济源盆地中晚三叠世地层沉积学、年代学研究及其对于恢复鄂尔多斯原型盆地的意义  

The sedimentology and chronology study on the Middle-Late Triassic strata of the Jiyuan Basin and its significance for the restoration of the prototype Ordos Basin

作　　者：刘溪 LIU Xi(China Coal Energy Research Institute Co., Ltd., Xi′an 710054, China)

机构地区：[1]中煤能源研究院有限责任公司,陕西西安710054

出　　处：《西北大学学报（自然科学版）》2022年第2期327-337,共11页Journal of Northwest University（Natural Science Edition）

基　　金：国家自然科学青年基金(41702117);国家自然科学重点基金(41330315)。

摘　　要：为研究鄂尔多斯盆地中晚三叠世东南缘的沉积范围,对其东部济源盆地西承留剖面中晚三叠世沉积地层进行实测,运用沉积学原理判断沉积环境,同时运用LA-ICP-MS碎屑锆石U-Pb同位素年代学方法,探讨其地层物质来源。研究结果表明,济源盆地西承留剖面中晚三叠世早中期以黄绿色长石砂岩和泥岩沉积为主;砂岩粒度较细,晚期以灰绿色泥岩、粉砂岩为主。沉积相自下而上从三角洲相经浅湖相向深湖相演变,展现了一个单向湖进过程,与鄂尔多斯盆地本部及东部外围的宁静盆地、沁水盆地及南召盆地为连续沉积;碎屑锆石年龄范围为220~2600 Ma,大致可分为2300~2600 Ma、1600~2100 Ma、220~330 Ma三个年龄段。与周缘地体年龄数据进行对比,认为物源主要来自华北板块北缘阴山—大青山—乌拉山一带出露的变质结晶基底、孔兹岩带、华北克拉通沉积盖层再旋回以及华北板块南缘,与现今鄂尔多斯盆地东南部三叠系延长组碎屑物源基本一致。因此推测,中晚三叠世济源盆地与鄂尔多斯盆地应属于同一沉积盆地。To study the extension range of eastern Ordos Basin in Middle-Late Triassic,the study measured Middle-Late Triassic strata in Xichengliu section of the Jiyuan Basin,which lies at the southeast direction of the Ordos Basin.By using principle of sedimentology to determine the sedimentary environment and using the U-Pb isotopic chronology method of zircon from LA-ICP-MS to discuss the material source,the results show that the early-middle term of Middle-Late Triassic strata of Xichengliu secetion is mainly composed of yellowish-green arkose and mudstones.Sandstone is generally fine granularity.In the late stage,it is dominated by greyish green mudstones and siltstones.The sedimentary facies evolved from delta facies to deep lacustrine facies from bottom to top,showing a one-way lacustrine process,which is continuous with the main part of Ordos Basin and Ningjing Basin,Qinshui Basin and Nanzhao Basin in the eastern periphery.The age range of detrital zircon is mainly from 220~2600 Ma and can be roughly divided into three groups:2300~2600 Ma,1600~2100 Ma,220~330 Ma.Compared with the age data of the surrounding terranes,it is considered that the provenance mainly comes from the metamorphic crystalline basement exposed in the Yinshan-Daqingshan-Wulashan area on the northern edge of the North China plate,the konzite belt,the sedimentary cover recycle of the North China Craton and the southern edge of the North China plate,which is consistent with the clastic provenance of the Triassic Yanchang Formation in the southeastern Ordos Basin.Therefore,it is speculated that Jiyuan Basin and Ordos Basin may belong to the same sedimentary basin in the Middle and Late Triassic.

关 键 词：沉积相 锆石U-PB年龄 中晚三叠世 济源盆地 鄂尔多斯盆地 

分 类 号：P531[天文地球—古生物学与地层学]