scholarly journals Auriferous Quartz Veining Due to CO2 Content Variations and Decompressional Cooling, Revealed by Quartz Solubility, SEM-CL and Fluid Inclusion Analyses (The Linglong Goldfield, Jiaodong)

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 417
Author(s):  
Qing Wei ◽  
Hongrui Fan ◽  
Jacques Pironon ◽  
Xuan Liu
Keyword(s):  
Fluid Inclusion ◽  
Meteoric Water ◽  
Gangue Mineral ◽  
Content Increase ◽  
Formation Processes ◽  
Solubility Behavior ◽  
Quartz Dissolution ◽  
Quartz Solubility ◽  
Quartz Veining

Quartz is the most common gangue mineral in hydrothermal veins. Coupled with capacities of hosting fluid inclusions and recording varieties of microtextures, its solubility behavior may provide unparalleled insights into hydrothermal processes. In this study, the Linglong goldfield in Jiaodong is targeted to investigate gold-producing quartz veining process. Scanning electron microscope (SEM)-cathodoluminescence (CL) imaging uncovered three episodes of quartz deposition, intervened by an episode of quartz dissolution. Based on newly-developed quartz solubility diagrams and CL-aided fluid inclusion microthermometry, it is proposed that precipitation of the earliest quartz (Qz1) was controlled by CO2 content increase and subordinately affected by decompressional cooling, leading to the formation of the early thick gold-barren veins (V1); the second generation of quartz (Qz2a) was formed by the same fluids that may have been diluted and cooled by meteoric water, leading to a greatly reduced quantity of quartz and the deposition of pyrite and gold; and the third generation of quartz (Qz2b) was deposited along with polymetallic sulfides, due to fluid cooling following a quartz dissolution event likely induced by cooling in retrograde solubility region and/or CO2 content decrease. This research may elucidate gold formation processes in orogenic intrusion—related deposits, and points to imperative CL-based in situ analyses for future studies.

Quartz precipitation and fluid inclusion characteristics in sub-seafloor hydrothermal systems associated with volcanogenic massive sulfide deposits

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Matthew Steele-MacInnis ◽  
Liang Han ◽  
Robert Lowell ◽  
J. Rimstidt ◽  
Robert Bodnar
Keyword(s):  
Fluid Inclusion ◽  
Fluid Inclusions ◽  
Hydrothermal System ◽  
Massive Sulfide ◽  
Hydrothermal Systems ◽  
Fluid Immiscibility ◽  
Quartz Dissolution ◽  
Vms Deposits ◽  
Quartz Solubility ◽  
Dissolution And Precipitation

AbstractResults of a numerical modeling study of quartz dissolution and precipitation in a sub-seafloor hydrothermal system have been used to predict where in the system quartz could be deposited and potentially trap fluid inclusions. The spatial distribution of zones of quartz dissolution and precipitation is complex, owing to the fact that quartz solubility depends on many inter-related factors, including temperature, fluid salinity and fluid immiscibility, and is further complicated by the fact that quartz exhibits both prograde and retrograde solubility behavior, depending on the fluid temperature and salinity. Using the PVTX properties of H2O-NaCl, the petrographic and microthermometric properties of fluid inclusions trapped at various locations within the hydrothermal system have been predicted. Vapor-rich inclusions are trapped as a result of the retrograde temperature-dependence of quartz solubility as the convecting fluid is heated in the vicinity of the magmatic heat source. Coexisting liquid-rich and vapor-rich inclusions are also trapped in this region when quartz precipitates as a result of fluid immiscibility that lowers the overall bulk quartz solubility in the system. Fluid inclusions trapped in the shallow subsurface near the seafloor vents and in the underlying stockwork are liquid-rich with homogenization temperatures of 200–400°C and salinities close to that of seawater. Volcanogenic massive sulfide (VMS) deposits represent the uplifted and partially eroded remnants of fossil submarine hydrothermal systems, and the relationship between fluid-inclusion properties and location within the hydrothermal system described here can be used in exploration for VMS deposits to infer the direction towards potential massive sulfide ore.

