云岗盆地石盒子组地层时代厘定及其地质意义  

Stratigraphic Age of the Shihezi Formation in the Yungang Basin and Its Geological Significance

作　　者：周瑞[1,2] 刘东娜 董宪姝[1] 郝春生[2] 周安朝 ZHOU Rui;LIU DongNa;DONG XianShu;HAO ChunSheng;ZHOU AnChao(Institute of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Gas Group Co.,LTD.,Taiyuan 030031,China;Shanxi Key Laboratory of Coal and Coal-measure Gas Geology,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学矿业工程学院,太原030024 [2]山西燃气集团有限公司,太原030031 [3]太原理工大学煤与煤系气地质山西省重点实验室,太原030024

出　　处：《沉积学报》2024年第5期1578-1591,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41802191)。

摘　　要：【目的】华北中北部云岗盆地缺失三叠系,而最新的1∶5万史家屯幅区域地质调查成果将云岗盆地羊圈头剖面顶部(原石盒子组)地层划为下三叠统刘家沟组。为了解决争议并验证这个新认识的可靠性,亟需进行进一步研究。【方法】通过对云岗盆地马道头和羊圈头剖面进行岩石地层对比和碎屑锆石测年,并与华北中北部其他同时代地层剖面进行对比,以确定其时代归属。【结果与结论】羊圈头剖面上段识别的所谓刘家沟组与马道头剖面石盒子组具有相似的岩相组合、砾石成分,岩性特征均以灰绿、黄绿色中厚层状中粗粒砂岩为主,夹少量薄层灰紫红色粉砂岩、砂质泥岩,同时还发育数层巨厚砾岩层,完全不同于华北地块府谷、宁武、太原西山以及沁水盆地刘家沟组地层的显著特征,即大量发育浅红色、肉红色厚层状中细粒长石砂岩。同时最年轻碎屑锆石年龄(288.0±4.7 Ma)也将本组最大沉积年龄限制到中二叠世,在此基础上将此套地层的时代归属划归为中二叠世,即石盒子组,而非刘家沟组。推测晚三叠世华北北部及北缘造山带发生了强烈的挤压抬升,导致云岗盆地三叠系地层遭受剥蚀,后期又被下侏罗统地层不整合覆盖。[Objective and Methods]Triassic strata are considered absent in the Yungang Basin in northcentral North China,while the Shihezi Formation at the top of the Yangquantou section within the Yungang Basin belongs to the Lower Triassic Liujiagou Formation based on the regional geological survey results of the 1:50000 Shijiatun map.To settle the dispute and determine the reliability of this new understanding,this study conducted lithostratigraphic correlation and detrital zircon dating of the Shihezi Formation from the Madaotou and Yangquantou sections within the Yungang Basin,and compared with other contemporaneous stratigraphic sections in northcentral North China to determine its deposition age[.Results and Conclusions]It shows that the‘so-called’Liujiagou Formation identified in the upper part of Yangquantou section has similar lithofacies associations and gravel compositions with the Shihezi Formation in the Madaotou section,and they are both characterized by grey-green or yellow-green medium-to thickbedded medium-to coarse-grained sandstone interbedded with thin-bedded purple-red siltstone and sandy mudstone,as well as several layers of thick conglomerates.This differs from the diagnostic characteristics of the Liujiagou Formation in the Fugu,Ningwu,Taiyuan Xishan,and Qinshui Basins in North China,which are characterized by abundant light to fresh red thick-bedded medium-to fine-grained arkose.Moreover,the youngest detrital zircons ages(288.0±4.7 Ma)constrained the maximum depositional age to the Middle Permian.Therefore,the strata at the top of the Yangquantou section belongs to the Middle Permian Shihezi Formation,not the Liujiagou Formation.It is inferred that the orogenic belts in the northern margin of North China likely experienced intense compression and uplift during the Late Triassic,resulting in the denudation of the Triassic strata within the Yungang Basin,which was then unconformable overlain by the Lower Jurassic strata.

关 键 词：二叠系 石盒子组 刘家沟组 碎屑锆石U-PB年龄 地层划分 云岗盆地 

分 类 号：P597.3[天文地球—地球化学]