摘要
利用阴极发光和LA-ICP-MS微区定年分析方法,对川东北前陆盆地中生界上三叠统须家河组和中侏罗统上沙溪庙组砂岩中碎屑锆石进行了U-Pb同位素分析,结果显示锆石具多成因类型,年龄具分组分段特征。上三叠统须家河组碎屑锆石年龄值有5组:213～283Ma、312～448Ma、694～710Ma、1430～1988Ma和2133～2708Ma;中侏罗统上沙溪庙组碎屑锆石年龄值有7组:163～194Ma、213～274Ma、404Ma、712Ma、1742～1972Ma、2116～2594Ma和3025～3140Ma。研究表明,川东北前陆盆地沉积物主要为源自秦岭造山带燕山期陆内造山岩浆活动产物(163～194Ma)、晚海西—印支期秦岭俯冲碰撞岩浆活动的产物(213～283Ma;213～274Ma)、北秦岭俯冲造山-构造岩浆作用的物质(312～448Ma;404Ma)、南秦岭南华纪与Rodinia超大陆裂解相关物质(694～710Ma;712Ma)、秦岭造山带褶皱基底(1430～1988Ma;1742～1972Ma)和秦岭造山带变质基底(2133～2708Ma;2116～2594Ma、3025～3140Ma)。结合已有古水流及区域资料综合分析,秦岭造山带与川东北前陆盆地具较好的盆山物质耦合关系。
U-Pb isotope dating of clastic zircons from Mesozoic upper Xujiahe Formation and Middle Juassic Shangshaximiao Formation of the forland basin in northeastern Sichuan was carried out by using cathodoluminescence（CL） imaging and LA-ICP-MS. The result shows that the zircons are characterized by multiple genesis and distinct age grouping. The detrital zircon ages of upper Triassic Xujiahe Formation are divided into 5 groups： 213-283 Ma, 312-448 Ma, 694-710 Ma, 1430-1988 Ma and 2133-2708 Ma. The detrital zircon ages of middle Jurassic Shangshaximiao Formation are divided into 7 groups： 163-194 Ma, 213-274 Ma, 404 Ma, 712 Ma, 1742-1972 Ma, 2116-2594 Ma and 3025-3140 Ma. Our study indicates that the sediments of northeastern Sichuan foreland basin have multiple origins： intra-continental orogenic magmatic activity in the Qinling orogenic belt during the Yanshanian（163～194 Ma）, collisional magmatic activity of the Qinling subduction during the late Hercynian-Indosinian（213～283 Ma;213～274 Ma）, orogeny-tectonic magmatism of northern Qinling subduction; the subduction-tectonic magmatic material in Northern Qinling orogenic belt （312-448 Ma; 404 Ma）, the Rodinia super-continent breakup substances in Nanhua （694-710 Ma; 712 Ma）; folded basement of Qinling orogenic belt （1430-1988 Ma; 1742-1972 Ma） and metamorphic basement of Qinling orogenic belt （2133-2708 Ma; 2116-2594 Ma, 3025-3140 Ma）. Based on the existing paleocurrent and regional geological data, there may exist a better coupling relationship between the Qinling orogenic belt and northeastern Sichuan foreland basin.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2010年第8期1118-1134,共17页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号40972136
40572121
40234041)
中央高校基本科研业务费专项资金(编号CHD2009JC070
CHD2009JC053)
中国石化海相前瞻性项目(编号YPH08006)资助成果
