TY - JOUR
T1 - Geochemical and geochronological constraints on the gold-sulfide mineralization and host granitoid rocks in the Bulghah and Al-Maham prospects, central Arabian Shield, Saudi Arabia
AU - Bakhsh, Rami A.
AU - Ali, Kamal A.
AU - Zoheir, Basem A.
AU - Eivind Augland, Lars
AU - Ahmed, Ahmed H.
AU - Stein, Holly J.
N1 - Funding Information:
This work is part of a project funded by the Deanship of Scientific Research (DSR) at KAU (King Abdulaziz University), Grant number (G-1436-145-211). Special thanks go to the DSR technical and financial support for their help. The authors gratefully acknowledge the logistical support provided by geologists of the Saudi Arabian Mining Company (Ma'aden) in the Sukhaybarat and Bulghah mining camps during the fieldwork. Basem Zoheir acknowledges the Alexander von Humboldt foundation for supporting his research stay at Kiel University. Access to the LA-ICP-MS facilities at the University of Oslo is highly appreciated. As Colorado State University provides neither salary support nor operational support for the AIRIE Program, we thank AIRIE for their generosity in support of this project. Constructive reviews of this manuscript by Prof. Ghaleb Jarrar and an anonymous reviewer are gratefully acknowledged. We thank Editor-in-Chief Prof. Mei-Fu Zhou for insightful comments and criticism that improved this manuscript.
Funding Information:
This work is part of a project funded by the Deanship of Scientific Research (DSR) at KAU (King Abdulaziz University), Grant number (G-1436-145-211). Special thanks go to the DSR technical and financial support for their help. The authors gratefully acknowledge the logistical support provided by geologists of the Saudi Arabian Mining Company (Ma'aden) in the Sukhaybarat and Bulghah mining camps during the fieldwork. Basem Zoheir acknowledges the Alexander von Humboldt foundation for supporting his research stay at Kiel University. Access to the LA-ICP-MS facilities at the University of Oslo is highly appreciated. As Colorado State University provides neither salary support nor operational support for the AIRIE Program, we thank AIRIE for their generosity in support of this project. Constructive reviews of this manuscript by Prof. Ghaleb Jarrar and an anonymous reviewer are gratefully acknowledged. We thank Editor-in-Chief Prof. Mei-Fu Zhou for insightful comments and criticism that improved this manuscript.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/1
Y1 - 2022/1
N2 - Among several gold-sulfide deposits and prospects scattered in the Afif terrane of the Arabian Shield, the Bulghah and Al-Maham prospects are investigated to assess the spatial and temporal relationships between gold mineralization and the host lithologies and regional structures. Both prospects are hosted by the sulfide-bearing Hulayfah Group metavolcano-sedimentary successions, and are confined to cross-cutting granitoid intrusions. Tonalite-granodiorite and monzogranite from the two areas have geochemical characteristics of metaluminous to weakly peraluminous calc-alkaline I-type granitoids. Younger alkali feldspar granite in the Bulghah area exhibits geochemical features of A-type granite, likely formed in a post-collisional or transitional setting. ID-TIMS dating of zircons from two granodiorite samples from the Al-Maham prospect yielded 206Pb/238U ages of ∼662 and 651 Ma. A tonalite sample from the Bulghah mine area gave a concordia age of 674.8 ± 0.8 Ma (2σ; MSWD = 0.42), whereas the alkali feldspar granite sample has an age of ∼ 631 ± 1 Ma. The newly defined ages can be considered as the upper age limit of the auriferous quartz veins, evidently attendant to the Nabitah orogeny (∼680–640 Ma). Gold-bearing quartz veins in the two prospects are identical in terms of ore mineralogy, textures and paragenesis. Gold-bearing quartz veins are associated with intersecting veinlets and stockwork of arsenopyrite, pyrite, and less common pyrrhotite, chalcopyrite, and sphalerite. Recrystallized pyrite and arsenopyrite are ubiquitous in quartz veins, whereas pyrrhotite-chalcopyrite intergrowths in-fills or replacements prevail in the deformed host metavolcanic rocks. Free gold typically occurs as fine inclusions in quartz veins, commonly in deformed pyrite and arsenopyrite crystals. The sulfides of Al-Maham prospect have significantly higher Re-Os concentrations (ppb level), compared with those in the Bulghah prospect, and define an isochron with a Model-1 age of 360 ± 2 Ma and an initial 187Os/188Os ratio of 1.962 ± 0.032. The obtained Re-Os age and the crustal initial Os isotope ratio do not necessarily define the primary age of gold mineralization since ore textures indicate that pyrrhotite was a paragenetically late sulfide phase in both prospects. Alternatively, this age may be interpreted as the time of remobilization and recrystallization of older sulfides in response to Hercynian uplift and deformation (370–290 Ma), manifested as intermittently rejuvenated reverse faults elsewhere in the Arabian Shield.
