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Brazilian Journal of Geology

Print version ISSN 2317-4889On-line version ISSN 2317-4692

Abstract

BASSOO, Roy  and  MURPHY, James Brendan. The 9 Mile Deposit of the Barama-Mazaruni Greenstone Belt of the Guiana Shield: geochemistry, geochronology and regional significance. Braz. J. Geol. [online]. 2018, vol.48, n.4, pp.671-683. ISSN 2317-4889.  https://doi.org/10.1590/2317-4889201820180072.

The granitoid and greenstone-hosted 9 Mile Deposit, located in the Paleoproterozoic Barama-Mazaruni Greenstone Belt of the Guiana Shield, is one of a series of gold deposits within the NW-SE trending Makapa-Kuribrong Shear Zone (MKSZ), which extends from Venezuela, through Guyana, and French Guiana. The 9 Mile Deposit is underlain by the upper section of a shallowly-dipping meta-rhyolite rock, which was intruded by a host granodiorite and subsequently intruded by of a series of mafic dykes. Auriferous quartz veins are associated with the NE-SW thrust which was crosscut by a steep E-W shear zone, at least 12 km in length. Field relationships and lithogeochemical data suggest that the granodiorite was crustally derived and emplaced in a volcanic arc or syn- to late-collisional setting. U-Pb (SHRIMP II) dating of zircons indicates the granodiorite intruded at approximately 2.15, Ga suggesting it is a local representative of a regional suite of syn- to late-tectonic granitoid plutons emplaced during the main phase of Trans-Amazonian Orogeny.

Keywords : Guyana; Guiana Shield; Paleoproterozoic; Tectonic evolution; Lithochemistry; Tran-Amazonian Orogeny; Gold deposit.

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