摘要
应用现代地表不同环境的碳酸盐成岩特征，分析“南永１井”井深１５２ｍ的珊瑚礁岩心的成岩变化，发现这１５２ｍ珊瑚礁层中有３个沉积间断面（分别位于井深１７，９０和１４２ｍ处），分为４个沉积旋回，分属４次海平面上升期建造，３个沉积间断面是３次海平面下降期形成的。
uring May and July, 1990, the Multidisciplinary Oceanographic Expedition Team of The Chinese Academy of Sciences to the Nansha Islands drilled a geological research well named Nanyong-1 Well in Yongshu Reef, Nansha Islands. The core hole was 152m deep and core recovery was 71 %. The core was wholly formed by coral reef. Studies on its sedimentary petrology show that the reef which is 152m thick may be divided into four sedimentary cycles by three sedimentary gap surfaces. The four sedimentary cycles were formed during four periods of sea-level rise, and they are from bottom to top:The first sedimentary cycle (Early Pleistocene)The core section was 152 - 142m deep and did not reach the line of demarcation.This core section was formed during the first period of sea-level rise. During the firstand second periods of the sea-level fall, the calcitization and dolomitization took place respectively in this sedimentary cycle.The secod sedimentary cycle (Early Pleistocene)This core section was 130-90m deep (the core in the depth of 142-130m was akarst cave). It was formed during the second period of sea-level rise. Calcitization tookplace in the second period of sea-level fall. Cementation crust of high Mg-calcite wasformed during the third period of sea-level rise. During the third period of sea-level fall,the cavities outside the cementation crust of high-Mg calcite were filled again with calcite cementation materials.The third sedimentary cycle (Middle Pleistocene and Epipleistocene)This section of the core was 90-17m deep, and was formed during the third periodof sea-level rise. Calcitization took place in the third period of sea-level fall.The fourth sedimentary cycle (Holocene)This section of the core was 17-0m deep. It was formed during the fourth period ofsea--level rise. Diagenesis had not taken place, its sediments were loose organic debrismainly including coral, and the contents of minerals were aragonite and high Mg-calcite.
出处
《热带海洋》
CSCD
1994年第2期1-8,共8页
基金
国家自然科学基金
中国科学院南沙综合科学考察项目
关键词
珊瑚礁
成岩作用
海平面
沉积旋回
Coral reef
diagellesis
sea-level
sedimentary cycle
