Quartz geochemical constraints on fluid evolution during low- to medium-temperature hydrothermal Sb and Au mineralization

Quartz trace elements record information about fluid evolution as well as metal migration and precipitation. Here, we summarize most of the reported (including this study) quartz trace element data (N = ~4,600) generated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) on various textural types and paragenetic stages of quartz in I-type porphyry-epithermal (Cu-Mo-Au-Ag-Te) and S- and A-type granitegreisen (Sn-W and rare metal) systems in the world. The results show that Li versus Al diagrams, combined with Ti-Ge-As-Sb contents, can be used to decipher the source and evolution of fluids in magmatic-hydrothermal systems. In I-type porphyry-epithermal systems, magmatic quartz has low Li/Al ratios from 0.001 to 0.173 (N = 483) with a mean of 0.039 ± 0.032. Hydrothermal quartz has progressively higher Li and Al concentrations that are dominated by cooling along fluid pathways. Quartz evolves from Ti rich to Ge rich from early to late stages in porphyry hydrothermal veins and is As and Sb rich in epithermal veins. In S- and A-type granite-greisen systems, magmatic quartz has high Li/Al ratios from 0.007 to 0.502 (N = 604) with a mean of 0.130 ± 0.063 and from 0.009 to 0.327 (N = 325) with a mean of 0.126 ± 0.065, respectively. Hydrothermal quartz has progressively lower Li and Al concentrations that are dominated by fluid-rock reactions and cooling along fluid pathways. Quartz evolves with decreasing Ti concentrations from magmatic to hydrothermal stages. Ge is abundant in pegmatite quartz in S-type systems. Variations in pH or precipitation rate along fluid pathways have a small influence on Li/Al ratios. The variation of quartz trace elements with elevation in individual systems suggests that they can be used as a vector to guide exploration in magmatic-hydrothermal systems.

Separation of Au and Sb mineralization in the Qukulekedong intrusion-related deposit, East Kunlun Orogen (NW China): Evidence from fluid inclusions, H–O isotopes, and quartz geochemistry

Genesis of gold and antimony deposits in the Youjiang metallogenic province, SW China: Evidence from in situ oxygen isotopic and trace element compositions of quartz

Southwestern Guizhou, China, is famous for hosting clusters of Carlin-type Au, Sb, and Hg-Tl deposits. These deposits are thought to be the products of a low-temperature hydrothermal metallogenic event. Calcite and fluorite are common and widespread gangue minerals in Au and Sb deposits, respectively. Ore-related calcite commonly coexists with stibnite, realgar, and orpiment at the periphery of high-grade orebodies in Au deposits, while ore-related fluorite is generally intergrown with stibnite in Sb deposits. In this study, ore-related calcite and fluorite samples from representative Au (Zimudang) and Sb (Dachang) deposits, respectively, were separated, and the rare earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm–Nd isochron ages were analyzed. This study aims to determine the formation ages of the calcite and fluorite and to constrain the age of low-temperature metallogenic event in Southwestern Guizhou. The calcite and fluorite samples contain relatively high total concentrations of REEs (8.21–22.5 μg/g for calcite, 21.7–36.6 μg/g for fluorite), exhibit variable Sm/Nd ratios (0.51–1.01 for calcite, 0.35–0.49 for fluorite), and yield Sm–Nd isochron ages of 148.4 ± 4.8 and 141 ± 20 Ma, respectively. These ages are consistent with the age range constrained by the low-temperature thermochronology of zircon (132–160 Ma), crosscutting relationships of stratigraphy or intrusions (96–160 Ma), and previous dating results (135–150 Ma) in Southwestern Guizhou. Collectively, the ages obtained in this study add new evidence to previous geochronology studies, such that the low-temperature hydrothermal mineralization in Southwestern Guizhou can be constrained to 135–150 Ma, corresponding to the Yanshanian orogeny, which was associated with a weak extensional tectonic environment.

