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胡文俊博士学术报告

更新时间:2019-06-18点击次数:13字号: T|T

报告题目:特罗多斯蛇绿岩中玻安岩的成因及其与共生熔岩的关系

High-Ca boninitic melt inclusions in the Troodos ophiolite and reappraisal of the genetic relations between different types of lavas

报告地点:资环学院纬地楼3楼会议室

报告时间:2019619日(星期三)下午2:00-4:00

报告人:胡文俊

报告人简介:

胡文俊,男,香港大学地球科学系博士,目前主要研究蛇绿岩中玻安质熔体包裹体, 以及俯冲初始阶段地幔演化规律。研究内容包括熔体包裹体, Re-Os同位素,橄榄石微量元素等方面。

报告简介:

特罗多斯蛇绿岩是世界上典型的蛇绿岩,也是最早被确定为SSZ型的蛇绿岩。本次报告讲述我们对位于麦基地区的熔岩中橄榄石熔体包裹体进行了系统性研究, 确定了玻安岩的形成温度压力等条件。同时,对区域类的数据进行重新归纳整理,依次厘定了不同熔岩间的成因联系。该研究为学界以SSZ型蛇绿岩为手段研究俯冲初始过程提供了重要的理论支持。

This study present major, trace element and Pb isotope data of melt inclusions in the olivines of the Margi ultrabasic lava, which belongs to the upper pillow lavas (UPL) of the Troodos ophiolite, and then carry out a review of the fresh glass and melt inclusions in the Troodos ophiolite. The melt inclusions in this study are high-Ca boninites, with significant Pb isotopic variation and strong enrichment in fluid-mobile trace elements relative to non-fluid mobile elements. Major element compositions reflect melting of a hybrid melt-depleted and silica-poor mantle source at 1400  and 1.5 GPa. Except the boninite in the UPL, the Troodos volcanic rocks also comprise a variety of volcanic rocks, including the later filled, depleted boninites in the UPL and an intermediate-acid unit and a basic to basic-intermediate unit in the lower pillow lavas (LPL). We propose that the depleted boninite originated from a further melting of the source of the boninite at shallower depth (1350  and 0.9 GPa). The LPL derived from a different, less depleted and shallow source (1260  and 0.8 GPa) that has been gradually affected by slab fluid. From the LPL to the UPL, it is clear that the contribution of the subduction component was increasing and the metasomatising agent changed from slab fluid to slab melt. Together with the fact that there is no clear stratigraphic break between the UPL and the LPL, a subduction initiation model involving two-source melting was proposed to explain the chemostratigraphic variation in the Troodos ophiolitic lavas.

  

  

                                                               (信息来源:汪方跃)  

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