塔里木溢流玄武岩省长英质火山岩的层位对比和岩浆成因研究

In this project, felsic volcanic rocks from the Tarim flood basalt province are choosed to study, in order to build detailed volcanostratigraphic sections in the field, and to build detailed volcanostratigraphic column sections for the volcanic layers in the drilling area by integrating methods of drilling core/chips identification, mineral chemistry, major,trace elements and isotopic signature. By using down hole physical logging data and seismological data, a volcano stratigraphy relationship is expected to be set up through out the whole Tarm basin. Based on detailed stratigraphical data, some key marker volcanic layers will be selected to separate zircons and to perform precise U-Pb dating,giving independent constrains on the eruption duration and spatio-temporal distribution of the Tarim flood basalt. Petrogenesis study on the achieved petrochemical and mineral chemical data set is supposed to do for volcanic layers with clear stratigrphical locations, in order to trace the tectonic back ground of the widely speaded felsic intrusions distributed around the Tarim block, as well as to discuss the mechanism of felsic volcanism in continental flood basalt province.

本项目拟选择塔里木溢流玄武岩省中的长英质火山岩，对野外露头区的火山岩剖面进行详细测量，在不同井区详细研究岩心岩屑的岩石学、矿物化学、主微量同位素特征，确定井区内火山地层柱状剖面；然后在测井和地震等地球物理方法支持下，对不同火山地层剖面的特征性火山岩层，尤其是火山碎屑岩层进行精细对比，建立全盆地长英质火山岩的层序对比关系；在确定火山层序的基础上，选择关键长英质火山岩层，分选锆石，进行高精度U-Pb同位素定年，确定关键标志性层位的绝对年龄，帮助构建塔里木溢流玄武岩省的时空格架；在火山层序研究和年代学研究基础上，结合岩石化学和矿物化学数据研究塔里木二叠纪长英质火山岩的成因，分析塔里木周边大量类似长英质侵入体的构造背景，探讨大陆溢流玄武岩省长英质火山作用的活动规律和形成机制。