Quartz chemistry is important for revealing fluid sources and evolution in hydrothermal deposits, but such information is lacking for many epithermal systems and deposit types. To investigate quartz chemistry in this system further, we collected representative samples of quartz from adularia-sericite epithermal Ag deposits in China and determined their chemical compositions. In adularia-sericite epithermal Ag-bearing systems, magmatic quartz from porphyry intrusions and host subvolcanic rocks displays SEM-CL spectral peaks at 360 and 415 nm and exhibits homogenous CL or weak zonal textures (alternating growth zones within individual quartz crystals). Trace elements in magmatic quartz have the lowest Sb concentrations (median = 0.1 ppm; n = 80). Hydrothermal quartz can be classified into type I and type II by CL false color and CL spectral peaks. Hydrothermal type I quartz has spectral peaks at 360 and 415 nm; it exhibits zonal or sector textures and is associated with base metal sulfides and minor Ag mineralization. Such hydrothermal type I quartz has low Sb concentrations (median = 4.5 ppm; n = 839), contains liquid-rich fluid inclusions, and is formed by cooling. The cooling trend is indicated by a positive correlation between the concentrations of Sb and Al, as well as between Li and Al. Hydrothermal type I quartz has an Fe center by electron spin resonance, whereas other centers are missing or weak at room temperature. In general, hydrothermal type II quartz mantles type I quartz. Hydrothermal type II quartz has an ultrahigh-intensity peak (by several orders of magnitude) at 580 nm, zonal textures, and is associated with abundant Ag mineralization. Hydrothermal type II quartz has the highest Sb concentrations (median = 71ppm; n = 185), which remain constant as Al decreases on an Sb vs. Al plot. This quartz has colloform, bladed, or zonal textures and contains coexisting liquid- and vapor-rich fluid inclusions indicative of boiling. Additionally, this quartz has a significantly higher E’1 center intensity, suggesting a high concentration of oxygen vacancies associated with rapid crystallization. The mineral paragenesis, analytical results, and geochemical models show that, in these Ag-bearing epithermal systems, hydrothermal type I quartz associated with base metal sulfides precipitated during cooling, whereas subsequent growth-zoned hydrothermal type II quartz with high Sb concentrations and Ag-minerals precipitated during boiling. These results suggest that the CL texture and spectra, trace elements, and electron spin resonance data of quartz could identify veins with potential for Ag mineralization in epithermal systems.

<p>  The Gubong gold deposit is located in the Cheonan metallogenic province which records a highest gold production areas in the Republic of Korea. The Gubong deposit is the richest gold deposit in the province and consists of five stages of massive quartz veins that fill fractures along fault shear zones orienting NE and NW hosted in Precambrian metasedimentary rocks (Gyeonggi massif).</p><p>  Ores and alteration minerals of Gubong deposit are sericite, chlorite, epidote, illite, K-feldspar, plagioclase, biotite, quartz, calcite, magnetite, ilmenite, rutile, zircon, monazite, apatite, pyrite, gersdorffite, arsenopyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, and electrum. Fluid inclusion microthermometry and textural relationships in veins indicate that early sulfide deposition is associated with H<sub>2</sub>O-CO<sub>2</sub>-CH<sub>4</sub>-NaCl±N<sub>2</sub> bearing hotter hydrothermal fluids (203~432<sup>o</sup>C, ≤ 13.4 wt % NaCl) and late sulfide deposition is associated with H<sub>2</sub>O-NaCl bearing fluids (202~399<sup>o</sup>C, 3.9~17.3 wt % NaCl) cooled and diluted possibly by mixing with meteoric water.</p><p>  Trace element analyses in quartz from veins were performed by using LA-ICP-MS (193-nm ArF Excimer laser combined with an Elan 6100 quadrupole mass spectrometer) at ETH Zürich. Concentration of trace elements in quartz including Li (<0.01~3.55 ppm), B (3.03~27.17 ppm), Na (3.23~72.79 ppm), Al (4.0~149.9 ppm), P (14.4~68.9 ppm), Sc (3.3~8.7 ppm), Ti (<0.10~1.43 ppm), Cr (<3.34~65.6 ppm), Ga (0.50~1.30ppm), Ge (0.57~2.15 ppm), Rb (<0.01~0.50 ppm), Sr (0.01~3.13 ppm), Sn (<0.29~7.24 ppm), Sb (<0.05~0.42 ppm), and Bi (<0.01~8.30 ppm) are reported. Some trace elements (Al, Na, Ga, P, Li) tend to correlate positively. Titanium versus aluminum concentrations in quartz from Gubong deposit are plotted in the field of orogenic Au deposit suggested by Rusk (2012). We analyzed quartz from other numerous Korean Au-Ag and W-Mo deposits to compare hydrothermal fluid conditions and to provide a geochemical tool for mineral exploration.</p><p>Reference</p><p>Rusk, B.G., 2012, Cathodoluminescent textures and trace elements in hydrothermal quartz: Quartz: Deposits, Mineralogy and Analytics, Jens Götze and Robert Möckel, Springer, p. 307-329.</p>

