Typomorphic Characteristics of Pyrites from the Shuangwang Gold Deposit, Shaanxi, China: Index to Deep Ore Exploration

The large Shuangwang gold deposit (>80 t gold) is located in the Western Qinling Orogen (WQO) of central China. It is an orogenic-type gold deposit hosted in an NW-extending breccia belt in the Devonian Xinghongpu Formation. Gold mineralization of the Shuangwang deposit is featured by hydrothermal breccia ores with strata fragments cemented by hydrothermal minerals dominated by ankerite, quartz, and pyrite with minor amounts of calcite and albite. Pyrite is the major gold-hosting sulfide and the most abundant ore mineral. Crystal habits, thermoelectricity, and trace-element composition of pyrites from the main ore-forming stage of the Shuangwang gold deposit were studied by microbinocular, BHTE-06 thermoelectric coefficient measuring instrument, and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Spatial distribution of the above data for pyrites was delineated by contour maps of morphology index, P-type frequency, and primary halo elements (e.g., supraore halo elements Ba and Sb; near-ore halo elements Pb, Zn, and Cu; and subore halo elements Co, Mo, and Bi). Based on the above results, four target areas (areas between prospecting lines 0 and 1, between lines 14 and 18 below orebody KT9; areas between prospecting lines 30 and 34, between lines 44 and 46 below orebody KT8) were put forward for deep gold exploration in the future. These targets are consistent with the depth extrapolation of proven gold orebodies, indicating the practicality of typomorphic characterization of pyrites as vector to deep/concealed gold orebodies. The effectiveness of the pyrite typomorphic parameter for deep gold prediction seems to be chemical composition, crystal habits, and then thermoelectricity.

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Late Jurassic to Early Cretaceous magmatism in the Xiong’ershan gold district, central China: implications for gold mineralization and geodynamics

Geological Magazine ◽

10.1017/s0016756819000888 ◽

2019 ◽

Vol 157 (3) ◽

pp. 435-457

Author(s):

Zhenshan Pang ◽

Fuping Gao ◽

Yangsong Du ◽

Yilun Du ◽

Zhaojian Zong ◽

...

Keyword(s):

Early Cretaceous ◽

Inductively Coupled Plasma ◽

Late Jurassic ◽

Gold Mineralization ◽

Central China ◽

Inductively Coupled ◽

Icp Ms ◽

Metamorphic Basement ◽

Plasma Mass Spectrometry ◽

Cretaceous Magmatism

AbstractThe Xiong’ershan area is the third largest gold-producing district in China. The Late Jurassic to Early Cretaceous magmatism in the Xiong’ershan area can be divided into two episodes: early (165–150 Ma) and late (138–113 Ma). Laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) zircon U–Pb dating yields ages of 160.7 ± 0.6 Ma and 127.2 ± 1.0 Ma for the Wuzhangshan and Huashan monzogranites in the Xiong’ershan area, respectively, representing the two magmatic episodes. The Wuzhangshan monzogranites exhibit adakite-like geochemical features (e.g. high Sr/Y ratios, low Yb and Y contents). Their Sr–Nd–Hf isotopic compositions are consistent with those of the amphibolites of the Taihua Group, indicating that the Wuzhangshan monzogranites were formed from partial melting of the Taihua Group metamorphic rocks. Compared to the Wuzhangshan rocks, the Huashan monzogranites have higher MgO, Cr, Co and Ni contents, but lower Sr/Y and Fe3+/Fe2+. All the samples from the Huashan monzogranites plot in the area between the Taihua Group amphibolite rocks and the mantle rocks in the (87Sr/86Sr)t vs εNd(t) and age vs εHf(t) diagrams, suggesting that the Huashan monzogranites were probably generated by mixing of mantle-derived magmas and the Taihua Group metamorphic basement melts. The gold mineralization (136–110 Ma) is coeval with the emplacement of the late-episode magmas, implying that crustal–mantle mixed magma might be a better target for gold mineralization compared to the ancient metamorphic basement melt. The data presented in this study further indicate that the transformation of the lithosphere from thickening to thinning in the Xiong’ershan area probably occurred between ~160 Ma and ~127 Ma, and that the gold mineralization in this area was probably related to lithospheric thinning.