In-situ investigation of the bulk heterojunction formation processes in the active layers of organic solar cells

2015 ◽  
Vol 10 (7-8) ◽  
pp. 600-605 ◽  
Author(s):  
K. Kvamen ◽  
S. Grigoryan ◽  
D. V. Anokhin ◽  
V. A. Bataev ◽  
A. I. Smirnov ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Formation Processes ◽  
Active Layers ◽  
In Situ Investigation

Magmatic-Hydrothermal Mineralization Processes at the Yidong Tin Deposit, South China: Insights from In Situ Chemical and Boron Isotope Changes of Tourmaline

2021 ◽  
Author(s):  
He-Dong Zhao ◽  
Kui-Dong Zhao ◽  
Martin R. Palmer ◽  
Shao-Yong Jiang ◽  
Wei Chen
Keyword(s):  
South China ◽  
Hydrothermal Fluids ◽  
Boron Isotope ◽  
Granitic Magma ◽  
Gangue Mineral ◽  
Rock Interaction ◽  
Hydrothermal Mineralization ◽  
Mineralization Processes ◽  
Tin Deposit

Abstract Owing to the superimposition of water-rock interaction and external fluids, magmatic source signatures of ore-forming fluids for vein-type tin deposits are commonly overprinted. Hence, there is uncertainty regarding the involvement of magmatic fluids in mineralization processes within these deposits. Tourmaline is a common gangue mineral in Sn deposits and can crystallize from both the magmas and the hydrothermal fluids. We have therefore undertaken an in situ major, trace element, and B isotope study of tourmaline from the Yidong Sn deposit in South China to study the transition from late magmatic to hydrothermal mineralization. Six tourmaline types were identified: (1) early tourmaline (Tur-OE) and (2) late tourmaline (Tur-OL) in tourmaline-quartz orbicules from the Pingying granite, (3) early tourmaline (Tur-DE) and (4) late tourmaline (Tur-DL) in tourmaline-quartz dikelets in the granite, and (5 and 6) core (Tur-OC) and rim (Tur-OR), respectively of hydrothermal tourmaline from the Sn ores. Most of the tourmaline types belong to the alkali group and the schorl-dravite solid-solution series, but the different generations of magmatic and hydrothermal tourmaline are geochemically distinct. Key differences include the hundredfold enrichment of Sn in hydrothermal tourmaline compared to magmatic tourmaline, which indicates that hydrothermal fluids exsolving from the magma were highly enriched in Sn. Tourmaline from the Sn ores is enriched in Fe3+ compared to the hydrothermal tourmaline from the granite and displays trends of decreasing Al and increasing Fe content from core to rim, relating to the exchange vector Fe3+Al–1. This reflects oxidation of fluids during the interaction between hydrothermal fluids and the mafic-ultramafic wall rocks, which led to precipitation of cassiterite. The hydrothermal tourmaline has slightly higher δ11B values than the magmatic tourmaline (which reflects the metasedimentary source for the granite), but overall, the tourmaline from the ores has δ11B values similar to those from the granite, implying a magmatic origin for the ore-forming fluids. We identify five stages in the magmatic-hydrothermal evolution of the system that led to formation of the Sn ores in the Yidong deposit based on chemical and boron isotope changes of tourmaline: (1) emplacement of a B-rich, S-type granitic magma, (2) separation of an immiscible B-rich melt, (3) exsolution of an Sn-rich, reduced hydrothermal fluid, (4) migration of fluid into the country rocks, and (5) acid-consuming reactions with the surrounding mafic-ultramafic rocks and oxidation of the fluid, leading to cassiterite precipitation.

scholarly journals Fluid Inclusion and Oxygen Isotope Constraints on the Origin and Hydrothermal Evolution of the Haisugou Porphyry Mo Deposit in the Northern Xilamulun District, NE China

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Qihai Shu ◽  
Yong Lai
Keyword(s):  
Fluid Inclusion ◽  
Meteoric Water ◽  
Early Time ◽  
Low Oxygen ◽  
Potassic Alteration ◽  
Low Salinity ◽  
Oxygen Isotopic ◽  
Homogenization Temperatures ◽  
Porphyry Mo Deposit ◽  
Positive Correlations

