摘要
二叠纪所发生的东吴运动是华南非常重要的构造事件之一。但在构造运动方式、动力学机制以及岩浆-沉积-成矿等方面存在明显的地区差异性。在扬子板块，东吴运动主要发生在中、晚二叠世之间，由地幔柱活动引起，表现为地壳的大规模抬升和大火成岩省的形成；而在华夏板块，东吴运动发生时间相对较早，始于早二叠世晚期，可能由古特提斯洋的俯冲、闭合以及陆陆碰撞引起，主要体现造山作用和前陆盆地的形成以及大量二叠纪花岗岩的侵入。对晚二叠世吴家坪组碎屑锆石所进行的LA-ICPMS U-Pb年龄系统研究表明，扬子和华夏碎屑锆石所构成的年龄频谱和所反映的信息亦存在明显的地区差异。来自扬子板块吴家坪组碎屑锆石年龄主要集中在250～272Ma，峰值为259Ma，这与峨眉山玄武岩的喷发时间非常一致，说明碎屑物质主要来自峨眉山大火成岩省；来自华夏板块龙潭组（相当于吴家坪组）碎屑锆石年龄明显与扬子板块吴家坪组碎屑锆石年龄不一样，华夏龙潭组碎屑锆石年龄变化范围宽广，介于250～3652Ma之间，具有258Ma、290Ma、447Ma、988Ma和1880Ma5个大的峰值以及360Ma、541Ma、823Ma和2500Ma4个小的峰值。这些锆石年龄，除了2500Ma外，在华夏地块中部有同期岩浆岩出露。这说明华夏吴家坪组碎屑物源复杂，源区经历了复杂的地壳演化历史，包括晋宁、加里东和印支等造山作用。华夏板块晚二叠世早期碎屑物源可能通过造山作用和短距离搬运来自华夏本身。
Dongwu Movement is one of the most important geological events in South China during Permian Period. However, there is a significant regional difference in the aspect of tectonism, magmatism and accompanying mineralization, and their dynamic mechanism. A large-scale crustal uplift and the formation of the large igneous province were response to the activity of the Emeishan mantle plume during Middle-Late Permian in the Yangtze Block, whereas fold orogeny, foreland basin formation and large area granite intrusion took place in the Cathaysian Block during late Early Permian to Late Permian, which caused by the subduction and closure of the Paleo-Tethys Ocean and later continental collision between both the Indosinian and South China blocks. Three samples from the Upper Permian Wujiaping Formation provide identical results, ranging from 250Ma to 272Ma, with a significant peak of 259Ma, and indicate their principal derivation from narrow source rocks of the Emeishan large igneous province in the Yangtze Block. In contrast, The age spectrum from six samples of the Upper Permian Longtan （equivalent Wujiaping） Formation is significantly different with a wide age span, ranging from 250Ma to 3652Ma, with five major age peaks at ca. 258Ma, ca. 290Ma, ca. 447Ma, ca. 988Ma and ca. 1880Ma, and four minor age peaks at ca. 360Ma, ca. 541Ma, ca. 823Ma and ca. 2500Ma. These zircon ages, except for 2500Ma, are coeval with exposed magmatic rocks in the Cathaysia Block of southeastern China. This suggests the provenance of the detrital material of the Longtan Formation in Cathaysian Block was from the Cathaysian Block itself through the short distance transportation, and experienced complex crustal evolution, includinz Jinning. Caledonian and lndosinian orogenies
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第10期3592-3606,共15页
Acta Petrologica Sinica
基金
国家重点基础研究发展计划(973)项目(2011CB808901)
国家科技重大专项(2011ZX5023-004-011)
国土资源部公益科研专项(201211024-03)
中国科学院重大项目(KZCX1-YW-15-1)
国家自然科学基金项目(40872080
41072081)联合资助
