scholarly journals Tectonic Control, Reconstruction and Preservation of the Tiegelongnan Porphyry and Epithermal Overprinting Cu (Au) Deposit, Central Tibet, China

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 398 ◽  
Author(s):  
Yang Song ◽  
Chao Yang ◽  
Shaogang Wei ◽  
Huanhuan Yang ◽  
Xiang Fang ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Isotopic Signature ◽  
Epithermal Deposit ◽  
Porphyry Deposit ◽  
Tectonic Control ◽  
Quartz Veins ◽  
High Sulfidation ◽  
Metallogenic Belt ◽  
Alteration Minerals ◽  
Central Tibet

The newly discovered Tiegelongnan Cu (Au) deposit is a giant porphyry deposit overprinted by a high-sulfidation epithermal deposit in the western part of the Bangong–Nujiang metallogenic belt, Duolong district, central Tibet. It is mainly controlled by the tectonic movement of the Bangong–Nujiang Oceanic Plate (post-subduction extension). After the closure of the Bangong–Nujiang Ocean, porphyry intrusions emplaced at around 121 Ma in the Tiegelongnan area, which might be the result of continental crust thickening and the collision of Qiangtang and Lhasa terranes, based on the crustal radiogenic isotopic signature. Epithermal overprinting on porphyry alteration and mineralization is characterized by veins and fracture filling, and replacement textures between two episodes of alteration and sulfide minerals. Alunite and kaolinite replaced sericite, accompanied with covellite, digenite, enargite, and tennantite replacing chalcopyrite and bornite. This may result from extension after the Qiangtang–Lhasa collision from 116 to 112 Ma, according to the reopened quartz veins filled with later epithermal alteration minerals and sulfides. The Tiegelongnan deposit was preserved by the volcanism at ~110 Ma with volcanic rocks covering on the top before the orebody being fully weathered and eroded. The Tiegelongnan deposit was then probably partly dislocated to further west and deeper level by later structures. The widespread post-mineral volcanic rocks may conceal and preserve some unexposed deposits in this area. Thus, there is a great potential to explore porphyry and epithermal deposit in the Duolong district, and also in the entire Bangong–Nujiang metallogenic belt.

The Nadun Cu–Au mineralization, central Tibet: Root of a high sulfidation epithermal deposit

2016 ◽  
Vol 78 ◽  
pp. 371-387 ◽  
Author(s):  
Jin-Xiang Li ◽  
Ke-Zhang Qin ◽  
Guang-Ming Li ◽  
Noreen J. Evans ◽  
Jun-Xing Zhao ◽  
...  
Keyword(s):  
Epithermal Deposit ◽  
High Sulfidation ◽  
Central Tibet

scholarly journals Amethyst occurrences in Tertiary volcanic rocks of Greece: mineralogical and genetic implications

2013 ◽  
Vol 47 (1) ◽  
pp. 477 ◽  
Author(s):  
P. Voudouris ◽  
I. Psimis ◽  
C. Mavrogonatos ◽  
C. Kanellopoulos ◽  
M. Kati ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Hydrothermal Fluids ◽  
Calc Alkaline ◽  
Northern Greece ◽  
Volcanic Arc ◽  
Quartz Veins ◽  
High Sulfidation ◽  
Host Rocks ◽  
Of Greece

Epithermal-altered volcanic rocks in Greece host gem-quality amethyst veins in association with various silicates, carbonates, oxides, sulfides and halides. Host rocks are Oligocene to recent calc-alkaline to shoshonitic lavas and pyroclastics of intermediate- to acid composition. The amethyst-bearing veins occur in the periphery of porphyry-type and/or high-sulfidation epithermal mineralized centers in northern Greece (e.g. Sapes, Kirki, Kornofolia/Soufli, Lesvos island) and on Milos island in the active Aegean Volcanic Arc. Hydrothermal alteration around the quartz veins includes sericitic, K-feldspar (adularia), argillic, propylitic and zeolitic types. Precipitation of amethyst in the northern Greece occurrences, took place during the final stages of the magmatic-hydrothermal activity from near-neutral to alkaline fluids, as indicated by the presence of gangue adularia, calcite, smectite, chlorite, sericite, pyrite, zeolites (laumontite, heulandite, clinoptilolite), analcime and minor amounts of barite, halite, epidote and fluorite in the quartz veins. Amethyst at Milos Island (Chondro Vouno and Kalogries-Vani areas), is accompanied by barite, smectite and lepidocrocite. Colloform-crustiform banding with alternations of amethyst, chalcedony and/or carbonates is a common characteristic of the studied amethyst-bearing veins. Fluid inclusion- and mineralogical data suggest that the studied amethyst were formed at: 174-246 °C (Sapes area), 100-175 °C (Kirki and Kornofolia areas) and 223-234°C (Lesvos island). The amethyst formation requires oxidizing conditions and is probably the result of mixing between meteoric or seawater with upwelling hydrothermal fluids. The involvement of seawater in the studied mineralization is supported by the presence of halite and abundant barite in the veins. Finally, the studied amethyst deposits should be evaluated as potential gemstone sources in Greece.

