2.7 Ga juvenile crust formation in the North China Craton (Taishan-Xintai area, western Shandong Province): Further evidence of an understated event from U–Pb dating and Hf isotopic composition of zircon

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• 作者：Yusheng Wanup>aup>up> ; up>up>bup>up> ; up>up>wanyusheng@bjshrimp.cnup> ; Dunyi Liuup>aup>up> ; up>up>bup> ; Shijin Wangup>cup> ; Enxiu Yangup>cup> ; Wei Wangup>aup>up> ; up>up>bup> ; Chunyan Dongup>aup>up> ; up>up>bup> ; Hongyin Zhouup>bup> ; Linli Duup>bup> ; Yueheng Yangup>dup> ; Chunrong Diwuup>eup>
• 关键词：Neoarchean ; Supracrustal rocks ; TTG rocks ; SHRIMP U&#x2013 ; Pb dating ; Hf isotope ; Western Shandong province ; North China Craton
• 刊名：Precambrian Research
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：186
• 期：1-4
• 页码：169-180
• 全文大小：2817 K

文摘

The evolution of the North China Craton (NCC) is well known for a marked 2.55–2.50 Ga tectonothermal event. However, supracrustal and intrusive rocks of 2.75–2.70 Ga are in fact widely distributed in the western Shandong Province, the most important area of Archaean basement in the eastern part of the NCC. This paper reports SHRIMP U–Pb dating and LA-ICPMS Hf isotopic composition of zircons from 2.75–2.70 Ga supracrustal and trondhjemite–tonalite–granodiorite (TTG) rocks in that area. Three fine-grained (hornblende) biotite gneiss samples (known locally as leptynite, with meta-volcanic or volcanosedimentary rock protoliths) and five TTG samples have SHRIMP zircon U–Pb ages varying from 2.75 to 2.70 Ga and 2.74 to 2.71 Ga, respectively. Zircons from most of the samples have high positive ub>Hfub>(t) values (+4.7 to +10.0) and tub>DMub>(Hf) ages (2.85–2.60 Ga) similar to their zircon U–Pb ages. This indicates that the rocks represent largely juvenile crustal additions derived from depleted mantle only a short time before. However, some granitoids show ub>Hfub>(t) zircon values of −13.6 to +5.1 and tub>DMub>(Hf) of 3.51–2.80 Ga. Therefore, the strong 2.75–2.70 Ga tectonothermal event in the western Shandong Province involved not only juvenile addition to the continental crust but also intracrustal recycling of older components. Combined with craton-wide data, it is shown that the NCC is similar to many other cratons around the world where tectonothermal events of 2.7 Ga are well developed. However, the main difference is that in the NCC, superimposed 2.5 Ga tectonothermal events were much stronger than in most other cratons.