Genesis and Fluid Evolution of the Hongqiling Sn-W Polymetallic Deposit in Hunan, South China: Constraints from Geology, Fluid Inclusion, and Stable Isotopes
5
Citation
60
Reference
10
Related Paper
Citation Trend
Abstract:
The Hongqiling is a vein-type Sn-W polymetallic deposit in southern Hunan (South China). It is geologically located on the northern margin of the Nanling metallogenic belt. Based on the mineral assemblage and vein crosscutting relationship, three mineralization stages were identified: Sn-W mineralization (S1: cassiterite, wolframite, scheelite, arsenopyrite, molybdenite, pyrite, chalcopyrite, and quartz), Pb-Zn mineralization (S2: chalcopyrite, pyrrhotite, galena, sphalerite, pyrite, quartz, and fluorite), and late mineralization (S3: quartz, fluorite, calcite, galena, sphalerite, and pyrite). According to laser Raman probe analysis, H2O dominates the fluid inclusions in the S1 and S2 stage quartz, with CO2 and trace N2 following close behind. The ore fluid has low salinity, low density, and a wide temperature range, as per our microthermometric data: the S1 stage has homogenization temperatures (Th) of 236–377.6 °C (average 305.3 °C) and salinity of 3.5–10.7 wt.% NaCleqv; the S2 stage has Th of 206.5–332 °C (average 280.7 °C) and salinity of 1.6–5.1 wt.% NaCleqv; and the S3 stage has Th of 170.9–328.7 °C (average 246 °C) and salinity of 0.2–5.9 wt.% NaCleqv. Based on the results of the aforementioned investigation, the fluid inclusions in quartz, fluorite, and calcite are mainly H2O-NaCl vapor-liquid two-phase. Additionally, examinations of inclusions in S1 wolframite and coexisting quartz using infrared and microthermometry show that the mineralizing fluid likewise belongs to the NaCl-H2O system. The Th of inclusions in wolframite is ~40 °C higher than that of coexisting quartz. Moreover, the fluid experienced a decrease in temperature accompanied by nearly constant salinity, which indicates that wolframite precipitation is due to fluid mixing and simple cooling, and the precipitation is earlier than quartz. In situ S and H-O isotope data show that the samples have δ34S = −2.58‰ to 1.84‰, and the ore fluids have δD = −76.6 to −51.5‰ (S1 and S2), and δ18Ofluid = −6.6 to −0.9‰ (S1) and −12.9 to −10.2‰ (S2). All these indicate that the mineralizing fluid was derived from the granitic magma at Qianlishan, with substantial meteoric water incursion during the ore stage. Such fluid mixing and subsequent cooling are most likely the primary controls for ore deposition.Keywords:
Wolframite
Cassiterite
Arsenopyrite
Molybdenite
Fluorite
Greisen
Fluorite is well known as an excellent tracer for REE fractionation in ore-forming processes (Balashov, 1976; Bau & Dulski, 1992). We present REE data for fluorite from three granite-related Sn–W deposits of the quartz– cassiterite and quartz–wolframite type, located in different regions of Eurasia: Ehrenfriedersdorf (Erzgebirge), Urmi (Russian Far East) and Aqshatau (Central Kazakhstan). Fluorite is a common mineral in all stages of oreformation on these deposits. Normally, REE distribution patterns of fluorites are similar to those of the host granites for endocontact samples, i.e., they are characterized by enrichment in both LREE and HREE and a strong negative Eu anomaly. In exocontact, distinct positive Eu anomalies are observed together with some depletion in HREE (Goldstein et al., 1995; see also Fig. 1, left). In contrast, an unusual REE distribution is found for a rare pale rose or pale blue fluorite in mineral associations relatively uncommon for deposits of the quartz–cassiterite and quartz–wolframite type (Fig. 1, right). Pale rose fluorite occurs in early tourmaline veins with beryl and cassiterite from the Ehrenfriedersdorf deposit (1). The pale rose fluorite in massive quartz–topaz–cassiterite metasomatites from Urmi forms similar intergrowth with tourmaline needles as in Ehrenfriedersdorf (2). In Aqshatau, pale rose fluorite in wolframite-bearing quartz–mica greisen with sericite (3) and pale blue fluorite from quartz-topaz bodies with beryl (4) yield the same REE characteristics as the samples from Ehrenfriedersdorf and Urmi: enrichment in HREE and strong depletion in LREE, occasionally with a weak positive Eu anomaly. Such REE behaviour cannot be explained by the influence of wall rocks (granites, schists, gneisses, etc.), or fractionation between different minerals and fluids within veins or metasomatites. We assume that these REE distribution patterns represent the primary REE characteristics of the fluids.
