彬县-铜川地区延长组油页岩晚白垩世以来的抬升剥蚀与冷却历史
Exhumation, Cooling and Erosion History of Triassic Oil Shale since Late Cretaceous, Binxian-Tongchuan Area of Ordos Basin

利用古温标与热年代学数据共同恢复油页岩的隆升冷却历史对于研究油页岩成矿的热背景有着重要的理论意义.利用钻孔ZK900磷灰石(U-Th)/He测年数据，结合已有的永参1井磷灰石裂变径迹资料分别获得铜川地区和彬县地区延长组油页岩晚白垩世以来的古地温、抬升冷却期次、抬升冷却速率及剥蚀厚度等数据，并对比了两个地区油页岩经历的构造热演化史的差异性.ZK900钻孔长6、长9和长10段磷灰石He年龄均值依次为43.83 Ma、31.87 Ma和22.88 Ma.铜川地区油页岩晚白垩世以来经历了97～40 Ma快速抬升、40～8 Ma缓慢抬升和8 Ma以来快速抬升3个阶段，剥蚀厚度及抬升速率分别为 600 m、10.5 m/Ma，10 m、0.3 m/Ma和1 290 m、161.3 m/Ma，对应的古温度及冷却速率分别为100～60 ℃、0.70 ℃/Ma，60～ 50 ℃ 、0.22 ℃/Ma和50～25 ℃、2.90 ℃/Ma.彬县地区延长组油页岩晚白垩世以来经历了3期抬升冷却过程：97～40 Ma，持续抬升冷却(130～75 ℃)，冷却速率为0.96 ℃/Ma，抬升速率为14.4 m/Ma，剥蚀厚度820 m；40～8 Ma温度基本未变(75～ 70 ℃ )，抬升/冷却速率均很低，分别为1.9 m/Ma与0.16 ℃/Ma，剥蚀厚度60 m；8 Ma以来急剧降温(70～31 ℃)，抬升速率125 m/Ma，冷却速率4.88 ℃/Ma，剥蚀厚度1 000 m.彬县－铜川地区三叠系油页岩晚白垩世以来经历了3个抬升阶段，始新世40 Ma和中新世8 Ma为该套油页岩成矿后期冷却的关键时刻.研究表明，彬县地区和铜川地区抬升冷却和剥蚀历史具有一定的差异性，在今后油页岩成矿及后期改造研究中应区别分析.
The recovery of exhumation history of oil shale with the method of geothermometer and thermochronology has scientific significance for the study of thermal background of oil shale mineralization and its reformation. Based on the theory of tectonothermal evolution, the paleogeotemperature, the exhumation-related cooling and the erosion of the Triassic oil shale since Late Cretaceous in the Binxian area and the Tongchuan area were recovered with the fission track data from the well Yongcan1 and the (U-Th)/He data from the drilling well ZK900, respectively. The tectonothermal evolution difference of the two areas are discussed. The average (U-Th)/He ages of the Chang6, Chang9 and Chang10 samples are 43.83 Ma, 31.87 Ma, and 22.88 Ma respectively. Three stages of exhumation-cooling since Late Cretaceous of the Tongchuan area were recovered: 97-40 Ma, fast exhumation; 40-8 Ma, slow exhumation, and 8 Ma to the present, extremely fast exhumation, respectively. The erosion thickness and exhumation rate are 600 m, 10.5 m/Ma and 10 m, 0.3 m/Ma and 1 290 m, 161.3 m/Ma, respectively. The paleotemperature and cooling rate are 100-60 ℃, 0.70 ℃/Ma and 60-50 ℃, 0.22 ℃/Ma and 50-25 ℃, 2.90 ℃/Ma, respectively. Three stages of exhumation-cooling since Late Cretaceous of the Triassic in the Binxian area were recovered: 97-40 Ma, increasing exhumation-cooling (130-75 ℃), cooling rate of 0.96℃/Ma, exhumation rate of 14.4 m/Ma, erosion thickness of 820 m; 40-8 Ma with little changed as 75-70 ℃, exhumation rate/cooling rate, 0.16 ℃/Ma and 1.9 m/Ma, erosion thickness of 60 m; 8 Ma to the present with shap cooling as 70-31 ℃, exhumation rate of 125 m/Ma, cooling rate of 4.88 ℃/Ma, erosion thickness of 1 000 m, respectively. There are three stages for the exhumation-cooling history of the oil shale (Triassic in the Binxian-Tongchuan