南海西沙海域西科1井第四系生物礁: 碳酸盐岩成岩作用特征

以西科1井第四系乐东组生物礁-碳酸盐岩地层为研究对象, 通过偏光显微镜观察、茜素红-S和铁氰化钾混合溶液染色、扫描电镜和矿物阴极发光性观察等分析方法研究了生物礁-碳酸盐岩的岩石学和成岩作用特征.西科1井生物礁-碳酸盐岩成岩作用包括较弱的压实作用、新生变形作用、微生物泥晶化作用、溶解作用、胶结作用.以典型胶结物岩相学产状为标志, 结合矿物阴极发光性特征识别出了大气水和海水成岩环境.其中, 大气水成岩环境以典型的新月形或悬垂形方解石胶结物为识别标志, 海水成岩环境以纤维状-针状文石为识别标志.成岩环境的垂向分布表现为: 0~27 m深度内为显著的大气水成岩环境; 27~42 m深度内以大气水成岩环境为主, 其次为海水成岩环境; 42~105 m深度内以大气水成岩环境为主, 海水成岩环境的影响弱; 105~172 m深度内大气水和海水成岩环境均出现; 172.00~214.89 m深度内为海水成岩环境. 

Diagenetic Characteristics of Quaternary Reef-Carbonates from Well Xike-1, Xisha Islands,the South China Sea

In this study, petrographic and diagenetic characteristics of Quaternary reef-carbonates in well Xike-1 have been illuminated according to the observation analyses of polarizing microscope, alizarine red S and potassium ferricyanide composite staining, scanning electron microscope(SEM) and cathode luminescence. It is found that the diagenesis types include predominately weak compaction, neomorphism, micritization, dissolution and cementation. The diagenetic environments have been identified using the typical petrographic occurrences of cements and the cathode luminescence features. Among which, meniscus and pendant calcite indicate meteoric diagenetic environment and fibrous-needle aragonite indicates marine diagenetic environment. Diagenetic environments can be divided into 5 zones vertically including significant typical meteoric environment at depth of 0-27 m; the complex diagenetic environment of predominately meteoric and secondly marine at depth of 27-42 m; meteoric environment with weak influence of marine environment at depth of 42-105 m; relatively distinct evidences of both meteoric and marine environments at depth of 105-172 m; obvious marine environment at depth of 172.00-214.89 m.