Structural and stratigraphic setting of the Ming and other sulphide deposits in the Rambler area, Nfld.

Abstract

The lithologies present in the Rambler Area are described, a sequence of lithofacies units is defined, and a simplistic model to explain the evolution of the rocks in the area is proposed. As a generalisation the rocks dip towards the northeast and become younger in that direction. The base of the sequence consists of basic (Komatiitic) lavas, and this is overlain by basic pyroclastic volcanic rocks. Towards the end of the basic pyroclastic stage a centre of acid volcanism developed, and the sulphide deposits can be related to exhalite activity during the waning stages of acid volcanism. The termination of basic pyroclastic volcanism was followed by deposition of a sequence of basic volcanogenic sediment and/or waterlain tuff, and extrusion of local pillow lava units. Abundant basic intrusions may be contemporaneous with the build-up of the volcanic pile. The volcanic sequence was intruded by the Burlington Granodiorite on the west, and Cape Brule Porphyry on the east. -- All the rocks in the area have been subjected to polyphaser deformation and to metamorphism in the upper greenschist facies. The first two deformation involved intense strain with 1