IMPLICATIONS OF LITHOLOGY, GEOCHEMISTRY AND MICROFACIES FOR CAMBRIAN PALEOENVIRONMENTS, PALEOCLIMATE, AND PALEOGEOGRAPHY OF EASTERN NEWFOUNDLAND, CANADA

The outcrops in the Manuels River area, Avalon Peninsula, Newfoundland, are classic localities for Cambrian research. The rocks comprise a concordant sedimentary succession deposited on the former microcontinent Avalonia. The upper Series 2 to Furongian succession is represented by the Brigus, Chamberlain’s Brook, Manuels River and Elliot Cove formations and consists predominantly of green, grey, and black mudstones and siltstones, in part highly fossiliferous, with minor limestone intercalations and volcanic ash layers. The succession rests on Neoproterozoic magmatic rocks and is conformably overlain by Ordovician sedimentary rocks.

According to widely accepted concepts, the succession was deposited in a cold-water shelf to outer-marine environment. However, microfacies analysis indicates a sedimentary environment influenced by sea-level changes in a setting shallower than outer-shelf. Varying amounts of organic carbon in the succession suggest deposition under fluctuating levels of oxygenation, probably related to sea-level changes.

The Cambrian paleogeography and movements of Avalonia are subject to controversial interpretations. Due to an only moderate diagenetic overprint, analysis of detrital clay minerals enables paleoclimatic interpretations, which, in combination with interpretation of the depositional environments and the fossil record, challenges previous reconstructions of the palaeogeographic position of Avalonia and Cambrian climate.

Financial support by the Klaus Tschira Foundation (KTS 00.195.2011 and 00.272.2015) is gratefully acknowledged.