Fluid inclusion and stable isotopic constraints on fluid sources and evolution of the Luojiahe Cu deposit in the southern margin of the North China Craton
Graphical abstract
Introduction
Since the first discovery of active hydrothermal vents at the Galapagos Rift in 1977 (Corliss et al., 1979), the study on ore-forming fluids of volcanogenic massive sulfide deposits (VMS) has expanded (Ripley and Ohmoto, 1977, Spooner and Bray, 1977, de Ronde, 1995, Bodnar et al., 2014). Fluid inclusions (FIs) trapped in hydrothermal minerals provide the best available way for constraining the physical and chemical conditions of ore-forming fluids in fossilized hydrothermal systems (Bodnar et al., 2014). By comparing the modern vent fluid data with FI data from fossilized hydrothermal systems, the compositions and physical nature of the ore-forming fluids, VMS mineralization processes and secular changes of seawater compositions throughout the Earth's history, are becoming better documented (e.g., Ohmoto et al., 1983, de Ronde, 1995, De Ronde et al., 1997, Franklin et al., 2005, Huston et al., 2010, Bodnar et al., 2014).
The Archean greenstone-hosted VMS deposits are the oldest VMS deposits and account for ca. 8% of the global VMS-hosted metal resource (Mercier-Langevin et al., 2014). However, FI studies on these ancient VMS deposits are still rare (De Ronde et al., 1997, Bodnar et al., 2014), because most of these deposits were remobilized by subsequent metamorphism (Marshall and Gilligan, 1993, Tornos et al., 2015). The origin of the ore-forming fluids entrapped in the VMS deposits is highly controversial (Ripley and Ohmoto, 1977, Broman, 1987, Hall, 1989, Giles and Marshall, 1994, De Ronde et al., 1997, Lowe and Byerly, 2003, Moura, 2005, Bradshaw et al., 2008, Xu et al., 2011), especially regarding the preservation of primary FIs, sources of metamorphic carbonic fluids (CO2 or CH4), and the roles of both primary vent fluids and metamorphic hydrothermal fluid systems in the mineralization (Xu et al., 2011).
The Luojiahe Cu deposit is hosted in the Archean greenstone terranes in the Zhongtiaoshan region (hereafter referred to as ZTS), in the southern margin of the North China Craton (Li, 1986). This deposit was argued to be a Neoarchean VMS deposit that was subsequently modified by deformation and metamorphism during the Zhongtiao Movement (ca. 1.85 Ga) (Zhen and Xi, 1990, Zhen et al., 1993, Huang et al., 2001, Jiang et al., 2013). Detailed FI study is essential to constrain the origin and evolution of the Luojiahe ore-forming fluids. In this paper, based on detailed field and petrographic observations and FI analyses, we identified primary FIs in the banded VMS ores and first detected significant CH4 in the hydrothermal quartz veins of the metamorphic mineralization stage. The fluid sources and evolution of the two metallogenic stages were discussed on the basis of FI systematics and C-H-O isotopes. Our study also provides new insight into the understanding of the original submarine hydrothermal processes and the possible role of CH4 in the metamorphic overprinting on the Archean VMS deposits.
Section snippets
Regional geology
The ZTS is located in the southern segment of the Trans-North China Orogen (Fig. 1A), along which the discrete Eastern and Western Blocks amalgamated to form the North China Craton (Zhao et al., 2001, Zhao et al., 2002a, Liu et al., 2012). The Neoarchean to the Late Paleoproterozoic ZTS ore deposits contain a total endowment of ca. 400 Mt. Cu metal (Xu, 2010). Archean rock units in this region consist mainly of low-grade granite-greenstone terranes (2.7–2.5 Ga), including granitoids (Sushui
Wall rocks
The Luojiahe Cu deposit is hosted in metamorphosed mafic volcanic-sedimentary rocks of the Neoarchean Songjiashan Group, which is exposed in the inliers of the younger andesite of the Xiyanghe Group (Gu et al., 1993, Sun and Hu, 1993; Fig. 2). The Songjiashan Group at Luojiahe consists of chlorite schist, spilite and marble (Fig. 3, Fig. 4B, and C). The major orebodies are hosted in graphite-bearing chlorite schist. At Luojiahe, trondhjemite (zircon U-Pb: 2471 ± 25 Ma; Zhao et al., 2016) was
Sample description
In this study, 120 samples were collected from the Exploration Tunnels No. 460 and No. 360 (in Orebody No. 1). Eighty-five (39 polished) thin sections were examined by transmitted- and reflected light microscopy. Fifty-five doubly polished sections for the different ore types were prepared for FI analyses, among which 25 were selected for microthermometry and laser Raman spectroscopy.
