Geology, geochemistry, fluid inclusions, and H-O-C-S-Pb isotope constraints on the genesis of the Atash-Anbar epithermal gold deposit, Urumieh-Dokhtar magmatic arc, central-northern Iran

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F23%3A10168506" target="_blank" >RIV/00025798:_____/23:10168506 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1016/j.oregeorev.2022.105285" target="_blank" >https://doi.org/10.1016/j.oregeorev.2022.105285</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.oregeorev.2022.105285" target="_blank" >10.1016/j.oregeorev.2022.105285</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geology, geochemistry, fluid inclusions, and H-O-C-S-Pb isotope constraints on the genesis of the Atash-Anbar epithermal gold deposit, Urumieh-Dokhtar magmatic arc, central-northern Iran

Popis výsledku v původním jazyce

The newly discovered Atash-Anbar gold deposit, with TILDE OPERATOR+D912 Mt of ore grading 2.13 g/t Au (locally up to 14 g/t), is located in the Buin-Zahra Range, central-northern Iran. Hosted by Middle Eocene (ca. 39.0 Ma) volcanic-subvolcanic rocks, the Au-polymetallic orebodies occur as NWMINUS SIGN and NEMINUS SIGN trending quartz-sulfide veins that are structurally controlled by NW-trending faults. The Middle Eocene host rocks are characterized by high-K calc-alkaline, peraluminous signatures, and moderately Eu negative anomalies (Eu/Eu* = 0.2MINUS SIGN 0.6). Four primary paragenetic stages of veining have been recognized: (I) smoky-grey quartz-chalcopyrite stage, (II) grey-white quartz-polysulfide stage, (III) white-pinkish barite-sulfide stage, and (IV) late quartz-carbonate stage. Fluid inclusion investigations coupled with laser Raman analyses indicate that the ore-forming fluids were formed in a NaClMINUS SIGN H2O+-CO2 system with two types of FIs: two phase, liquid-rich inclusions (type I) and two phase, vapor-rich inclusions (type II). The primary coexisting types I and II inclusions are observed in gold-bearing ore-stage II, sharing similar homogenization temperatures in the range of 233-286 oC and 243-281 oC, but contrasting salinity values of 10.7-14.8 and 14.6-15.5 wtpercent NaCl equivalent, respectively. Fluid inclusion examinations show that fluid phase separation occurred concurrently with gold precipitation during the ore-stage II. The delta18Ofluid values calculated from the delta18OSMOW and deltaDSMOW values of the inclusions in quartz veins are 4.9-11.1per mille and MINUS SIGN 84.6per mille to MINUS SIGN 68.3per mille, respectively. delta13CPDB and delta18OSMOW values of Fe-dolomite are MINUS SIGN 6.5per mille to MINUS SIGN 5.0per mille and 3.1per mille-4.9per mille, respectively. H-O-C isotope data indicate magmatic origin of initial ore-forming fluids with minor addition of meteoric water through time. The delta34S values (MINUS SIGN 3.1per mille to MINUS SIGN 1.2per mille, avg. = MINUS SIGN 2.0per mille) of the ore-stage II sulfides suggest that sulfur comes from a homogeneous magmatic source. The Pb isotopic compositions of sulfides (207Pb/204Pb = 15.420-15.525, 206Pb/204Pb = 18.423-18.536, 208Pb/204Pb = 37.135-38.208) indicate that the Pb in the Atash-Anbar gold deposit is a mixture of crust and mantle components. We conclude that (1) the Atash-Anbar is an IS epithermal system that (2) resulted from Eocene subduction of the Neo-Tethys Ocean plate beneath the central Iran plate and thus (3) ore-forming fluid and its metal components (i.e., Ag, Pb, and Zn) were emanated through crystallization of the final phase of a granite porphyry intrusion.

Název v anglickém jazyce

Geology, geochemistry, fluid inclusions, and H-O-C-S-Pb isotope constraints on the genesis of the Atash-Anbar epithermal gold deposit, Urumieh-Dokhtar magmatic arc, central-northern Iran

Popis výsledku anglicky

The newly discovered Atash-Anbar gold deposit, with TILDE OPERATOR+D912 Mt of ore grading 2.13 g/t Au (locally up to 14 g/t), is located in the Buin-Zahra Range, central-northern Iran. Hosted by Middle Eocene (ca. 39.0 Ma) volcanic-subvolcanic rocks, the Au-polymetallic orebodies occur as NWMINUS SIGN and NEMINUS SIGN trending quartz-sulfide veins that are structurally controlled by NW-trending faults. The Middle Eocene host rocks are characterized by high-K calc-alkaline, peraluminous signatures, and moderately Eu negative anomalies (Eu/Eu* = 0.2MINUS SIGN 0.6). Four primary paragenetic stages of veining have been recognized: (I) smoky-grey quartz-chalcopyrite stage, (II) grey-white quartz-polysulfide stage, (III) white-pinkish barite-sulfide stage, and (IV) late quartz-carbonate stage. Fluid inclusion investigations coupled with laser Raman analyses indicate that the ore-forming fluids were formed in a NaClMINUS SIGN H2O+-CO2 system with two types of FIs: two phase, liquid-rich inclusions (type I) and two phase, vapor-rich inclusions (type II). The primary coexisting types I and II inclusions are observed in gold-bearing ore-stage II, sharing similar homogenization temperatures in the range of 233-286 oC and 243-281 oC, but contrasting salinity values of 10.7-14.8 and 14.6-15.5 wtpercent NaCl equivalent, respectively. Fluid inclusion examinations show that fluid phase separation occurred concurrently with gold precipitation during the ore-stage II. The delta18Ofluid values calculated from the delta18OSMOW and deltaDSMOW values of the inclusions in quartz veins are 4.9-11.1per mille and MINUS SIGN 84.6per mille to MINUS SIGN 68.3per mille, respectively. delta13CPDB and delta18OSMOW values of Fe-dolomite are MINUS SIGN 6.5per mille to MINUS SIGN 5.0per mille and 3.1per mille-4.9per mille, respectively. H-O-C isotope data indicate magmatic origin of initial ore-forming fluids with minor addition of meteoric water through time. The delta34S values (MINUS SIGN 3.1per mille to MINUS SIGN 1.2per mille, avg. = MINUS SIGN 2.0per mille) of the ore-stage II sulfides suggest that sulfur comes from a homogeneous magmatic source. The Pb isotopic compositions of sulfides (207Pb/204Pb = 15.420-15.525, 206Pb/204Pb = 18.423-18.536, 208Pb/204Pb = 37.135-38.208) indicate that the Pb in the Atash-Anbar gold deposit is a mixture of crust and mantle components. We conclude that (1) the Atash-Anbar is an IS epithermal system that (2) resulted from Eocene subduction of the Neo-Tethys Ocean plate beneath the central Iran plate and thus (3) ore-forming fluid and its metal components (i.e., Ag, Pb, and Zn) were emanated through crystallization of the final phase of a granite porphyry intrusion.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Ore Geology Reviews

ISSN

0169-1368

e-ISSN

—

Svazek periodika

153

Číslo periodika v rámci svazku

105285

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

28

Strana od-do

1-28

Kód UT WoS článku

000925191000001

EID výsledku v databázi Scopus

2-s2.0-85146055363