Experimental evidence for a relationship between liquid immiscibility   and ore-formation in felsic magmas

CORC > 北京大学 > 地球与空间科学学院

	Experimental evidence for a relationship between liquid immiscibility and ore-formation in felsic magmas
	Zhu, YF ; Zeng, YS ; Ai, YF
刊名	applied geochemistry
	1996
关键词	SILICATE MELTS FLUID WATER SPECIATION GLASSES
英文摘要	Geological studies demonstrate that liquid immiscibility in felsic magma closely associates with the ore forming process. In order to obtain experimental evidence demonstrating the relationship between the ore forming process and liquid immiscibility in felsic magma, we carried out a series of experiments at high temperature and atmospheric pressure. The experimental results show that the granite KBF4 similar to Na2MoO4 system is a homogeneous melt at high temperature. With decrease in temperature, however, the melt decomposes into two immiscible melts: silicate melt and ore-forming melt. The ore-forming melt exists as globules in the silicate phase. Molybdenm, Ca, Na, Mg, P, Mn, F, B, and OH are concentrated in these globules. The ore forming melt is characterized with very low SiO2 and Al2O3 concentrations but the concentration of MoO3 and CaO is very high. In contrast, the silicate melts are significantly enriched in SiO2 and Al2O3, and depleted in MoO3 and CaO. In the silicate melt the concentrations of network modifying elements (e.g. Mo, Ca, Na, P, Mg) and volatiles (F, OH) are very low. The differences between the two immiscible melts exist not only in chemical composition but also in structure. The ore-forming melt structurally consists of [MoO4], [MoOF4], [B(OH)(4)], and OH, while the silicate melt is [SiO4]. Because of the difference in composition and structure the two immiscible melts possess different physical properties. Compared to silicate melt, the ore-forming melt has a lower density and viscosity, which permits the globules to behave as bubbles in granite magma and to move and concentrate in the upper part of magma chamber. This process is probably responsible for the concentration of ore-forming elements in the upper part of granite bodies and their immediate aureoles. The present experimental results suggest that liquation in felsic magma can be the first step in the ore-forming process during granitoid evolution. Copyright (C) 1996 Elsevier Science Ltd; Geochemistry & Geophysics; SCI(E); 9; ARTICLE; 3; 481-487; 11
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/156166]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Zhu, YF,Zeng, YS,Ai, YF. Experimental evidence for a relationship between liquid immiscibility and ore-formation in felsic magmas[J]. applied geochemistry,1996.
APA	Zhu, YF,Zeng, YS,&Ai, YF.(1996).Experimental evidence for a relationship between liquid immiscibility and ore-formation in felsic magmas.applied geochemistry.
MLA	Zhu, YF,et al."Experimental evidence for a relationship between liquid immiscibility and ore-formation in felsic magmas".applied geochemistry (1996).