The Diagenetic Alteration of the Carbonate Rocks from the Permian Qixia Formation as Response to Two Periods of Hydrothermal Fluids Charging in the Central Uplift of Sichuan Basin, SW China

The hydrothermal fluid–carbonate rock reaction is frequently regarded to occur in deep-burial diagenesis, and the hydrothermal dissolution is usually distributed and takes place along the faults. Previous studies have suggested that there was hydrothermal fluid activity locally in the Permian Qixia Formation in Sichuan Basin, likely related to the Emeishan basalt eruption. However, the effect of hydrothermal fluids on the carbonate rocks of the Qixia Formation in the central uplift of Sichuan Basin is still unclear. Based on the characteristics and geochemical parameters of the diagenetic minerals, this study aims to reveal the diagenetic alteration related to the hydrothermal fluid–rock reaction in the Qixia Formation and reestablish the diagenetic evolution by using the timing of diagenetic mineral precipitation. The methods include petrographic observation; trace and rare earth element (REE) analysis; C, O and Sr isotope measurement; fluid inclusion temperature measurement and cathodoluminescence analysis. According to the petrographic characteristics, the dolostones are mainly of crystalline structure, namely fine-medium crystalline dolostone, meso-coarse crystalline dolostone, and coarse crystalline dolostone, with the cathodoluminescence color becoming brighter in that order. The limestones from the Qixia Formation are of the bioclastic limestone type, with no cathodoluminescence color. Compared with dolostones, limestones have higher Sr content, lower Mn content, and heavier oxygen isotopes. With the crystalline size of dolostone becoming coarser, the oxygen isotopes of dolostones tend to become lighter. The meso-coarse crystalline dolostone has the highest Mn content and negative carbon isotope. Both limestones and dolostones have an obvious positive Eu anomaly in the Qixia Formation. However, the REE patterns of fine-medium crystalline dolostones are very different from those of meso-coarse crystalline dolostone. It is credible that there were two periods of hydrothermal fluid charging, with different chemical compositions. The first period of hydrothermal fluids could laterally migrate along the sequence boundary. Fine-medium crystalline dolostones were almost completely distributed below the sequence boundary and were dolomitized during the shallow burial period. As products of the hydrothermal fluid–dolostone reaction, the saddle-shaped dolomites in the meso-coarse crystalline dolostones were the evidence of the second period of hydrothermal fluids. As a result, the dolomitization model was established according to the timing of diagenetic mineral precipitation, which can improve the geological understanding of the effect of hydrothermal fluid activities on the carbonate rocks in the Qixia Formation.

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Analysis of Hydrothermal Systems Beneath Tayukeng through Long-Term Geochemical Signals of Hydrothermal Fluids in Tatun Volcano Group, Taiwan

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18147411 ◽

2021 ◽

Vol 18 (14) ◽

pp. 7411

Author(s):

Hsin-Fu Yeh ◽

Hung-Hsiang Hsu

Keyword(s):

Surface Temperature ◽

Hydrothermal System ◽

Hydrothermal Fluid ◽

Thermal Water ◽

Hydrothermal Systems ◽

Hydrothermal Fluids ◽

Geochemical Variations ◽

Northern Taiwan

The Tatun Volcano Group (TVG) is located in northern Taiwan and consists of many springs and fumaroles. The Tayukeng (TYK) area is the most active fumarole site in the TVG. In this study, we analyzed the long-term geochemical variations of hydrothermal fluids and proposed a mechanism responsible for the variation in TYK. There are two different aquifers beneath the TYK area: a shallow SO42−-rich aquifer and a deeper aquifer rich in Cl−. TYK thermal water was mainly supplied by the shallow SO42−-rich aquifer; therefore, the thermal water showed high SO42− concentrations. After 2015, the inflow of deep thermal water increased, causing the Cl− concentrations of the TYK to increase. Notably, the inferred reservoir temperatures based on quartz geothermometry increased; however, the surface temperature of the spring decreased. We inferred that the enthalpy was lost during transportation to the surface. Therefore, the surface temperature of the spring does not increase with an increased inflow of deep hydrothermal fluid. The results can serve as a reference for understanding the complex evolution of the magma-hydrothermal system in the TVG.

