柴达木盆地红柳泉-跃东地区新近系下油砂山组沉积体系展布特征及控制因素

在层序地层学研究的基础上，对柴达木盆地红柳泉-跃东地区新近系下油砂山组作了细致的沉积相分析研究。下油砂山组发育冲积扇相、扇三角洲相、辫状河三角洲相、湖泊相和浊积相等几种沉积相类型，分析了其发育特征及分布范围。以识别出的4个三级层序为单位，详细分析了沉积相的平面展布特征：Ⅰ层序沉积时期，西北地区为冲积扇和扇三角洲、中西部地区为辫状河三角洲发育区；Ⅱ层序沉积时期，沉积相分布格局与Ⅰ层序基本一致；Ⅲ层序沉积时期，西北地区的冲积扇、扇三角洲发育范围有所缩小，中西部地区辫状河三角洲发育范围持续扩张，分布范围较前期增大；Ⅳ层序沉积时期，西北地区依旧发育冲积扇，中西部地区辫状河三角洲沉积快速地向东推进，辫状河三角洲前缘亚相已达研究区中心。结合构造、物源、气候等因素分析了沉积相展布及演化的控制因素。

Distribution characteristics and controlling factors of depositional systems of the Neogene Xiayoushashan Formation in Hongliuquan Yuedong area,Qaidam Basin

Detailed analyses of sedimentary facies of the Neogene Xiayoushashan Formation in Hongliuquan Yuedong area，Qaidam Basin，have been made based on the sequence stratigraphic studies. The alluvial fan，fan deltaic，braided fluvial deltaic，lacustrine and turbidite facies were developed during the deposition of the Xiayoushashan Formation. The development characteristics and distribution of the sedimentary facies were analyzed. The planar distribution of the sedimentary facies was analyzed in detail based on the 4 third order sequences identified. During the deposition of sequenceⅠ，the alluvial fan and fan deltaic facies were developed in the northwestern area，while the central western area was dominated by braided fluvial deltaic facies. During the deposition of sequence Ⅱ，the distribution framework of sedimentary facies is similar as sequence Ⅰ. During the deposition of sequence Ⅲ，the distribution extent of the alluvial fan and fan delta in the northwestern area shrank，while the braided fluvial delta in central western area expanded and the area was larger than that in the former stage. During the deposition of sequence Ⅳ，the alluvial fan was developed in the northwestern area，the braided fluvial delta in the central western area stretched quickly to the east，and the braided fluvial delta front reached the center of the study area. Due to tectonic uplifting，the lacustrine basin experienced an evolution process and the depocenter shifted eastwards during the deposition of the Xiayoushashan Formation.