Fluid Inclusion Characteristics of the Kışladağ Porphyry Au Deposit, Western Turkey

The deposit occurs in a mid-Miocene monzonite magmatic complex represented by three different intrusions, namely Intrusion 1 (INT#1), Intrusion 2 (INT#2, INT #2A), and Intrusion 3 (INT#3). Gold mineralization is hosted in all intrusions, but INT#1 is the best mineralized body followed by INT#2. SEM-CL imaging has identified two different veins (V1 and V2) and four distinct generations of quartz formation in the different intrusions. These are: (i) CL-light gray, mosaic-equigranular quartz (Q1), (ii) CL-gray or CL-bright quartz (Q2) that dissolved and was overgrown on Q1, (iii) CL-dark and CL-gray growth zoned quartz (Q3), and (iv) CL-dark or CL-gray micro-fracture quartz fillings (Q4). Fluid inclusion studies show that the gold-hosted early phase Q1 quartz of V1 and V2 veins in INT#1 and INT#2 was precipitated at high temperatures (between 424 and 594 °C). The coexisting and similar ranges of Th values of vapor-rich (low salinity, from 1% to 7% NaCl equiv.) and halite-bearing (high salinity: >30% NaCl) fluid inclusions in Q1 indicates that the magmatic fluid had separated into vapor and high salinity liquid along the appropriate isotherm. Fluid inclusions in Q2 quartz in INT#1 and INT#2 were trapped at lower temperatures between 303 and 380 °C and had lower salinities between 3% and 20% NaCl equiv. The zoned Q3 quartz accompanied by pyrite in V2 veins of both INT#2 and INT#3 precipitated at temperatures between 310 and 373 °C with a salinity range from 5.4% to 10% NaCl eq. The latest generation of fracture filling Q4 quartz, cuts the earlier generations with fluid inclusion Th temperature range from 257 to 333 °C and salinity range from 3% to 12.5% NaCl equiv. The low salinity and low formation temperature of Q4 may be due to the mixing of meteoric water with the hydrothermal system, or late-stage epithermal overprinting. The separation of the magmatic fluid into vapor and aqueous saline pairs in the Q1 quartz of the V1 vein of the INT#1 and INT#2 and CO2-poor fluids indicates the shallow formation of the Kışladağ porphyry gold deposit.

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Fluid-inclusion studies of high-grade metamorphic rocks of the Ashuanipi complex, eastern Superior Province: constraints on the retrograde P–T path and implications for gold metallogeny

Canadian Journal of Earth Sciences ◽

10.1139/e92-180 ◽

1992 ◽

Vol 29 (10) ◽

pp. 2309-2327 ◽

Cited By ~ 3

Author(s):

Robert P. Moritz ◽

Serge R. Chevé

Keyword(s):

High Temperature ◽

Fluid Inclusion ◽

Fluid Inclusions ◽

High Salinity ◽

Aqueous Fluid ◽

Metamorphic Rocks ◽

Gold Deposition ◽

High Grade ◽

Low Salinity ◽

T Path

The high-grade metamorphic rocks of the Ashuanipi complex have been the subject of a microthermometric fluid-inclusion study. Four types of fluid inclusions were observed: CO2-rich fluids; low-temperature, high-salinity H2O fluids; CH4 ± N2-rich fluids; and high-temperature, low-salinity H2O fluids. The regionally distributed CO2-rich fluids are the earliest fluids, and their calculated isochores indicate a clockwise post-peak metamorphic P–T–t path for the Ashuanipi complex. The low-temperature, high-salinity aqueous fluid inclusions are also distributed regionally and can be interpreted as late brines, retrograde metamorphic fluids, or the wicked-off aqueous component of H2O–CO2 fluid inclusions. Both CH4 ± N2-rich fluids and the high-temperature, low-salinity aqueous fluid inclusions were found only locally in gold-bearing metamorphosed banded iron formations. Fluid-inclusion microthermometry, arsenopyrite thermometry, and metamorphic petrologic study at Lac Lilois, one of the principal gold showings, suggest that some gold deposition may have occurred during regional post-peak metamorphic exhumation and cooling at P–T conditions near the amphibolite–greenschist transition. However, it is possible that gold deposition began at higher near-peak metamorphic P–T conditions. Another major gold showing, Arsène, is characterized by CH4 ± N2-rich fluid inclusions, tentatively inferred to be either directly related to gold deposition or responsible for secondary gold enrichment. The association of CH4 ± N2-rich fluids with gold occurrences in the Ashuanipi complex is comparable to gold deposits of the Abitibi greenstone belt and of Wales, Finland, and Brazil.