The Haisugou porphyry Mo deposit is located in the northern Xilamulun district, northeastern China. Based on alteration and mineralization styles and crosscutting relationships, the hydrothermal evolution in Haisugou can be divided into three stages: an early potassic alteration stage with no significant metal deposition, a synmineralization sericite-chlorite alteration stage with extensive Mo precipitation, and a postmineralization stage characterized by barren quartz and minor calcite and fluorite. The coexistence of high-salinity brine inclusions with low-salinity inclusions both in potassic alteration stage (~440°C) and locally in the early time of mineralization stage (380–320°C) indicates the occurrence of fluid boiling. The positive correlations between the homogenization temperatures and the salinities of the fluids and the low oxygen isotopic compositions (δ18Ofluid < 3‰) of the syn- to postmineralization quartz together suggest the mixing of magmatic fluids with meteoric water, which dominated the whole mineralization process. The early boiling fluids were not responsible for ore precipitation, whereas the mixing with meteoric water, which resulted in temperature decrease and dilution that significantly reduced the metal solubility, should have played the major role in Mo mineralization. Combined fluid inclusion microthermometry and chlorite geothermometer results reveal that ore deposition mainly occurred between 350 and 290°C in Haisugou.

Is it possible to determine formation processes of organic deposits through polysaccharides? Pilot study from the prehistoric site in Brandýs nad Labem, Czech Republic

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1273-1280
Author(s):  
Klement Rejšek ◽  
Jan Turek ◽  
Valerie Vranová ◽  
Roman Hadacz ◽  
Lenka Lisá
Keyword(s):  
Czech Republic ◽  
Pilot Study ◽  
Organic Material ◽  
Archaeological Site ◽  
Soil Samples ◽  
Formation Processes ◽  
Cultural Layer ◽  
Different Types ◽  
Organic Deposits

This paper deals with a possible interpretation value of biochemical methods in comparison with the classic tools of geoarchaeology for the evaluation of formation processes. Organic rich layers from the archaeological site Brandýs nad Labem-Vrábí were tested with the aim to determine the origin of several different types of soil organic material by analyzing the content of different sugars. The studied soil body showed signs of cultural layer, redeposited soils, and in situ developed soil. The analysis of different sugars was highlighted: soil samples taken from these layers were analyzed to assess the ratios of mannose + galactose to arabinose + xylose, and of rhamnose + fucose to arabinose + xylose, content of Corg and different nitrates, as well as different rates of absorbance. The results show that the interpretation values of polysaccharides evaluation didn’t bring significant results itself, but in combination with classical tools of geoarchaeology may bring interpretable and new results.

Excavation of the Lower Palaeolithic Site at Amey's Eartham Pit, Boxgrove, West Sussex: A Preliminary Report.

1986 ◽  
Vol 52 ◽  
pp. 215-245 ◽  
Author(s):  
M. B. Roberts ◽  
M. R. Bates ◽  
C. Bergman ◽  
A. P. Currant ◽  
J. R. Haynes ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Preliminary Report ◽  
Site Formation ◽  
Middle Pleistocene ◽  
Site Formation Processes ◽  
Formation Processes ◽  
Environmental Reconstruction ◽  
Multidisciplinary Research ◽  
Lower Palaeolithic

The acheulian site at Boxgrove contains one of the most extensive areas of in situ fauna and flintwork yet discovered in Britain. This material is found in a complex sequence of sediments which represent depositional conditions from a 42 m sea level rise to the onset of a full periglacial climate. Excavation of the archaeological horizon has been accompanied by a programme of multidisciplinary research examining site formation processes, palaeolandscape and palaeoecological development, using sedimentological and environmental reconstruction techniques. Dating of the site is tentative as no absolute dates are available at present. However, comparative analysis with other British sites would suggest a position for the Boxgrove sequence within the Middle Pleistocene. The archaeological horizon is interpreted as being deposited towards the latter part of an interglacial or an interstadial period.

A new approach towards the study of thermal decomposition and formation processes of nanoalloys: the double complex salt [Pd(NH3)4][PtCl6]

2018 ◽  
Vol 42 (7) ◽  
pp. 5071-5082 ◽  
Author(s):  
Tatyana I. Asanova ◽  
Igor P. Asanov ◽  
Min-Gyu Kim ◽  
Mihaela Gorgoi ◽  
Jonas Sottmann ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Complex Salt ◽  
Decomposition Process ◽  
Formation Processes ◽  
Thermal Decomposition Process ◽  
Double Complex ◽  
New Approach ◽  
Double Complex Salt

The thermal decomposition process of the [Pd(NH3)4][PtCl6] double complex salt was investigated using in situ XAFS, XPS, HAXPES, and XRD.

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