Geology and Genesis of the Tuwu Porphyry Cu Deposit, Xinjiang, Northwest China

2020 ◽  
Author(s):  
Yin-Hong Wang ◽  
Fang-Fang Zhang ◽  
Chun-Ji Xue ◽  
Jia-Jun Liu ◽  
Zhao-Chong Zhang ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Growth Curves ◽  
Northwest China ◽  
Hydrothermal Activity ◽  
Positive Trend ◽  
Alteration Zones ◽  
Porphyry Cu ◽  
Potential Applications ◽  
Magmatic Reservoir ◽  
Porphyry Cu Deposit

Abstract The Tuwu porphyry Cu deposit is located in the northern segment of the Jueluotage metallogenic belt in Eastern Tianshan, on the southern margin of the Central Asian orogenic belt, Xinjiang, northwest China. Tuwu is hosted by diorite porphyry and tonalite porphyry intrusions, which intruded volcanic rocks of the Carboniferous Qi’eshan Group. Four stages (I-IV) of hydrothermal activity have been identified. Chalcopyrite is the dominant ore mineral and mainly occurs in vein stages II (quartz-chalcopyrite-pyrite ± sericite ± bornite ± enargite veins with phyllic halos) and III (quartz-molybdenite-chalcopyrite ± pyrite ± chlorite ± epidote veins). Re-Os dating of molybdenite samples yielded an isochron age of 335.6 ± 4.1 Ma (2σ, mean square of weighted deviates = 0.15, n = 8). Silicon, oxygen, and carbon stable isotope compositions of quartz and calcite provide evidence for predominantly magmatic contributions with a late meteoric water component at Tuwu. Chalcopyrite samples from stages I and III record a narrow range of bulk δ34S values between –3.9 and 0.4‰, whereas pyrite samples from stages I to IV show decreasing δ34S values from 1.7 to 0.2‰. Chalcopyrite has 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios similar to those of porphyry intrusions, and Pb isotope data from sulfide samples display a positive trend transecting the growth curves of crustal lead. The ore-forming components (metals and sulfur) were sourced from a mantle-derived magmatic reservoir with some upper crustal components in a subduction-related arc setting. Plagioclase compositions in the porphyry intrusions are consistent with magmatic H2O contents of ~7 wt %. Copper sulfides in the high-grade phyllic alteration zones at Tuwu are characterized by elevated δ65Cu values consistent with deposits from oxidized and hydrous magmatic-hydrothermal fluids, whereas lower δ65Cu values and low copper grades correspond to the potassic alteration zones. Recognition of copper isotope zonation patterns at Tuwu has potential applications in the exploration of porphyry Cu deposits.

scholarly journals Compositions of Cu-(Fe)-Sulfides in the 109 Reduced Granite-Related Cu Deposit, Xinjiang, Northwest China: Implications to the Characteristics of Ore-Forming Fluids

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Rui Liu ◽  
Genwen Chen ◽  
Jianxing Yang
Keyword(s):  
Trace Elements ◽  
Oxygen Fugacity ◽  
Porphyry Copper ◽  
Northwest China ◽  
Low Oxygen ◽  
Concentration Data ◽  
Porphyry Cu ◽  
Western Tianshan ◽  
Forming Characteristics ◽  
Porphyry Cu Deposit

In general, porphyry Cu deposit is related to the highly oxidized ore-forming system. However, there are many porphyry Cu deposits that are related to the reduced ore-forming system, and the ore-forming characteristics of reduced porphyry Cu deposit are unclear. Cu-(Fe)-sulfides are the main Cu-hosting minerals in porphyry Cu deposits and are also economically important, and the composition of Cu-(Fe)-sulfides has closely relationship with ore-forming characteristics. In this study, concentration data obtained via laser ablation inductively coupled plasma mass spectrometry are reported for chalcopyrite, bornite, and chalcocite from the 109 porphyry Cu deposit formed in a reduced granite-related mineralization system in western Tianshan, Xinjiang, northwest China. The results show that the chalcopyrite hosts several trace elements including Zn, Ge, Se, In, and Sn; the bornite hosts Mo, Ag, Zn, Se, and Bi; and the chalcocite hosts Mo, Ag, Zn, Sn, Se, and Bi. The smooth time-resolved depths profiles and limited variations of trace element concentrations in these sulfides suggest that their presence is isomorphic. The microstructures of the chalcopyrite and bornite were observed by high-resolution transmission electron microscopy. Their lattices are neatly arranged, also indicating that the trace elements exist mainly as isomorphisms in the chalcopyrite and bornite. Ge, Sn, and In are hosted in the chalcopyrite but absent in bornite and chalcocite, indicating that chalcopyrite has a high potential for hosting these elements. Ge and Sn are preferentially hosted in the chalcopyrite, possibly due to relatively high temperatures and low oxygen fugacity during its formation. Indium is preferentially hosted in the chalcopyrite, possibly due to the In2+ substitution for Fe2+ controlled by Goldschmidt’s rules, which state that substitution occurs between a substituent and host owing to similarities in their radii and charges. However, the concentration of Ag is low in chalcopyrite but significantly high in bornite and chalcocite, indicating that this element is preferentially hosted in the latter two minerals. The abundance of Ag, a low-temperature element, in Cu-(Fe)-sulfides may largely be dependent on temperature. The Au content is below the minimum level of detection in all sulfides, which is obviously different from the classic porphyry copper deposits. In addition, the concentrations of Zn, Ge, As, Sb, and Te in the chalcopyrite and those of Zn, Se, As, Sb, and Bi in the bornite from the 109 porphyry Cu deposit show obvious differences from those of classic porphyry Cu deposits. Therefore, some elements in Cu-(Fe)-sulfides can be used as indicators of ore-forming oxygen fugacity. Bornite and chalcocite are generally enriched in Ag, indicating that the mining of porphyry Cu deposits may be concerned with the precious metal Ag in bornite and chalcocite. In addition, chalcopyrite may host sufficient Se and Zn, and bornite and chalcocite could host sufficient Se, Zn, and Bi, suggesting that sulfides may be hosts for deleterious elements.

