| 摘要: |
| 冈底斯弧背断隆区东西向分布的巨斑状花岗闪长岩获得217Ma的单颗粒锆石U—Pb年龄，首次精确地肯定冈底斯地区存在印支期岩浆活动，200Ma左右的花岗闪长岩在冈底斯弧背断隆区有较广泛的分布。综合最新获得的统计资料，雅鲁藏布江缝合带南侧的上三叠统朗杰学群古水流方向由北向南，碎屑物具有造山带成分特点，冈底斯可能在晚三叠世存在隆起区。岩浆活动和沉积作用表明，冈底斯具有复杂的演化历史，作者将发生在这一地区由晚三叠—早侏罗世构造热事件所形成的造山带称为古冈底斯。 |
| 关键词: 印支期花岗闪长岩 单颗粒锆石 U—Pb年龄 古冈底斯 |
| DOI： |
| 分类号:P534.51 P588.121 |
| 基金项目:中国地质调查局青藏高原1∶25万申扎县幅地质调查项目(20001300009141)部分成果。 |
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| Discovery of Indosinian megaporphyritic granodiorite in the Gangdise area:evidence for the existence of Paleo-Gangdise |
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LI Cai 1 WANG Tianwu 1 LI Huimin 2 ZENG Qinggao 3
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| Abstract: |
| E-W-trending megaporphyritic granodiorite in the Gangdise back-arc fault uplift area has a sin-gle-grain zircon U-Pb age of 217Ma.For the first time it is confirmed that Indosinian magmatic activity occurred in the Gangdise area and that200Ma granodiorite is widely distributed there.The latest statistical data indicate that the direction of the paleocurrents of the Upper Triassic Langjiexue Group on the south-ern side of the Yarlung Zangbo suture is from north to south and that the clastic materials have the fea-tures of an orogenic belt.So an uplift probably existed in the Late Triassic in the Gangdise area.Magmatic activity and sedimentation indicate that Gangdise has a complex evolutionary history.The authors consider that the orogenic belt formed by the Late Triassic-Early Jurassic tectono-thermal event in the area should be called Paleo-Gangdise. |
| Key words: Indosinian granodiorite,single-grain zircon,U-Pb age,Paleo-Gangdise, |
