贺兰山中段中三叠统二马营组沉积特征及沉积环境演化

The sedimentary characteristics and evolution of sedimentary environment of the middle Triassic Ermaying Formation in the middle Helan mountain

通过对贺兰山中段二马营组野外露头和柱状图对比研究,认为宁夏贺兰山中段三叠统二马营组为干燥气侯条件下形成的内陆辫状河相沉积,现今保留下来的主要为河床滞留沉积和心滩沉积.同时,根据二马营组岩性特征在横向和纵向上的变化规律,得出二马营组沉积环境总的演化规律为冲积扇—辫状河—湖泊,是一个典型的扇退—湖进型层.

Contrastive study by histogram of Ermaying group in the middle Helan Mountain, it is considered that Ermaying group was sediment of inland braided river which formed in dry and hot weather conditions, now preserved mainly riverbed deposition and retention heart beach deposits. According to horizontal and vertical changes of lithologic characteristics at Ermaying group, it is concluded that the evolution of sedimentary environment was from alluvial fan, to braided river, finally to lake, it is a typical sequence of fan regression and lake forming system.