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Geochronological Constraint on the Evolution of the Aktyuz Terrane, Kyrgyz North Tianshan, and the Fate of the Taldybulak Levoberezhny Gold Deposit

Frontiers in Earth Science ◽

10.3389/feart.2021.664361 ◽

2021 ◽

Vol 9 ◽

Author(s):

Wei Xi ◽

Nuo Li ◽

Xiaohong Xia ◽

Xiaoxiao Ling ◽

Yanshuang Wu

Keyword(s):

Gold Deposit ◽

Inductively Coupled Plasma ◽

Gold Mineralization ◽

Detrital Zircons ◽

Ultrahigh Pressure ◽

Weighted Mean ◽

Inductively Coupled ◽

Isotopic Analyses ◽

Plasma Mass Spectrometry ◽

Data Points

The Aktyuz Terrane in Kyrgyz North Tianshan is of particular interest due to the occurrence of high and ultrahigh pressure (HP–UHP) rocks and it containing the third largest gold deposit in Kyrgyz North Tianshan, i.e., Taldybulak Levoberezhny (abbreviated to Taldybulak Lev.). To constrain the ages of the host Kemin Complex and its auriferous monzogranite porphyry, detailed zircon U–Pb dating [by laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS) and secondary ion mass spectroscopy (SIMS)] and Lu–Hf isotopic analyses were carried out. The intensively altered auriferous monzogranite porphyry yielded two weighted mean ages of 444 ± 3 Ma (n = 14, mean squared weighted deviation (MSWD) = 0.49, by LA-ICPMS) and 440 ± 5 Ma (n = 8, MSWD = 0.82, by SIMS) that are indistinguishable within error ranges. Such ages are consistent with a previously reported sulfide Re–Os isochron age of 434 ± 18 Ma, supporting a Silurian porphyry gold mineralization. The granitic gneiss yielded a protolith age of 773 ± 7 Ma (n = 7, MSWD = 0.04) and two metamorphic ages of 514 ± 4 Ma (n = 8, MSWD = 0.09) and 483 ± 3 Ma (n = 11, MSWD = 0.04). Detrital zircons from one fuchsite schist sample yielded highly variable ages from 729 ± 13 Ma to 2,463 ± 30 Ma, with 12 data points weighted at 740 ± 5 Ma (MSWD = 0.95). The metamorphic overgrowth yielded a weighted mean age of 460 ± 4 Ma (n = 4, MSWD = 0.15). Detrital zircons in the migmatitic amphibolite are aged from 788 ± 7 Ma to 3,447 ± 32 Ma, with two major concentrations at 941 ± 7 Ma (n = 13, MSWD = 0.95) and 794 ± 5 Ma (n = 8, MSWD = 0.19). The metamorphic overgrowth yielded an average age of 555 ± 4 Ma (n = 8, MSWD = 0.65). The detrital and xenocryst zircons, and evolved εHf(t) values (−20.9 to −7.8) and old two-stage Hf model ages (1,367–3,159 Ma), revealed the presence of a Precambrian basement that may be dated back to the Archean Eon. The two metamorphic ages may correlate with oceanic subduction and continental collision, respectively.

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Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil

Mineralogical Magazine ◽

10.1180/minmag.2010.074.4.645 ◽

2010 ◽

Vol 74 (4) ◽

pp. 645-658 ◽

Cited By ~ 6

Author(s):

F. C. J. Vilalva ◽

S. R. F. Vlach

Keyword(s):