EXPLORATION OF A HIGH-SULFIDATION EPITHERMAL DEPOSIT WITHIN THE ANTELOPE VALLEY VOLCANIC CENTER, SIERRA COUNTY CALIFORNIA

2017 ◽  
Author(s):  
Sommer M. Casady ◽  
◽  
Hannah Aird ◽  
Hannah Aird ◽  
Andrew Guglielmo ◽  
...  
Keyword(s):  
Volcanic Center ◽  
Epithermal Deposit ◽  
High Sulfidation

Three stages of arc migration in the Carboniferous-Triassic in northern Qiangtang, central Tibet, China: Ridge subduction and asynchronous slab rollback of the Jinsha Paleotethys

2021 ◽  
Author(s):  
Yin Liu ◽  
Wenjiao Xiao ◽  
Brian F. Windley ◽  
Kefa Zhou ◽  
Rongshe Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Volcanic Rocks ◽  
Late Triassic ◽  
Geochemical Data ◽  
The Tibetan Plateau ◽  
Ridge Subduction ◽  
Temporal Relationships ◽  
Slab Rollback ◽  
Geodynamic Processes ◽  
Central Tibet

Carboniferous-Triassic magmatism in northern Qiangtang, central Tibet, China, played a key role in the evolution of the Tibetan Plateau yet remains a subject of intense debate. New geochronological and geochemical data from adakitic, Nb-enriched, and normal arc magmatic rocks, integrated with results from previous studies, enable us to determine the Carboniferous-Triassic (312−205 Ma), arc-related, plutonic-volcanic rocks in northern Qiangtang. Spatial-temporal relationships reveal three periods of younging including southward (312−252 Ma), rapid northward (249−237 Ma), and normal northward (234−205 Ma) migrations that correspond to distinct slab geodynamic processes including continentward slab shallowing, rapid trenchward slab rollback, and normal trenchward rollback of the Jinsha Paleotethys rather than the Longmuco-Shuanghu Paleotethys, respectively. Moreover, varying degrees of coexistence of adakites/High-Mg andesites (HMAs)/Nb-enriched basalt-andesites (NEBs) and intraplate basalts in the above-mentioned stages is consistent with the magmatic effects of slab window triggered by ridge subduction, which probably started since the Late Carboniferous and continued into the Late Triassic. The Carboniferous-Triassic multiple magmatic migrations and ridge-subduction scenarios provide new insight into the geodynamic processes of the Jinsha Paleotethys and the growth mechanism of the Tibetan Plateau.

scholarly journals Gold-hosting supracrustal rocks on Storø, southern West Greenland: lithologies and geological environment

2007 ◽  
Vol 13 ◽  
pp. 41-44 ◽  
Author(s):  
Christian Knudsen ◽  
Jeroen A.M. Van Gool ◽  
Claus Østergaard ◽  
Julie A. Hollis ◽  
Matilde Rink-Jørgensen ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
West Greenland ◽  
Metasedimentary Rocks ◽  
Quartz Veins ◽  
Rock Types ◽  
Minimum Age ◽  
Arc Setting ◽  
Basic Volcanic ◽  
Back Arc ◽  
Different Sources

A gold prospect on central Storø in the Nuuk region of southern West Greenland is hosted by a sequence of intensely deformed, amphibolite facies supracrustal rocks of late Mesoto Neoarchaean age. The prospect is at present being explored by the Greenlandic mining company NunaMinerals A/S. Amphibolites likely to be derived from basaltic volcanic rocks dominate, and ultrabasic to intermediate rocks are also interpreted to be derived from volcanic rocks. The sequence also contains metasedimentary rocks including quartzites and cordierite-, sillimanite-, garnet- and biotite-bearing aluminous gneisses. The metasediments contain detrital zircon from different sources indicating a maximum age of the mineralisation of c. 2.8 Ga. The original deposition of the various rock types is believed to have taken place in a back-arc setting. Gold is mainly hosted in garnet- and biotite-rich zones in amphibolites often associated with quartz veins. Gold has been found within garnets indicating that the mineralisation is pre-metamorphic, which points to a minimum age of the mineralisation of c. 2.6 Ga. The geochemistry of the goldbearing zones indicates that the initial gold mineralisation is tied to fluid-induced sericitisation of a basic volcanic protolith. The hosting rocks and the mineralisation are affected by several generations of folding.

scholarly journals Fracture Fillings and Implication of Fluid Activities in Volcanic Rocks: Dixi Area in Kelameili Gas Field, Junggar Basin, Northwestern China

