Emplacement timing, temperature, and redox conditions of the Kambélé auriferous pluton, Batouri gold District, SE Cameroon

Abstract

The Kambélé auriferous pluton in south-eastern Cameroon is within the Central African Fold Belt (CAFB). New zircon LA-ICP-MS U-Pb ages, REEs patterns, zircon Ce 4+ / Ce 3+ ratios, and Ti-in-zircon thermometry, have been used to decipher the timing of mineralisation, redox conditions and emplacement temperature of the pluton. Cathodoluminescence images of 12 representative zircon grains from the Kambélé pluton reveal two types of zircon grains: type 1 grains are characterized by dark cores, serrated margins and poorly defined zonation; type 2 grains are euhedral to subhedral, elongated, with core to rim zonation and with darker rims indicative of a pristine magmatic source. The zircon grains are depleted in light rare earth elements. Chondrite-normalised REE patterns show undefined Ce anomalies and negative Eu anomalies indicating moderately oxidised to reduced conditions. Zircon U-Pb age of the granitoid is constrained to Neoproterozoic with a mean age of 589±36 Ma indicating gold mineralisation during the Pan African orogeny. Crystallization temperatures range from 525-1033°C with a mean temperature of ~712°C, concomitant with granitoid emplacement temperatures within the Adamawa Yadé Domain of the CAFB.

Tourmaline occurrence and gold mineralization at a granitoid-metasediment contact in the Upper Lom Basin, east Cameroon

“…Zircon U-Pb age data revealed that granitoid intrusions were emplaced within an age bracket of ca. 670-620 Ma [20,27,57,58], with an average mean age of ca. 635 Ma obtained on syn-tectonic granitoid in the Bétaré Oya gold district [27], south of the present study.…”

“…Such high δ 11 B values suggest the involvement of an I-type granitic pluton [73]. Neoproterozoic granitoids in the eastern Cameroon goldfields are also I-type metaluminous to slightly peraluminous and associated with gold mineralization [57,58]. As an incompatible element, B is readily transported by granitic melts and hydrous fluids derived therefrom [74].…”