当前位置:首页 >> 天文/地理 >>

Genesis+of+Cu-rich+Ores+in+Magmatic+Ni-Cu+Sulfide+Deposit


Vol. 88 Supp. 2

ACTA GEOLOGICA SINICA (English Edition)
http://www.geojournals.cn/dzxben/ch/index.aspx http://mc.manuscriptcentral.com/ags

Aug. 2014

ZHAO Yun, XUE Chunji, YANG YongQiang and KE Junjun, 2014. Genesis of Cu-rich Ores in Magmatic Ni-Cu Sulfide Deposit. Acta Geologica Sinica (English Edition), 88(supp. 2): 342-343.

Genesis of Cu-rich Ores in Magmatic Ni-Cu Sulfide Deposit
ZHAO Yun1,2, XUE Chunji1,2, YANG Yongqiang1,2 and KE Junjun1,2
1 School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 2 National key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Beijing

Magmatic Ni-Cu sulfide deposit is one of the major types of deposit that containing Ni, Cu and PGE, and is hosted by mafic-ultramafic intrusions occurring in cratons and orogenic belts. The geological settings and oreforming mechanisms of magmatic Ni-Cu deposits have been well documented in previous studies (Naldrett, 2004; Barnes and Lightfoot, 2005). On the contrary, the Cu-rich ores in magmatic Ni-Cu sulfide deposit have received less attention possibly because of its fewer reserves and difficulties in distinguishing from Ni-rich or PGE-rich ores during exploration. Recently, some Cu-rich orebodies have attracted the interest of many Chinese geologists (i.e., Jinchuan; Jiao et al., 2012; Kalatongke; Gao et al., 2012; Chen et al., 2013; Xiarihamu; Gao, 2013, conference comunication). The studies on the spatial distribution, ore structure, sulfide composition and PGE geochemistry of Cu-rich ores have shown much difference from the other ore types. Therefore, the research on oreforming mechanism of Cu-rich ores can not only point out prospecting orientation, but also are important in understanding the diverse mineralization process of magmatic sulfide deposits.

research has implied that Os, Ir, Ru, and Rh are concentrated in the MSS, whereas Pt, Pd, Au and semimetals (Bi, Te, Sb and As) tended to partition into the residual Cu-rich sulfide liquid (Li et al., 1996; Mungall et al., 2005; Godel and Barnes, 2008; Helmy et al., 2010). The silicate magma solidified at or above 1,000° C, whereas the Cu-rich sulfide liquid solidified when the temperature decreases to below 900°C. Thus, the Cu-rich sulfide liquid can migrate into dilatent spaces in the footwall or the hanging wall or along the contact between the country rock and solid mafic-ultramafic intrusions to form veins even that extend into the country rock (Naldrett. 2004; Barnes and Lightfoot. 2005). Jiao et al. (2012) summarized the genesis of Cu-rich ores in the segmentⅠexploration line 6-7 with altitude of 1120 m at Jinchuan: sulfide experiences MSS, and then the residual sulfide and Cu-, Pt-, Pd-rich concentrates are influenced by gravity and tectonic activities. This viewpoint shares many similar opinions with Chen et al. (2013). In these cases the Cu-rich veins should represent fractionated sulfide liquid.

1 The Present Genesis Theory of Cu-rich Ores Within Cratons
Magmatic sulfide ores are resulted from droplets of immiscible sulfide-oxide liquids within silicate magma, and then concentrating in particular processes (Naldrett. 2004). Barnes and Lightfoot (2005) proposed that the vein material from Noril’sk and Cape Smith in cratons probably represents Cu-rich fractionated liquid. The forming mechanism of Cu-rich ores in cratons can be summarized as follow: with decrease of temperature, the sulfide liquid fractionated to Fe-rich monosulfide solidsolution (MSS) cumulate and a Cu-rich sulfide liquid (Barnes and Lightfoot, 2005). Experimental and empirical
* Corresponding author. E-mail: 2008zhaoyun.love@163.com

2 The Studies on Cu-rich Ores from Some Typical Deposits Within Orogenic Bselt
Many important magmatic Ni-Cu sulfide deposits are distributed in the southern margin of the Central Asian Orogenic Belt (CAOB), such as the Kalatongke, Tulargen in eastern Xinjxiang, NW China. The Kalatongke Cu-Ni sulfide deposit appears to have formed from two different pulses of PGE-poor and Cu-rich magmas that underwent different degrees of assimilation and fractional crystallization (Gao et al., 2012). On basis of the intercalated relationship of the ore types in Tulargen (Fig. 1), we propose the sequence of the ores from early to late stages are as follow: disseminated Ni-rich ores →disseminated Ni-Cu-rich ores→ weakly disseminated Cu ores→ disseminated Cu-rich ores→ Cu-rich ore vein. 342

ACTA GEOLOGICA SINICA (English Edition)

Vol. 88 Supp. 2

Aug. 2014

from the segregation and fractionation of the same sulfide melts. On the contrary, the mechanism of Cu-rich ores occurring in orogenic belt is much more complex, and the sulfide ores may result from different magma pulses.

