Two disequilibrium quartz-feldspar O-18/O-16 fractionations within the Aral granite batholith, Altay Mountains of China: Evidence for occurrence of two stages of O and H isotopic exchange of a heterogeneous granite system with aqueous fluids

	Two disequilibrium quartz-feldspar O-18/O-16 fractionations within the Aral granite batholith, Altay Mountains of China: Evidence for occurrence of two stages of O and H isotopic exchange of a heterogeneous granite system with aqueous fluids
	Liu, W
刊名	JOURNAL OF PETROLOGY
	2000-09-01
卷号	41 期号:9 页码:1455-1466
关键词	Altay granite initial O-18/O-16 heterogeneity pseudoisotherm quartz-feldspar O-18/O-16 reversal
ISSN号	0022-3530
英文摘要	O-18/O-16 and D/H isotope compositions are reported for coexisting quartz, feldspar and biotite from four lithological units within the Aral granite batholith, Altay Mts of China. The data exhibit a reversed and an anomalously large positive quartz-feldspar O-18/O-16 fractionation. These two O-18/O-16 fractionations, together with a marked decrease in the delta D values of biotite, are interpreted in terms of a model involving two stages of isotopic exchange with aqueous fluids. The first stage of O-18/O-16 exchange with an O-18-rich aqueous fluid occurred during subsolidus cooling. Kinetic effects of the first stage of O-18/O-16 fractionation that was recorded in the megacrystic coarse-grained granites of Group I and the megacryst-bearing mdium- to coarse-grained granites of Group II. Robust parameters for the first stage of exchange are obtained by modelling on the hypothesis of initial (18O)/O-16 heterogeneity in the granite plus subsolidus O-18/O-16 exchange. The spread in the measured delta(18)O values of quartz reflects the initial heterogeneity of the granite. Calculated isochrons illustrate that an initially heterogeneous system reacting with an externally buffered fluid can generate arrays that mimic isotherms. The second stage of isotopic exchange with O-18- and D-depleted meteoric water occurred after magma solidification, resulting in the anomalously large positive quartz-feldspar O-18/O-16 fractionation and a marked decrease in the delta D values of biotite. These kinetic effects have been recorded in the finer-grained granites of Groups III and IV. However, the coarser-grained granites of Groups I and II have essentially survived the second stage of O-18/O-16 exchange.
语种	英语
出版者	OXFORD UNIV PRESS
WOS记录号	WOS:000089337000005
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/75842]
专题	中国科学院地质与地球物理研究所
通讯作者	Liu, W
作者单位	Acad Sinica, Inst Geol & Geophys, Res Ctr Mineral Resources Explorat, Beijing 100101, Peoples R China
推荐引用方式 GB/T 7714	Liu, W. Two disequilibrium quartz-feldspar O-18/O-16 fractionations within the Aral granite batholith, Altay Mountains of China: Evidence for occurrence of two stages of O and H isotopic exchange of a heterogeneous granite system with aqueous fluids[J]. JOURNAL OF PETROLOGY,2000,41(9):1455-1466.
APA	Liu, W.(2000).Two disequilibrium quartz-feldspar O-18/O-16 fractionations within the Aral granite batholith, Altay Mountains of China: Evidence for occurrence of two stages of O and H isotopic exchange of a heterogeneous granite system with aqueous fluids.JOURNAL OF PETROLOGY,41(9),1455-1466.
MLA	Liu, W."Two disequilibrium quartz-feldspar O-18/O-16 fractionations within the Aral granite batholith, Altay Mountains of China: Evidence for occurrence of two stages of O and H isotopic exchange of a heterogeneous granite system with aqueous fluids".JOURNAL OF PETROLOGY 41.9(2000):1455-1466.