【作者】 牛新生；

【导师】 王成善；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2009， 博士

【摘要】 异地碳酸盐岩块体是指已固结或半固结的经过一定距离搬运再沉积而产于正常沉积地层中规模较大的碳酸盐岩块,它和碳酸盐碎屑流一起均属于再沉积碳酸盐岩。在南西至甘孜―理塘,北西至东昆仑南缘,北至西秦岭,东南至龙门山的广大松潘地区内发育有多个时代形成的异地碳酸盐岩块体和碳酸盐碎屑流。围绕异地碳酸盐岩块体存在有构造成因说和沉积成因说之争,深入研究异地碳酸盐岩块体和碳酸盐碎屑流有助于揭示区内古生代碳酸盐岩沉积的面貌,进一步认识松潘地区基底性质和三叠系盆地性质。论文以发育于如年各组、香蜡台组、黑斯组和新都桥组中的碳酸盐岩块体以及西秦岭地区的碳酸盐碎屑流为主要研究对象,通过化石鉴定以确定再沉积碳酸盐岩的原始沉积时代,通过微相分析确定再沉积碳酸盐岩的原始环境,通过对寄主沉积层的研究确定了再沉积碳酸盐岩的沉积环境,系统研究了其沉积特征和古地理意义。炉霍―道孚和川主寺地区所发育的异地碳酸盐岩块体和寄主沉积层之间为同沉积关系。异地碳酸盐岩块体出现于火山岩或碎屑岩中,孤立岩块与火山岩相接触的地方常见有烘烤边,并发生大理岩化,出现于碎屑岩中的异地碳酸盐岩块体长轴平行于寄主沉积层,顶部为其顶超,岩块发育常伴有碳酸盐碎屑流沉积,岩块的出现不改变地层的正常沉积序列。炉霍―道孚和川主寺地区的异地碳酸盐岩块体的时代均为晚泥盆世至三叠纪,岩块的原始形成环境为局限海、开阔海、台地―边缘浅滩、台地―边缘礁等碳酸盐台地环境。地球化学和沉积学分析表明,炉霍―道孚和川主寺地区的异地碳酸盐岩块体均是同沉积裂谷作用的产物,后期受到构造作用的改造。松潘地区盆地腹地存在有统一稳定的基底,其上广泛沉积有晚古生代至三叠纪碳酸盐台地沉积。研究区自泥盆纪起一直处于被动大陆边缘持续拉张裂陷的构造环境中,导致了碳酸盐台地多次拉张解体事件。中三叠世安尼期,自北而南,拉张作用逐渐增强,形成了地堑―地垒相间的地理地貌,北秦岭台地、白龙江台地、摩天岭台地、若尔盖隐伏台地及炉霍―道孚孤立台地由北向南分布。炉霍―道孚地区的碳酸盐台地一直持续到晚三叠世卡尼克期。更多还原

【Abstract】 Allochthonous carbonate blocks are exotic biggish carbonate blocks that have an consolidated or semiconsolidated state appearing in normal sedimentary stratum by a long distance transporting and redepositing. Both allochthonous carbonate blocks and carbonate debris flows belong to resedimented carbonates. There are a lot of allochthonous carbonate blocks and carbonate debris flows formed time after time in Songpan area which is Southwest to Ganzi-Litang, Northwest to southern slope of East Kunlun, North to West Qinling, Southwest to Longmenshan. Two opposing views of tectonic genetic and sedimentary genetic had been debating continuously for allochthonous carbonate blocks. The research on allochthonous carbonate blocks and carbonate debris flows will help us reveal the visage of Paleozoic carbonate sediments and recognize further Songpan area basement and Triassic basin property.Allochthonous carbonates blocks in Runiange Formation, Xianglatai Formation, Heisi Formation and Xinduqiao Formation in the hinterland of Songpan area and carbonate debris flows in West Qinling are the research objects of this paper. Determining the original age of resedimented carbonates by fossil, determining the original environments of resedimented carbonates by microfacies analysis, determining the resedimented environments by research on host stratum, its sedimentary features and paleographic implications have been studied systematically.Allochthonous carbonate blocks in Luhuo-Daofu and Chuanzhusi region have a syn-sedimentary relation with host stratum. Allochthonous carbonate blocks appeared in volcanic rock or clastic rock. Contacts between isolated blocks and volcanic rock often have a roasted band and have been metamorphosed into marble. Allochthonous carbonate blocks in clastic rock often were parallel to host stratum with a toplap in block rock top. Allochthonous carbonate blocks often accompanied by carbonate debris flows and never changed normal stratum sequence. The age of allochthonous carbonate blocks in Luhuo-Daofu and Chuanzhusi region is from Late Devonian to Triassic. The origin genetic environments of allochthonous carbonate blocks were restricted sea, open sea, platform-shallow, platform-edge reef and other carbonate platform environments. Geochemistry and sedimentology analysis shows that allochthonous carbonate blocks in Luhuo-Daofu and Chuanzhusi region were the results of syn-sedimentary rift and reconstructed by tectonism later.There is a uniform and static basement with carbonate platform sediments-covered from Ltea Paleozoic to Triassic in the hinterland of Songpan area. Research area existed in a sustaining extension rifting environment of passive continental margin. Carbonate platforms were destroyed many times. The extension increased gradually from north to south in research with a series of grabens and hosts. From north to south, there were North Qingling platform, Bailongjiang platform, Motianling Platform, Ruoergai hidden platform and Luhuo-Daofu isolated platform in Anisian. Luhuo-Daofu carbonate platform deposition ended in Carnian.更多还原