Xinjiang Laboratory of Mineral Resources and Digital Geology

Urunchi, China

Xinjiang Laboratory of Mineral Resources and Digital Geology

Urunchi, China
SEARCH FILTERS
Time filter
Source Type

Yu J.,Peking University | Li N.,Xinjiang Institute of Ecology and Geography | Li N.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Shu S.-P.,Peking University | And 3 more authors.
Ore Geology Reviews | Year: 2017

Western Tianshan along the southwestern margin of the Central Asian Orogenic Belt is well-endowed with epithermal and porphyry Au deposits. The Kuruer Cu-Au deposit, recently discovered in the eastern part of Western Tianshan, was considered as a high sulfidation epithermal deposit. However, our geological, fluid inclusion and stable isotopic studies indicate that it actually formed in transition from high sulfidation to porphyry. The host rocks include the Dahalajunshan Formation volcanic and volcano-sedimentary rocks such as andesite, rhyolite, ignimbrite and tuff. Cu-Au mineralization mainly occurs as quartz-dominated stockworks or disseminations, with abundant pyrite and chalcopyrite and minor galena and sphalerite. Gold occurs as invisible phase in sulfides. Hydrothermal alteration includes a silicic core, surrounded by phyllic alteration and peripheral propylitic alteration. Based on field observations, paragenetic and crosscutting relationship, the mineralization process can be roughly divided into three stages. The early stage is characterized by the assemblage of quartz + pyrite + chalcopyrite while the middle stage contains quartz and chalcopyrite at absence of pyrite. The late stage is characterized by calcite. ±. quartz. ±. chlorite. ±. chalcopyrite veins.Fluid inclusions at the early stage are mainly liquid-rich aqueous and CO2-rich inclusions and minor vapor-rich aqueous and solid-bearing inclusions. Their homogenization temperatures and salinities can be up to 420°C and 39wt.% NaCl eq., respectively, indicating that the initial ore-forming fluids are high temperature, high salinity, H2O-CO2-NaCl systems. In the middle stage, there are only liquid-rich aqueous inclusions, with homogenization temperatures and salinities of 130-190°C and 0.18 to 10.7wt.% NaCl eq., respectively. Liquid-rich aqueous inclusions in the late stage display much lower temperatures and salinities, ranging from 110 to 130°C and 0.18-2.7wt.% NaCl eq., respectively. Obtained δDH2O and δ18OH2O values of quartz from the middle stage are -98 to -107‰ and -2.1 to 0.74‰, respectively. The δ34S values of 9 chalcopyrite samples range from -10.2 to -2.4‰, with an average of -4.1‰. We conclude that the initial ore-forming fluids are magmatic in origin, and further cooled and diluted by mixing with meteoric water. Intensive fluid boiling and mixing facilitated hydrothermal alteration and mineralization. © 2017 Elsevier B.V.


Zhang B.,Peking University | Li N.,Xinjiang Institute of Ecology and Geography | Li N.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Shu S.-P.,Peking University | And 8 more authors.
Ore Geology Reviews | Year: 2017

