扬子克拉通后太古宙碎屑沉积岩地球化学及其构造意义

王选策; 高山; 刘勇胜

扬子克拉通后太古宙碎屑沉积岩地球化学及其构造意义

王选策¹,
高山^{1, 2},
刘勇胜¹

1.
中国地质大学地球科学学院, 湖北武汉 430074
2.
西北大学地质学系大陆动力学实验室, 陕西西安 710069

基金项目:

国家自然科学基金重点项目 40133020

详细信息

中图分类号: P591
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出版历程
- 收稿日期: 2002-12-25
- 刊出日期: 2003-05-25

Geochemical Evolution of Post-Archean Pelites from Yangtze Craton and Its Tectonic Significance

1.
Faculty ofEarth Sciences, China University ofGeosciences, Wuhan 430074, China
2.
Key Laboratory of Continental Dynamics, Department ofGeology, Northwest University, Xi'an 710069, China

摘要

摘要: 系统分析了扬子克拉通从中元古代到白垩纪不同时代8个碎屑沉积岩的主量元素和微量元素成分.这8个样品的REE分配模式与全球典型细粒碎屑沉积岩PAAS、NASC、ES及全球平均大陆上地壳一致.志留纪—泥盆纪样品以高w (La) /w (Co)、w (La) /w (Sc)、w (Th) /w (Co)、w (Th) /w (Sc) 比值为特征, 物源上表现出北秦岭的特征, 表明扬子克拉通曾与华北克拉通南缘的北秦岭在志留纪—泥盆纪对接.
- 碎屑沉积岩 /
- 源区 /
- 上地壳 /
- 地球化学 /
- 扬子克拉通
Abstract: The North China and Yangtze cratons, the most important tectonic units of China, finally coalesced via collision with the formation of the E-W-trending Qinling Mountains. The North Qinling and South Qinling belts constitute the southern active margin of the North China craton and northern China passive margin of the Yangtze craton, respectively. Both the North China and Yangtze cratons and the North Qinling belt, characterized by a relatively uniform, non-evolutionary composition of clastic sediments in post-Archean La-Th-Sc-Co system, can be distinguished from each other in provenance in terms of La/Co, La/Sc, Th/Co, Th/Sc ratios. Systematic chemical compositions are analyzed (by ICP-MS ELAN 6100 DRC) for Cretaceous to Meso-Proterozoic sediments from the Yangtze craton. The REE patterns of these clastic sedimentary rocks are similar to those of the global typical sedimentary rocks such as PAAS, NASC, ES and the global upper continental crust (UC).The Silurian and Devonian pelites are characteristic of North Qinling belt with high La/Co, La/Sc, Th/Co, Th/Sc ratios. The value of δ (Eu) is sensitive to the mafic material. When the mafic material become a kind of provenance, the value of δ (Eu) changes from 0.61-0.62 to 0.68-0.69, showing that the Yangtze craton accreted to the North Qinling on the southern margin of North China cratons in the Silurian-Devonian period.
- clastic sedimentary rock /
- provenance /
- upper crust /
- geochemistry /
- Yangtze craton

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图 1 扬子克拉通后太古宙泥质岩稀土元素分配模式

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图 2 扬子克拉通后太古宙泥岩元素比值变化

Fig. 2. Variation of element ratios in post-Archean pelites from Yangtze craton

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图 3 扬子克拉通后太古宙泥质沉积岩全岩Ce异常

Fig. 3. Variation of Ce anomaly in post-Archean pelites from Yangtze craton

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表 1 扬子克拉通后太古宙碎屑沉积岩(泥质岩) 化学组成

Table 1. Chemical composition of post-Archean pelites from Yangtze craton

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