云南兰坪盆地古近系碎屑岩重矿物分布规律及其指示意义

对兰坪盆地古近系59件砂岩样品进行分析，结果表明，稳定重矿物的含量平均为38.4%，较稳定矿物及不稳定矿物含量低，平均分别为2.3%和1.1%；指相矿物（赤）褐铁矿含量较高，平均为50.5%。根据稳定系数、ZTR指数、ATi指数、GZi指数及其在剖面中的变化规律，将兰坪盆地构造演化划分为构造平缓期和构造活动期。古近纪构造活动在盆地不同部位、不同时期存在一定的差异，总体上显示中南部构造活动较北部有一定的延迟。重矿物组合显示，盆地古近系的源岩存在多种岩石类型，其中以沉积岩为主，而基性岩、中酸性侵入岩和变质岩都较少。重矿物组合及特征指数揭示了云龙组物源主要来自盆地东缘；果郎组物源以东缘为主，西缘为辅。指相重矿物组合显示，兰坪盆地古近系的沉积环境为水体较浅的强氧化环境。

Heavy mineral distribution regularity of Paleogene detrital rocks in Lanping basin,Yunnan Province

The analytical results of 59 Paleogene sandstone samples from Lanping basin indicate that the average content of stable heavy minerals is 38.4%, the relatively stable and unstable minerals are very rare, respectively possessing 2.3% and 1.1%. The average content of the facies minerals hematite and limonite is high, possessing about 50.5%. According to stability coefficient, ZTR index, ATi index and the variation characteristics of heavy mineral index along the profile, the tectonic evolution is divided into two periods: flat period and active period. The tectonic activities of different parts and periods of the basin show some differences; on the whole, the activity of south central basin was later than that of the north basin in time. The heavy mineral assemblage suggests that the Paleogene provenance had several kinds of rock styles, dominated by sedimentary rock, with minor basic rock, intermediate-acidic intrusive rock and metamorphic rock. From east to west, the ZTR index decreases gradually. In combination with tectonic setting of the study area and previous research findings on the basement of the basin, the authors infer that, in Yunlong period, the provenance mainly came from the eastern margin of the basin, and the provenance of Guolang Group mainly came from the eastern margin of the basin, followed by the western margin. The facies of heavy mineral assemblage shows that the ancient sedimentary environment of Lanpin basin was a strong oxidation environment of swallow water.