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| 西琛1井碳酸盐岩的矿物成分、地化特征及地质意义 | |
| 引用本文： | 魏喜,贾承造,孟卫工,张方礼.西琛1井碳酸盐岩的矿物成分、地化特征及地质意义[J].岩石学报,2007,23(11):3015-3025. |
| 作者姓名： | 魏喜 贾承造 孟卫工 张方礼 |
| 作者单位： | 1. 中国石油,勘探开发研究院博士后流动站,北京,100083;中国石油,辽河油田分公司博士后工作站,辽宁盘锦,124010 2. 中国石油,勘探开发研究院博士后流动站,北京,100083 3. 中国石油,辽河油田分公司博士后工作站,辽宁盘锦,124010 4. 中国石油,辽河油田分公司勘探开发研究院,辽宁盘锦,124010 |
| 基金项目： | 中国地质大学(北京)优秀博士论文扶持奖励基金 |
| 摘 要： | 西沙群岛晚新生代碳酸盐岩是南海形成演化的产物,它的矿物组成、化学成分和Sr同位素组成可以较好地反映其形成时的古海洋环境.西沙群岛西琛1井是南海最深的全取心钻井,揭示3层白云岩和4层石灰岩.其中.白云岩层具有MgO含量高、Sr总量低的特点,同时出现岩盐、赤铁矿和菱锰矿等指相矿物,反映了古海水盐度较高的氧化环境,对应着三个冰期事件;石灰岩层具有MgO含量低、Sr总量高的特点,同时出现菱铁矿和黄铁矿等指相矿物,反映了古海水盐度较低的还原环境,对应着四个间冰期事件.整体上看,西沙群岛晚新生代碳酸盐岩中Sr的总量和87Sr/86Sr自下而上表现为递增趋势,受控于欧亚和印度板块碰撞引起的青藏高原隆升大的构造背景.但又具有明显的分层性,其中,中-上中新统白云岩层Sr含量偏低,而87Sr/86Sr增加趋势明显,与最大一次冰期事件引起的海退和强烈的白云岩化作用有关;上上新统-全新统石灰岩层Sr总量骤增,87Sr/86Sr明显减小,且变化幅度大,与中新世的白云岩化作用和第四纪幔源岩浆强烈喷发有关. |
| 关 键 词： | 古海洋环境 碳酸盐岩矿物和地球化学成分 西沙群岛西琛1井 晚新生代 |
| 修稿时间： | 2007年1月17日 |
Mineral content and geochemistry characteristics of carbonate rock in well No. Xichen-1 and geological significance |
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| WEI Xi,JIA ChengZao,MENG WeiGong,ZHANG FangLi.Mineral content and geochemistry characteristics of carbonate rock in well No. Xichen-1 and geological significance[J].Acta Petrologica Sinica,2007,23(11):3015-3025. | |
| Authors: | WEI Xi JIA ChengZao MENG WeiGong ZHANG FangLi |
| Abstract: | Cenozoic carbonate rocks in Xisha islands are the products of the South China Sea formation and evolution,as a result, their mineral component,chemistry composition,the contents of total Sr,and the ~(87)Sr/~(86)Sr preferably reflect marine paleoenvironment in which the rock formed.As the deepest cored well,Xichen 1 opens out 3 layers of dolostone and 4 layers of limestone.The dolostone terrane bears high MgO content,low total Sr content,and contains some facies minerals,such as rock salt,hematite and dialogite, which represent a high palaeosalinity and oxygenation environment,corresponding with 3 glacial events.The limestone terrane boars low MgO content,high total Sr content,and also contains some facies minerals,such as siderite and pyrite,which represent a low palaeosalinity and reducing environment,corresponding with 4 interglacial events.As a whole,the contents of total Sr,and the ~(87)Sr/~(86)Sr in late Cenozoic carbonate rock increase by degrees from bottom to top,which were controlled by Qinghai-Tibot uplift tectonic setting aroused by collision between Eurasian and Indian plates.While the contents of total Sr and the ~(87)Sr/~(86)Sr in late Cenozoic carbonate rock still present an obviously subsection characteristics.In middle-upper Miocene dolostone,the total Sr content is low,but the ~(87)Sr/~(86)Sr shows an evidently increasing trend,which are related with strong dolomitization and regression caused by the biggest glacier event;In upper-upper Pliocene to Holocene limestone,the total Sr content is high and the ~(87)Sr/~(86)Sr shows an evidently decreasing trend with a large variety range,which are controlled by both dolomitization and violent mantle magma eruption. |
| Keywords: | Marine paleoenvironment Mineral and geochemical composition of reef carbonates Xisha Islands Late Cenozoic |
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