柴西红沟子地区晚新生代岩石磁学特征及对青藏高原北缘隆升的响应

柴达木盆地为青藏高原东北缘的一个内陆沉积盆地,发育了巨厚的中-新生代沉积地层,这些地层记录了盆地及周缘山地的构造、环境演变历史。本文通过对柴达木盆地西北部红沟子地区晚新生代天然剖面沉积物岩石磁学的研究,表明在约9.8 Ma磁化率值突然增大,同时沉积物中磁铁矿的含量也明显增加。结合剖面沉积物岩相、岩性及沉积速率等分析,依据沉积物磁学性质与环境变化和构造运动之间的关系,我们认为该地区晚新生代物源变化,可能是造成岩石磁学特征在大约9.8 Ma变化的主要原因,同时可能还暗示了青藏高原东北缘一次强烈的构造隆升事件,阿尔金山作为柴达木盆地的物源之一,也响应了此次构造运动,隆升到了一定高度使剥蚀速度增加,这一过程被柴西地区的红沟子构造所记录。

The Late Cenozoic rock magnetic characteristics of the Honggouzi section in the western Qaidam Basin and its response to the uplift of the NE Tibetan Plateau

The Qaidam Basin is an inland basin in the northeastern Tibetan PlateauIt has developed thick Mesozoic Cenozoic sedimentary strataThese strata recorded the evolution of the structure and environment of the basin and its surrounding mountainsBased on Late Cenozoic sedimentary rock magnetic study of the Honggouzi section in the northwest Qaidam Basin，we found that the value of magnetic susceptibility increased dramatically in the～9.8 Ma，together with significant increase the amount of magnetiteCombined with sedimentary facies，lithology and sedimentation rate，and based on the relationship between the magnetic properties of sediments and environmental change，and the tectonic activities，we believe that the dramatic changes of rock magnetic characteristics may have been caused by the changes of sedimentary provenances in～9.8 MaIt may imply a significant uplift event of the northeastern margin of Tibet PlateauAltyn Tagh was one of sources of the Qaidam Basin，which responded to this tectonic movementThe mountin reached certain height so that the erosion rate increased，this process was recorded by Honggouzi.