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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 ◽

10.1155/2017/4094582 ◽

2017 ◽

Vol 2017 ◽

pp. 1-19 ◽

Cited By ~ 5

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.

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Ore Forming Fluid of Epithermal Quartz Veins at Cisuru Prospect, Papandayan District, West Java, Indonesia

Journal of Geoscience Engineering Environment and Technology ◽

10.25299/jgeet.2019.4.3.2279 ◽

2019 ◽

Vol 4 (3) ◽

pp. 170

Author(s):

Kha Yay Oo ◽

Wayan Warmada ◽

Anastasia Dewi Titisari ◽

Koichiro Watanabe

Keyword(s):

Fluid Inclusion ◽

Melting Temperature ◽

Fluid Inclusions ◽

Measurement Data ◽

Homogenization Temperature ◽

Salinity Range ◽

Ice Melting ◽

West Java ◽

Quartz Veins ◽

Lapilli Tuff

The Cisuru area is located in Talegong Sub-district, Garut Regency, West Java, Indonesia which is belongs to the central part of Southern Mountain Slope. The aim of this research is to understand the nature and characteristic of fluid inclusion from quartz veins (especially drill core samples) in the study area. Rock units in the area are characterized by Tertiary volcanic rocks and volcaniclastic sequence which is mainly composed of andesite, andesitic breccia, volcanic breccia, lapilli tuff, dacite and related to the intrusion of diorite. The Cisuru epithermal mineralization is dominantly hosted by andesite, dacite, breccia and lapilli tuff, and would probably be controlled by both permeable rocks and NS and NE-SW trending strike-slip faults. The mineralization is shown as void filling and replacement within the silica zone, veinlets along with the open space/fractures and dissemination. Fluid inclusion from quartz veins was studied to know nature, characteristics and origin of hydrothermal fluids. Microthermometric measurements of fluid inclusions were realized by using a Linkam THMSG 600 combined freezing and heating stages. Homogenization temperature and final ice melting temperature were measured for primary two-phase inclusion from quartz veins. Base on the study of the fluid inclusion, the value of homogenization temperature (Th) range from 200 ºC to 395 °C and ice melting temperature range from -0.1 to - 4.5 where salinity range from 0.2 to 7.2 wt. % NaCl equivalent. Fluid inclusion petrography and microthermometric measurement data exhibit that fluid mixing, dilution and boiling were main processes during the hydrothermal evolution. The formation temperature of each quartz vein is 260 ºC to 290 ºC and also their formation depth is estimated between 560m to 925m respectively. Combination of fluid inclusions petrography, microthermometric measurement, and estimate paleo depth from Cisuru area were suggested under the epithermal environment.

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Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada: P, T and X constraints of fluids using fluid inclusion thermometry and decrepitate analysis

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s0263593300007458 ◽

2000 ◽

Vol 91 (1-2) ◽

pp. 303-319 ◽

Cited By ~ 6

Author(s):

Sarah Carruzzo ◽

Daniel J. Kontak ◽

D. Barrie Clarke

Keyword(s):