The Axi deposit is the largest low-sulfidation epithermal gold deposit in Chinese Western Tianshan, Central Asian Orogenic Belt. In this contribution, combined petrological observations, electron microprobe analysis (EMPA) and X-ray backscattered electron images (BSE) have been conducted on Fe-S-As minerals to reveal their textural and compositional evolution. Pyrite and arsenopyrite are ubiquitous. Their texture and composition show gradual changes with time. Four generations of pyrite can be identified, named Py1, Py2, Py3 and Py4 from early to late. The coarse-grained, euhedral to subhedral Py1 (mostly 100-300. μm) from the quartz-chalcedony stage is the earliest, and predates gold mineralization. Sometimes they contain silicate and arsenopyrite (Apy1) inclusions. Compositionally, they are enriched in Pb (up to 0.60. wt%), but depleted in As (0.06-7.61. wt%, mostly <0.30. wt%) and Au (0.01. wt%-0.25. wt%, mostly <0.10. wt%). Subhedral to anhedral Py2 grains (50-1000. μm) coexist with other sulfides such as chalcopyrite, sphalerite, galena and tetrahedrite in the quartz-polymetallic sulfides stage. They are unusually rich in Au (with a mean value of 0.06. wt%), Ag (with a mean value of 0.04. wt%), Cu (with a mean value of 0.21. wt%) and As (with a mean value of 3.06. wt%), implying a syn-mineralization feature. Subsequent Py3 occurs as very fine-grained disseminations of euhedral crystals (10-50. μm) in quartz-polymetallic sulfides stage and carbonate-quartz stage. They display clear oscillatory zoning and contain arsenopyrite (Apy3), sphalerite and Sb-Te mineral inclusions. Their Au content vary greatly from 0.02. wt% to 1.02. wt%, with corresponding As content varying from 0.07. wt% to 8.28. wt%. The post-mineralization Py4 crystals (30-5000. μm) mainly occur as foliated, sheaf, or radiaxial aggregates in carbonate-quartz stage. They have the lowest Au (with a mean value of 0.04. wt%), As (with a mean value of 0.32. wt%), Co (with a mean value of 0.04. wt%) and Ni (with a mean value of 0.04. wt%) concentrations, although dramatically high S contents (with a mean value of 52.72. wt%). Correspondingly, there are three generations of arsenopyrite: Apy1 (20-50. μm) and Apy3 (3-15. μm) mainly occur as inclusions in Py1 and Py3, respectively, whereas the latest Apy4 (<5-60. μm) can occur either as serrated grains surrounding Py4 or overgrowth Py1 and Py3, or as individual euhedral to sub-euhedral grains. They also contain considerable, but much higher Au contents than pyrite, with the values of 0.6. wt%-1.1. wt% for Apy1, 0.18. wt%-1.32. wt% for Apy3 and 0.50. wt%-1.75. wt% for Apy4, respectively. Besides, they also contain considerable amounts of trace elements such as Co, Zn, Pb, Sb and Se. Arsenopyrite geothermometer constrains the ore-forming temperature responsible for Apy3 formation to 325-385. °C. Our result reveals that significant invisible gold accommodated by sulfides is the main cause of refractory ores at the Axi deposit. © 2017 Elsevier B.V.


Yu J.,Peking University | Li N.,Xinjiang Institute of Ecology and Geography | Li N.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Qi N.,Peking University | And 3 more authors.
Journal of Asian Earth Sciences | Year: 2017

The Western Tianshan in NW China is one of the most important gold provinces in the Central Asian Orogenic Belt (CAOB). The recently discovered Kuruer Cu-Au deposit has been interpreted to represent a transition from high-sulfidation epithermal to porphyry mineralization system. In this study, we present new LA-ICP-MS zircon U-Pb ages for the many magmatic rock types at Kuruer, including the Dahalajunshan Formation andesitic tuff (333.2±1.6Ma), diorite porphyry (269.7±2.0Ma), slightly-altered (264.4±2.6Ma) and intensively-altered (270.5±2.5Ma) albite porphyry. These ages reveal two distinct magmatic episodes: The Early Carboniferous Dahalajunshan Formation (wall rocks) andesitic tuff samples contain narrow ranges of SiO2 (60.29-61.28wt.%), TiO2 (0.96-0.98wt.%), Al2O3 (16.55-16.57wt.%) and Fe2O3 T (5.36-5.57wt.%). The tuff is characterized by LREE enrichment and HFSE depletion, as well as LREE/HREE enrichment ((La/Yb)N =8.31-8.76) and negative Eu anomalies (δEu=0.64-0.76). Zircon εHf (t) values are 5.4-8.2, and two-stage Hf model ages (T DM2) are 821-1016Ma, indicating partial melting of a moderately depleted mantle wedge with Precambrian continental crustal input. The ore-forming Middle Permian diorite porphyry and (quartz) albite porphyry have variable major oxide compositions (e.g., SiO2 =53.09-53.12wt.% for the diorite porphyry, 70.84-78.03wt.% for the albite porphyry, and 74.07-75.03wt.% for the quartz albite porphyry) but similar chondrite-normalized REE and primitive mantle-normalized multi-element patterns. These porphyries display LREE enrichment and HFSE depletion, as well as elevated LREE/HREE enrichment and negative Eu anomalies. The positive zircon εHf(t) values (11.7-15.9 for the diorite porphyry, 8.9-14.9 for the albite porphyry) and young two-stage Hf model ages (T DM2) (282-542Ma for the diorite porphyry, 337-717Ma for the albite porphyry) indicate a major juvenile continental crustal involvement. We propose that the Carboniferous and Middle Permian magmatism was formed in a continental arc and post-collisional settings, respectively, with the latter episode responsible for the Cu-Au mineralization. © 2017 Elsevier Ltd.


