宁武盆地及周缘岩体裂变径迹对山西地块中—新生代构造演化的约束

宁武盆地及周缘岩体的抬升剥蚀对于山西地块中—新生代构造演化具有重要的指示意义。本文对宁武盆地及周缘岩体进行裂变径迹分析，磷灰石裂变径迹年龄97～47 Ma,锆石裂变径迹年龄161～141 Ma。裂变径迹记录了早白垩世早期(145～125 Ma)、晚白垩世(85～70 Ma)、古新世晚期—始新世早期(59～53 Ma)和渐新世晚期(28 Ma)的4次抬升剥蚀事件。综合分析山西地块的裂变径迹数据，表明隆起区晚古生代以来发生了多期抬升剥蚀事件。山西地块中—新生代构造演化具有时空差异。周缘岩体样品的裂变径迹年龄大于盆地内沉积地层样品的年龄，指示了周缘山体先于盆地抬升剥蚀。晋东北抬升剥蚀时限早于晋西南。山西裂谷系西南端裂开较早。裂谷系发育具有由南向北扩展的特征，这与地层保留记录相一致。山西地块现今地貌格局是在中生代发育一系列雁行状排列的复背斜和复向斜构造基础上发展而成的。

Fission track study of the Ningwu basin and its peripheral plutons: Implications for Mesozoic-Cenozoic tectonic evolution of the Shanxi block

Uplift- erosion of Ningwu basin and its peripheral plutons has important significance for the Mesozoic- Cenozoic tectonic evolution of the Shanxi block. The fission track analysis made from Ningwu basin and peripheral plutons shows that apatite fission track ages vary from 97 Ma to 47 Ma, and zircon fission track ages vary from 161 Ma to 141 Ma. The fission track recorded four uplift erosion events: the early stage of Early Cretaceous (145~125 Ma), the late stage of Late Cretaceous (85~70 Ma), the early stage of Eocene (59~53 Ma) and the late stage of Late Oligocene (28 Ma). The fission track data show that multiple uplift erosion events have occurred since Late Paleozoic. Meso- Cenozoic tectonic evolution of Shanxi block has temporal and spatial differences. The fission track age of peripheral plutons samples is older than sedimentary strata samples, indicating that peripheral plutons was uplifted erosion prior to the basin and the uplift erosion of northeast Shanxi block was earlier than that of southwest. The formation of fracture was earlier in the southwest of Shanxi rift system. The development of rift system extends from south to north, which is consistent with strata conservation record. In the Mesozoic, the regional tectonics formed a series of en- echelon complex anticlines and synclines. In the Cenozoic, Indian Ocean plate compression on Eurasia may have formed the current geomorphological pattern of Shanxi block. It is closely related to the multi- stage tectonic movement in the northeastern margin of Tibetan Plateau.