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 154 ◽  
Author(s):  
Mingyou Feng ◽  
Tian Liu ◽  
Tong Lin ◽  
Xiaohong Liu ◽  
Ningxin Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Volcanic Rocks ◽  
Junggar Basin ◽  
Hydrothermal Fluids ◽  
Northwestern China ◽  
Volatile Components ◽  
Gas Field ◽  
Weakly Alkaline ◽  
Quartz Veins ◽  
Calcite Veins

The Carboniferous Batamayineishan Formation of the Kelameili Gas Field is a specific weathered crust-related volcanic reservoir that has a significant production rate in the Junggar Basin, Northwestern China, attributed to debatable processes of fluid evolution. The results suggest that various types of fluids occurring in volcanic rocks lead to the filling of quartz and calcite in fractures and their associated alteration haloes. The silica that formed quartz veins was mainly derived from deep hydrothermal fluids, while the carbon dioxide that formed calcite veins originated from sources characterized by mixing and alteration of deep hydrothermal and hydrocarbon fluids. Siliceous hydrothermal fluids rich in sulphur dioxide and other volatile components were driven by a pressure gradient and buoyancy, and circulated both laterally and vertically along the fractures, forming quartz veins and tension fractures under different temperature conditions. Moreover, changes in salinity, pressure, and carbon dioxide of deep fluids, varying from acidic to weakly alkaline, resulted in earlier calcite precipitation in contraction fractures and weathered fractures. Tectonic uplift resulted in the long-term exposure of volcanic rocks, where fresh water mixed with the partially alkaline fluid escaping the basin to form calcite cements, thus retaining the characteristics of a seepage environment in the weathered fractures. Structural fractures occurred due to tectonic movements during the burial period. Filling and leakage of hydrocarbons caused pore fluids to convert from acidic to alkaline, precipitating late sparry calcite in dissolution fractures. Late hydrothermal fluid metasomatism, brought about by infiltration into the permeable zone, caused partial dissolution of local calcite along cleavage cracks.

Copper-Gold Fertility of Arc Volcanic Rocks: A Case Study from the Early Permian Lizzie Creek Volcanic Group, NE Queensland, Australia

2020 ◽  
Author(s):  
Helge Behnsen ◽  
Carl Spandler ◽  
Isaac Corral ◽  
Zhaoshan Chang ◽  
Paul H.G.M. Dirks
Keyword(s):  
Major Element ◽  
Regional Scale ◽  
Volcanic Rocks ◽  
Early Permian ◽  
Magma Evolution ◽  
High Sulfidation ◽  
Volcanic Group ◽  
Volcanic Suite ◽  
Copper Gold

Abstract The Early Permian Lizzie Creek Volcanic Group of the northern Bowen Basin, NE Queensland, Australia, has compositions that range from basalt through andesite to rhyolite with geochemical signatures (e.g., enrichment in Cs, Rb, Ba, U, Th, and Pb, depletion in Nb and Ta) that are typical of arc lavas. In the Mount Carlton district the Lizzie Creek Volcanic Group is host to high-sulfidation epithermal Cu-Au-Ag mineralization, whereas farther to the south near Collinsville (~50 km from Mount Carlton) these volcanic sequences are barren of magmatic-related mineralization. Here, we assess whether geochemical indicators of magma fertility (e.g., Sr/Y, La/Yb, V/Sc) can be applied to volcanic rocks through study of coeval volcanic sequences from these two locations. The two volcanic suites share similar petrographic and major element geochemical characteristics, and both have undergone appreciable hydrothermal alteration during, or after, emplacement. Nevertheless, the two suites have distinct differences in alteration-immobile trace element (V, Sc, Zr, Ti, REE, Y) concentrations. The unmineralized suite has relatively low V/Sc and La/Yb, particularly in the high SiO2 rocks, which is related to magma evolution dominated by fractionation of clinopyroxene, plagioclase, and magnetite. By contrast, the mineralized suite has relatively high V/Sc but includes high SiO2 rocks with depleted HREE and Y contents, and hence high La/Yb. These trends are interpreted to reflect magma evolution under high magmatic H2O conditions leading to enhanced amphibole crystallization and suppressed plagioclase and magnetite crystallization. These rocks have somewhat elevated Sr/Y compared to the unmineralized suite, but as Sr is likely affected by hydrothermal mobility, Sr/Y is not considered to be a reliable indicator of magmatic conditions. Our data show that geochemical proxies such as V/Sc and La/Yb that are used to assess Cu-Au fertility of porphyry intrusions can also be applied to cogenetic volcanic sequences, provided elemental trends with fractionation can be assessed for a volcanic suite. These geochemical tools may aid regional-scale exploration for Cu-Au mineralization in convergent margin terranes, especially in areas that have undergone limited exhumation or where epithermal and porphyry mineralization may be buried beneath cogenetic volcanic successions.

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