Magmatism of the Baikal Rift, Russia: Asthenospheric Upwelling Along a Lithospheric Boundary

该项目将整合沿南贝加尔湖裂谷500公里长的样带收集的玄武岩和捕虏体的同位素、全岩主要元素和微量元素以及矿物化学数据。样带从东南的元古代-古生代岩石圈穿过缝合线延伸至西北的太古宙克拉通。贝加尔湖裂谷为验证两个主要假设提供了绝佳的机会：1)玄武岩地球化学的时空演化是否与软流圈衍生的熔体和跨越裂谷走向的岩石圈柱的相互作用有关。2)玄武岩的非放射性成因铅同位素特征是否与亚亚非放射性成因OIB地幔源有关（Allegre et al., 1987）或与广泛的地壳污染有关？该项目是由美国国家科学院和苏联科学院联合主办的关于里约热内卢格兰德裂谷和贝加尔湖裂谷的美苏比较裂谷研讨会的产物，它将包括在麻省理工学院进行的实地工作和广泛的化学分析。

This project will integrate isotopic, whole-rock major and trace element, and mineral chemistry data from basalts and xenoliths collected along a 500-km-long transect across the southern Baikal Rift. The transect extends from Proterozoic-Paleozoic lithosphere in the southeast across the suture onto the Archean craton in the northwest. The Baikal Rift offers an excellent opportunity to test two major hypotheses: 1) whether the spatial and temporal evolution of basalt geochemistry can be related to interaction of asthenospheric derived melts and contrasting lithospheric columns across the strike of the rift. 2) Is the unradiogenic Pb isotopic character of the basalts related to an unradiogenic sub-Asian OIB mantle source (Allegre et al., 1987) or to widespread crustal contamination. The project is an outgrowth of the U.S.-U.S.S.R comparative rift workshop on the Rio Grande and Baikal rifts sponsored jointly by the U.S. National Academy of Sciences and the Academy of Sciences of the U.S.S.R. It will involve field work as well as extensive chemical analyses to be done at MIT.