Trace Element ◽

Inductively Coupled Plasma ◽

Alkali Feldspar ◽

Trace Element Composition ◽

Inductively Coupled ◽

Coupled Substitution ◽

Plasma Mass Spectrometry ◽

Compositional Variations ◽

End Members ◽

South Brazil

AbstractTurkestanite, a rare Th- and REE-bearing cyclosilicate in the ekanite–steacyite group was found in evolved peralkaline granitesfrom the Morro Redondo Complex, south Brazil. It occurswith quartz, alkali feldspar and an unnamed Y-bearing silicate. Electron microprobe analysis indicates relatively homogeneous compositions with maximum ThO2, Na2O and K2O contentsof 22.4%, 2.93% and 3.15 wt.%, respectively, and significant REE2O3 abundances(5.21 to 11.04 wt.%). The REE patterns show enrichment of LREE over HREE, a strong negative Eu anomaly and positive Ce anomaly, the latter in the most transformed crystals. Laser ablation inductively coupled plasma mass spectrometry trace element patterns display considerable depletions in Nb, Zr, Hf, Ti and Li relative to whole-rock sample compositions. Observed compositional variations suggest the influence of coupled substitution mechanisms involving steacyite, a Na-dominant analogue of turkestanite, iraqite, a REE-bearing end-member in the ekanite–steacyite group, ekanite and some theoretical end-members. Turkestanite crystals were interpreted as having precipitated during post-magmatic stages in the presence of residual HFSE-rich fluidscarrying Ca, the circulation of which wasenhanced by deformational events.

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New Insights Into the Control of Visible Gold Fineness and Deposition: A Case Study of the Sanshandao Gold Deposit, Jiaodong, China

American Mineralogist ◽

10.2138/am-2020-7475 ◽

2021 ◽

Vol 106 (1) ◽

pp. 135-149

Author(s):

Hong-Wei Peng ◽

Hong-Rui Fan ◽

Xuan Liu ◽

Bo-Jie Wen ◽

Yong-Wen Zhang ◽

...

Keyword(s):

Gold Deposit ◽

Inductively Coupled Plasma ◽

Gold Mineralization ◽

Isotope Analysis ◽

Trace Element Analysis ◽

Sulfide Minerals ◽

Element Analysis ◽

Rock Interaction ◽

Inductively Coupled ◽

Icp Ms

Abstract Mineralogical distribution, textures, electron probe microanalysis of visible gold, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace element analysis of pyrite, and LA-multicollector (MC-)ICP-MS sulfur isotope analysis of sulfide minerals are examined in an ore zone extending obliquely to –4 km depth in the Sanshandao gold deposit Jiaodong, China. We relate these results to the temporal and spatial ore-forming processes in the deposit to further elucidate the controls on the deposition of visible Au and fineness variation. Two generations of Au mineralization are identified. The early generation is represented by beresitization and quartz-pyrite veins in which visible Au grains are associated with pyrite (Py1 and Py2) and are characterized by high fineness [729–961; fineness = 1000×Au/(Au+Ag)]. Py1 and Py2 are both enriched in Co, Ni, and Bi and depleted in As and Au. Texturally, gold and pyrite are pristine crystals, homogeneous in composition. These features are attributed to the sulfidation of the granitic wallrock (fluid/rock interaction) that effectively destabilizes Au in the ore-forming fluids during pyrite deposition. Fineness decreases continuously from 870 at –2650 m depth to 752 at –420 m depth. The Co and Ni contents of Py1 and Py2 decrease significantly from –4000 m to –420 m depth, whereas the As contents increase. The mean δ34S values of Py1 increase from 10.5 to 11.8‰. The spatial variations are interpreted to be related to gradual cooling, decompression, and an enhanced degree of fluid/rock interaction with decreasing depth, which facilitated the initiation of visible gold mineralization at ca. –2700 m depth. The late generation of Au mineralization is represented by quartz-polysulfide veins in which visible Au grains are associated with multiple sulfide minerals (Py3, galena, chalcopyrite, arsenopyrite, and sphalerite). It is characterized by low fineness (549–719), and heterogeneous textures with Ag-rich parts (218–421). Py3, occurring as the rim of pyrite grain, is interpreted to form by replacement via a dissolution-reprecipitation reaction. Py3 is distinctly enriched in As (median of 10 000 ppm) and Au (2.2 ppm), but depleted in Co, Ni, and Bi. The δ34S values of the polysulfide minerals decrease sharply by 4 to 5‰ at depths from –1909 to –1450 m. These features are interpreted to be generated by significant decompression and phase separation of fluid, where most ore elements (e.g., Au, Ag, As, and base metal elements) are destabilized. Our study suggests that remobilization did not affect the generation of visible Au mineralization at Sanshandao.