Quartz samples were classified into three groups (Q1 to Q3) based on their field occurrence and morphological
Fluid inclusion types
Primary FIs have generally negative crystal- or elliptical shapes, and occur in clusters or as isolated/randomly distributed FIs in quartz. Four primary FI types were identified based on their phases at room temperature (Roedder, 1984, Lu et al., 2004), phase transitions during total homogenization and laser Raman spectroscopy. These FI types were summarized in Table 1 and described in the following sections.
- 1)
L-type (liquid-rich) FIs: They (5 to 23 μm in size) contain 10 to 35 vol.% vapor phases,
Preservation of primary fluid inclusions
The preservation of primary FIs in metamorphosed VMS deposits is highly controversial (Ripley and Ohmoto, 1977, Broman, 1987, Hall, 1989, Giles and Marshall, 1994, De Ronde et al., 1997, Lowe and Byerly, 2003, Moura, 2005, Bradshaw et al., 2008, Xu et al., 2011). Ripley and Ohmoto (1977) first reported that primary FIs in the Raul VMS Cu deposit (Peru) underwent amphibolite-facies metamorphism. Many subsequent studies also supported that primary FIs in metamorphosed VMS deposits could be
Conclusions
- 1.
The Luojiahe Cu deposit underwent two mineralization stages, i.e., primary VMS mineralization (Stage I) and metamorphic remobilization (Stage II). The Stage I ore-forming fluids consist predominantly of evolved seawater (125–220 °C; 23.9–27.9 wt.% NaCl equiv.) and minor magmatic fluids (249–339 °C; 34.5–42.2 wt.% NaCl equiv.).
- 2.
The main Stage I mineralization may have led by 1) fluid mixing of heated evolved seawater and cold seawater in the near-surface environment; and 2) fluid unmixing led by
Acknowledgements
This study was financially supported by the National Basic Research Program of China (no. 2012CB416603). The Zhongtiaoshan Non-Ferrous Metals Group Co., Ltd. is thanked for its field assistance. We thank Drs. Bo Wei and Rongqing Zhang (Guangzhou Institute of Geochemistry, CAS) for their constructive suggestions. Cenozoic Geoscience Editing & Consultancy is thanked for the language editing. This is contribution No. IS-2263 from GIGCAS.
References (111)
- et al.
Seawater-basalt interaction at 200 °C and 500 bars: implications for origin of sea-floor heavy-metal deposits and regulation of seawater chemistry
Earth Planet. Sci. Lett.
(1975) - et al.
Fluid inclusions in hydrothermal ore deposits
Fluid inclusions of the massive sulfide deposits in the Skellefte district, Sweden
Chem. Geol.
(1987)- et al.
Abiogenic Fischer–Tropsch synthesis of methane at the Baogutu reduced porphyry Cu deposit, western Junggar, NW-China
Geochim. Cosmochim. Acta
(2014) - et al.
Baogutu: an example of reduced porphyry Cu deposit in western Junggar
Ore Geol. Rev.
(2014) - et al.
Fluid chemistry of Archean seafloor hydrothermal vents: implications for the composition of circa 3.2 Ga seawater
Geochim. Cosmochim. Acta
(1997) - et al.
Analysis of fluid inclusions in seafloor hydrothermal precipitates: testing and application of an integrated GC/IC technique
Chem. Geol.
(2001) - et al.
SHRIMP and LA-ICP-MS zircon geochronology of the Xiong'er volcanic rocks: implications for the Paleo-Mesoproterozoic evolution of the southern margin of the North China Craton
Precambrian Res.
(2009) Temperature and salinity history of the Precambrian ocean: implications for the course of microbial evolution
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2005)- et al.
A numerical model to estimate trapping conditions of fluid inclusions that homogenize by halite disappearance
Geochim Cosmochim Acta
(2012)
U–Pb geochronology and Hf isotope geochemistry of detrital zircons from the Zhongtiao Complex: constraints on the tectonic evolution of the Trans-North China Orogen
Precambrian Res.
Determination of stable isotope composition in uranium geological samples
World Nucl. Geosci.
Remobilization, syn-tectonic processes and massive sulfide deposits
Ore Geol. Rev.
Geochemical constraints on primary productivity in submarine hydrothermal vent plumes
Deep-Sea Res. I Oceanogr. Res. Pap.
Fluids from the Neves Corvo massive sulfide ores, Iberian pyrite belt, Portugal
Chem. Geol.