Cassiterite
Wolframite
Fluorite
Greisen
Tourmaline
Topaz
Cite
Citations (5)
Abstract The formation of sulphide and cassiterite-bearing chlorite-rich greisens in the Navalcubilla granite has been modelled theoretically. Numerical simulation on the reaction of a hydrothermal fluid with a granitic rock predicts assemblages very similar to those found in nature, with progressive formation of muscovite, quartz, chlorite, microcline and plagioclase zones. The hydrothermal alteration of the rock produces a neutralization of the inflowing acid fluid, a drop in the f S 2 and, to a lesser degree, an increment in f O 2 . During hydrothermal alteration, f S 2 and f O 2 change abruptly between metasomatic zones, but chlorite seems to control their major changes. Scheelite and cassiterite are concentrated in the internal zones, while sulphides are related to the more external zones. Fluid-rock reactions seem to be very effective for precipitating cassiterite and scheelite, even from very Sn and W-poor fluids. Appreciable amounts of sulphides are only expected in systems with high concentrations of base metals. Boiling and simple cooling of the fluids acidifies and oxidizes them but chemical changes are not strong enough to induce significant precipitation of ore minerals, at least when the temperature changes are small. Continued circulation of fluids along fractures with previously precipitated quartz + wolframite produces replacement of wolframite by scheelite and sulphides.
Greisen
Cassiterite
Scheelite
Wolframite
Muscovite
Metasomatism
Cite
Citations (1)
This paper is concerned, primarily, with the nature and genesis of the multi mineralic veins at Tekka, Perak, Peninsular Malaysia. The rock types in the area include marble, schist and granite. The granite emplacement and resulting tensional fractures, that trend approximately E-Wand dip northwards, provided passage ways for ascending mineralising agents, and the veins and adjacent country rocks became the sites of deposition of an impressive number of mineral species. The genesis of these mineralised bodies was complex and involved at least three phases of mineralisation that were separated by periods of renewed fracturing. From a mineralogical and temporal point of view the veins can be classified into three main types:- (a) An early quartz-tourmaline type with or without cassiterite, wolframite, arsenopyrite and minor amounts of other sulphide-bearing species. (b) A second (later) type consisting of quartz with or without cassiterite, wolframite, arsenopyrite and minor amounts of other sulphide-bearing minerals. (c) A third, and still later, type consisting of quartz, stannite, other sulphides and sulpho-salts, with or without cassiterite and arsenopyrite. The common non-metallic gangue minerals present are quartz, tourmaline, topaz, sericite, muscovite and fluorite, and, in addition, a number of supergene secondary products which includes varlamoffite. Wall-rock alteration adjacent to the veins includes silicification, tourmalinisation, greisenisation and kaolinisation. The deposit is best classified as xenothermal because of the telescoping of high-temperature mineral species such as cassiterite, columbite/tantalite and wolframite which are closely associated with ones believed to be low-temperature minerals, such as galena and stibnite.
Cassiterite
Arsenopyrite
Wolframite
Topaz
Greisen
Tourmaline
Sericite
Pegmatite
Gangue
Cite
Citations (3)
A study has been made of the Sn-W and sulphide vein mineralization at Cerro Avión and Valdehornillos, south end of the Villar del Ciervo granite (Salamanca, Spain). In this paper we summarize the mineralogical and chemical characteristics of the ore minerals, the processes of hydrotermal alteration, the mineral paragenesis, and the sulphur isotopic ratios of several sulphides. A first mineralization stage resulted in greisenization of the granite and deposition of cassiterite and wolframite, as well as some arsenopyrite disseminated within the greisenized granite. The main mineralization stage formed mostly arsenopyrite, with lesser amounts of other sulphides and bismuth. Scheelite resulted from the transformation of wolframite. Supergenic stage forming scorodite, covellite and iron oxides. Temperatures of formation, as derived from the arsenopyrite and chlorite geothermometers, range from 500 to 450 °C for the first stage, and between 315-250 °C for the main stage. Sulphur isotopes indicate an igneous derivation for the sulphur.
Cassiterite
Arsenopyrite
Wolframite
Greisen
Scheelite
Ore genesis
Cite
Citations (1)
Cassiterite crystals of different deposits from the southeastern and southern Brazil were studied by SEM-EDS techniques. The cassiterite samples are from Sao Joao Del Rei and Monte Belo-Capivara (pegmatites), Bairro Guarau (rare metal granite), Bairro dos Correas (greisen) and Itupeva, Inhandjara and Putuna (greisenized veins). The chemical composition of the crystals and their solid microinclusions were determined. The cassiterite from pegmatites are caracterized by Ta 2 O 5 > 1% and the predominance of niobo-tantalates microinclusions. The cassiterite from greisen and greisenized veins hosts ilmenorutile. Ilmenite, wolframite and bismute microinclusions can occur. The cassiterite from the rare metal granite hosts columbite, columbite-tantalite, ytriocolumbite, ilmenorutile, ilmenite, iron oxide (magnetite), hafnian zircon and wolframite
Cassiterite
Wolframite
Greisen
Pegmatite
Ilmenite
Columbite
Base metal
Cite
Citations (1)
Wolframite
Cassiterite
Greisen
Tourmaline
Columbite
Topaz
Pegmatite
Country rock
Titanite
Ore genesis
Scheelite
Arsenopyrite
Cite
Citations (35)