Zhang Z.,Xinjiang Institute of Ecology and Geography | Zhang Z.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Liu F.,Chinese Academy of Geological Sciences | Zhou K.,Xinjiang Institute of Ecology and Geography | And 4 more authors.
Scientia Geologica Sinica | Year: 2015

Tuchushan copper-iron deposit is a representative iron-polymetallic deposit in Yamansu Carboniferous fore-arc/arc belt of eastern Tianshan, the orebodies occurs as lenses, veins and stratums, which is hosted in volcanic rocks of the Upper Carboniferous Dikan'er Lower Formation. Homogenization temperature of fluid inclusions in skarn period vary from 151℃ to >380℃, salinity range from 1.91% to 23.18% NaCl equiv, density range from 0.76 g/cm3 to 1.09 g/cm3, and homogenization temperature of fluid inclusions in hydrothermal period vary from 101℃ to 280℃, salinity range from 0.35% to 23.05 % NaCl equiv, density range from 0.74 g/cm3 to 1.13 g/cm3, which have the characteristic of high-middle temperature, middle-low salinity and density, also belong to NaCl-H2O system.(Chlorite)-epidote skarn and magnetite-(specularite)ore have similar chondrite-normalized REE distribution patterns and are riched in LREE, is characterized by negative Eu anomaly and no Ce anomaly, also similar to volcanic of the Dikan'er Lower Formation, indicating that ore-forming material was derived from the volcanic. The authors hold that skarn might have resulted from volcanic hydrothermal interaction with cabonate and deposit was formed in high-middle temperature, comparatively wide oxidation-reduction environment. The genesis of mineral deposit is belong to volcanic hydrothermal metasomatic type. © 2015, Science Press. All right reserved.


Zhang Z.,Xinjiang Institute of Ecology and Geography | Zhang Z.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Chai F.,Xinjiang University | Zhou K.,Xinjiang Institute of Ecology and Geography | And 3 more authors.
Scientia Geologica Sinica | Year: 2015

Tuchushan copper-iron deposit is hosted in volcanic rocks of the Upper Carboniferous Dikan'er Formation. The genesis of mineral deposit is belong to volcanic hydrothermal metasomatic type. Basalts in ore district are rich in aluminum and sodium, but loss potassium, phosphorus and titanium, indicating that the rocks are calc-alkaline volcanic rock series. The rocks are characterized by enrichment of light rare earth elements, large ion lithophile elements and loss of high filed strength elements. The characteristics of trace elements show that genesis of rocks are related to fluid of subduction, primary magmas have experienced crystallization differentiation of olivine or clinopyroxene and chromite, also suggest basalts and iron orebodies were formed in back-arc basin environment. LA-ICP-MS U-Pb zircon dating on diorite and moyite from ore district yielded concordant ages of 326.2±1.6 Ma and 318.2±2.5 Ma, indicating that they were formed in Carboniferous. Based on the contacting relation of diorite, moyite, iron orebody and volcanic rocks, we hereby confine the age of iron mineralization is similar to the forming time of volcanic rocks of the Dikan'er Formation, which is before the age of diorite(326 Ma), but the age of copper mineralization is appreciably later than 326 Ma. © 2015, Science Press. All right reserved.


Ye T.,Xinjiang Institute of Ecology and Geography | Ye T.,Xinjiang Laboratory of Mineral Resources and Digital Geology | Ye T.,University of Chinese Academy of Sciences | Li N.,Xinjiang Institute of Ecology and Geography | Li N.,Xinjiang Laboratory of Mineral Resources and Digital Geology
Scientia Geologica Sinica | Year: 2015

Laser ablation-inductively coupled plasma-mass spectrometer(LA-ICP-MS)is a newly-developed techniques for in situ trace element analysis of sulfides and oxides, offering high sensitives, low detection limit, and simultaneous capture of up to 20 trace elements. In this contribution, we review its application to gold deposit, and conclude that once combined with backscattered electron mode of scanning electron microscopy, X-ray elemental mapping, in situ sulfur/iron isotope analyses, pyrite LA-ICP-MS analysis can be used to determine the distribution of trace elements in pyrite, track their remobilization-transportation during deformation-metamorphism, probe into the composition and evolution the ore-forming fluids, determine potential sources of metals, depict detailed ore-forming processes, and constrain the genesis of ore deposits. © 2015, Science Press. All right reserved.

Loading Xinjiang Laboratory of Mineral Resources and Digital Geology collaborators
Loading Xinjiang Laboratory of Mineral Resources and Digital Geology collaborators