摘要
通过对西科1井岩心碳酸盐岩样品进行矿物组成分析,来研究礁体的发育过程和古海洋环境的变化.初步研究结果表明：西科1井岩心碳酸盐岩的矿物由低镁方解石、高镁方解石、文石和白云石组成.矿物组成特征表明,井深35.4m处为一重要的地层界面或环境变化界面.在岩心（井深0~748m）中共识别出5个白云岩层,其中上新统莺歌海组一层（井深：289.3~312.3m,厚约23m）,上中新统黄流组三层（分别位于井深：373.3~412.7m,厚约39.4m;424.7~450.6m,厚约26.1m;469.70~564.96m,厚约95.2m）,中中新统梅山组一层（井深：615.20~636.96m,厚约21.7m）.各层的白云岩化程度不尽相同,5层白云岩中白云石矿物含量的最大值在79.3%~100%之间.生物礁的发育主要受控于古海洋环境的变化,与古气候变化有关的海平面升降间接地控制了岛礁碳酸盐岩的白云岩化作用.石岛西科1井中的5层白云岩应该是在较长时间稳定环境条件下发育而成,主要应该是蒸发泻湖渗透回流作用下早期形成的方解石类碳酸岩白云岩化的结果,但并不排除混合水白云岩化作用的可能性.
The reef carbonate rocks of well Xike-1 are analyzed for mineral compositions to explore the development process of reef and paleo-ocean environmental changes. It is found that carbonate minerals in the core of well Xike-1 are mainly composed of calcite （ low-Mg and high-Mg）, aragonite and dolomite. Mineral characteristics suggest that there is an important strati- graghic or environmental change interface at the core depth of 35.4 m. Five dolomite layers have been identified in the core（0- 748 m） including one layer （289.3--312.3 m core depth） in the Yinggehai Formation of Pliocene, three layers （373.3--412.7 m, 424.7--450.6 m and 469.70--564.96 m respectively） in Huangliu Formation of Upper Miocene, and one layer （615.20-- 636.96 m） in the Meishan Formation of Middle Miocene. The biggest value of dolomite contents varies from 79.3% to 100%, indicating dolomitization difference in different dolomite layers. The development of the reef is mainly controlled by paleo-ocean environment changes and dolomitization of island reef is associated with sea-level changes controlled by paleoclimate events, such as the formation of ice sheet in Arctic in Pliocene, Messinian event in Late Miocene and expansion of ice sheet in Antarctic in Middle Miocene. The five dolomite layers should have been developed during a long-term stable environment mainly by the lagoon seepage-refluction model and possibly by mixed-water model.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2015年第4期597-605,共9页
Earth Science-Journal of China University of Geosciences
基金
中国海洋石油总公司项目(No.CNOOC-2013-ZJ-01)
国家重大专项(No.2011ZX05025-002-02-04)
