论文部分内容阅读
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。
Detrital zircon U-Pb geochronology expands the ways and methods of provenance analysis of the basin. In order to further improve the source-sink system of the Lenghu-5 area in the northern part of the Qaidam basin, the source rocks of the Lower Jurassic in different periods of Early Jurassic Spatial distribution law. The results show that the Early Jurassic source region of Lenghu-5 mainly develops in two age ranges of 250 ~ 300Ma and 400 ~ 450Ma. The ages of detrital zircons are mainly from 400 to 450 Ma in the early Jurassic and from 250 to 300 Ma and 400 to 450 Ma in the late stage. Among them, the detrital zircons aged from 250 to 300 Ma originated mainly from the Little Seestend Mountain, while detrital zircons from 400 to 450 Ma mainly originated from the western Seishong Mountain and the eastern part of the Altun Mountains. In addition, the features of the detrital components and the features of the heavy minerals show that the Lower Jurassic detrital sediments have the characteristics of mixed deposition of near and far sources. The age distribution of detrital zircons reflects that there are two tectono-geological events in the Late Paleozoic and Late Late Paleozoic in the study area, suggesting that these two magmatic activities and / or metamorphisms are relatively active and provide the major Zircon sources, resulting in cold lake No. 5 region Jurassic with multi-temporal mixture source characteristics.