Ore-Forming Fluid Evolution of Shallow Polyhalite Deposits in the Kunteyi Playa in the North Qaidam Basin

Polyhalite occurrence in the Kunteyi Playa in the Qaidam Basin has been known for many years. However, the genetic mechanism of this deposit remains unclear. In this study, a typical section in the playa depocenter is selected to study the polyhalite mineralogy combined with the homogenization temperature and composition of halite fluid inclusions in shallow evaporitic strata. The results show that 1) the main evaporite minerals in the strata are halite and polyhalite; no common gypsum is found; 2) analyses of homogenization temperatures of halite fluid inclusions indicate that a higher temperature is needed for polyhalite generation compared with other saline minerals; and 3) the fluid inclusion chemical analysis shows that they are sulfate-type minerals with a shortage of Ca. Thus, it can be concluded that the formation of polyhalite is not related to gypsum replacement, and deep oilfield brines may provide a Ca source and a higher temperature for polyhalite formation, where the mixing and interaction occurred between K- and Mg-enriched sulfate brines and deep Ca-enriched brines under the control of climate and tectonics in the study area. While most polyhalite was generated natively, some formed during secondary generation, which was potentially related to replacement with carnallites or sylvites.

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Genesis of the Longmendian Ag–Pb–Zn Deposit in Henan (Central China): Constraints from Fluid Inclusions and H–C–O–S–Pb Isotopes

Geofluids ◽

10.1155/2020/7352821 ◽

2020 ◽

Vol 2020 ◽

pp. 1-21

Author(s):

Xinglin Chen ◽

Yongjun Shao ◽

Chunkit Lai ◽

Cheng Wang

Keyword(s):

Fluid Inclusions ◽

Central China ◽

Granitic Magma ◽

Two Phase ◽

Quartz Veins ◽

The North ◽

Granitic Magmatism ◽

Polymetallic Sulfides ◽

Homogenization Temperatures ◽

Stage 1

The Longmendian Ag–Pb–Zn deposit is located in the southern margin of the North China Craton, and the mineralization occurs mainly in quartz veins, altered gneissic wallrocks, and minor fault breccias in the Taihua Group. Based on vein crosscutting relations, mineral assemblages, and paragenesis, the mineralization can be divided into three stages: (1) quartz–pyrite, (2) quartz–polymetallic sulfides, and (3) quartz–carbonate–polymetallic sulfides. Wallrock alteration can be divided into three zones, i.e., chlorite–sericite, quartz–carbonate–sericite, and silicate. Fluid inclusions in all Stage 1 to 3 quartz are dominated by vapor-liquid two-phase aqueous type (W-type). Petrographic and microthermometric analyses of the fluid inclusions indicate that the homogenization temperatures of Stages 1, 2, and 3 are 198–332°C, 132–260°C, and 97–166°C, with salinities of 4.0–13.3, 1.1–13.1, and 1.9–7.6 wt% NaCleqv, respectively. The vapor comprises primarily H2O, with some CO2, H2, CO, N2, and CH4. The liquid phase contains Ca2+, Na+, K+, SO42−, Cl−, and F−. The sulfides have δ34S=–1.42 to +2.35‰ and 208Pb/204Pb=37.771 to 38.795, 207Pb/204Pb=15.388 to 15.686, and 206Pb/204Pb=17.660 to 18.101. The H–C–O–S–Pb isotope compositions indicate that the ore-forming materials may have been derived from the Taihua Group and the granitic magma. The fluid boiling and cooling and mixing with meteoric water may have been critical for the Ag–Pb–Zn ore precipitation. Geological and geochemical characteristics of the Longmendian deposit indicate that the deposit is best classified as medium- to low-temperature intermediate-sulfidation (LS/IS) epithermal-type, related to Cretaceous crustal-extension-related granitic magmatism.

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Genesis of the Zhijiadi Ag-Pb-Zn Deposit, Central North China Craton: Constraints from Fluid Inclusions and Stable Isotope Data

Geofluids ◽

10.1155/2017/4153618 ◽

2017 ◽

Vol 2017 ◽

pp. 1-23 ◽

Cited By ~ 4

Author(s):

Tao Liu ◽

Suo-Fei Xiong ◽

Shao-Yong Jiang ◽

Hua-Liang Li ◽

Qi-Zhi Chen ◽

...

Keyword(s):

Fluid Inclusions ◽

North China Craton ◽

North China ◽

Early Stage ◽

Homogenization Temperature ◽

Main Stage ◽

Magmatic System ◽

Hydrothermal Deposit ◽

Homogenization Temperatures ◽

Late Stages

The Zhijiadi Ag-Pb-Zn deposit is located in the central North China Craton. Fluid inclusions (FIs) studies indicate three types of FIs, including aqueous, aqueous-carbonic, and daughter mineral-bearing multiphase inclusions. The daughter minerals in FIs are mainly composed of marcasite, chalcopyrite, calcite, and dolomite. Microthermometric data show that the homogenization temperature and salinity of FIs decrease gradually from early to late stages. Homogenization temperatures from early to main to late stages span from 244 to 334°C, from 164 to 298°C, and from 111 to 174°C, respectively, while their salinities are 4.0–9.9 wt.% NaCl equiv., 0.5–12.7 wt.% NaCl equiv., and 0.2–8.8 wt.% NaCl equiv., respectively. Trapping pressures drop from 203–299 MPa (the early stage) to 32–158 MPa (the main stage). The dropping of pressure and temperature and mixing and/or dilution of ore-forming fluids result in the formation of ore deposit. Combined with C-O-S-Pb isotopic compositions, the initial ore-forming fluids and materials were likely derived from a magmatic system. As a whole, we proposed that this deposit belongs to medium-low temperature hydrothermal deposit related to volcanic and subvolcanic magmatism strictly controlled by the fault zones.

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Isotope-Geochemical Features of Apoultrabasic Metasomatites of the Sayan–Baikal Folded Area

Russian Geology and Geophysics ◽

10.2113/rgg20194154 ◽

2021 ◽

Vol 62 (9) ◽

pp. 1021-1035

Author(s):

M.V. Rampilova ◽

G.S. Ripp ◽

M.O. Rampilov ◽

B.B. Damdinov ◽

L.B. Damdinova ◽

...

Keyword(s):

Low Temperature ◽

Isotopic Composition ◽

Fluid Inclusions ◽

Siberian Craton ◽

Carbonate Rocks ◽

Fluid Phase ◽

Homogenization Temperature ◽

Crustal Component ◽

Geochemical Study ◽

Homogenization Temperatures

Abstract —The paper is concerned with a geochemical study of apoultrabasic metasomatites of the Ospa–Kitoi, Parama, and Ust’-Kelyana ophiolite massifs located in the southern folded framing of the Siberian craton. The isotope (O, C, H, Sr, and Rb) systems of dunites, serpentinites, nephrites, listvenites, and talc–carbonate rocks are studied. The isotopic composition of oxygen in olivines from dunites is characterized by δ18O = 4.6–5.5‰. The δ18O values of serpentinites (4.67–7.35‰) point to the mantle genesis of fluids and might have been inherited from ultrabasic rocks. Nephrites are slightly enriched in heavy oxygen isotope (δ18O = 6.13–9.54‰). This indicates that their fluid phase was transported from serpentinites and captured a small portion of the crustal component. The widest variations in δ18O values, from 8.12 to 17.46‰, are observed in minerals from listvenites. Carbonates from these rocks show a highly heterogeneous isotopic composition of oxygen (δ18O = 12.9–18.8‰) and carbon δ13C = –2.8 to +2.8‰). These rocks formed with the contribution of metamorphogenic fluids. According to the isotopic composition of hydrogen, the examined serpentinites are divided into two groups: with δD values specific to “magmatic water” (δD = –73.50 to –85.00‰) and those typical of meteoric fluids (δD = –151.90 to –167.20‰). The listvenites are characterized by low Rb and high Sr contents. Their 87Sr/86Sr values (0.70702–0.70971) indicate the contribution of a crustal source. The study of fluid inclusions in minerals from listvenites has shown that the rocks formed under relatively low-temperature conditions. The homogenization temperatures of fluid inclusions in quartz and magnesite from listvenites of the Ospa–Kitoi massif are 184–290 ºC and 122–182 ºC, respectively. In the Parama massif, the homogenization temperature of fluid inclusions in quartz is 130–170 ºC. The solutions that formed listvenites of the Ospa–Kitoi massif were slightly saline (TDS = 2.9–8.4 wt.% NaCl eq.), with NaCl and Na2CO3 being the main salt components.

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Fluid inclusion evidence for boiling process of petroleum fluid in the north Qaidam Basin (NW China)

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2006.06.744 ◽

2006 ◽

Vol 70 (18) ◽

pp. A368

Author(s):

Y.T. Liu ◽

K. Hu ◽

J. Cao ◽

S.Y. Yang ◽

L.L. Yan ◽

...

Keyword(s):

Fluid Inclusion ◽

Qaidam Basin ◽

Nw China ◽

The North ◽

Boiling Process ◽

North Qaidam ◽

Petroleum Fluid

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Intensified Late Miocene Deformation in the Northern Qaidam Basin, Northern Tibetan Plateau, Constrained by Apatite Fission-Track Thermochronology

Frontiers in Earth Science ◽

10.3389/feart.2021.750993 ◽

2021 ◽

Vol 9 ◽

Author(s):

Pengju He ◽

Chunhui Song ◽

Yadong Wang ◽

Yihu Zhang ◽

Wenqi Chen ◽

...

Keyword(s):

Tibetan Plateau ◽

Late Miocene ◽

Fission Track ◽

Qaidam Basin ◽

Thrust Belt ◽

Apatite Fission Track ◽

The North ◽

Northern Tibetan Plateau ◽

Fission Track Thermochronology ◽

North Qaidam

The Cenozoic tectonic evolution of the North Qaidam-Qilian Shan fold-thrust belt in the northern Tibetan Plateau is important to understanding the tectonic rejuvenation of orogeny and growth of the plateau. However, the deformation processes in this region remain controversial. This study presents new apatite fission track (AFT) data from Paleogene strata in the northern Qaidam Basin to investigate the time of deformation in this site. Thermal modeling of these partially annealed detrital AFT ages shows a thermal history with a noticeable transition from heating to cooling after ∼10 Ma. This transition is attributed to the intensified thrusting and folding of the northern Qaidam Basin since ∼10 Ma. Integrated with published tectonics and thermochronology results, we suggest the North Qaidam-Qilian Shan fold-thrust belt experienced prevailing tectonism since the late Miocene.

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Fluid evolution from quartz veins in micaschists from the thermal aureole around the Acari batholith, Northeast Brazil

Geologia USP Série Científica ◽

10.11606/issn.2316-9095.v21-160595 ◽

2021 ◽

Vol 21 (4) ◽

pp. 13-30

Author(s):

Laécio Cunha de Souza ◽

Regina Celia de Oliveira Brasil Delgado ◽

Heitor Neves Maia

Keyword(s):

Fluid Inclusions ◽

Aqueous Fluid ◽

Fluid Circulation ◽

Two Phase ◽

Quartz Veins ◽

Melting Temperatures ◽

Three Phase ◽

Higher Temperature ◽

Homogenization Temperatures ◽

Liquid Vapor

Micaschists that host the Acari batholith (Ediacaran age, 572 to 577 My) are characterized by a large number of quartz veins. The veins are more abundant in higher-temperature metamorphic zones and, together with lower metamorphic zones, form an aureole centered in the batholith. Most of the fluid inclusions are two-phase (H2O-CO2 and liquid/vapor), but three-phase varieties (liquid/vapor/salt cubes; liquid/liquid/vapor) occur locally. The analyzed veins come from the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite metamorphic zones. CO2 melting temperatures (TmCO2) vary from -62.6 to -56.7°C, suggesting CH4 and/or N2. Eutectic temperatures (Te) in quartz veins show average values of -30.8°C in the biotite + chlorite + muscovite and biotite + garnet zones, and -38.6°C in the cordierite + andalusite and cordierite + sillimanite zones. Ice-melting temperatures (Tmice) are lower in the higher-temperature metamorphic zones. The mode values are -3.8, -5.5, -5.6, and -7.3°C, corresponding respectively to the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite zones. A fluid characterized by the H2O-Na-Cl (KCl)-MgCl2-FeCl2-CaCl2 system is defined by: Tmice from near -1.9 to -32°C, the presence of salt cubes mainly in the cordierite + andalusite and cordierite + sillimanite zones, and recorded eutectic temperatures (Te) from -16.5 to -59.1°C. In addition, total homogenization temperatures (Tht) ranging from 117 to 388°C were obtained for primary aqueous fluid inclusions. This indicates a long period of fluid circulation under conditions of falling temperatures. Our results are consistent with an increase in the salinity of the aqueous fluid across the thermal aureole toward the granitic batholith.

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Easily altered minerals and reequilibrated fluid inclusions provide extensive records of fluid and thermal history: gypsum pseudomorphs of the Tera Group, Tithonian-Berriasian, Cameros Basin

Open Geosciences ◽

10.2478/s13533-011-0055-x ◽

2012 ◽

Vol 4 (2) ◽

Cited By ~ 2

Author(s):

Laura González-Acebrón ◽

Robert Goldstein ◽

Ramon Mas ◽

Jose Arribas

Keyword(s):

Fluid Inclusions ◽

Thermal History ◽

Isotopic Analysis ◽

Northern Spain ◽

Quartz Veins ◽

Cameros Basin ◽

Complex Fluid ◽

Higher Temperature ◽

Homogenization Temperatures ◽

Lower Temperature

AbstractThis study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysis and fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine deposits in Northern Spain. Limestones and dolostones, formed in the alkaline lakes, contain lenticularly shaped gypsum pseudomorphs, considered to form in an evaporative lake. The gypsum was replaced by quartz and non-ferroan calcite (Ca-2), which partially replaces the quartz. Quartz contains solid inclusions of a preexisting non-ferroan calcite (Ca-1), anhydrite and celestine.High homogenization temperatures (T h) values and inconsistent thermometric behaviour within secondary fluid inclusion assemblages in quartz (147–351°C) and calcite (108–352°C) indicate high temperatures after precipitation and entrapment of lower temperature FIAs. Th are in the same range as other reequilibrated fluid inclusions from quartz veins in the same area that are related to Cretaceous hydrothermalism.Gypsum was replaced by anhydrite, likely during early burial. Later, anhydrite was partially replaced by Ca-1 associated with intermediate burial temperatures. Afterward, both anhydrite and Ca-1 were partially replaced by quartz and this by Ca-2. All were affected during higher temperature hydrothermalism and a CO2-H2O fluid. Progressive heating and hydrothermal pulses, involving a CO2-H2O fluid, produce the reequilibration of the FIAs, which was followed by uplift and cooling.

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Gangue mineral textures and fluid inclusion characteristics of the Santa Margarita Vein in the Guanajuato Mining District, Mexico

Open Geosciences ◽

10.2478/s13533-011-0057-8 ◽

2012 ◽

Vol 4 (2) ◽

Cited By ~ 3

Author(s):

Daniel Moncada ◽

Robert Bodnar

Keyword(s):

Fluid Inclusion ◽

Fluid Inclusions ◽

Homogenization Temperature ◽

High Potential ◽

Mining District ◽

Gangue Mineral ◽

Gold Silver ◽

Continuous Mining ◽

Homogenization Temperatures ◽

Silver Mineralization

AbstractSuccessful exploration for mineral deposits requires tools that the explorationist can use to distinguish between targets with high potential for mineralization and those with lower economic potential. In this study, we describe a technique based on gangue mineral textures and fluid inclusion characteristics that has been applied to identify an area of high potential for gold-silver mineralization in the epithermal Ag-Au deposits at Guanajuato, Mexico. The Guanajuato mining district in Mexico is one of the largest silver producing districts in the world with continuous mining activity for nearly 500 years. Previous work conducted on the Veta Madre vein system that is located in the central part of this district identified favorable areas for further exploration in the deepest levels that have been developed and explored. The resulting exploration program discovered one of the richest gold-silver veins ever found in the district. This newly discovered vein that runs parallel to the Veta Madre was named the Santa Margarita vein. Selected mineralized samples from this vein contain up to 249 g/t of Au and up to 2,280 g/t Ag. Fluid inclusions in these samples show homogenization temperatures that range from 184 to 300°C and salinities ranging from 0 to 5 wt.% NaCl. Barren samples show the same range in homogenization temperature, but salinities range only up to 3 wt.% NaCl. Evidence of boiling was observed in most of the samples based on fluid inclusions and/or quartz and calcite textures. Liquid-rich inclusions with trapped illite are closely associated with high silver grades. The presence of assemblages of vapor-rich-only fluid inclusions, indicative of intense boiling or “flashing”, shows the best correlation with high gold grades.

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