Tectonically-induced neptunian dykes and breccias of the Paleoproterozoic Teena Dolomite: Significance to stratiform zinc deposits in the McArthur Basin, Australia

Abstract

A widespread system of breccias and neptunian dykes is present within the Paleoproterozoic Teena Dolomite of the McArthur Basin. Most breccia types within the unit are infilled by early fibrous marine cements and dark grey sediments. We interpret the dominant breccia types as in-situ synsedimentary fracture systems (neptunian dykes) while some matrix-supported breccias are likely to be mass flow deposits. Fibrous marine cements filling the neptunian dykes have several different textures and all now consist of dolomite. Petrographic evidence indicates the cements were likely precipitated as calcite and dolomitized during early diagenesis. The trace and rare earth element chemistry of the mari..