鄂尔多斯盆地东南部延长组中期物源分析及其对秦岭造山带隆升作用的指示  

Provenance Analysis of Middle Yanchang Formation in the Southeastern Ordos Basin and Its Indications for the Uplift of the Qinling Orogenic Belt

作　　者：弓汶琪 弓虎军[1] 王苏里[1] 罗芬红 王苗苗 GONG Wenqi;GONG Hujun;WANG Suli;LUO Fenhong;WANG Miaomiao(Department of Geology,Northwest University,Xi’an 710000,Shaanxi,China)

机构地区：[1]西北大学地质学系,陕西西安710000

出　　处：《西北地质》2025年第1期118-134,共17页Northwestern Geology

基　　金：国家自然科学基金项目“大陆构造与动力学”(41421002);“黄土高原新近纪红粘土碎屑锆石的时空分布特征及物源区指示意义”(41372036)联合资助。

摘　　要：为了厘清盆地东南部延长组中期沉积物源,从而限定秦岭造山带隆升启动时限,利用碎屑锆石U-Pb测年方法,对鄂尔多斯盆地东南部金锁关、下寺湾、黄陵和黄龙地区延长组中期物源进行分析。结果表明:金锁关地区碎屑锆石年龄组合主要分布为2200~2700 Ma、1700~2100 Ma、900~1200 Ma、400~500 Ma、205~382 Ma;黄龙、下寺湾、黄陵地区碎屑锆石年龄组合主要分布为2200~2700 Ma、1700~2100 Ma、205~382 Ma。综合研究认为:①存在一个湖盆沉积中心,将延长组中期盆地东南部研究区内部分割两个不同的区域,湖盆沉积中心以南的金锁关地区物源与盆地南部华北克拉通南缘和北秦岭构造带相关。湖盆沉积中心以北的黄龙、黄陵和下寺湾地区物源主要与盆地北部阴山地块、孔兹岩带以及华北克拉通北缘华力西期—印支期热事件岩浆岩岩体相关。②长7期金锁关沉积物与秦岭造山带有良好的沉积响应,其中最年轻锆石颗粒反映造山带在(234.7±4)Ma左右开始隆升造山。In order to clarify the provenance of the southeastern part of the Ordos Basin and distinct the initiation time of the Qinling orogenic belt uplift during the middle Yanchang Formation,detrital zircon U-Pb dating method was used to analyze the provenance of the Jinsuoguan,Xiashiwan,Huangling and Huanglong areas,which is part of the Ordos Basin.The age assemblages of detrital zircons in Jinsuoguan area are 2200~2700 Ma,1700~2100 Ma,900~1200 Ma,400~500 Ma and 205~382 Ma.The detrital zircon age assemblages in Huanglong,Xiasiwan and Huangling are 2200~2700 Ma,1700~2100 Ma and 205~382 Ma.Comprehensive study found:①The lacustrine depositional center divides two different areas inside the southeastern study area of the middle Yanchang Formation basin,south of lake basin center of jinsuoguan main stem from the south of the southern margin of the north China craton basin and north Qinling tectonic belt.The provenance of the huanglong,Huangling and Xiashiwan areas which are located at the north of lake center is mainly derived from the Yinshan block、the Konzi rock belt and hercynian indosinian thermal event magmatic rocks in the north Margin of the North China Craton.②The sediments have a good sedimentary response to the Qinling orogenic belt in Jinsuoguan during in chang 7,the youngest zircon grains reflect that the orogenic belt began to uplift around(234.7±4)Ma.

关 键 词：碎屑锆石U-Pb定年 沉积物源 秦岭造山带 鄂尔多斯盆地 延长组 

分 类 号：P597[天文地球—地球化学]