Nova Scotia ◽

Fluid Inclusion ◽

Electron Microprobe ◽

Meteoric Water ◽

Mineral Deposits ◽

Fluid Inclusion Data ◽

Metasedimentary Rocks ◽

Low Salinity ◽

South Mountain Batholith ◽

Highly Evolved

The 370 Ma peraluminous South Mountain Batholith (SMB) intrudes Meguma Supergroup metasedimentary rocks in Nova Scotia. The New Ross area of the SMB contains polymetallic mineralisation (Sn, W, U, Mo, Cu and Mn) in pegmatite, greisen and vein directly or indirectly associated with highly evolved fractions of the SMB. Eight mineral deposits from this area have several fluid inclusion types hosted by quartz: (1) monophase liquid (L); (2) monophase vapour (V); (3) aqueous, L-V (4) aqueous, L-rich + solids; (5) aqueous, L-rich + halite. Inclusions have irregular to equant shapes and are pseudo-secondary or secondary. The irregularity and variability of L:V ratios within fluid inclusion populations suggest post-entrapment modifications of inclusions (i.e. necking).Thermometric data indicate three distinct fluids in terms of salinity: (1) 19-25 wt. % equiv. NaCl (rarely 14-25 wt. % NaCl equiv.), (2) 29-43 wt. % equiv. NaCl, and (3) 0-9 wt. % equiv. NaCl. Temperatures of first melting and ice/hydrohalife melting indicate CaCl2 in solution. Proximity of the deposits to Meguma Supergroup metasedimentary rocks suggests that this Ca component may be externally derived. The majority of the low-salinity fluid population has the composition of meteoric water. Electron microprobe analyses of artificially decrepitated mounds identify Na, Ca and K as major solutes, with a continuum in terms of compositions. Other solute components in the mounds are Fe and Ba, and a variety of metals of unknown speciation also occur (Cu, Zn, Fe, Ni). Homogenisation temperatures (Th) range from c. 80°C to 370°C, but for inclusion assemblages the range is 10°C to 20°C. Given the 3 kbar depth of emplacement of the SMB, estimated entrapment temperatures are c. 200°C to 550°C. The fluid inclusion data appear to reflect: (1) trapping of mixed Na-K-Ca brines during isobaric cooling in pegmatite and greisen deposits as indicated by large ranges in Th; (2) formation of deposits at different ambient pressures (i.e. depth); and (3) mixing of fluids of different reservoirs (i.e. magmatic, metamorphic, meteoric).

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Isotope analysis of vein-hosted fluid inclusions: A case study on fracture-controlled fluid flow in the Albanian foreland fold-and-thrust belt

10.5194/egusphere-egu2020-20149 ◽

2020 ◽

Author(s):

Stefan de Graaf ◽

Casimir Nooitgedacht ◽

Hubert Vonhof ◽

Jeroen van der Lubbe ◽

John Reijmer

Keyword(s):

Fluid Flow ◽

Fluid Inclusion ◽

Fluid Inclusions ◽

Continuous Flow ◽

Isotope Exchange ◽

Meteoric Water ◽

Isotope Ratios ◽

Isotope Data ◽

Exchange Processes ◽

Migration Pathways

Vein-hosted fluid inclusions may represent remnants of subsurface paleo-fluids and therefore provide a valuable record of fracture-controlled fluid flow. Isotope data (&#948;2H and &#948;18O) of fluid inclusions are particularly useful for studying the provenance and type of paleo-fluids circulating in the subsurface. Although isotopic analysis of sub-microliter amounts of fluid inclusion water is not straightforward, major steps forward have been made over the past decade through the development of continuous-flow set-ups. These techniques make use of mechanical crushing at a relatively low-temperature (110&#730;C) and allow for on-line analysis of both &#948;2H and &#948;18O ratios of bulk fluid inclusion water. However, continuous-flow techniques have mostly been used in speleothem research, and have not yet found a widespread application on vein systems for hydrogeological reconstructions.We used isotope data of fluid inclusions hosted in calcite vein cements to reconstruct regional fluid migration pathways in the Albanian foreland fold-and-thrust system. Tectonic forces during thrust emplacement typically instigate distinct phases of fracturing accompanied by complex fluid flow patterns. The studied calcite veins developed in a sequence of naturally fractured Cretaceous to Eocene carbonate rocks as a result of several fracturing events from the early stages of burial onward. Fluid inclusion isotope data of the veins reveal that fluids circulating in the carbonates were derived from an underlying reservoir, which consisted of a mixture of meteoric water and evolved marine fluids, probably derived from deep-seated evaporites. The meteoric fluids infiltrated in the hinterland before being driven outward into the foreland basin. The fluid inclusion isotope data furthermore show that meteoric water becomes increasingly dominant in the system through time as migration pathways shortened and marine formation fluids were progressively flushed out.The diagenetic stability of fluid inclusions is of key interest in the study of their isotope ratios. Recrystallization, secondary fluid infiltration and isotope exchange processes could potentially drive alterations of fluid inclusion isotope signatures after entrapment. In this case, however, isotope signatures of fluid inclusions seem to have remained largely unaltered, despite the Cretaceous to Tertiary age of the vein system. Oxygen isotope exchange processes between the fluid inclusion water and host mineral could have been inhibited at the relatively low temperatures of vein formation (i.e. <80&#730;C). Although more research into the diagenetic stability of fluid inclusion isotope ratios is required, the fluid inclusion isotope record has potential as a powerful tool for fluid provenancing in subsurface fluid flow systems.

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Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula, NW Turkey

Open Geosciences ◽

10.2478/s13533-012-0169-9 ◽

2014 ◽

Vol 6 (2) ◽

Cited By ~ 2

Author(s):

Gulcan Bozkaya ◽

David Banks ◽

Fatih Ozbas ◽

Jon Wallington

Keyword(s):

Fluid Inclusions ◽

Meteoric Water ◽

Large Range ◽

Magmatic Fluid ◽

Biga Peninsula ◽

Epithermal Mineralization ◽

Wide Range ◽

Nw Turkey ◽

Fracture Opening ◽

Enclosing Rocks

AbstractTesbihdere is one of a number of spatially close epithermal Cu-Pb-Zn-Ag-Au deposits hosted by andesites and rhyolites, typical of deposits in the Biga peninsula. Microthermometry of fluid inclusions shows a wide range of temperatures, ∼360–170°C, and salinities, ∼10-0.5 wt.% NaCl, in the different deposits studied. Dilution of a moderately saline magmatic? fluid with meteoric water occurred at constant temperature indicating, the temperature of both fluids was controlled by the geological environment. Boiling was not a major factor, but did occur in very minor amounts. The large range of temperatures within individual samples can only reasonably be explained by variations from near lithostatic to hydrostatic pressure during vein and fracture opening. That this pressure decrease did not produce extensive boiling suggests that vein opening was gradual rather than aggressive, allowing the pressure and temperature decrease to follow a path close to the L-V boiling curve. P-T reconstruction places emplacement of these ore veins at between 300–500 m beneath the surface. Similarities of LA-ICPMS of fluid inclusions from Tesbihdere, Azitepe and Basmakci, supports the conclusion that they were part of the same contemporaneous mineralizing system. The fluids are dominated by Na, with the concentrations of K>Ca>Mg combined equivalent to the concentration of Na. The range of K/Na ratios is not consistent with the fluid inclusion temperatures as the calculated temperatures are significantly higher indicating the fluids were not close to equilibrium with the enclosing rocks. Elevated K concentrations are consistent with acid-sulphate waters in shallow epithermal systems. Ore metals Cu, Zn and Pb are present in significant concentrations ∼500, 300 and 200 ppm respectively and the low Fe/Mn ratios are indicative of a relatively oxidising fluid. The negative δ 34S values of sulphides are consistent with boiling and oxidising redox conditions.

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Ar–Ar dating for hydrothermal quartz from the 2.4 Ga Ongeluk Formation, South Africa: implications for seafloor hydrothermal circulation

Royal Society Open Science ◽

10.1098/rsos.180260 ◽

2018 ◽

Vol 5 (9) ◽

pp. 180260

Author(s):

Takuya Saito ◽

Hua-Ning Qiu ◽

Takazo Shibuya ◽

Yi-Bing Li ◽

Kouki Kitajima ◽

...

Keyword(s):

South Africa ◽

Fluid Inclusion ◽

Fluid Inclusions ◽

Hydrothermal System ◽

Magmatic Fluid ◽

Crustal Fluid ◽

Hydrothermal Quartz ◽

Argon Isotopes ◽

Stepwise Crushing ◽

Binary Mixing

Fluid inclusions in hydrothermal quartz in the 2.4 Ga Ongeluk Formation, South Africa, are expected to partially retain a component of the ancient seawater. To constrain the origin of the fluid and the quartz precipitation age, we conducted Ar–Ar dating for the quartz via a stepwise crushing method. The obtained argon isotopes show two or three endmembers with one or two binary mixing lines as the crushing proceeds, suggesting that the isotopic compositions of these endmembers correspond to fluid inclusions of each generation, earlier generated smaller 40 Ar- and K-rich inclusions, moderate 40 Ar- and 38 Ar Cl (neutron-induced 38 Ar from Cl)-rich inclusions and later generated larger atmospheric-rich inclusions. The K-rich inclusions show significantly different 40 Ar/ 38 Ar Cl values compared to the 38 Ar Cl -rich inclusions, indicating that it is difficult to constrain the quartz formation age using only fluid inclusions containing excess 40 Ar. The highest obtained 40 Ar/ 36 Ar value from the fluid inclusions is consistent with an expected value of the Ongeluk plume source, suggesting that the quartz precipitation was driven by Ongeluk volcanism. Considering the fluid inclusion generations and their compositions, the hydrothermal system was composed of crustal fluid and magmatic fluid without seawater before the beginning of a small amount of seawater input to the hydrothermal system.