Development of a certified reference material (CRM) for seven trace elements (Al, Ca, Fe, K, Mg, Na and Ti) in high purity quartz

We present electron microprobe, secondary ion mass spectrometry, and laser ablation inductively coupled mass spectrometry data for common trace elements (Li, Al, Ti, Na, K, Fe) in quartz. Our samples from both magmatic and hydrothermal environments all show heterogeneity at the single grain scale. ConcentrationsofAlandTi determinedbyEPMA,SIMS,andLA-ICP-MSareinroughagreementandconfirmtherobustnessof these analytical methods. The highest precision data were obtained from SIMS, but this is outweighed by the lack of a high quality quartz reference sample for calibrating this technique. Due to its large sampling volume, laser ablation analyses gave only average values for trace elements in zoned quartz. Because of its better spatial resolution in conjunction with the ability to combine spot analyseswithcathodoluminescenceimaging EPMAprovedthemost reliable insitu methodfor obtainingquantitativetraceelement dataofquartzatconcentrationsinexcessof afew10' sofppmandatthe<10µ mscale.However,oursamplecontainedfewelements at such high concentration levels. We found in our samples a positive correlation between CL signature and the observed Ti contents for the samples investigated. In particular, blue luminescing zones were found to have elevated Ti concentrations as compared to other nearby domains. Using a mathematical spectral deconvolution weshow thehighlycomplex natureof CL emission- it appearsthat other trace elementmight play a less pronounced role in this process. Our examples demonstrate the value of CL for documenting multi-phase alteration in quartz. In agreement with previously proposed models, we confirm a significant correlation between mono- and tri-valent cation concentrations in quartz. A very strong correlation in alkali metal contents is particularly obvious. Ti was found to be universally present in magmatic quartz, but at much lower abundance in hydrothermal quartz.

The composition of quartz has historically been considered unimportant for mineral exploration, although this perspective is changing with the advancement of analytical techniques. The ability to measure trace element variations in quartz provides a unique window into the evolution of mineral deposits. Granites are currently of interest as they can host late-stage magmatic-hydrothermal mineralisation, such as Sn and other critical metals. The Nebo, Bobbejaankop, and Lease granites in the Zaaiplaats Tin Field of the Bushveld Complex represent well-exposed expressions of endogranitic Sn-mineralisation. These granites display an upward increase in their degree of hydrothermal alteration. Disseminated Sn-mineralisation is restricted to the Bobbejaankop and Lease granites and high-grade cassiterite-bearing tourmaline-quartz hydrothermal pipes that radiate upwards through these granites, terminating below the roof contact. Trace element compositions of the quartz from the Zaaiplaats Tin Field shows evidence that supports the suggested fractionation and fluid-saturation models of ore genesis. The Al/Ti and Ge/Ti ratios in quartz increase from the base to the roof and illustrate the sequential fractionation and increase in the degree of fluid-rock interaction. The trace element data display a shift from a magmatic fractionation-controlled evolution to a hydrothermally-controlled system influenced by the saturation of a late-stage magmatic-hydrothermal fluid. Thus, trace element variations in quartz can record the point of fluid-saturation and the magmatic-hydrothermal transition. Therefore, the recognition of the most evolved, fluid-saturated facies indicates lithologies with the best mineralisation potential for cassiterite. The use of trace elements in quartz extends beyond granite-hosted deposits and is potentially applicable to various mineralised systems.

