Structural Controls on Sulfide Mobilization at the High-Grade Flying Fox Ni-Cu-PGE Sulfide Deposit, Forrestania Greenstone Belt, Western Australia

摘要

The Flying Fox komatiite-hosted Ni deposit is located in the Forrestania greenstone belt of the Yilgarn craton in Western Australia. The host volcanosedimentary succession has been metamorphosed to amphibolite facies and deformation has sheared and dismembered the orebody, creating 11 distinct ore shoots. The ore shoots are hosted at the base of a komatiite sequence structurally overlying deformed metasedimentary rocks. The Ni sulfide orebody has undergone six phases of deformation: (1) D_(laReg): E-W compression resulted in tilting of the stratigraphy, (2) D_(1bFF): continued E-W compression resulted in coaxial flattening along the footwall sedimentary rock-sulfide/komatiite contact and the basalt-hanging-wall sedimentary rock contact, (3) D_(2ff): ENE-WSW compression resulted in noncoaxial shearing of the D_(1bFF) structures, (4) D_(3ff): ESE-WNW compression resulted in shallow-angle thrusts, (5) D_(4ff): during E-W extension, normal ductile-brittle faults formed by the pooling and dilation of granitic magma along the F_2 structural contact between the footwall sedimentary and komatiite rocks, and (6) D_(5ff): intrusion of a Proterozoic dolerite dike during N-S extension accompanied by late-stage brittle normal faulting.