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Fluid Evolution, H-O Isotope and Re-Os Age of Molybdenite from the Baiyinhan Tungsten Deposit in the Eastern Central Asian Orogenic Belt, NE China, and Its Geological Significance

Minerals ◽

10.3390/min10080664 ◽

2020 ◽

Vol 10 (8) ◽

pp. 664

Author(s):

Ruiliang Wang ◽

Qingdong Zeng ◽

Zhaochong Zhang ◽

Yunpeng Guo ◽

Jinhang Lu

Keyword(s):

Fluid Inclusion ◽

Fluid Inclusions ◽

Meteoric Water ◽

Orogenic Belt ◽

Central Asian Orogenic Belt ◽

Tungsten Deposit ◽

Ne China ◽

Central Asian ◽

Three Stages ◽

O Isotope

The quartz-vein-type Baiyinhan tungsten deposit is located at the eastern part of the Central Asian Orogenic Belt, NE China. Analyses of fluid inclusions, H-O isotope of quartz and Re-Os isotope of molybdenite were carried out. Three stages of mineralization were identified: The early quartz + wolframite + bismuth stage, the middle quartz + molybdenite stage and the late calcite + fluorite stage. Quartz veins formed in the three stages were selected for the fluid inclusion analysis. The petrographic observation and fluid inclusion microthermometry results revealed three types of fluid inclusions: CO2-H2O (C-type), liquid-rich (L-type) and vapor-rich (V-type). The homogenization temperatures of C-type, V-type and L-type inclusions were 233–374 °C, 210–312 °C, and 196–311 °C, respectively. The salinity of the three types of inclusions was identical, varying in the range of 5–12 wt%. The H-O isotope analyses results showed that quartz had δ18OH2O and δDSMOW compositions of −2.6‰ to 4.3‰ and −97‰ to −82‰, respectively, indicating that the ore-forming fluids were mainly derived from magmatic water with a minor contribution of meteoric water. The addition of meteoric water reduces the temperature and salinity of the ore-forming fluids, which leads to a decrease of the solubility of tungsten and molybdenum in the fluids and eventually the precipitation of minerals. Re-Os isotopic analysis of five molybdenite samples yielded an isochron age of 139.6 ± 7.6 Ma (2σ) with an initial 187Os of −0.05 ± 0.57 (MSWD = 3.5). Rhenium concentrations of the molybdenite samples were between 3.1 ug/g and 8.5 ug/g. The results suggest that the metals of the Baiyinhan deposit have a crust origin, and the mineralization is one episode of the Early Cretaceous tungsten mineralization epoch which occurred at the eastern part of the Central Asian Orogenic Belt.

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Significance of Calcite Trace Elements Contents and C-O Isotopic Compositions for Ore-Forming Fluids and Gold Prospecting in the Zhesang Carlin-Like Gold Deposit of Southeastern Yunnan, China

Minerals ◽

10.3390/min10040338 ◽

2020 ◽

Vol 10 (4) ◽

pp. 338

Author(s):

