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Early Cretaceous bimodal magmatism related epithermal mineralization: A case study of the Gaosongshan gold deposit in the northern Lesser Xing'an Range, NE China
被引:12
|作者:
Liu, Yang
[1
]
Chu, Xiaolei
[1
]
Sun, Jinggui
[1
,2
]
Han, Jilong
[1
]
Ren, Liang
[1
]
Gu, Alei
[3
]
Zhao, Keqiang
[4
]
Zhao, Chuntao
[1
]
机构:
[1] Jilin Univ, Coll Earth Sci, Changchun 130061, Peoples R China
[2] Minist Land & Resources China, Key Lab Mineral Resources Evaluat Northeast Asia, Changchun 130061, Peoples R China
[3] China Geol Survey, Tianjin Ctr Geol Survey, Tianjin 300170, Peoples R China
[4] Chinese Acad Geol Sci, Geophys & Geochem Prospecting Acad, Langfang 065000, Peoples R China
基金:
中国国家自然科学基金;
关键词:
Zircon U-Pb dating;
Geochemistry;
Bimodal volcanism;
Gaosongshan deposit;
Northern Lesser Xing'an Range;
China;
TECTONIC IMPLICATIONS CONSTRAINTS;
ND ISOTOPIC EVIDENCE;
U-PB GEOCHRONOLOGY;
ZIRCON U;
VOLCANIC-ROCKS;
PORPHYRY CU;
MO DEPOSIT;
HF ISOTOPE;
GEOCHEMICAL CHARACTERISTICS;
METALLOGENIC SYSTEM;
D O I:
10.1016/j.oregeorev.2020.103563
中图分类号:
P5 [地质学];
学科分类号:
0709 ;
081803 ;
摘要:
Low-sulfidation (LS) gold mineralization is partially associated with bimodal volcanism in origin. Sources of ore mineralized fluids and relevant dynamic processes remain poorly understood. To better understand these issues, a study including deposit geology, petrology, zircon U-Pb dating, and element and Sr-Nd-Hf isotope geochemistry of bimodal volcanic rocks at Gaosongshan was conducted. The bimodal volcanic rocks are composed of andesitic rocks (basalt andesite-andesite-trachyandesite-andesitic pyroclastic) of the Meifeng Formation and overlying rhyolite lava of the Fuminhe Formation cut by equivalent porphyry stocks, which contain pyrite bearing granular-textured quartz cavity with a sugary appearance, with trapped single-phase magmatic fluids. The andesitic suite formed at approximately 106-108 Ma, prior to eruption of the younger rhyolitic magmas (105.6 +/- 1.7 Ma; n = 13, MSWD = 1.2). The andesites show calc-alkaline affinities, which is a subductionrelated characteristic, and show moderate La/YbN (7.91-11.36) and weakly negative europium anomalies (0.80-1.02), indicating a source in the asthenospheric mantle with varying contamination by both subduction and continental materials. A-type rhyolitic rocks are geochemically comparable to the andesitic suite, and their higher La/YbN (13.01-30.05) and lower Eu/Eu* (0.66-0.73) indicate evolved products of andesitic magmas. The estimated oxygen fugacity of dry (<1.2% water) rhyolite lava is FMQ -1.87, whereas rhyolite porphyry is more oxidized (FMQ + 0.12) and water rich (2.5-2.8%) with probably being water saturated at 2.0-2.4 km depths. Therefore, it is assumed that the essential constraints of bimodal magmatism on epithermal gold mineralization are sequential processes from ascending and gradual differentiation of crustal-level mantle-derived basaltic magmas to releases of hydrothermal solutions from the silica-rich magma reservoir at shallower levels. Most importantly, the oxygen fugacity of and the fluid fluxes from dry rhyolitic melts are critical restricting parameters for the limited reserves at Gaosongshan; thus, this research contributes objective evidence for investigations of deposit genesis and prospecting targets.
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页数:20
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