High oxidation magmatic evolution in the Naruo porphyry Cu deposit, Tibet, China

2019 ◽  
Vol 76 ◽  
pp. 26-43 ◽  
Author(s):  
Xiangping Zhu ◽  
Duoji ◽  
Guangming Li ◽  
Hongfei Liu ◽  
Huaan Chen ◽  
...  
Keyword(s):  
Magmatic Evolution ◽  
Porphyry Cu ◽  
High Oxidation ◽  
Porphyry Cu Deposit

scholarly journals Different trends between extreme and median surface aerosol extinction coefficients over China inferred from quality controlled visibility data

2017 ◽  
Author(s):  
Jing Li ◽  
Chengcai Li ◽  
Chunsheng Zhao
Keyword(s):  
Northwest China ◽  
Positive Trend ◽  
Median Surface ◽  
Aerosol Extinction ◽  
Significance Level ◽  
The North ◽  
Synoptic Conditions ◽  
The Mean ◽  
Mean Trend ◽  
Year 2000

Abstract. Although the temporal changes of aerosol properties have been widely investigated, the majority focused on the averaged condition without much emphasis on the extremes. However, the latter can be more important in terms of human health and climate change. This study uses a previously validated, quality-controlled visibility dataset to investigate the long-term trends of extreme surface aerosol extinction coefficient (AEC) over China, and compare them with the median trends. Two methods are used to independently evaluate the trends, which arrive at consistent results. The sign of extreme and median trends are generally coherent, whereas their magnitudes show distinct spatial and temporal differences. In the 1980s, an overall positive trend is found throughout China with the extreme trend exceeding the mean trend, except for Northwest China and the North China Plain. In the 1990s, AEC over Northeast and Northwest China starts to decline while the rest of the country still exhibits an increase. The extreme trends continue to dominate in the south while it yields to the mean trend in the north. After year 2000, the extreme trend becomes weaker than the mean trend overall in terms of both the magnitude and significance level. The annual trend can be primarily attributed to winter and fall trends. The results suggest that the decadal changes of pollution in China may be governed by different mechanisms. Synoptic conditions that often result in extreme air quality changes might dominate in the 1980s, whereas emission increase might be the main factor for the 2000s.

Mineralogical characterization of fibrous zeolites from the Kahrizak volcanic suite, south Tehran, Iran

Clay Minerals ◽  
2010 ◽  
Vol 45 (4) ◽  
pp. 507-517 ◽  
Author(s):  
M. Kusehlar ◽  
F. Tutti ◽  
H. Mirnejad ◽  
A. E. Lalonde
Keyword(s):  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Scattered Electron ◽  
Northern Iran ◽  
Mineralogical Characterization ◽  
Thin Sections ◽  
Rich Solution ◽  
Cavity Filling ◽  
Fibrous Zeolites

AbstractSelected samples of large cavity filling and vein-type fibrous zeolites from Eocene volcanic rocks in the Kahrizak region, northern Iran, have been studied for their mineralogical and chemical characteristics. X-ray powder diffraction and electron microprobe analyses confirmed the presence of natrolite, mesolite and scolecite with compositions of [Na14.922Ca0.202K0.015Ba0.002] [Al15.697Si24.267O80]·nH2O, [Ca15.714Na14.224][Al46.431Si73.398O240]·nH2O and [Ca7.804Na0.142K0.024Ba0.012Mg0.006][Al15.320Si24.437O80]·nH2O, respectively. In addition, examination of textural relationships in thin sections and back-scattered electron images reveals a paragenetic order in which the Ca-rich zeolites crystallized first. It is most probable that the fibrous zeolites of Kahrizak were formed during two pulses of hydrothermal activity in the area. Scolecite and mesolite were precipitated from Ca-rich solution, whereas the second stage Na-rich, low-temperature fluid crystallized natrolite and reacted with Ca-species.

