柴达木盆地北缘冷湖五号下侏罗统碎屑锆石U—Pb定年及其地质意义

发布时间：2018-03-15 23:12

本文选题：柴北缘　切入点：冷湖五号　出处：《天然气地球科学》2017年09期 　论文类型：期刊论文

【摘要】：碎屑锆石U—Pb年代学拓展了盆地物源分析的途径和方法。为进一步完善柴北缘冷湖五号地区源—汇体系分析,利用冷湖五号LK-1井下侏罗统碎屑锆石样品,讨论了冷湖五号早侏罗世不同时期的物源区空间展布规律。结果显示:冷湖五号早侏罗世物源区主要发育在250~300Ma、400~450Ma 2个年龄区间。碎屑锆石年龄组成表现出早侏罗世早期以400~450Ma为主,后期逐渐演变为250~300Ma和400~450Ma共存的局面。其中,年龄为250~300Ma的碎屑锆石主要来源于小赛什腾山,而400~450Ma的碎屑锆石主要来自赛什腾山西段和阿尔金山东段。此外,碎屑组分特征及重矿物组合特征显示下侏罗统碎屑沉积物具有近源和远源混合沉积的特征。碎屑锆石的年龄分布反映研究区存在早古生代和晚古生代晚期2期区域性构造地质事件,暗示这2期岩浆活动和/或变质作用较为活跃,并为冷湖五号地区提供了主要的锆石来源,导致冷湖五号地区下侏罗统具有多时代混合物源特征。
[Abstract]:The U-Pb geochronology of clastic zircon has expanded the approaches and methods of source analysis in the basin. In order to further improve the source-sink system analysis of Lenghu No. 5 area in the northern margin of Qaihai, the Jurassic clastic zircon samples of Lenghu No. 5 downhole are used to further improve the analysis of the source-sink system. The spatial distribution of the provenances of Lenghu 5 early Jurassic in different periods was discussed. The results show that the provenances of Lenghu 5 early Jurassic are mainly developed in two ages of 450 Ma, 250 Ma, 300 Ma and 400 Ma. The age composition of detrital zircon shows that 400 ~ 450 Ma is the main age of early Jurassic. In the later stage, the coexistence of 250 ~ 300 Ma and 400 ~ 450 Ma was gradually developed. Among them, the clastic zircon of 250 ~ 300 Ma mainly originated from the lesser Sajestan Mountains, while the 400 ~ 450Ma zircon mainly came from the Shanxi section of Seston and the eastern part of the Aljinshan Mountains. In addition, the zircon of 400-450Ma mainly came from the Shanxi section of Saiteng and the eastern part of Aljinshan. The characteristics of clastic composition and heavy mineral assemblage show that the clastic sediments of the Lower Jurassic have the characteristics of near-source and distant mixed sediments. The age distribution of detrital zircons reflects the existence of early Paleozoic and late late Paleozoic in the study area. Regional tectonic geological events, It is suggested that the magmatic activities and / or metamorphism in these two periods are active and provide the main zircon source for the Lenghu 5 area, which leads to the multi-epoch mixture characteristics of the Lower Jurassic in the Lenghu 5 area.
【作者单位】：甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室;中国科学院大学;中国石油青海油田公司勘探开发研究院;钦州学院广西高校北部湾石油天然气资源有效利用重点实验室;
【基金】：中国科学院“西部之光”人才培养计划(编号:Y304RC1SGQ) 甘肃省自然科学基金(编号:1308RJZA310) 甘肃省重点实验室专项(编号:1309RTSA041) 广西中青年教师基础能力提升项目(编号:2017KY0787)联合资助
【分类号】：P534.52;P618.13

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