滇西姚关上三叠统大水塘组钙屑浊积岩沉积特征及控制因素探讨

Discussion of Sedimentary Characteristics and Controlling Factors of Calcarenitic Turbidite,Dashuitang Formation,Upper Triassic in Yaoguan of Western Yunnan

笔者等在滇西姚关一带工作中,首次在上三叠统大水塘组中发育一套地质特征典型、沉积序列明显的钙屑浊积岩。其底面侵蚀构造清楚,各层段厚度变化较大,粒度分布上表现为从底到顶由粗变细的正粒序特征。鲍马序列发育不完整,c段多不明显,多为a、b、d、e段组合。初步认为浊流活动可能受近北东向古断裂控制,其活动与滇西陆内裂解事件有关。

In Yaoguan area, a series of calcarenitic turbidite which the geological characteristics are typical and the sedimentary sequence is obvious was found in Dashuitang formation of upper Triassic. The bottom erosion structure is clear, the thickness of each layer changes a lot, the grain size shows obverse order feature which becomes thinner from the bottom to the top. Bouma sequence develops incompletely, section C isn＇ t obvious, most composition are section A, B, D and E. it＇ s thought that turbidity current may be controlled by NE ancient fracture, its activities has relation with inland breakup event in western Yunnan.