scholarly journals Geomagnetic Survey to Explore High-Temperature Geothermal System in Blawan-Ijen, East Java, Indonesia

2018 ◽  
Vol 31 ◽  
pp. 02003 ◽  
Author(s):  
Yunus Daud ◽  
Syamsu Rosid ◽  
Fikri Fahmi ◽  
Faris Maulana Yunus ◽  
Reza Muflihendri
Keyword(s):  
High Temperature ◽  
Magnetic Anomaly ◽  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Geothermal System ◽  
Geothermal Area ◽  
Variation Reduction ◽  
Geomagnetic Survey ◽  
Surface Alteration ◽  
Steep Topography

Ijen geothermal area is high-temperature geothermal system located in Bondowoso regency, East Java. It is categorized as caldera-hosted geothermal system which is covered by quaternary andesitic volcanic rocks with steep topography at the surrounding. Several surface thermal manifestations are found, such as altered rocks near Mt. Kukusan and a group of Blawan hotsprings in the northern part of the caldera. Geomagnetic survey was conducted at 72 stations which is distributed inside the caldera to delineate the existence of hydrothermal activity. Magnetic anomaly was obtained by reducing total magnetic measured on the field by IGRF and diurnal variation. Reduction to pole (RTP) method was applied with geomagnetic inclination of about -32°. In general, the result shows that high magnetic anomaly is distributed at the boundary of study area, while low magnetic anomaly is observed in the centre. The low anomaly indicates demagnetized rock that probably caused by hydrothermal activity. It has a good correlation with surface alteration observed close to Mt. Kukusan as well as high temperature reservoir drilled in the centre of caldera. Accordingly, the low magnetic anomaly also presents the possibility of geothermal reservoir in Ijen geothermal area.

scholarly journals Lower Moscovian limestones of the Bogdashan Range (NW China) as an indicator of cessation of arc magmatism in the Junggar region

2019 ◽  
Vol 27 (1) ◽  
pp. 57-78
Author(s):  
D. V. Alexeiev ◽  
Yu. S. Biske ◽  
A. V. Djenchuraeva ◽  
B. Wang ◽  
O. L. Kossovaya ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Foreland Basin ◽  
Northwest China ◽  
Island Arc ◽  
Tien Shan ◽  
Lower Permian ◽  
Carbonate Sediments ◽  
Tropical Zone ◽  
Middle Carboniferous ◽  
Marine Facies

The field revision of the Carboniferous and Lower Permian stratigraphy of the northern Bogdashan (South Junggar, Northwest China) shows that the Lower to Middle Carboniferous island arc volcanic rocks, widely developed in this region, are overlapped everywhere by carbonate and terrigenous-carbonate sediments, containing occasional lava flows and overlain up the section by thick terrigenous series practically devoid of volcanic rocks. The deposition of limestone occurred at the stage of dying off of a volcanic arc, and the question of their age is of fundamental importance for dating this event. Carbonates are represented by facies of lagoons, shoals, and bioherms that formed on the leveled surface of the arc and on the slopes of the last active volcanoes. Bioherms are Waulsortian mounds and are mainly composed of algal limestones and carbonate mud. There are no framestones composed of corals and sponges (chaetetids) typical of the tropical zone. The facies of shallow crinoid-fusulinid limestones typical of the adjacent territories of the Southern Tien Shan and Tarim are poorly represented. Paleogeographically, the position of bioherms corresponds to the northern boundary of the realm of Pennsylvanian reefs. On the basis of foraminifers, brachiopods, and corals, the age of carbonates is early Moscovian (ca. 315–310 Ma). Cessation of island-arc volcanism, followed by the accumulation of limestone in Bogdashan, occurred sub-synchronously with formation of the West Junggar (Bayingou) suture and may reflect docking of the Bogdashan arc to the Yili active margin of the Kazakhstan continent. Further subsidence of Bogdashan and adjacent regions of the Junggar and Turfan basins, which was somewhat slower at the end of the Carboniferous and more intense in the Early and Middle Permian, may reflect the development of the foreland basin that formed along the northern flank of the Tien Shan orogen. Marine facies were locally preserved in this basin until the Artinskian (ca. 285 Ma), and later the Junggar and Turfan basins lost connection to the ocean and developed in continental environments.

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