柴达木盆地西部新生代原型盆地恢复-矿产普查与勘探专业论文 word格式.docx

摘 要
柴达木盆地新生代的沉积特征及原型盆地边界的迁移,反映了盆地的形成及演化历史。本文综合野外剖面、岩心描述以及室内分析等多方面信息,采用资料统计、沉积相分析与综合作图相结合的研究思路,系统研究了柴达木盆地古近系-新近系沉积相类型及其平面分布,恢复了柴达木盆地古近系-新近系的原型盆地边界。
首先,柴达木地区的物源区主要有东昆仑物源区、南祁连物源区、阿尔金物源区, 通过柴达木盆地古近纪-新近纪各时期重矿物分析和岩石薄片分析,确定了各地区各时代的母岩性质和物源来源。
其次,在实测野外剖面、观察露头现象以及描述岩心特征的基础上,综合岩石学特征、沉积构造特征、粒度概率曲线特征等几方面,将研究区的沉积相总结为洪积扇相、扇三角洲相、三角洲相、辫状河相以及湖泊相五大类。
再次,采用单因素分析法,通过绘制岩性厚度及厚度地层比的等值线图,掌握各种沉积相在空间上的展布规律。其中冲积扇相主要发育在阿尔金斜坡带、祁漫塔格山前以及赛什腾山前地区,扇三角洲相主要发育在阿尔金斜坡西段,三角洲相主要发育在阿拉尔以及跃进地区,河流泛滥平原广泛分布于滨浅湖沉积的外缘或区间。
最后,采用边缘相分析法、机械沉积分异法以及古老地层为边界的方法,结合沉积相平面展布图,恢复了柴达木盆地古近纪-新近纪各时期的盆地原始沉积边界,从而了解盆地演化历史并确定了当时原型盆地的范围。
关键词:物源,粒度分析,沉积相,新生代,柴达木盆地,原型盆地
ABSTRACT
The sedimentary characteristics and migration of prototype basin boundary during Cenozoic, reflect the formation and evolution history of Qaidam Basin. The author multipled the field exploration, core observation and the home analysis, using the study rout of the reference statistics, analysis of facies prehensive drawing, systematically studied the Paleogene-Neogene facies of Qaidam Basin and their distribution, recovered prototype basin’s boundary of Cenozoic.
Firstly, there are three source provenance: East Kunlun source area, South Guylain source area and Altun Mountain source area; through the analysis of heavy minerals and rock thin section, the author made sure the mother rock quality and source provenance.
Secondly, on the basis of section measurement, outcrop observation and core observation, comprehensiving the lithographic and sedimentary structure and Grain probability curves characters, the author concluded that the research area developed alluvial fan facies, fan delta facies, delta facies, braided river facies and lacustrine facies.
Thirdly, using single factor analysis, through drawing isograms of Lithology thickness and percentage thickness, the author mastered distribution rules of each facies. The alluvial fan facies existed in the Altun slope belt and in front of Qimantage Mountain and Saishenteng Mountain, the fan delta facies devel