean lithospheric material, and to examine its relation to southern Hemisphere mantle heterogeneity.