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Constrains of eruption environment and hydrothermal fluid on the Permian pyroclastic reservoirs in the Sichuan Basin, SW China

Petroleum ◽

10.1016/j.petlm.2021.03.005 ◽

2021 ◽

Author(s):

Xiaohong Liu ◽

Yiqian Zhuo ◽

Mingyou Feng ◽

Benjian Zhang ◽

Maolong Xia ◽

...

Keyword(s):

Sichuan Basin ◽

Hydrothermal Fluid ◽

Sw China ◽

The Sichuan Basin

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Formation of coagulated colloidal silica in high-temperature mineralizing fluids

Mineralogical Magazine ◽

10.1180/0026461026640048 ◽

2002 ◽

Vol 66 (4) ◽

pp. 547-553 ◽

Cited By ~ 13

Author(s):

B. J. Williamson ◽

J. J. Wilkinson ◽

P. F. Luckham ◽

C. J. Stanley

Keyword(s):

High Temperature ◽

Hydrothermal Fluid ◽

Colloidal Silica ◽

Fluid Transport ◽

Experimental Studies ◽

Hydrothermal Fluids ◽

Ore Formation ◽

Colloidal Gel ◽

Material Forming ◽

Mineralizing Fluids

AbstractRecent experimental studies have suggested that colloidal silica can form in high-T (300 to >700°C) hydrothermal fluids (Wilkinson et al., 1996). Natural evidence in support of this was found by Williamson et al. (1997) who proposed a colloidal (gel) silica origin for <50 μm irregularly-shaped inclusions of quartz contained in greisen topaz from southwest England. Confocal and microprobe studies, presented here, strengthen this argument although rather than forming a gel in the hydrothermal fluid, it is suggested that the colloidal silica aggregated as a viscous coagulated colloid, with much of its volume (<10 to 30 vol.%) consisting of metal (mainly Fe) -rich particles. This is evident from the largely solid nature of metal-rich shrinkage bubbles contained at the margins of the inclusions of quartz which shows that the material forming the inclusions contained much less liquid than would be expected in a silica gel. These findings may have important implications for models of ore formation since the precipitation of a coagulated colloid could inhibit hydrothermal fluid transport and cause co-deposition of silica and entrained ore-forming elements. The mode of formation of the colloidal silica and further implications of the study are discussed.

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The emergence of subaerial crust and onset of weathering 3.7 billion years ago

10.5194/egusphere-egu21-4701 ◽

2021 ◽

Author(s):

Desiree Roerdink ◽

Yuval Ronen ◽

Harald Strauss ◽

Paul Mason

Keyword(s):

Carbonate Rocks ◽

Hydrothermal Fluid ◽

Plate Tectonics ◽

Chemical Weathering ◽

Crystal Morphology ◽

Sr Isotope ◽

Fluid Mixtures ◽

Mixing Ratios ◽

Biosphere Evolution ◽

Evolution Trend

Reconstructing the emergence and weathering of continental crust in the Archean is crucial for our understanding of early ocean chemistry, biosphere evolution and the onset of plate tectonics. However, considerable disagreement exists between the various elemental and isotopic proxies that have been used to trace crustal input into marine sediments, and data are scarce prior to 3 billion years ago. Here we show that chemical weathering modified the Sr isotopic composition of Archean seawater as recorded in 3.52 to 3.20 Ga stratiform marine-hydrothermal barite deposits from three different cratons. We use a combination of barite crystal morphology, oxygen, multiple sulfur and strontium isotope data to select barite samples with the most seawater-like isotopic compositions, and subsequently use these in a hydrothermal mixing model to calculate a plausible seawater Sr isotope evolution trend from measured 87Sr/86Sr data. From modeled mixing ratios between seawater and hydrothermal fluids required for barite precipitation and comparison of 87Sr/86Sr in theoretical seawater-hydrothermal fluid mixtures with those recorded in the barite, we obtain a novel seawater Sr isotope evolution trend for Paleoarchean seawater that is much more radiogenic than the curve previously determined from carbonate rocks. Our findings require the presence and weathering of subaerial and evolved (high Rb/Sr) crust from 3.7 &#177; 0.1 Ga onwards, and demonstrate that crustal weathering affected the chemistry of the oceans 500 million years earlier than previously thought.

