长江中下游地区二叠纪碳酸盐斜坡沉积及其成矿意义  

Deposition of carbonate slope and ore-forming in Permian strata in the Middle-Lower Reaches of the Yangtze River,east China

作　　者：李双应[1] 孟庆任[2] 万秋[1] 孔为伦[1] 何刚[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩石学报》2008年第8期1733-1744,共12页Acta Petrologica Sinica

基　　金：安徽省自然科学基金项目(9075507);国家自然科学基金项目(40572076);中国石化总公司项目资助

摘　　要：长江中下游地区二叠系发育,主要由碳酸盐岩、硅质岩和碎屑岩组成。其二叠系不仅是华南地区最重要的烃源岩,而且也是长江中下游铜等多金属成矿带的重要赋矿层位之一,因此,进一步确定其沉积相以及古地理意义重大。发育在长江中下游地区的二叠系以往多被认为主要属于浅水碳酸盐台地沉积,其次是较深水的陆棚沉积或者裂陷槽沉积。但进一步研究发现,二叠系的碳酸盐斜坡沉积相发育,它主要由砾屑石灰岩、泥晶粉屑灰岩、硅质岩和泥晶灰岩组成,斜坡主要发育于中二叠世的栖霞期和茅口期,其次是吴家坪期和长兴期。碳酸盐斜坡主要沿安徽铜陵—东至—宿松一线以及湖北大冶—江西瑞昌一线分布,其成因大致受江南断裂和长江断裂控制。同沉积断裂不仅控制着碳酸盐斜坡的发育和展布,同时也构筑了深水盆地、斜坡和浅水台地沉积体系,构成油气生、储、盖单元的组合,为二叠系成为华南地区最重要的烃源岩提供了成因解释。控制斜坡发育的断裂既可以是含矿热水溶液、海底热泉和火山的通道,同时斜坡带也可以成为金属硫化物矿床的富集场所,因此,它对长江中下游铜多金属成矿带的层控和喷流成因提供了可选择的解释。长江中下游地区中、晚二叠世断裂发育,显示盆地的伸展特征,符合古特提斯洋东扩构造背景。The Permian developed in the Middle-Lower Reaches of the Yangtze River （MLRYR） mostly consisted of carbonate rocks, siliceous rocks, elastic rocks and some shale. The Permian is not only one of the most important source rocks of oil and gas but also one of the most important ore-bearing sequences of copper multimetal ores in the MLRYR. Therefore, it is necessary further to study on the Permian sedimentary facies and palaeogeography in the MLRYR. Permian sediments in the MLRYR had been regarded as mostly belonging to deposit of shallow carbonate platform and secondly to deposit of deep shelf or rift valley. Based on our study for recent years, rich deposits from carbonate slope in Permian have been recognized, the petrofacies is consisted of limestone conglomerate, sand silicic wackestones, siliceous rocks and mierite. The carbonate slope developed mostly in Qixia and Maokou stages and secondly Wujiaping and Changxing stages, and distributed along the trend from Tongling, through Susong and Ruiehang, to Daye, and their development may be controlled by faults such as the Jiangnan and Changjiang faults. The sedimentary system of carbonate slope with shallow platform and deep basin provided condition for forming association of oil and gas generating, reserving and caproek, and it can be understood why Permian is important source rocks of oil and gas in South China. The faults can also become the passageway of the hydrothermal and volcanic matter, and the faults and slopes may supply the room for ore-forming, therefore it gave an explanation to can be chosen for the origin of bedded sulfide ore and exhalative process in the coppor-muhimetal ore-forming belt of the MLRYR. The Middle-Late Permian faults developing in the MLRYR characterized the stretch feature of the basin, and it reveals spreading toward east of tectonic setting of palaeo-Tethys.

关 键 词：碳酸盐斜坡 沉积相 成矿意义 二叠系 长江中下游地区 

分 类 号：P588.245[天文地球—岩石学]