Mineral chemistry, bulk rock geochemistry, and S-isotope signature of lode-gold mineralization in the Bétaré Oya gold district, south-east Cameroon

2017 ◽  
Vol 53 (6) ◽  
pp. 2579-2596 ◽  
Author(s):  
Akumbom Vishiti ◽  
Cheo Emmanuel Suh ◽  
Bernd Lehmann ◽  
Elisha Mutum Shemang ◽  
Njumbe Lionel Junior Ngome ◽  
...  
Keyword(s):  
Gold Mineralization ◽  
Mineral Chemistry ◽  
Bulk Rock ◽  
Lode Gold ◽  
Isotope Signature ◽  
S Isotope

New constraints on the Sulfur isotope signature of the sub-continental lithospheric mantle wedge: in situ δ34S analyses of pentlandite from the exhumed orogenic garnet-bearing peridotite of the Ulten Zone, Eastern Italian Alps

2020 ◽  
Author(s):  
Giulia Consuma ◽  
Roberto Braga ◽  
Marco L. Fiorentini ◽  
Laure Martin ◽  
Peter Tropper ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Mantle Wedge ◽  
Isotope Composition ◽  
Mineral Chemistry ◽  
Isotope Signature ◽  
Fine Grained ◽  
Continental Lithospheric Mantle ◽  
The Impact ◽  
S Isotope

<p>Orogenic peridotites associated with high-grade felsic rocks record mass exchange between crust and mantle reservoirs at convergent plate margins. In this geodynamic framework, fluids released by submerging slabs can mobilize redox-sensitive elements such as carbon (C) and sulfur (S) and percolate the mantle wedge, eventually forming hydrate minerals associated with carbonate and sulfide phases at appropriate T, P and f O<sub>2</sub> conditions. The introduction of sulfur into the sub-continental lithospheric mantle (SCLM) wedge and its mobilization at grain-scale can be investigated by means of in situ δ<sup>34</sup>S analyses of mantle wedge sulfides, which may have inherited the composition of the fluid sources. To date, the impact of the S transfer through the SCLM wedge is poorly known and limited in situ S isotope values of sulfides from mantle wedge peridotite are available in literature. Our study focuses on the Ulten Zone (UZ) orogenic-garnet peridotites, which provide an ideal case to investigate the S mobilization through the SCLM wedge and the effects of crustal fluids on the sulfide δ<sup>34</sup>S signature, especially during the exhumation stage. We therefore integrate a well-constrained paragenesis with mineral chemistry and in situ S isotope signature of sulfides. The UZ peridotites were involved in a collisional setting during the Variscan orogenesis, recording HP-eclogite-facies conditions and exhumation after their incorporation in a mélange with the associated garnet-kyanite gneisses. A suite of coarse to fine-grained peridotites was investigated in order to cover all the metasomatic stages preserved in these rocks, considering the grade of serpentinization and the occurrence of carbonates. Microstructural observations and major element compositions indicate that pentlandite (± chalcopyrite ± chalcocite ± sphalerite) is the ubiquitous primary sulfide, which is commonly replaced by secondary heazlewoodite and millerite in medium to highly serpentinized peridotite. Pentlandite occurs in different textural positions related to several metasomatic stages: (i) polycrystalline aggregates (pentlandite + Cl-apatite + phlogopite + ilmenite + calcite-brucite intergrowths) included in spinel (in garnet); (ii) interstitial in matrix; (iii) in carbonate and serpentine veins. Overall, the S isotope signature of pentlandite exhibits a relatively narrow range between -1.62 and +3.76 ‰. The relatively low S isotope values require a mantle-like source for the metasomatizing fluids enriched in sulfur, with possible contamination with fluids of other different sources. These new results show that sulfur was introduced into the lithospheric mantle and mobilized by influxes of late metasomatic fluids, in part related to the serpentinization, and provide additional constraints on the S isotope composition of the SCLM wedge.</p>

Geochemistry and mineral chemistry of lode gold mineralisation, SE Egypt: implications for ore genesis and exploration

2012 ◽  
Vol 6 (12) ◽  
pp. 4635-4646 ◽  
Author(s):  
Basem A. Zoheir ◽  
Mohamed G. Abdel-Fattah ◽  
Sameh M. ElAlfy
Keyword(s):  
Mineral Chemistry ◽  
Ore Genesis ◽  
Lode Gold

Zircons, Dikes, and Gold Mineralization at Jundee-Nimary: Post ca. 2.66 Ga Archean Lode Gold in the Yandal Belt, Western Australia

2005 ◽  
Vol 100 (7) ◽  
pp. 1389-1405 ◽  
Author(s):  
M. S. Baggott ◽  
N. M. Vielreicher ◽  
D. I. Groves ◽  
N. J. McNaughton ◽  
M. Gebre-Mariam
Keyword(s):  
Western Australia ◽  
Gold Mineralization ◽  
Lode Gold
Sign in / Sign up

Export Citation Format

Share Document