ARNAUD, EMMANUELLE V., McMaster University, School of Geography and Geology, Hamilton, Canada

ABSTRACT: Sedimentological Analysis of the Glacigenic Port Askaig Formation, Scotland

The development of depositional models for glacially-influenced basins is difficult due to the complex relation between the preserved sediment record and external controls on sedimentation: poorly sorted coarse-grained facies and sea level fluctuations can result from glacial and non-glacial processes. The purpose of the proposed research is to gain a better understanding of the sedimentary signature of both tectonic and climatic controls on deposition in glaciated basins through a detailed sedimentological analysis of the Neoproterozoic Port Askaig Formation in Scotland.

The Port Askaig Formation consists of 47 diamictite units interbedded with a wide variety of facies that are interpreted to record glaciomarine sedimentation in an extensional basin. Field work will consist of logging extensive outcrop exposures to describe vertical changes in the nature of sedimentary facies and bounding surfaces. Sedimentary facies will then be grouped into genetically-related facies associations and analyzed to establish spatial and temporal changes in depositional setting. An allostratigraphy will be developed from significant changes in facies associations, which in turn, will be used to discriminate the effects of external controls such as tectonic events and climate change.

Identification of external controls on sedimentation patterns is important for the development of accurate depositional models that may be used to predict coarse-grained facies distribution. The proposed work will not only contribute to a better understanding of the nature of glaciation during the Neoproterozoic but will also lead to improved resource exploration models for hydrocarbon-bearing glaciated basins such as the Parana Basin of Brazil and the Cooper Basin of Australia.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid