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Open AccessEditorial

Editorial for Special Issue “Fluid Inclusions: Study Methods, Applications, and Case Histories”

by Martin Feely

Minerals 2018, 8(7), 307; https://doi.org/10.3390/min8070307 - 21 Jul 2018

Cited by 1 | Viewed by 2093

Abstract

The pioneering work of H.C. Sorby [1] in the mid-19th century highlighted the scientific importance of fluid inclusions in minerals [...] Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

Research

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Open AccessArticle

Anomalously High Cretaceous Paleobrine Temperatures: Hothouse, Hydrothermal or Solar Heating?

by Jiuyi Wang and Tim K. Lowenstein

Minerals 2017, 7(12), 245; https://doi.org/10.3390/min7120245 - 13 Dec 2017

Cited by 14 | Viewed by 4249

Abstract

Elevated surface paleobrine temperatures (average 85.6 °C) are reported here from Cretaceous marine halites in the Maha Sarakham Formation, Khorat Plateau, Thailand. Fluid inclusions in primary subaqueous “chevron” and “cumulate” halites associated with potash salts contain daughter crystals of sylvite (KCl) and carnallite [...] Read more.

Elevated surface paleobrine temperatures (average 85.6 °C) are reported here from Cretaceous marine halites in the Maha Sarakham Formation, Khorat Plateau, Thailand. Fluid inclusions in primary subaqueous “chevron” and “cumulate” halites associated with potash salts contain daughter crystals of sylvite (KCl) and carnallite (MgCl₂·KCl·6H₂O). Petrographic textures demonstrate that these fluid inclusions were trapped from the warm brines in which the halite crystallized. Later cooling produced supersaturated conditions leading to the precipitation of sylvite and carnallite daughter crystals within fluid inclusions. Dissolution temperatures of daughter crystals in fluid inclusions from the same halite bed vary over a large range (57.9 °C to 117.2 °C), suggesting that halite grew at different temperatures within and at the bottom of the water column. Consistency of daughter crystal dissolution temperatures within fluid inclusion bands and the absence of vapor bubbles at room temperature demonstrate that fluid inclusions have not stretched or leaked. Daughter crystal dissolution temperatures are reproducible to within 0.1 °C to 10.2 °C (average of 1.8 °C), and thus faithfully document paleobrine conditions. Microcrystalline hematite incorporated within halite crystals also indicate high paleobrine temperatures. We conclude that halite crystallized from warm brines rich in K-Mg-Na-Cl; sylvite and carnallite daughter crystals were nucleated during cooling of the warm brines sometime after deposition. Hothouse, hydrothermal, and solar-heating hypotheses are compared to explain the anomalously high surface paleobrine temperatures. Solar radiation stored in shallow density stratified brines is the most plausible explanation for the observed paleobrine temperatures and the progressively higher temperatures downward through the paleobrine column. The solar-heating hypothesis may also explain high paleobrine temperatures documented from fluid inclusions in other ancient halites. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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11729 KiB

Open AccessArticle

Quartz-Amethyst Hosted Hydrocarbon-Bearing Fluid Inclusions from the Green Ridge Breccia in the Snoqualmie Granite, North Cascades, WA, USA

by Martin Feely, Alessandra Costanzo, Franzisca Lindner, Joe George, John Parnell, Stephen Bowden, Mas’ud Baba and Peter Owens

Minerals 2017, 7(9), 174; https://doi.org/10.3390/min7090174 - 19 Sep 2017

Cited by 5 | Viewed by 6880

Abstract

The Green Ridge Breccia cuts the composite Miocene Snoqualmie Batholith in King County, WA, USA. The granite was emplaced at ~5 km depth between ~17 and 20 Ma and the crosscutting NW trending breccia contains large angular blocks of the host granite (<1 [...] Read more.

The Green Ridge Breccia cuts the composite Miocene Snoqualmie Batholith in King County, WA, USA. The granite was emplaced at ~5 km depth between ~17 and 20 Ma and the crosscutting NW trending breccia contains large angular blocks of the host granite (<1 m in longest dimension). The brecciated granite blocks are cemented by quartz-amethyst euhedra (<10 cm in longest dimension) bearing vugs. A notable feature is the presence of centimetric scale amber coloured oil inclusions within the quartz-amethyst crystals. Fluid inclusion studies using Transmitted Light Petrography, UV Microscopy, Microthermometry, Laser Raman Microspectroscopy and Gas Chromatography-Mass Spectrometry record the presence and the fluid composition of three fluid inclusion types hosted by the euhedra: primary Type 1 (liquid rich two-phase (L + V) aqueous inclusions) and secondary Type 2 bituminous two-phase (S + L) inclusions and Type 3 amber coloured oil bearing two-phase immiscible liquid inclusions. The Green Ridge Breccia was the locus for convective hydrothermal fluid flow that formed the quartz-amethyst vugs formed at T~390 °C assuming a trapping pressure of ~1.65 kb. Later, hydrocarbon fluids migrated downwards from the roof source rock (e.g., the Guye Sedimentary Member) and were trapped in the euhedra. This was followed by unroofing of the batholith and exposure of the Green Ridge Breccia. This study highlights the potential for other oil migrations into the Snoqualmie Batholith in areas where it forms the basement capped by the Guye Sedimentary Member. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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1873 KiB

Open AccessArticle

Hydrogen from Radiolysis of Aqueous Fluid Inclusions during Diagenesis

by John Parnell and Nigel Blamey

Minerals 2017, 7(8), 130; https://doi.org/10.3390/min7080130 - 25 Jul 2017

Cited by 9 | Viewed by 4350

Abstract

A suite of Permian sylvite samples from Boulby potash mine, Yorkshire, UK, consistently yield traces of hydrogen upon analysis by a cold crush technique for liberating volatiles from entrapped fluid inclusions. In contrast, accompanying halite samples do not yield hydrogen. These data suggest [...] Read more.

A suite of Permian sylvite samples from Boulby potash mine, Yorkshire, UK, consistently yield traces of hydrogen upon analysis by a cold crush technique for liberating volatiles from entrapped fluid inclusions. In contrast, accompanying halite samples do not yield hydrogen. These data suggest the formation of hydrogen by radiolysis of water due to irradiation from potassium in the sylvite. The data indicate radiolysis as a mechanism for subsurface hydrogen generation, where it is available as an electron donor for a deep biosphere. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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Open AccessArticle

Re-Equilibration Processes in Fluid Inclusion Assemblages

by Ronald J. Bakker

Minerals 2017, 7(7), 117; https://doi.org/10.3390/min7070117 - 07 Jul 2017

Cited by 22 | Viewed by 5327

Abstract

Post-entrapment modifications reduce the reliability of fluid inclusions to determine trapping conditions in rock. Processes that may modify fluid inclusion properties are experimentally identified in this study using synthetic fluid inclusions in quartz with a well-defined composition and density. Modifications are characterized with [...] Read more.

Post-entrapment modifications reduce the reliability of fluid inclusions to determine trapping conditions in rock. Processes that may modify fluid inclusion properties are experimentally identified in this study using synthetic fluid inclusions in quartz with a well-defined composition and density. Modifications are characterized with microthermometry (homogenization and dissolution temperatures) and Raman-spectroscopy in binary fluid systems H₂O-D₂O and H₂O-NaCl. Three distinct processes were identified in this study: (1) diffusion of H₂O and D₂O; (2) crystal-recovery, expulsion of H₂O and accumulation of quartz in inclusions (preferential H₂O loss); (3) irreversible total volume increase at the α-β quartz transition. Diffusion is caused by H₂O fugacity gradients and can be modelled according to classical diffusion models. The variability of re-equilibrated properties in fluid inclusion assemblages depends on time, temperature, diffusion distance and the size of fluid inclusions. Negative pressure gradients (internal under-pressure) induce the crystal-recovery process, in which H₂O is preferentially extracted from inclusions that simultaneously shrink by the inward growth of quartz. This process reduces the H₂O concentration and increases the fluid density by total volume loss. Temperature and time are also controlling factors of this process, which is able to transport H₂O against fugacity gradients. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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Open AccessArticle

The Hydrothermal Fluid Evolution of Vein Sets at the Pipeline Gold Mine, Nevada

by Nigel J.F. Blamey, Andrew R. Campbell and Matt T. Heizler

Minerals 2017, 7(6), 100; https://doi.org/10.3390/min7060100 - 13 Jun 2017

Cited by 6 | Viewed by 6196

Abstract

The origin of sediment-hosted Nevada gold deposits has been highly debated, especially regarding the relative contribution of multiple mineralizing events, particularly relating to the Cretaceous. We examined the Pipeline gold mine in north-central Nevada, focusing on data from the four vein sets in [...] Read more.

