- 责任者：Qiu Xiaofei (Isotope Geochemistry Laboratory ; Wuhan Center ; China Geological Survey ; Wuhan 430205 ; China) ; Ling Wenli
- 刊名：Geological Bulletin of China
- 出版年：2013
- 卷期：32(9)
- 关键词：火山岩 ; volcanic rocks ; 铪同位素 ; hafnium isotopes ; 湖北 ; Hubei Province
- 页码：p.1394-1401
- 图表：5 illus., 1 table, 34 refs.
- 分类号：0801
- issnNo：ISSN1671-2552
- isbnNo：CN11-4648/P
Based on documented geochronological and whole-rock geochemical data, this paper reports for the first time the zircon Hf isotopic composition of the Shennongjia andesitic ignimbrite, with the purpose of constraining the magmatic source and petro- genesis. The results obtained by the authors reveal that the Nd-Hf decoupling occurs in the rocks. Although the samples have rel- atively constant elemental geochemical characteristics and Nd isotopic composition, highly variable zircon 8,c（t） values （-24.0-＋0.3） are existent in a single sample, corresponding to zircon Hf isotope model age （Try, a） of 2587-1608 Ma and suggesting that terrestrial clastic components contamination occurred during the generation and upwelling of magma. Such a component evidently modified part of the zircon Hf isotopic composition during magma crystallization but did not affect the whole geochemical and Nd isotopic composition, revealing that the zircon in-situ Hf isotope was more sensitive to the clastic contamination than whole-rock Nd iso- tope during the formation and evolution processes of magma. Combined with whole-rock geochemical features, this paper points out that the Shennongjia andesitic ignimbrite might have been derived from Proterozoic mafic lower crustal anatexis caused by up- welling of mantle-derived magma, and experienced the contamination of subducted clastic rocks during its upwelling.