Jiasheng Wang ◽

Jinyang Chang ◽

Chao Li ◽

Zhenchun Han ◽

Tao Wang ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Gold Deposit ◽

Meteoric Water ◽

Gold Mineralization ◽

Mining Area ◽

Gold Deposits ◽

Hydrothermal Fluids ◽

Magmatic Fluid ◽

Isotopic Compositions

The Zhesang gold deposit of southeastern Yunnan is an important component of the Dian-Qian-Gui (Yunnan, Guizhou, and Guangxi) “Golden Triangle”, which hosts a multitude of Carlin-like gold deposits (CLGDs). Calcite is one of the most common gangue minerals in Zhesang. The calcites that have been found in the mining area are classified as ore-stage and post-ore calcites. The ore-stage calcite exhibits a clear paragenetic relationship with gold-bearing arsenopyrite and with an alteration halo that has been cut by the post-ore calcite. To elucidate the origin of the ore-forming fluids of the Zhesang gold deposit and to investigate the possibility of utilizing calcite geochemistry as prospecting indicators, the rare earth elements (REEs), Y, Fe, Mn and Mg contents, and C-O isotopic compositions of calcites from Zhesang have been analyzed. The ore-stage calcite is enriched in middle rare earth elements (MREEs) relative to light rare earth elements (LREEs) and heavy rare earth elements (HREEs) (MREE/LREE = 1.11–1.61, MREE/HREE = 6.12–8.22), whereas post-ore calcite exhibits an enrichment in LREE (LREE/HREE = 4.39–14.93, MREE/LREE = 0.35–0.71). The ore-stage and post-ore calcites were both formed by hydrothermal fluids; however, these hydrothermal fluids may have different sources. The Fe contents of the ore-stage calcite are significantly higher than those of post-ore calcite (4690–6300 μg/g versus 2030–2730 μg/g). Ore-stage calcite also has significantly lower δ18OV-SMOW values than post-ore calcite (11.03–12.49‰ versus 16.48–17.14‰). These calcites with an MREE/LREE ratio greater than 0.92, MREE/HREE ratio greater than 5.69, Fe content greater than 3827 μg/g, and δ18OV-SMOW value less than 14.40‰ represent ore-stage calcites and are important prospecting guidelines. According to the REE, C-O isotopic characteristics of the calcites and the previous findings, it is inferred that the ore-forming fluids of the Zhesang gold deposit were a mixture of crustal fluid by meteoric water leaching wall rocks and a small amount of basic magmatic fluid. The formation of post-ore calcite might be derived from meteoric water and marine carbonates interaction. The ore-forming fluids of the Zhesang gold deposit may be associated with the intrusion of diabase that outcrops in the mining area, and that the basic magmatic activities of the Indosinian period also provided some of the ore-forming materials and heat for gold mineralization.

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Geologia e Geoquímica (ETR e Inclusões Fluidas) das Mineralizações (F, BA) da Parte Norte do Distrito Fluorítico de Santa Catrina, Sul do Brasil

Pesquisas em Geociências ◽

10.22456/1807-9806.21121 ◽

1999 ◽

Vol 26 (2) ◽

pp. 3

Author(s):

FLÁVIO FRANÇA DA ROCHA ◽

ARTHUR CÉZAR BASTOS NETO

Keyword(s):

Fluid Inclusions ◽

Meteoric Water ◽

Normal Fault ◽

Salinity Range ◽

Alkaline Magmatism ◽

Second Phase ◽

Southern District ◽

Extensional Tectonic ◽

Primary Fluid ◽

Hydrothermal Event

This work deals on the fluorite deposits from the Grão Pará (GP) and Rio Bravo Alto (RBA) veins systems both situated at the northern part of Santa Catarina Fluorite District. The GP deposits are controlled by an ancient shear zone. Ore deposition is related to two tectonic phases: (1) dextral transtensive reactivation related to a NE/SW compression; deposition of green-purple massive or coarse banded fluorite; tectonic and hydraulic breccias assign successive transitions from hydrostatic to tectonic regimes; the ore was affected by latter silicification; (2) reactivation as normal fault, related to a extensional tectonic; deposition of purple and yellow banded fluorite, collapse breccias and cocardes. First phase fluorite was deposited at temperatures decreasing from 170º to 120ºC; silicification temperature is around 140ºC. Second phase fluorite was deposited at temperatures between 140º and 120ºC. The fluid inclusions salinity range from 0 to 2% eq. NaCl. The isotopic composition of water from primary fluid inclusions in the fluorite at RBA (δD ͌ -60‰ SMOW) is typical of meteoric water from interior continental region. The RBA fluorite has the same HREE signature as fluorite from the southern district deposits and regional granites. REE and fluid inclusion data reject a link with alkaline magmatism. Fluorine was leached from accessory fluorite of regional granites. The fluorite deposition was connected to a single hydrothermal event correlated to the earlier hydrothermal event described at the southern district.

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