The origin of sediment-hosted Nevada gold deposits has been highly debated, especially regarding the relative contribution of multiple mineralizing events, particularly relating to the Cretaceous. We examined the Pipeline gold mine in north-central Nevada, focusing on data from the four vein sets in this atypical deposit where there is evidence for Cretaceous gold mineralization. Only the third, a quartz-sericite-pyrite-calcite vein set, has any link with the alteration styles and gold mineralization within the Pipeline deposit. Our geochemical results from fluid inclusion microthermometry and gas analysis show that the fluids from which quartz deposited were sourced from condensing magmatic volatiles and were trapped at ~300 °C and 2 kbar lithostatic pressure (~8 km). ⁴⁰Ar/³⁹Ar dating of sericite demonstrates that the quartz-sericite-pyrite veins formed at ~92 Ma, matching the dates of gold-associated epigenetic illite. Ore fluids enriched in CO₂ and H₂S caused decarbonation thereby releasing Fe²⁺ that reacted with H₂S to form pyrite. Decreasing H₂S destabilized gold bisulfide complexes and deposited gold. We conclude that this process can occur in a single Cretaceous event in advance of potential Tertiary mineralization. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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5211 KiB

Open AccessArticle

The Use of Integrated Fluid Inclusion Studies for Constraining Petroleum Charge History at Parsons Pond, Western Newfoundland, Canada

by James Conliffe, Elliot T. Burden and Derek H. C. Wilton

Minerals 2017, 7(3), 39; https://doi.org/10.3390/min7030039 - 12 Mar 2017

Cited by 17 | Viewed by 5694

Abstract

This study, based on fluid inclusion petrography, microthermometry and ultraviolet microspectroscopy of inclusion oil, investigates the petroleum charge history at Parsons Pond, western Newfoundland. To address this matter, drill core and cuttings samples of allochthonous and autochthonous strata in the Parson’s Pond area [...] Read more.

This study, based on fluid inclusion petrography, microthermometry and ultraviolet microspectroscopy of inclusion oil, investigates the petroleum charge history at Parsons Pond, western Newfoundland. To address this matter, drill core and cuttings samples of allochthonous and autochthonous strata in the Parson’s Pond area were collected from three exploration wells. Fluid inclusions were examined from fragments of calcite and quartz veins, diagenetic cements in sandstone, and in large hydrothermal dolomite and calcite crystals. Primary aqueous inclusions in authigenic sandstone cements indicate that cementation occurred at relatively shallow depths and low temperatures (<50 °C). Hydrocarbon-bearing fluid inclusions (petroleum, wet gas and gas) are generally restricted to calcite and quartz veins, indicating that petroleum and gas migration at Parson’s Pond is fracture-controlled. No hydrocarbons were observed in the diagenetic cements of the essentially tight sandstones. Fluid inclusion microthermometry and ultraviolet microspectroscopy indicate the presence of multiple generations of hydrocarbon fluid, ranging in composition from ~33 API gravity petroleum to pure CH₄. Petrographic evidence suggests that hydrocarbons were generated multiple times during progressive burial and heating. In addition, the distribution of hydrocarbon bearing inclusions with depth suggests that deeper levels are gas-prone, with petroleum confined to relatively shallow depths. Although only gas flow was encountered during the drilling of exploration wells at Parson’s Pond, the presence of petroleum-bearing fluid inclusions in calcite and quartz veins indicates that the historical production from shallow wells in the Parsons Pond area likely tapped small reservoirs of fractured petroliferous strata. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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8554 KiB

Open AccessArticle

Pressure–Temperature–Fluid Constraints for the Poona Emerald Deposits, Western Australia: Fluid Inclusion and Stable Isotope Studies

by Dan Marshall, Peter J. Downes, Sarah Ellis, Robert Greene, Lara Loughrey and Peter Jones

Minerals 2016, 6(4), 130; https://doi.org/10.3390/min6040130 - 09 Dec 2016

Cited by 26 | Viewed by 5880

Abstract

Emerald from the deposits at Poona shows micrometre-scale chemical, optical, and cathodoluminescence zonation. This zonation, combined with fluid inclusion and isotope studies, indicates early emerald precipitation from a single-phase saline fluid of approximately 12 weight percent NaCl equivalent, over the temperature range of [...] Read more.

Emerald from the deposits at Poona shows micrometre-scale chemical, optical, and cathodoluminescence zonation. This zonation, combined with fluid inclusion and isotope studies, indicates early emerald precipitation from a single-phase saline fluid of approximately 12 weight percent NaCl equivalent, over the temperature range of 335–525 °C and pressures ranging from 70 to 400 MPa. The large range in pressure and temperature likely reflects some post entrapment changes and re-equilibration of oxygen isotopes. Secondary emerald-hosted fluid inclusions indicate subsequent emerald precipitation from higher salinity fluids. Likewise, the δ¹⁸O-δD of channel fluids extracted from Poona emerald is consistent with multiple origins yielding both igneous and metamorphic signatures. The combined multiple generations of emerald precipitation, different fluid compositions, and the presence of both metamorphic and igneous fluids trapped in emerald, likely indicate a protracted history of emerald precipitation at Poona conforming to both an igneous and a metamorphic origin at various times during regional lower amphibolite to greenschist facies metamorphism over the period ~2710–2660 Ma. Full article

(This article belongs to the Special Issue Fluid Inclusions: Study Methods, Applications and Case Histories)

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