准噶尔盆地玛湖凹陷夏子街扇区三叠系百口泉组绿帘石分布特征及成因

Distribution characteristics and genesis of epidote from the Triassic Baikouquan Formation in Xiazijie fan area,Mahu sag,Junggar Basin

准噶尔盆地玛湖凹陷夏子街扇区三叠系百口泉组重矿物中绿帘石占绝对优势,且含量变化大。为了解研究区绿帘石的分布特征及其成因,利用重矿物、能谱及扫描电镜等资料,借助聚类分析和相关性分析等多元统计方法,对绿帘石的分布特征及成因进行了系统的研究。结果表明:(1)根据绿帘石含量可将研究区划分为绿帘石高值区、中值区和低值区;(2)绿帘石高值区位于扇三角洲前缘亚相,中值区和低值区主要位于扇三角洲平原亚相,且低值区比中值区更靠近物源;(3)绿帘石高值区不仅有岩浆绿帘石,自生绿帘石也普遍发育,因此绿帘石含量高;中值区绿帘石主要为岩浆绿帘石;低值区地层遭受了抬升剥蚀,溶蚀淋滤作用对搬运沉积的绿帘石破坏强烈,故显示低值。

The epidote is the dominant component of heavy minerals and its content changes greatly in Baikouquan formation,Xiazijie fan area,Mahu sag,Junggar Basin. In this paper,we use heavy mineral,energy spectrum,scanning electron microscopy and other data,with the help of multivariate statistical methods such as cluster analysis,correlation analysis and so on,to systematically study the distribution characteristics and genesis of epidote. The results indicated that:(1) Based on the content of epidote,the study area can be divided into high value area,medium value area and low value area.(2) The high value area is located on the fan delta front,while the medium and low value area are on fan delta plain.The low value area is more proximal to the source than the medium value area.(3) The high value area shows an abundance of magmatic and authigenic epidotes,whereas the medium value area only has magmatic epidote. The low value area is mainly caused by the subsequent tectonic uplift and erosion of strata,which led to the leaching of epidote during sediment transportation and deposition.