3D seismic analysis of an Upper Palaeozoic carbonate succession of the Eastern Finnmark Platform area, Norwegian Barents Sea

Abstract

This paper presents 3D seismic data to enhance our understanding of the seismic stratigraphy and buildup developments of the Finnmark Platform. We focus on carbonate buildup distributions and platform geometry in space and upper Palaeozoic time. Multi-attribute analysis, neural network techniques and the use of inverted impedance data reveal seismic anomalies that can be linked with significant geological geometries such as buildups, subtle prograding clinoforms, karstified surfaces or platform breaks. The seismic expressions show a platform development mainly driven by climatic changes and differential subsidence. Seismic data indicate the first progradation of a low angle warm-water carbonate ramp during Mid Carboniferous times. A gradual change from a low angle (mixed) carbonate ramp to a more restricted carbonate shelf with a marked break and slope occurs during Upper Carboniferous/Lower Permian (Gipsdalen Group). Large buildups on the platform are identified both as individual mounds and unique continuous complexes (e.g. network of polygonal ridges as well as a 30-km long barrier complex). Multi-attribute analysis reveals a distinct karst event on top of the Gipsdalen Group. Climatic cooling during the Lower Permian (Bjarmeland Group) resulted in an even more restricted platform as seen in the seismic data with developments of 200-m high bryozoan mounds in deeper waters of the platform slope. Further cooling during Mid Permian (Tempelfjorden Group) resulted in a major chert event with development of a series of spiculitic chert mounds.