The system NaCl-CaCl2-H2O: I. The ice liquidus at 1 atm total pressure
Geochim. Cosmochim. Acta
The P-V-T-X-fO2 evolution of H2O-CH4-CO2-bearing fluid in a wolframite vein: reconstruction from fluid inclusion studies
Geochim. Cosmochim. Acta
Carbon isotopes as biogeochemical recorders of life over 3.8 Ga of Earth history: evolution of a concept
Precambrian Res.
Submarine venting of magmatic volatiles in the Eastern Manus Basin, Papua New Guinea
Geochim. Cosmochim. Acta
The Lost City hydrothermal system: constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes
Geochim. Cosmochim. Acta
Methane-rich fluid evolution of the Baogutu porphyry Cu–Mo–Au deposit, Xinjiang, NW China
Chem. Geol.
Chemical fluxes from hydrothermal alteration of the oceanic crust
Numerical model to determine the composition of H2O–NaCl–CaCl2 fluid inclusions based on microthermometric and microanalytical data
Geochim. Cosmochim. Acta
Controls on the siting and style of volcanogenic massive sulfide deposits
Ore Geol. Rev.
Graphite and carbonates in the 3.8 Ga old Isua supracrustal belt, southern West Greenland
Precambrian Res.
Controls on formation of low-sulfidation epithermal deposits in Mexico: constraints from fluid inclusion and stable isotope data
Precambrian crustal evolution of the Zhongtiao Mountains
Earth Sci. Front.
Source of parental melts to carbonatites–critical isotopic constraints
Mineral. Petrol.
Graphitic carbons and biosignatures
Elements
The Paleoproterozoic Aripuanã Zn-Pb-Ag (Au, Cu) volcanogenic massive sulfide deposit, Mato Grosso, Brazil: geology, geochemistry of alteration, carbon and oxygen isotope modeling, and implications for genesis
Econ. Geol.
A fluid inclusion model for the genesis of the ores of the Dolgellau Gold Belt, North Wales
J. Geol. Soc.
Genesis of the Wolverine volcanic sediment-hosted massive sulfide deposit, Finlayson Lake District, Yukon, Canada: mineralogical, mineral chemical, fluid inclusion, and sulfur isotope evidence
Econ. Geol.
Questioning the evidence for Earth's oldest fossils
Nature
Analysis of phase equilibria in COHS fluid inclusions: mineralogy
From organic matter to graphite: graphitization
Elements
Metamorphic fluids and their relationship to the formation of metamorphosed and metamorphogenic ore deposits
Rev. Econ. Geol.
Equations for calculation of NaCl/(NaCl + CaCl2) ratios and salinities from hydrohalite-melting and ice-melting temperatures in the H2O-NaCl-CaCl2 system
Acta Petrol. Sin.
Multiple sulfur isotope analyses support a magmatic model for the volcanogenic massive sulfide deposits of the Teutonic Bore Volcanic Complex, Yilgarn Craton, Western Australia
Econ. Geol.
Diagnostic fluid inclusions of different types hydrothermal gold deposits
Acta Petrol. Sin.
The tectonic environment for the formation of the Xiong'er Group and the Xiyanghe Group
Geol. Rev.
Oxygen isotope exchange between quartz and water
J. Geophys. Res.
Comparison of stable isotope reference samples
Nature
On the Galapagos Rift
Science
The Mattagami Lake Mine Archean Zn-Cu sulfide deposit, Quebec; hydrothermal coprecipitation of talc and sulfides in a sea-floor brine pool; evidence from geochemistry, 18O/16O, and mineral chemistry
Econ. Geol.
Metamorphic fluids: the evidence from fluid inclusions
Sulfate was a trace constituent of Archean seawater
Science
Fluid Chemistry and Isotopic Characteristics of Seafloor Hydrothermal Systems and Associated VMS Deposits: Potential for Magmatic Contributions. Magmas, Fluids and Ore Deposits
Contrasting fluid types at the Nevoria gold deposit in the Southern Cross greenstone belt, western Australia: implications of auriferous fluids depositing ores within an Archean banded iron-formation
Econ. Geol.
The Strata Division in Songjiashan Subgroup of Jiangxian Group of Late Archean in Zhongtiaoshan Area
Shanxi Metall.
Volcanic-associated massive sulfide deposits
Econ. Geol.
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2018, Ore Geology ReviewsCitation Excerpt :The precision of temperature measurement is ±0.1 °C between −100 and 25 °C, ±1 °C between 25 and 400 °C, and ±2 °C above 400 °C. The analytical procedures are similar to that described by Jiang et al. (2017). Laser Raman analyses were conducted at the Key Laboratory of Mineralogy and Metallogeny, GIGCAS, by using the Horiba Xplora Laser Raman Microspectroscopy.