Seismic Stratigraphic Interpretation of Late Palaeozoic Carbonates and Paleogeography of the Loppa High.

Abstract

This thesis presents a detailed study of Late Palaeozoic stratigraphic successions on the Loppa High using seismic 2D and 3D data and well logs. Four intervals of interest have been mapped using carbonate stratigraphy methods. These intervals are highly affected by phases of tectonic activity on the Loppa High, which lasted from Devonian through Late Palaeozoic and into Triassic time. Climate change and extensive sea level change due to continental drift, tectonic activity and periodic icehouse conditions are the main controls on Late Palaeozoic carbonate successions on the Loppa High. The oldest interval (Int1) is recognised as Carboniferous successions deposited in a tropical environment containing a mix of carbonate and siliciclastic sediments. The overlying interval (Int2) is recognised as a package consisting mainly of evaporite precipitation, which developed in a spill-out system during seasonal lowstands while the world experienced general icehouse conditions. The following interval (Int3), overlaying Int1 and Int2, is recognised as a Permian succession primarily consisting of carbonates. Carbonate build-ups are present near the south-western Loppa High, from the middle of the interval (Polarrev Formation) and are vertically extending to the top of the interval. The youngest interval (Int4) is a carbonate succession of Changhsingian age consisting of at least the mid-shelf carbonates of the Røye Formation.