摘要
The Gankoumbol-Djouzami-Beka(GDB)area investigated in this study is part of the Central Cameroon Shear Zone(CCSZ)which is a network of anas-tomosing NE-SW-trending brittle-ductile mega shear.Primary gold mineral-ization in the area is restricted to secondary structures in the hydrothermally altered metagranitoids and metasediments pointing to a link between defor-mation,fluid flow and attendant mineral alteration synchronous with gold precipitation.Here,we document the spectrum of fault rocks that adorn the shear zone at the GDB area,ranging from ultramylonite/mylonite at the center of the shear zone that grades outwards through protomylonite to cataclasite at the margins.Shear sense indicators point to sinistral shear with a dominant prolate-type strain ellipsoid.The metagranitoid is subalkaline,with fault rocks characterized by alterations such as K-feldspar alteration,silicification,sericit-ization and sulphidation which affects the geochemistry of this altered assem-blage.The least altered metagranitoid and fault rocks samples show LREE en-richment,depletion in HREE and a negative Eu anomaly depicting plagioclase fractionation over the various alteration categories.On the multielement var-iation plots,positive Rb,K,Sm,Pb,and Th anomalies and negative Nb,Sr,Ba,Ti and Zr anomalies are observed,resulting from hydrothermal alteration for the fault rocks.Gold(up to 1.8 g/t)mineralization is associated with sericiti-zation,silicification and sulphidation.Hydrothermal alteration in fault rocks results to enrichment Mn,Cu,S,Au,Te,Fe,Bi,Ba,Mo,Mg,and depletion in Nb,Sn,As,Sb and Ga.Au-S-Cu-Mn-Te-Fe-Mo-Bi metal association consti-tutes a pathfinder element class reflecting gold mineralization contemporane-ous with sulphidation.
