NEOPROTEROZOIC STRATIGRAPHY OF THE BONAVISTA PENINSULA: PRELIMINARY RESULTS, REGIONAL CORRELATIONS AND IMPLICATIONS FOR SEDIMENT- HOSTED STRATIFORM COPPER EXPLORATION IN THE NEWFOUNDLAND AVALON ZONE

Existing regional bedrock maps of the Bonavista Peninsula of eastern Newfoundland assign all Neoproterozoic strata to the Musgravetown Group, a unit that has been characterized in much of the geological literature as a thick, and widespread succession of slightly deformed continental red beds. Mapping described below, however, has instead shown that significant parts of the Bonavista Peninsula consist of silicified and non-silicified marine and deltaic, clastic sedimentary rocks, correlative with several of the principal late Neoproterozoic units of the Avalon Peninsula to the southeast: viz., the Conception Group (including the Mistaken Point Formation), the Trepassey, Fermeuse and Renews Head formations of the overlying St. John's Group, and the Gibbett Hill Formation of the Signal Hill Group. The lithologically contrasting Musgravetown Group is widely developed west of the Conception and St. John's groups, and is typified by openly folded and in many areas, gently dipping to sub-horizontal, shallow-marine to fluvial siliciclastic rocks of the Rocky Harbour and overlying Crown Hill formations, respectively. The Rocky Harbour Formation has been tentatively divided into six component facies of potential member status. One of the most extensive of these is a purple to greygreen conglomerate facies that overlies subaerial volcanic rocks (Bull Arm Formation of the Musgravetown Group) in the west and folded and silicified marine sedimentary rocks (Conception Group) in the east. Chalcocite mineralization within the Musgravetown Group occurs in grey beds within the red bed dominated Crown Hill Formation and in grey and green gritty sandstones of the underlying Rocky Harbour Formation. Preliminary findings allow the Neoproterozoic stratigraphic record for the Bonavista Peninsula to be correlated, at varying levels of detail, with large parts of the Avalon Peninsula, and the western Bonavista Bay and northern Fortune Bay regions. This correlation, coupled with the nature of the Neoproterozoic basins and the lithofacies of basin-fills, have significant ramifications for exploration for sediment-hosted stratiform copper and Sedex-style base metals in eastern Newfoundland.