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    鄂尔多斯盆地东北部差异隆升过程裂变径迹分析

    Differential uplift on the northeast margin of Ordos Basin: Evidence from apatite fission track analysis

    • 摘要: 基于磷灰石裂变径迹(AFT)的分析方法,探讨鄂尔多斯盆地东北缘差异隆升过程及其隆升强度,为鄂尔多斯盆地东北缘(晋西挠摺带府谷-吴堡区段)构造演化历史及其与多种能源矿产耦合关系提供新的认识。不同构造单元及其不同层系样品的AFT分析表明:研究区北段府谷-兴县地区构造抬升相对较早,且经历了白垩纪晚期(86~56Ma)和古近纪(44~37 Ma)两次隆升过程,平均隆升速率分别为24.5 m/Ma和41.8 m/Ma;研究区中段紫金山地区抬升相对较晚,主控构造事件发生在晚白垩世末期-古近纪早期(68~56 Ma)和古近纪中晚期(35 Ma),平均隆升速率分别为48.8 m/Ma和49.2 m/Ma;研究区南段临县-吴堡地区抬升最晚(35~21 Ma),平均隆升速率为73.9 m/Ma。因此,鄂尔多斯盆地东北缘晚白垩世以来的差异隆升过程具有北段抬升早、中段抬升相对较晚和南段抬升更晚的特点,南北区段统一的强烈构造抬升活动主要发生在古近纪以来的晚近时期,且构造隆升强度由南向北逐渐减弱。结合已有的成矿(藏)年代学资料分析表明,鄂尔多斯盆地东北缘关键构造事件及其隆升强度与多种矿产耦合成矿(藏)事件关系密切,构造事件与成藏(矿)事件呈现出显著的协同耦合特点。

       

      Abstract: Apatite fission track analysis provides the opportunity for revealing differential uplift processes and uplift rate during the Mesozoic-Cenozoic on the northeast margin (Fugu-Wubao section of Jinxi flexural fold zone) of Ordos Basin, and offers new constraints and knowledge to the whole basin tectonic evolution history and the relationship between tectonic evolution and the coupling coexistence of multiple energy resources. The AFT age of different tectonic units and their different strata reveal that the uplift of Fugu-Xingxian area along the northern section of the study area was earlier during 86-56 Ma in the late Cretaceous and 44-37 Ma in Paleogene with the rate of speed being 24.5 m/Ma and 41.8 m/Ma. The uplift of Zijinshan area of the middle section of the study area was relatively late, and the key tectonic events took place at 68-56 Ma and 35 Ma during the late Cretaceous to middle-late Paleogene, with the rate of speed being 48.8m/Ma and 49.2 m/Ma respectively. The uplift of Linxian-Wubao area along the south section of the study area was during 35-21 Ma with the rate of speed being 73.9 m/Ma. Therefore, the north section uplifted early, the middle section uplifted relatively late, and the south section uplifted last. What is more, the overall tectonic activation period mainly happened late in Paleogene in Fugu-Wubao section of Jinxi flexural fold zone, and the tectonic uplift rate weakened gradually from the south to the north in the northeast of Ordos Basin. Additionally, the relationship analysis of the tectonic event and the mineralizing chronology revealed that the key structural events and moderate uplift speed controlled reservoir formation time or mineralization time of the coupling coexistence of multiple energy resources on the northeast margin of Ordos Basin, and show the collaborative and coupled relationship between the tectonic events and accumulations.

       

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