The 9 Mile Deposit of the Barama-Mazaruni Greenstone Belt of the Guiana Shield: geochemistry, geochronology and regional significance

ABSTRACT: 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.