东海地球动力学环境与过程的同位素证据及盆地动力学模式

在东海地球动力学环境与过程研究现状分析基础上,讨论了采自盆地东西部油气钻井玄武岩样品的岩石化学、微量元素和同位素测试分析的成果,阐述了玄武岩岩石结构与岩石成分特征,计算岩浆起源深度与岩浆起源温度。通过岩浆源区地幔性质与深部过程分析,指出Sm-Nd、Pb-Pb、Nd-Pb同位素体系反映的深部地幔流体具有古生代向新生代转型的双重特征,与古生代地幔岩浆来源具有较明显亲和性,其中既有古老地幔物质存在,又有新生地幔物质参与,表明研究区地壳深部流体活动十分频繁。结合海洋一期"863"双船折射大剖面有关地质-地球物理解释成果的综合分析认识,提出了盆地地球动力学成因模式。

Isotopic evidences for geodynamic environment and process of the East China Sea and its basin dynamic model

Basalt samples from two oil drills respectively in the west and east of the East China Sea continental shelf basin were studied for the analysis of the geodynamic environment and process of the basin.Textures and compositions of the basalt samples were known from their petrological,petrochemical,trace element and isotopic testing analyses,and based on this,we have calculated the depth and temperature for the magma origin.It was discovered from the analysis of mantle nature and deep process in the magma source area that the deep mantle fluxes reflected by Sm-Nd,Pb-Pb and Nd-Pb isotopic system gave a transition nature from the Paleozoic to the Cenozoic,showed an evident affinity to Paleozoic mantle magma and consisted of both old and young mantle materials,indicating frequent mantle flux activities in deep crust of the study area.Also two-ship refraction profiling survey of Project 863 was carried out in the sea basin,and with the help of geologic-geophysical interpretation results from the survey,a model for geodynamic formation of the basin was established.