藏北查桑上三叠统复理石沉积大地构造背景的初步探讨
Apreliminary study on the tectonic setting of Upper Triassic flysch at Chasang, North Tibet
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摘要: 藏北羌塘地块的构造性质和构造局是中国地学界长期争论的重要问题。这里人迹罕至,研究程度很低,基础地质资料缺乏。这是有关地质问题得不到解决的根本原因之一。本项研究的首要目的也是为该地区的地质研究提供一份基础资料,羌塘地块腹地查桑地区的上三叠统肖茶上涨且,下部为细碧岩、中基性火山岩、玄武质角砾岩来灰岩和大理岩,上部主要为碎屑岩(复理石)和灰岩,我们在肖茶卡组上部的复理石中采集砂岩、粉砂岩样品,进行主量元Abstract: Is Qiangtang block in North Tibet anancient continental block or fold belt? And how is its composition (tectonic framework)?These are the geological topics still in debate. Qiangtang is far from human society. Itis one of the places in the world with lowest geological working degree. The lacking ofbasic geological data is an important reason, which makes the related geological problemsdifficult to get clear and correct interpretation. Chasang is located at the inner part ofQiangtang. The Upper Triassic Xiaochaka Formation there is composed of spillite, basalt,medium-basic volcanic rocks, basaltic breccia, intercalated with limestone and marble atthe lower part, clastic rocks (flysch) and limestone at the upper part. Sandstone andsiltstone samples were collected from the flysch of the upper part of Xiaochaka to domajor element geochemical analysis for tectonic-setting discrimination. The result of thisresearch indicates that the tectonic setting of Xiaochaka flysch is oceanic island arc ofan active continental margin, and its sedimentary provenance is mainly intermediatevolcanic rocks.
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Key words:
- North Tibet /
- Qiangtang /
- Chasang /
- Xiaochaka Formation /
- Flysch
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