Fingerprinting the Hydrothermal Fluid Characteristics from LA-ICP-MS Trace Element Geochemistry of Garnet in the Yongping Cu Deposit, SE China

被引:24
作者
Zhang, Yu [1 ]
Liu, Qingquan [2 ,3 ]
Shao, Yongjun [3 ]
Li, Hongbin [4 ]
机构
[1] Chinese Acad Sci, Guangzhou Inst Geochem, Key Lab Mineral & Metallogeny, Guangzhou 510640, Guangdong, Peoples R China
[2] Cent South Univ, Sch Resources & Safety Engn, Changsha 410083, Hunan, Peoples R China
[3] Cent South Univ, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha 410083, Hunan, Peoples R China
[4] Akita Univ, Grad Sch Engn & Resource Sci, Akita 0100862, Japan
关键词
trace elements of garnet; fluid inclusion; Yongping Cu deposit; Qin-Hang Metallogenic Belt; RARE-EARTH-ELEMENTS; JIANGXI PROVINCE; COPPER-DEPOSIT; U-PB; SKARN DEPOSITS; GOLD DEPOSIT; SOUTH CHINA; CONSTRAINTS; PETROGENESIS; SYSTEM;
D O I
10.3390/min7100199
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 large Yongping Cu deposit is situated in the eastern Qin-Hang Metallogenic Belt, Southeast China and on the southern side of the Yangtze-Cathaysia suture zone, and is characterized by large stratiform orebodies. Garnet represents the main non-metallic mineral at Yongping, and shows variations in color from dark red to green to light brown with distance from the Shizitou porphyritic biotite granite stock. An in situ elemental analysis using EPMA and LA-ICP-MS and fluid inclusions microthermometric measurement on the Yongping garnet were conducted to constrain the hydrothermal and physicochemical mineralization conditions and the ore origin. The Yongping garnet ranges from nearly pure to impure and radite, is characterized by low concentrations of MnO (0.11-0.71 wt %) with a wide range of Y/Ho (2.1-494.9) and does not exhibit any melting inclusions or fluid-melt inclusions, indicating that they are likely to be resulted from hydrothermal replacements. The Yongping garnet is rich in LREEs, Cs, Th, U and Pb; relatively depleted in HREEs, Rb, Sr and Ba; but exhibits distinct Eu anomalies (delta Eu of the dark red, green and light brown garnet range 2.12-20.54, 0.74-1.70 and 0.52-0.85, respectively) with the homogenization temperatures and salinities of the fluid inclusions principally ranging from 387-477 degrees C and 7.8-16.0 wt % NaCl equivalent, respectively. The distinct trace elements and microthermometric characteristics reveal that the garnet was formed in a physicochemical conditions of medium-high temperature, 44-64 MPa pressures, mildly acidic pH levels, and unstable oxygen fugacity, and indicate that they were primarily formed by infiltration metasomatism, quite fitting with the scenario that the preferential entrance of magmatic-hydrothermal fluids derived from the Shizitou stock into the relatively low-pressure fracture zones between the limestone and quartz sandstone in the Yejiawan Formation, and further led to the formation of the Yongping stratiform mineralization.
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页数:27
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