Chemostratigraphy of the Middle Triassic, Central Iberian Basin – An Analogue for the Triassic Central Graben, North Sea

Abstract

The distal continental deposits of the Triassic Skagerrak Formation (North Sea Central Graben - Goldsmith et al. 1995) form important hydrocarbon reservoirs, but erecting a detailed stratigraphy for this formation proves difficult, despite some recent advancements. These successions typically lack biostratigraphic markers and their E-log correlation is hampered by the thick repetitive nature of the sandstone - shale successions. However, over the last fifteen years, North Sea Triassic successions have been correlated successfully using chemical stratigraphy, or chemostratigraphy, which involves the characterisation and correlation of strata using whole rock inorganic geochemistry. The technique is now an effective method for correlating the Skagerrak Formation and has also been widely applied across much of the Central Graben, North Sea - many of the chemostratigraphic studies are proprietary and only limited amounts of onshore studies have been published (Pearce et al. 2008). This paper attempts to redress the shortage of published chemostratigraphic datasets from non-marine successions. The research has focused on the Central Iberian Basin, where outstanding quality of outcrops allows a three-dimensional study of the fluvial systems to be undertaken.