西藏昂仁县扯假错渐新统日贡拉组地层沉积相及沉积演化特征

Sedimentary facies and sedimentary evolution of the Oligocene Rihongla Formation in the Chejiaco area,Ngamring,Xizang

沉积相是研究古环境、古气候及岩相古地理的基础与重要依据。本文报道西藏昂仁县扯假错剖面渐新统日贡拉组的岩性特征、基本层序、沉积相及垂向上沉积演化特征。该组为一套紫红色碎屑岩系,为砾岩、砂岩夹粉砂岩和泥质岩,具典型的河流环境沉积特征,为进一步研究该地区该时期的沉积环境提供了线索。

The sedimentary facies analysis is fundamental to all the palaeoenvironmental,palaeoclimatic,and palaeogeographic interpretation in the reconstruction of sedimentary facies and palaeogeography. The present paper gives a detailed description of lithology,basic sequence,sedimentary facies and vertical sedimentary evolution of the Oligocene Rihongla Formation in the Chejiaco area,Ngamring,Xizang. The Rihongla Formation consists dominantly of a succession of purplish red terrigenous siliclastic rocks including conglomerates,sandstones,siltstones and mudstones which are indicative of a typical fluvial sedimentary environment. The channel subfacies in this Formation may be subdivided into the channel bar,point bar and channel lag microfacies,and laid down in the mountainous areas to alluvial plains during the Oligocene.