晚三叠世松潘甘孜和川西前陆盆地的物源对比:构造演化和古地理变迁的线索  

The Contrast between Provenances of Songpan—Garze and Western Sichuan Foreland Basin in the Late Triassic:Clues to the Tectonics and Palaeogeography

作　　者：邓飞[1] 贾东[1] 罗良[1] 李海滨[1] 李一泉[1] 武龙[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学系,南京210093

出　　处：《地质论评》2008年第4期561-573,共13页Geological Review

基　　金：国家自然科学基金资助项目(编号40672132;40372091)的成果

摘　　要：为了研究龙门山褶皱冲断带两侧的松潘甘孜和川西前陆盆地在大地构造和沉积学方面存在的联系，笔者等分别在松潘甘孜东缘马尔康－理县地区和川西前陆盆地都江堰地区进行了采样和碎屑锆石的LA—ICPMSU—Pb定年工作。269颗锆石的定年结果显示，中－晚三叠世拉丁期－诺利期松潘甘孜复理石盆地东缘沉积地层中的碎屑锆石年龄主要集中在250～280Ma、1800～1900Ma和2400～2500Ma、200～245Ma、400～450Ma，对应的物源主要为东昆仑岛弧、华北陆块基底、义敦岛弧以及北秦岭。与之相比，川西前陆盆地诺利期－瑞替期的须家河组地层中的碎屑锆石年龄大致主要集中在1800～1900Ma和2400～2500Ma、720～850Ma、950～1200Ma、400～450Ma。该统计结果总体上继承了松潘甘孜数据体的特征，揭示出须家河组物源来自西部——松潘甘孜褶皱带的再旋回沉积和龙门山前陆冲断带。In order to study the relation between Songpan Garze and Western Sichuan Foreland Basin in the aspects of tectonics and sedimentology, writers sampled from the Middle to Upper Triassic （Ladinian to Norian） strata in Ma＇erkang Lixian area in the easternmost part of Songpan--Garze complex and Dujiangyan area in Western Sichuan Foreland Basin for the research of U-Pb geochronology of detrital zircons by LA-ICPMS. Here a total of 269 zircon ages are reported. The analyses indicate that the easternmost part of Songpan--Garze basin derived clast mainly from Eastern Kunlun（with zircons aged 250-280 Ma）, North China block（1800-1900 Ma ＆ 2400-2500 Ma）, Yidun arc（〈245 Ma） and Northern Qinling orogen（400-450 Ma） in the Mid--Late Triassic（Ladinian to Norian）. By contrast, in western Sichuan Foreland Basin, analyses of detrital zircons in the Xujiahe Formation show similar characteristics to data inSongpan Garze, with populations of 1800-1900 Ma, 2400-2500 Ma, 720-850 Ma, 950- 1200 Ma and 400-450 Ma. It is revealed that the deposit was recycled from the Songpan Garze complex and the Longmen Mountains.

关 键 词：松潘甘孜 川西前陆盆地 碎屑锆石 物源 构造演化和古地理重建 

分 类 号：P531[天文地球—古生物学与地层学]