运用磷灰石裂变径迹分析鄂尔多斯盆地周缘中新生代沉降隆升史

Analysis on the Meso-Neozoic subsidence and uplift history of the periphery of Ordos basin using apatite fission track

通过对鄂尔多斯盆地磷灰石裂变径迹资料深入分析与反演模拟,定性-半定量地研究了该区相关岩石组合的地热演化史。结果表明,晚侏罗世-晚白垩世早期（160～90 Ma）盆地具东升西降的特点,东部以约25 m/Ma的速率隆升,造成1500～2000 m的剥蚀量;晚白垩世末至始新世早期（90～23 Ma）,盆地具整体隆升特点,盆地南部和西部隆升幅度达1500～2000 m,盆地东部表现为弹性回返,隆升缓慢,幅度小于500 m;中新世早期以来（23 Ma至今）,全盆快速隆升,周边隆升速率达45～108 m/Ma,造成1000～2500 m的剥蚀量。对盆地内砂岩型铀矿年龄资料对比分析表明,后生铀成矿作用过程基本上都发生在盆缘相对快速隆升阶段。

By analyzing apatite fission track data and inverse modeling, the thermal history of relevant rock assemblage has been studied qualitatively to semi-quantitatively in Ordos basin. Studies show that the basin was characterized by uplift in the east and subsidence in the west in Late Jurassic and Early Cretaceous and the eastern part of the basin was uplifted at the rate of 25 m/Ma, leading to the denudation of 1500～2000 m. In Late Cretaceous to the Early Eocene （90～230 Ma）, the basin was uplifted as a whole, the southern and western parts of the basin were uplifted with the amplitude of less than 500 m. Since the Late Miocene （23 Ma to present）, the whole basin was uplifted quickly and the uplifting rate was up to 45～108 m/Ma in the periphery of the basin, leading to the denudation of 1000-2500 m. Combined with the mineralization ages of sandstone type uranium deposits in the basin, it is concluded that the epigenesis of uranium mineralization mostly took place in the relatively quick uplifting stage of strata.