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Early Paleozoic Adakitic Granitoids from the Xingshuping Gold Deposit of East Qinling, China: Petrogenesis and Tectonic Significance

Minerals ◽

10.3390/min11101032 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1032

Author(s):

Pei Zan ◽

Shouyu Chen ◽

Jinduo Chen ◽

Shengli Li

Keyword(s):

Gold Deposit ◽

Inductively Coupled Plasma ◽

Volcanic Rocks ◽

Major And Trace Elements ◽

Biotite Granite ◽

Early Paleozoic ◽

Inductively Coupled ◽

Icp Ms ◽

Monzonitic Granite ◽

Plasma Mass Spectrometry

This study discussed the pertrological classification, geochronology, petrogenesis and tectonic evolution of early Paleozoic granites from the Xingshuping gold deposit in the East Qinling orogenic belt. In order to achieve this target, we carried out an integrated study of zircon U–Pb age, whole-rock major and trace elements, as well as Sr–Nd–Hf isotope compositions for the Xingshuping granites (part of the Wuduoshan pluton) from the Erlangping unit. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating constrains the emplacement age of the Xingshuping granites at 446.2 ± 1.2 Ma. The rocks at Xingshuping can be divided into two types: mainly biotite granite and monzonitic granite. The biotite granites are typical adakitic rocks, while the monzonitic granites show characteristics similar to normal arc volcanic rocks. The geochemical compositions reveal that they were derived from a clay-rich, plagioclase-rich and biotite-rich psammitic lower continental crust source, with contributions of mantle-derived magmas. The distinction is that the biotite granites were primarily derived from partial melting in a syn-collision extension setting, whereas the monzonitic granite went through a fractional crystallization process in an intraplate anorogenic setting.

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Decoupling of Au and As during rapid pyrite crystallization

Geology ◽

10.1130/g48443.1 ◽

2021 ◽

Author(s):

Ya-Fei Wu ◽

Katy Evans ◽

Si-Yu Hu ◽

Denis Fougerouse ◽

Mei-Fu Zhou ◽

...

Keyword(s):

Mass Spectrometry ◽

Inductively Coupled Plasma ◽

Secondary Ion Mass Spectrometry ◽

Electron Backscatter Diffraction ◽

Local Variation ◽

Hydrothermal Systems ◽

Central China ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

Backscatter Diffraction

Gold (Au) is largely hosted by pyrite in a variety of hydrothermal systems, but the incorporation of Au into pyrite under disequilibrium conditions remains poorly understood. We integrate synchrotron X-ray fluorescence microscopy, electron backscatter diffraction, nanoscale secondary ion mass spectrometry, and laser ablation–multicollector–inductively coupled plasma–mass spectrometry to constrain the processes that sequester Au into zoned pyrite in the hydrothermal cement of breccia ores from the world-class Daqiao orogenic Au deposit, central China. Euhedral pyrite cores with oscillatory and sector zoning, variable δ34S values, and lower Au-As contents than the mantles are attributed to crystallization during oxidation of metal-depleted ore fluids with local variation in fluid conditions. The isotopically uniform colloform mantles are formed by pyrite crystallites separated by low-angle boundaries and are characterized by unusual decoupling of Au and As. Mantle formation is attributed to rapid disequilibrium precipitation from a metal-rich FeS2-supersaturated fluid. Incorporation of Au into the pyrite mantles was facilitated by abundant lattice defects produced by rapid nucleation. Gold-As–poor pyrite rims were deposited from an evolved ore fluid or other metal-depleted fluids. These results show that chemical variations recorded by fine layering within minerals can provide valuable insights into disequilibrium mass transfer and ore formation. The decoupling between Au and As in pyrite mantles indicates that As is not always a reliable proxy for Au enrichment in rapidly crystallized porous pyrite.

