鹤庆—松桂地区上三叠统中窝组含矿岩系沉积相特征及演化

Characteristics and Evolution of Sedimentary Facies in Upper Triassic Zhongwo Formation Ore-Bearing Rock Series from Heqing-Songgui Area

鹤庆—松桂地区隶属云南省大理州鹤庆县,地处青藏高原东南缘横断山脉中段,夹持于马鞍山与金沙江之间,属于金沙江西岸的鹤庆—松桂盆地。本文以该地区上三叠统中窝组含矿岩系为主要的研究对象,对其沉积相特征、划分与演化进行了系统研究。并通过野外露头、探槽揭露及钻井岩芯等的岩性组合、古生物组合、沉积构造、粒度等的详细观察,认为研究区主要为有障壁局限海湾—澙湖沉积环境。其含矿岩系发育有顶部潮下带、潮间带、潮上带、潮上—沼泽等沉积相,各类沉积相在空间上有规律的分布。在对剖面结构及岩层地球化学特征的深入分析的基础上,通过北西—南东、南南西—北北东、东西向三条沉积相剖面进行对比研究,恢复其岩相古地理面貌及演化特征,并认为中窝组底部的含铝岩系受下伏北衙组灰岩上段顶部不整合面古地形、喀斯特地貌的严格控制,为以后铝土矿的勘探提供理论依据。

Heqing-Songgui area is located in Heqing County of Dali prefecture in YunNan province,it is situated in southeast of Tibetan Plateau and the middle of Hengduan mountains,between Maan mountain and Jinsha river,it belongs to Heqing-Songgui basin where the west bank of Jinsha river. This paper is as ore-bearing rock series on Zhongwo Formation of upper triassic in Heqing-Songgui area,and for the characteristics and classification of sedimentary facies and evolution has carried on the systematic research. According to the detailed observation of the rock types' characteristics,restricted gulf facies-lagoon facies have been developed in the study area. Top of subtidal zone,intertidal zone,supralittoral zone,upralittoral-swamp are developed. Based on depth analysis about profile structure and rock geochemistry,by NW-SE /SSW-NNE /EW three sedimentary facies profiles comparative studying,restored facies and palaeogeography their appearance and evolution. Al-bearing rock series which in the bottom of Zhongwo Formation is strictly controlled by unconformity surface topography and karst landform which is on the upper top of Beiya Formation limestone,it can provide theoretical basis for Bauxite exploration.