AB - Among several gold-sulfide deposits and prospects scattered in the Afif terrane of the Arabian Shield, the Bulghah and Al-Maham prospects are investigated to assess the spatial and temporal relationships between gold mineralization and the host lithologies and regional structures. Both prospects are hosted by the sulfide-bearing Hulayfah Group metavolcano-sedimentary successions, and are confined to cross-cutting granitoid intrusions. Tonalite-granodiorite and monzogranite from the two areas have geochemical characteristics of metaluminous to weakly peraluminous calc-alkaline I-type granitoids. Younger alkali feldspar granite in the Bulghah area exhibits geochemical features of A-type granite, likely formed in a post-collisional or transitional setting. ID-TIMS dating of zircons from two granodiorite samples from the Al-Maham prospect yielded 206Pb/238U ages of ∼662 and 651 Ma. A tonalite sample from the Bulghah mine area gave a concordia age of 674.8 ± 0.8 Ma (2σ; MSWD = 0.42), whereas the alkali feldspar granite sample has an age of ∼ 631 ± 1 Ma. The newly defined ages can be considered as the upper age limit of the auriferous quartz veins, evidently attendant to the Nabitah orogeny (∼680–640 Ma). Gold-bearing quartz veins in the two prospects are identical in terms of ore mineralogy, textures and paragenesis. Gold-bearing quartz veins are associated with intersecting veinlets and stockwork of arsenopyrite, pyrite, and less common pyrrhotite, chalcopyrite, and sphalerite. Recrystallized pyrite and arsenopyrite are ubiquitous in quartz veins, whereas pyrrhotite-chalcopyrite intergrowths in-fills or replacements prevail in the deformed host metavolcanic rocks. Free gold typically occurs as fine inclusions in quartz veins, commonly in deformed pyrite and arsenopyrite crystals. The sulfides of Al-Maham prospect have significantly higher Re-Os concentrations (ppb level), compared with those in the Bulghah prospect, and define an isochron with a Model-1 age of 360 ± 2 Ma and an initial 187Os/188Os ratio of 1.962 ± 0.032. The obtained Re-Os age and the crustal initial Os isotope ratio do not necessarily define the primary age of gold mineralization since ore textures indicate that pyrrhotite was a paragenetically late sulfide phase in both prospects. Alternatively, this age may be interpreted as the time of remobilization and recrystallization of older sulfides in response to Hercynian uplift and deformation (370–290 Ma), manifested as intermittently rejuvenated reverse faults elsewhere in the Arabian Shield.
KW - Afif terrane
KW - Arabian Shield
KW - Gold-sulfide mineralization, I-type and A-type granitoids
KW - Re-Os isotope systematics
KW - U-Pb zircon ages
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U2 - 10.1016/j.jseaes.2021.105004
DO - 10.1016/j.jseaes.2021.105004
M3 - Article
AN - SCOPUS:85119278880
SN - 1367-9120
VL - 223
JO - Journal of Asian Earth Sciences
JF - Journal of Asian Earth Sciences
M1 - 105004
ER -