摘要
为了探讨川西前陆盆地上侏罗统—白垩系的物源属性及源区构造背景,对该区上侏罗统—白垩系泥质岩的稀土元素(REE)地球化学特征进行系统分析,结果表明,构造区及沉积环境对泥质岩的REE特征及其沉积分异作用有一定的控制性。在沉积成岩过程中,泥质岩的REE特征在一定程度上受到沉积作用的改造;泥质岩具有明显的LREE富集、HREE丰度低、负Eu异常以及大多数样品具有较明显负Ce异常的特点;从J3到K2,泥质岩均具有较高的REE分异程度,不同阶段的REE平均分异程度相对稳定;泥质岩形成于一种总体偏氧化、局部具还原性质的沉积环境;源区母岩以沉积岩和花岗质岩石为主,也可能有玄武岩成分的混入;源区构造背景主要为大陆岛弧,也有来自被动大陆边缘的物源。
REE of the Upper-Jurassic and Cretaceous argillaceous rocks from the western Sichuan foreland basin were tested and analyzed,and the geochemical characteristics of REE,sedimentary environments,provenance properties and tectonic settings of provenances of argillaceous rocks from the research area were also discussed.Current study shows that tectonic provinces and sedimentary environments have a control to a certain extent on the REE characteristics and sedimentary differentiation of REE of argillaceous rocks,and that REE characteristics of argillaceous rocks were mainly reconstructed to a certain extent by sedimentation.Although the testing samples present dominantly significant LREE enrichment,low-abundance HREE and negative Eu anomaly,most of them display obviously negative Ce anomaly.Results suggest that all argillaceous rocks have high differentiation degree and stably average differentiation degree from Upper Jurassic to Upper Cretaceous.A sedimentary environmental model characterized by overall oxidation and local deoxidation was suggested for the argillaceous rocks in research area.Source rocks are mainly sedimentary rocks and granitic rocks,probably with a few locally-involved basalt components.Analysis of provenances of argillaceous rocks show that the tectonic setting is mainly continental island arc and partly passive continental margin.
出处
《现代地质》
CAS
CSCD
北大核心
2010年第1期140-150,共11页
Geoscience
基金
中国地质大学(北京)地质过程与矿产资源国家重点实验室研究课题(GPMR2008K01A)
中国石油化工股份有限公司重点研究项目(R0800-06-ZS-286)
关键词
川西
前陆盆地
上侏罗统—白垩系
泥质岩
稀土元素
沉积环境
物源
构造背景
western Sichuan foreland basin Upper-Jurassic to Cretaceous argillaceous rock rare earth element sedimentary environment provenance tectonic setting