Heavy δ26Mg values in carbonate indicate a magmatic-hydrothermal origin of Carlin-type Au deposit

Genetic significance of trace elements in hydrothermal quartz from the Xiangzhong metallogenic province, South China

Ore deposits (occurrences) of Au, As, Sb, Hg, etc. distributed in Southwest Guizhou constitute the important portion of the low-temperature metallogenic domain covering a large area in Southwest China, with the Carlin-type Au and Sb deposits being the most typical ones. In this paper the Au and Sb ore deposits are taken as the objects of study. Through the petrographic analysis, microthermomitric measurement and Raman spectrophic analysis of fluid inclusions in gangue minerals and research on the S and C isotopic compositions in the gold ore deposits we can reveal the sources of ore-forming materials and ore-forming fluids and the rules of ore fluid evolution. Ore deposits of Au, Sb, etc. are regionally classified as the products of ore fluid evolution, and their ore-forming materials and ore fluids were probably derived mainly from the deep interior of the Earth. Fluid inclusion studies have shown that the temperatures of Au mineralization are within the range of 170–361°C,the salinities are 0.35 wt%–8 wt% NaCl eq.; the temperatures of Sb mineralization are 129.4–214°C and the salinities are 0.18 wt%–3.23 wt% NaCl eq.; the ore-forming fluid temperatures and salinities tend to decrease progressively. In the early stage (Au metallogenic stage) the ore-forming fluids contained large amounts of volatile components such as CO2, CH4, N2 and H2S, belonging to the H2O-CO2-NaCl fluid system; in the late stage (Sb metallogenic stage) the ore-forming fluids belong to the Sb-bearing H2O-NaCl system. The primitive ore-forming fluids may have experienced at least two processes of immiscibility: (1) when early ore-bearing hydrothermal solutions passed through rock strata of larger porosity or fault broken zones, CO2, CH4, N2 would escape from them, followed by the release of pressure, resulting in pressure release and boiling of primitive homogenous fluids, thereafter giving rise to their phase separation, thus leading to Au unloading and mineralization; and (2) in the late stage (Sb metallogenic stage ) a large volume of meteoric water was involved in the ore-forming fluids, leading to fluid boiling as a result of their encounter, followed by the drop of fluid temperature. As a result, the dissolubility of Sb decreased so greatly that Sb was enriched and precipitated as ores. Due to differences in physic-chemical conditions between Au and Sb precipitates, Au and Sb were respectively precipitated in different structural positions, thus creating such a phenomenon of Au/Sb paragenesis and differentiation in space.

Classification, mineralogy and industrial potential of SiO2 minerals and rocks.- Assessment of High Purity Quartz Resources.- Quality requirements of quartz sand in the building industry.-Petrological and chemical characterisation of high-purity quartz deposits with examples from Norway.- Evaluation of the potential of the pegmatitic quartz veins of the Sierra de Comechigones (Argentina) as a source of high purity quartz by a combination of LA-ICP-MS, ICP, cathodoluminescence, gas chromatography, fluid inclusion analysis, Raman and FTIR spectroscopy.- Brazilian quartz deposits and a perspective about industrial use, gemstone and color treatment.- First-principles calculations of the E'1 center in quartz: Structural models, 29Si hyperfine parameters and association with Al impurity.- Gamma-Irradiation Dependency of EPR and TL-Spectra of Quartz.- Analysis of low element concentrations in quartz by electron microprobe.-In situ analysis of trace elements in quartz using laser ablation inductively coupled plasma mass spectrometry.- Cathodoluminescence microanalysis of the defect microstructures of bulk and nanoscale ultrapure SiO2 polymorphs for device applications.- Trace element characteristics, luminescence properties and real structure of quartz.- Mineralogy, geochemistry and cathodoluminescence of authigenic quartz from different sedimentary rocks.- CL textures and trace elements in hydrothermal quartz.- Quartz regeneration and the use of quartz as a carrier of genetic information.

Chemical signature of quartz from S- and A-type rare-metal granites – A summary

Gold and antimony metallogenic relations and ore-forming process of Qinglong Sb(Au) deposit in Youjiang basin, SW China: Sulfide trace elements and sulfur isotopes