琼东南盆地新近系重矿物分布特征及其物源指示意义

Characteristics of heavy minerals and their implications for Neogene provenances evolution in Qiongdongnan Basin

采用回归分析、主成分分析、ZTR指数和Q型聚类分析对琼东南盆地新近系的重矿物资料进行研究。研究结果表明:水动力条件对重矿物分布影响较小,而且琼东南盆地新近纪构造活动微弱,因此,重矿物的分布特征主要受物源控制;三亚组和梅山组沉积时期的物源供给特征基本一致,主要为海南岛物源,并受到松南—宝岛凹陷一带的局部基性火山活动影响;黄流组沉积时期,海南岛物源供给增强,同时,乐东凹陷受到红河物源的影响;莺歌海组沉积时期,盆地的物源供给体系变得更加复杂,局部的火山作用消失,盆地北部仍以海南岛物源为主,而西部的崖南凹陷和乐东凹陷分别受到莺西物源和红河物源的影响,其母岩类型均为高级变质岩类。

Regression analysis, principal component analysis, ZTR index and Q-type cluster analysis were carried out for heavy minerals components acquired from the Neogene strata in Qiongdongnan Basin. The results indicate that hydrodynamic conditions have little impact on the distribution of heavy minerals. Combined with weak tectonic activities in Neogene, provenance should be the primary factor influencing components and distribution of heavy minerals. In Sanya Fm and Meishan Fm, sediment supplies are generally similar, which include Hainan Provenance and partial basic volcanic activities from Songnan and Baodao depressions. In Huangliu Fro, the contribution of Hainan provenance increases, meanwhile, sediments from Red River provenance sink in Ledong depression. When it comes to Yinggehai Fm, sediment supplies tend to be more complex. Hainan provenance still dominates the northern continental shelf, whereas partial volcanism disappears, Yanan depression and Ledong depression are respectively affected by western-Yinggehai provenance and Red River provenance, and both of their source rocks are high-grade metamorphic.