重矿物在沉积物源分析中的应用——以内蒙古西部额济纳旗及邻区石炭系—二叠系为例

The application of heavy minerals to analyzing sediment provenance: A case study of the Carboniferous-Permian strata in Ejin Banner and its adjacent areas

分析旧司阶—吴家坪阶额济纳旗及其邻区主要地层中的碎屑岩重矿物组合特征,结合区域地质特征、碎屑岩岩石学特征、碎屑锆石测年资料、古水流方向、沉积体系特征等,阐述了石炭系—二叠系沉积物的物源体系。重矿物组合特征显示,研究区北部黑鹰山-额济纳旗坳陷和南部的柳园-芒汗超克坳陷的碎屑岩重矿物组合类型和含量都有差异,指示它们来自不同的物源区;碎屑锆石测年资料显示,绿园-拐子湖凹陷的埋汗哈达剖面埋汗哈达组碎屑锆石的年龄可分为2类:436Ma±13Ma和1467Ma±110Ma,古水流方向也显示有北部物源区存在,说明沉积物源受敦煌-阿拉善-狼山古陆和马鬃山-拐子湖隆起带的双重作用;北部坳陷沉积物源来自马鬃山-拐子湖隆起带。

Based on analyzing composite characteristics of heavy minerals from clastic rocks of Jiusi-Wujiaping Stage in Ejina Banner and its adjacent areas, in combination with regional geological features, lithologic character of clastic rocks, detrital zircon dating data, ancient flow direction and the depositional system, this paper deals with the provenance system of the Carboniferous-Permian sedi- ments. Heavy mineral combinational features reveal that combination types and content of heavy minerals are different in northern Heiying Mountain, Ejin Banner depression and southern Liuyuan-Manghanchaoke depression, suggesting that they were probably de- rived from different sedimentary sources. According to detrital zircon dating data, there are two types of detrital zircon age of Maihan- hada Formation in Lvyuan-Guaizihu depression, being 436Ma± 13Ma and 1467Ma±110Ma in age respectively. Ancient flow direction also reveals the existence of northern sedimentary source. These data suggest that the sedimentary source experienced dual action from both Dunhuang-Alashan-Langshan ancient land and Mazongshan-Guaizihu uplift belt. The sedimentary source of northern depression was Mazongshan-Guaizihu uplift.