Acknowledgement
We thank Hui Weidong, Wu Jian, Yong Wenfu and Wang Huqiang of the Hexin mine for sharing their knowledge about the the mining status of Tulargen and their assistance in our filed work. The manuscript benefited enthusiastic helps from Zhaoxiaobo of China University of Geosciences. References
Chen Liemeng, Song Xieyan, Reid R. KeaYS, Tian Yulong, Wang Yushan, Deng Yufeng, and Xiao Jiafei ., 2013. Segregation and Fractionation of magmatic Ni-Cu-PGE sulfides in the Western Jinchuan Intrusion, Northwestern China: insights from Platinum Group Element geochemistry. Economic Geology, 108: 1793-1811. Jiao Jiangang, Tang Zhongli, Yan Haiqing, Xu Gang, He Ke and Duan Jun., 2012. PGE characteristics of Cu-rich ores in the Jinchuan Cu-Ni sulfide deposit and its genesis. Northwestern Geology, 45(4):242-253 (in Chinese with English abstract). Gao Jianfeng, Zhou Meifu, Peter C. Lightfoot, Wang Christina Yan and Qi Liang. 2012. Origin of PGE-poor and Cu-rich magmatic sulfides from the Kalatongke Deposit,Xinjiang, Northwest China. Economic Geology, 107: 481-506. Gao Yongwang. 2013. Geological characteristics and prospecting significance of Xiarihamu Cu-Ni magmatic sulfide deposit. The sixth national metallogenic theory and prospecting method academic seminar. Barnes, S-J. and Lightfoot, P.C. 2005. Formation of magmatic nickel-sulfide ore deposits and processses affecting their copper and platinum-group element contents. In Hedenquist, J.W., Thompson, J.F.H., Goldfarb, R.J. and Richards, J.P. (eds.) Economic Geology 100th Anniversary Volume, p. 179213. Anthony J. Naldrett .2004. Magmatic Sulfide Deposits Geology, Geochemistry and Exploration. Berlin: Springer., 727.

Fig. 1. The ore types and their contact and intercalated relationships in Tulargen.
(a). Disseminated Ni-rich ore is cut by Cu-rich ore vein. (b). Disseminated Ni-Cu-rich ore. (c). Disseminated Ni-rich ore is in the the core, whereas weakly disseminated Cu-rich ore is on the rim. (d). Disseminated Ni-rich ore is cut by disseminated Cu-rich ore.

In addition, the PGE characteristics suggest that Cu-rich ores and Ni-rich ores of Tulargen cannot form from the segregation and fractionation of the same sulfide melts. On the contrary, sulfide ores result from different silicate magma pulse. From the discussion above, we can see that the present theories based on cratons cannot summarize the unique mineralization mechanism of magmatic Ni-Cu sulfide deposit within orogenic belt.

3 Conclusion
The Cu-rich vein material of magmatic Ni-Cu sulfide deposit within cratons probably represents Cu-rich fractionated liquid. The Cu-rich ores and Ni-rich ores are

343


相关文章:
河南省西峡县上庵-天宝寨金铜矿床地质特征及矿床成因探讨
mineralization is obviously controlled by structure and magmatic rock. wall ...keywords au-cu deposit; geological characteristics; ore genesis analysis; ...
河南省西峡县上庵-天宝寨金铜矿床地质特征及矿床成因探讨
Mineralization is obviously controlled by structure and magmatic rock. Wall ...Keywords Au-Cu deposit; geological characteristics; ore genesis analysis; ...
Volcanogenic Massive Sulfide Deposits (VMS)
Ore Genesis of the Kal... 暂无评价 11页 ...Volcanogenic Massive Sulfide Deposits (VMS) ...rich magmatic solutions from the heat source over...
10、Mineralizing Fluids
Even for deposits that have an obvious igneous affiliation a question exists...ore genesis is related to the old enigma of where and how magmas ...
更多相关标签: