Geochemical characteristics and zircon U-Pb isotopic ages of island-arc basic igneous complexes from the Tianshui area in West Qinling

被引：26

作者：

Pei X. ^{[1
]}

Li Z. ^{[1
]}

Liu H. ^{[1
]}

Li G. ^{[1
]}

Ding S. ^{[1
]}

Li Y. ^{[1
]}

Hu B. ^{[1
]}

Guo J. ^{[1
]}

机构：

[1] Faculty of Earth Sciences and Land Resources, Chang'an University

来源：

Frontiers of Earth Science in China | 2007年 / 1卷 / 1期

关键词：

Basic igneous complex; Early Paleozoic; Geochemistry; Island-arc setting; Tianshui area; West Qinling; Zircons U-Pb isotopic ages;

D O I：

10.1007/s11707-007-0008-3

中图分类号：

学科分类号：

摘要：

The Liushuigou intermediate-basic meta-igneous complex at Guanzizhen, Tianshui area, is mainly composed of metagabbro, metagabbro diorite and metadiorite, while the Baihua basic meta-igneous complex consists mainly of pyroxenite, gabbro (gabbro diorite), diorite and quartz diorite. They form a relatively complete comagmatic evolutionary series. The geochemical characteristics of intermediate-basic igneous rocks indicate that they belong to a tholeiite suite. Their chondrite-normalized REE patterns are nearly flat and are LREE-slightly enriched type, and their primitive mantle-normalized and MORB-normalized trace element spider-grams are generally similar; the LILEs Cs, Ba, Sr, Th and U are enriched, while Rb and K and the HFSEs Nb, P, Zr, Sm, Ti and Y are depleted. All these show comagmatic evolutionary and genetic characteristics. The tectonic environment discrimination by trace element reveals that these igneous complexes formed in an island-arc setting. The Thermal Ionization Mass Spectrometry (TIMS) single-grain zircon U-Pb age for the Liushuigou intermediate-basic meta-igneous rocks in the Guanzizhen area is (507.5 ± 3.0) Ma, representing the age of these igneous complexes, which indicates that island-arc-type magmatite rocks in the northern zone of West Qinling are Late Cambrian and also reveals that the timing of subduction of the paleo-ocean basin represented by the Guanzizhen ophiolite and resulting island-arc-type magmatic activity are probably Late Cambrian to Early Ordovician. © Higher Education Press and Springer-Verlag 2007.

引用

页码：49 / 59

页数：10

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