| 摘要: |
| 班公湖蛇绿岩带位于班公湖-怒江结合带西段,蛇绿岩均遭受了强烈挤压构造变形而形成蛇绿混杂岩带。通过对不同类型的蛇绿混杂岩片按正常蛇绿岩层序重新组合排列,恢复后的蛇绿岩层序综合剖面可与典型洋壳剖面对比,自下而上层序为:①变质橄榄岩,主要为强蛇纹石化斜辉橄榄岩和纯橄岩;②堆积岩,由层状辉长岩和层状橄榄岩组成;③辉长辉绿岩岩墙群;④镁铁质熔岩,可分为块状熔岩和枕状熔岩;⑤深海—半深海沉积,岩性为放射虫硅质岩、浊积岩、灰岩等。地质构造和地球化学特征对比综合分析表明,该区蛇绿岩主要形成于中特提斯洋中脊、洋岛环境,中特提斯洋可能为比较成熟的大洋盆地,而不是发育不完全的陆间小洋盆或边缘海盆地。 |
| 关键词: 蛇绿岩 地球化学 班公湖带 西藏 |
| DOI： |
| 附件 |
| 投稿时间：2004-12-15 |
| 基金项目: |
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| Sequences,geochemistry and genesis of the Bangong Lake ophiolites in Xizang |
| CAO Sheng-hua, LIAO Liu-gen, DENG Shi-quan, XIAO Ye-bin, XU Ping |
| (Jiangxi Institute of Geological Survey, Nanchang 330201, Jiangxi, China) |
| Abstract: |
| The Bangong Lake ophiolite zone is aligned to the western part of the Bangong-Nujiang suture zone,where the ophiolites are subjected to severe compression and tectonic deformation,giving rise to the formation of the ophiolitic mélange zone.The restored generalized section of the ophiolite sequences may be comparable with representative oceanic crust sections,including from the base upwards:① metamorphic peridotite composed of highly serpentinized orthopyroxene peridotite and dunite;② cumulates composed of bedded gabbro and peridotite;③ gabbro-diabase dike swarms;④ mafic lava including massive and pillow lava;⑤ abyssal-bathyal sediments composed of radiolarian siliceous rocks,turbidite and limestone.The geological, tectonic and geochemical data show that the ophiolites in the study area were formed in the Meso-Tethyan mid-oceanic ridge and oceanic-island environments.The Meso-Tethyan Ocean may be a mature oceanic basin rather than a small poorly developed intercontinental oceanic basin or marginal sea basin. |
| Key words: ophiolite geochemistry Bangong Lake area Xizang |
