Chemical compositions of garnet and clinopyroxene and their genetic significances in Yemaquan skarn iron-copper-zinc deposit, Qimantagh, eastern Kunlun

被引:12
作者
Zuo, Pengfei [1 ]
Liu, Xuefei [1 ]
Hao, Jinhua [2 ]
Wang, Yashuai [1 ]
Zhao, Rui [1 ]
Ge, Songsheng [3 ]
机构
[1] China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China
[2] China Univ Geosci, Acad Sci, Beijing 100083, Peoples R China
[3] Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
基金
中国国家自然科学基金;
关键词
Skarn iron-copper-zinc deposit; Prograde skarns; Skarn zonation; Mineralization zonation; Yemaquan; HF ISOTOPIC COMPOSITIONS; LATE TRIASSIC GRANITOIDS; QINGHAI-TIBET PLATEAU; RARE-EARTH-ELEMENTS; GOLD DEPOSIT; STABILITY RELATIONS; METALLOGENIC MODEL; CU MINERALIZATION; FLUID INCLUSION; MINING DISTRICT;
D O I
10.1016/j.gexplo.2015.07.011
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The Yemaquan skarn deposit in the northwestern part of the Qimantagh is located in the eastern Kunlun orogenic belt. The deposit is hosted in carbonate rocks, siltstones, and sandstones of the Cambrian-Ordovician Tanjianshan Group and Late Carboniferous Di'aosu Formation. These rocks are intruded by Triassic calc-alkaline granitoid that extended NW-SE. Three stages of mineralization have been identified, i.e., pre-ore stage, syn-ore stage, and post-ore stage. The prograde skam stage, which corresponds to the pre-ore stage, is dominated by clinopyroxene and garnet. Clinopyroxene is much more abundant than garnet in the deposit and consists of three types of clinopyroxene in the deposit. In terms of the end-members diopside (CaMgSi2O6), hedenbergite (CaFeSi2O6), and johannsenite (CaMnSi2O6), namely, type I (with an average composition of Di(92)Hd(7)Joh(1)) type II (with an average of composition of Di(62)Hd(36)Joh(2)), and type III (with an average composition of Di(24)Hd(54)Joh(22)) occurred from the proximal intrusions to the distal wall rocks. Type I, II, and III clinopyroxenes are associated with copper-iron, iron, and zinc-lead mineralization, respectively. Garnet mostly occurred in the middle of exoskarn zonations and is associated with type II dinopyroxene. The distribution of the garnet in the skarn zonation could be explained by the stability fields of dinopyroxene, which is strongly dependent on composition. Based on mineral assemblages, the formation of type II and type III, comparative to type I clinopyroxene, is in more reduced condition in the distal skarn. Moreover sulfur isotope carried out on sulfide minerals from both the prograde and retrograde stages show a variable and wide range of delta S-34 values (-6.9 to 4.2%. delta S-34), suggesting that the skarn-forming fluid may have been affected by the reduced wall rocks. The low garnet/clinopyroxene ratios observed at the deposit might be caused by the dinopyroxene composition variations and reduced wall rocks. (C) 2015 Elsevier B.V. All rights reserved.
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页码:143 / 154
页数:12
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