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Geochronology and geochemistry of the Pola de Allande granitoids (northern Spain): their bearing on the Cadomian-Avalonian evolution of northwest Iberia

Canadian Journal of Earth Sciences ◽

10.1139/e98-074 ◽

1998 ◽

Vol 35 (12) ◽

pp. 1439-1453 ◽

Cited By ~ 53

Author(s):

Javier Fernández-Suárez ◽

Gabriel Gutiérrez-Alonso ◽

George A Jenner ◽

Simon E Jackson

Keyword(s):

Inductively Coupled Plasma ◽

Trace Element Composition ◽

Variscan Belt ◽

Calc Alkaline ◽

Northern Spain ◽

Isotopic Signatures ◽

Magmatic Arc ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

Northwest Iberia

The Pola de Allande pre-Variscan tonalite-granodiorite plutons are located in the Narcea Antiform, at the boundary zone between the Cantabrian and west Asturian Leonese zones of the Iberian Variscan belt. These granitoids were intruded into a Neoproterozoic siliciclastic sedimentary sequence with subordinate volcanic intercalations and were subsequently overprinted by Variscan thrust-related shear deformation. U-Pb laser ablation inductively coupled plasma - mass spectrometry (ICP-MS) dating of zircons from two plutons yielded concordant ages of intrusion of 605 ± 10 and 580 ± 15 Ma. To the authors' knowledge, this is the first reported U-Pb Cadomian-Avalonian age for igneous rocks in this section of the Iberian Variscan belt. These intrusions are coeval with the main episode of dominantly calc-alkaline magmatic activity related to Cadomian-Avalonian subduction. Major and trace element composition of the granitoids is characteristic of I-type high-K calc-alkaline granitoids generated in continental arc settings, and are comparable to those of coeval granitoids in other areas of the Cadomian-Avalonian belt. Sr and Nd isotopic signatures indicate that the genesis of the Pola de Allande granitoids involved either mixing of mantle melts of Cadomian extraction with an older enriched crust (Eburnean-Icarthian, i.e., ca. 2 Ga old crust) or melting of a mafic infracrustal protolith with a Grenville age (ca. 1.2 Ga) mantle extraction. The Neoproterozoic sediments, hosting the Pola de Allande granitoids and present in large areas of northwest Iberia, may represent the back-arc basin of the subduction complex in which the Avalon composite terrane constituted the main magmatic arc.

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Ore-Forming Processes at the Xiajinbao Gold Deposit in Eastern Hebei Province: Constraints from EPMA and LA-ICPMS Analysis

Minerals ◽

10.3390/min8090388 ◽

2018 ◽

Vol 8 (9) ◽

pp. 388

Author(s):

Cheng Wang ◽

Yongjun Shao ◽

Kuanxin Huang ◽

Haodi Zhou ◽

Jianguo Zhang ◽

...

Keyword(s):

Gold Deposit ◽

Inductively Coupled Plasma ◽

North China ◽

Northern Margin ◽

Inductively Coupled ◽

The North ◽

Geochemical Study ◽

Plasma Mass Spectrometry ◽

Three Stages ◽

High Concentrations

The Xiajinbao gold deposit is located at the northern margin of the North China Craton. Hydrothermal pyrites belonging to three stages were identified: Py1; Py2; and Py3. Geochemical study of these pyrites was conducted using electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry to investigate the distributions of minor and trace elements, constrain pyrite genesis, and to obtain an improved understanding of the ore-forming processes. Py1 and Py2 contain high concentrations of Au and are interpreted to have been deposited from fluids from a dominantly magmatic source. Py3 grains have the lowest Co/Ni ratios. All generations of pyrite were deposited by mixing of meteoric waters with magmatic-hydrothermal fluids. Boiling of early ore-forming fluids led to the precipitation of Py1 and gold. Decreasing fO2 in the ore-forming system resulted in the formation of Py2 and gold. Fluid mixing was the dominant controlling factor for the precipitation of Py3 together with small amounts of gold.

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