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Assessment of the seasonal cycle of nitrate in PM2.5 using chemical compositions and stable nitrogen and oxygen isotopes at Nanchang, China

Atmospheric Environment ◽

10.1016/j.atmosenv.2020.117371 ◽

2020 ◽

Vol 225 ◽

pp. 117371 ◽

Cited By ~ 1

Author(s):

Li Luo ◽

Yuan-Yuan Pan ◽

Ren-Guo Zhu ◽

Zhong-Yi Zhang ◽

Neng-Jian Zheng ◽

...

Keyword(s):

Oxygen Isotopes ◽

Seasonal Cycle ◽

Chemical Compositions ◽

Nitrogen And Oxygen Isotopes

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Coupled partitioning of Au and As into pyrite controls formation of giant Au deposits

Science Advances ◽

10.1126/sciadv.aav5891 ◽

2019 ◽

Vol 5 (5) ◽

pp. eaav5891 ◽

Cited By ~ 15

Author(s):

C. Kusebauch ◽

S. A. Gleeson ◽

M. Oelze

Keyword(s):

Partition Coefficients ◽

Hydrothermal Fluid ◽

Iron Sulfide ◽

Gold Deposits ◽

Hydrothermal Systems ◽

Hydrothermal Fluids ◽

Balance Model ◽

Mass Balance Model ◽

Depositional Process ◽

Partitioning Behavior

The giant Carlin-type Au deposits (Nevada, USA) contain gold hosted in arsenic-rich iron sulfide (pyrite), but the processes controlling the sequestration of Au in these hydrothermal systems are poorly understood. Here, we present an experimental study investigating the distribution of Au and As between hydrothermal fluid and pyrite under conditions similar to those found in Carlin-type Au deposits. We find that Au from the fluid strongly partitions into a newly formed pyrite depending on the As concentration and that the coupled partitioning behavior of these two trace elements is key for Au precipitation. On the basis of our experimentally derived partition coefficients, we developed a mass balance model that shows that simple partitioning (and the underlying process of adsorption) is the major depositional process in these systems. Our findings help to explain why pyrite in Carlin-type gold deposits can scavenge Au from hydrothermal fluids so efficiently to form giant deposits.

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Hydrogeochemistry, Geothermometry, and Genesis of the Hot Springs in the Simao Basin in Southwestern China

Geofluids ◽

10.1155/2019/7046320 ◽

2019 ◽

Vol 2019 ◽

pp. 1-23 ◽

Cited By ~ 2

Author(s):

Yuqi Zhang ◽

Xun Zhou ◽

Haisheng Liu ◽

Mingxiao Yu ◽

Kuo Hai ◽

...

Keyword(s):

Carbonate Rocks ◽

Hot Springs ◽

Cold Water ◽

Metamorphic Rocks ◽

Formation Mechanisms ◽

Chemical Compositions ◽

Red Beds ◽

Incongruent Dissolution ◽

Geothermal Waters ◽

Isotopic Analyses

In the Simao Basin in southwest China widely occur red beds of poor permeability. Nevertheless, more than 100 springs exist in the basin, some of which are hot springs with varying temperature. Hot springs contain abundant information on hydrogeochemical processes and groundwater circulation. In this study, hydrochemical and isotopic analyses and mixed models are used to examine the sources of recharge, heat, and solutes of the hot springs to better understand the subsurface processes and formation mechanisms of different hot springs in the basin. Three types of springs are found in the Simao Basin: springs of HCO3-Na type occur in the metamorphic rocks, springs of HCO3-Ca(Mg) and Cl-HCO3-Na-Ca types in the carbonate rocks, and springs of Cl(SO4)-SO4(Cl)-HCO3-Na(Ca) type in the red beds. Data of δ2H and δ18O indicate that the hot springs in the Simao Basin are meteoric in origin. Incongruent dissolution is the dominant process affecting the chemical compositions of the spring waters. The hydrochemical constituents of the hot springs in the metamorphic rocks, carbonate rocks, and red beds are influenced by the weathering of albite and the dissolution of carbonate, gypsum, anhydrite, and halite. The geothermal waters are mixed with shallow cold waters in their ascending processes, and the mixing ratios of cold water range from 58% to 94%. Due to the effect of mixing, the reservoir temperatures (51°C-127°C) calculated with the quartz geothermometer are regarded as the minimum reservoir temperatures. More reliable reservoir temperatures (91°C-132°C) are estimated with the fixed-Al method. The following mechanisms contribute to the formation of hot springs in the Simao Basin: the groundwater receives recharge from infiltration of precipitation and undergoes deep circulation, during which groundwater is heated by heat flow and incongruently dissolves the subsurface minerals and emerges in the form of hot springs along the permeable fracture or fault zones.

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Velocity–porosity–mineralogy trends in chalk and consolidated carbonate rocks

Geophysical Journal International ◽

10.1093/gji/ggz304 ◽

2019 ◽

Vol 219 (1) ◽

pp. 662-671 ◽

Cited By ~ 2

Author(s):

Jack Dvorkin ◽

Abrar Alabbad

Keyword(s):

Carbonate Rocks ◽

Pore Space ◽

Rock Physics ◽

Elastic Wave Velocity ◽

Velocity Versus ◽

Shear Moduli ◽

Diagenetic Alteration ◽

Medium Porosity ◽

Physics Model ◽

Rock Physics Model

SUMMARY Published laboratory elastic-wave velocity versus porosity data in carbonate rocks exhibit significant scatter even at a fixed mineralogy. This scatter is usually attributed to the strong variability in the rock-frame or pore-space geometry, which, in turn, is driven by the richness and complexity of diagenetic alteration in these very reactive sediments. Yet, by examining wireline data from oil-bearing high-to-medium porosity chalk deposits, we find surprisingly tight velocity–porosity trends. Moreover, these trends are continued into the low-porosity domain by data from a location thousands of miles away from the chalk field. This congruence implies a universality of diagenetic trends, at least in the massive deposits under examination. We also find that the elastic bulk and shear moduli of the pure-calcite end member are somewhat smaller than such values reported in the literature. Using the end-member elastic constants relevant to the data under examination, we establish a theoretical rock physics model to match and generalize these data.

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PECULIARITIES OF DISTRIBUTION AND COMPOSITION OF BETAFITE FROM DIFFERENT FORMATIONS OF THE ALDAN SHIELD (SAKHA-YAKUTIA)

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.84.01 ◽

2019 ◽

pp. 8-15

Author(s):

V. Guliy ◽

I. Poberezhska ◽

N. Bilyk

Keyword(s):

Chemical Composition ◽

Mineral Composition ◽

Oxygen Isotopes ◽

Carbonate Rocks ◽

Aldan Shield ◽

Mineralogical Composition ◽

Significant Feature ◽

Carbon And Oxygen Isotopes ◽

Primary Composition ◽

Geological Formations

Character of Nb and Ta distribution in the different geological formations of the Aldan Shield are given in this article. To get idea about betafite from different endogenic etalon formations the authors analyzed its well known locations in the pegmatites, skarns, carbonatites, metasomatites and late veins segregations. Geological setting and mineralogical composition of the apatite-bearing rocks from the Aldan Shield are described, and the most significant in scale metamorphosed carbonate and silicate varieties among them have been distinguished. Apatite mineralization in magnesium skarns and metasomatites is developed locally. Titanite and betafite are the main concentrators of Nb and Ta and apatite is typical accompanying mineral in the studied rocks. Betafite was detected in the pegmatite bodies from magnesium skarns and metasomatites of the Shield with irregular distribution within rocks rich and poor in apatite, but was not found in the most developed apatite-carbonate rocks which are regarded as ores of the Seligdar type, so it cannot be mineralogical indicator for this type of ores. Late carbonate generations are significantly enriched in light carbon and oxygen isotopes in contrast to positive δ13Ñ values in apatitecarbonate bodies of the Seligdar deposit and its family and the highest δ18Î values. We used these indicators to distinguish origin of the rocks with various carbonate generations, which have different amounts of betafite. Appearance of betafite is determined by primary composition of the initial rocks. Chemical composition of betafites from the skarns and metasomatites is similar, but with local variations. The most significant feature of the mineral composition is very low Ta content. Titanite is characterized by variable amounts of Nb and Ta in scale of sectors as well as within separate grains.

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