首页|Sr, Nd and O isotope geochemistry of the mafic-ultramafic complexes in the southern margin of the Altay orogenic belt and discussion of their sources

Sr, Nd and O isotope geochemistry of the mafic-ultramafic complexes in the southern margin of the Altay orogenic belt and discussion of their sources

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The Sr, Nd and O isotopic compositions of the Kalatongke and Xibodu mafic-ultramafic complexes from the southern margin of the Altay orogenic belt show that they have similar isotopic compositions, characterized by low(87Sr/86Sr)t and high ∈Nd(t) values (6.3-9.1). It suggests that they were derived from a depleted asthenospheric mantle.However, most of the samples have δ18O values >6‰(5.4‰-10.2‰), indicating crustal contamination. A combi-nation of Sr and O isotopic data shows the incorporation of crustal materials into the depleted mantle. They were pro-duced by the melting of depleted mantle by the incorporation of subducted oceanic crust, and this incorporation might have occurred in the Early Paleozoic in the light of their Nd modelages and regional tectonics. The Kalatongke complex mighthave undertaken the contamination of the upper crust whereas the Xibodu complex does not have any signature of contami-nation of the upper crust. In addition, the similarities of the sources of the two complexes, which were located at the northern and southern sides of the regional Irtysh fault zone respectively, suggest that this fault might not be the boundary between the Altay and Junggar orogenic belts.

mafic-ultramafic complexSrNd and O isotopessource regionAltay orogenic belt

ZHANG Zhaochong、CHAI Fengmei、YAN Shenghao、CHEN Bailin、HE Lixin、HE Yongsheng、ZHOU Gang

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State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China

Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China

Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

No. 4 Geological Party, Xinjiang Bureau of Geology and Resources, Altay 836500, China

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2007

地球科学前沿
高等教育出版社

地球科学前沿

影响因子：0.585
ISSN：2095-0195
年,卷(期)：2007.1(1)
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