The structure of the Norwegian Central Trough (Central Graben area)

Abstract

The structural geology of the Norwegian Central Trough (also known as the Central Graben) is complex and poorly understood. Previous publicized attempts to explain the structural evolution have failed to account for the variety of observations made from the data by oversimplifying the problem and forcing a particular chosen model. Building from detailed data analysis, seven distinct tectonic phases which affect the area can be defined. Triassic salt tectonics significantly modifies the response to later tectonic phases. Early Jurassic uplift and erosion precede the intense block-fault subsidence of the third phase in the Oxfordian to Volgian. A marked change in the Mid-Volgian heralds the fourth tectonic phase typified by block rotation and related erosion. A distinct early Cretaceous phase of subsidence follows a different pattern from Jurassic subsidence, and is tectonically linked to the sixth phase of inversion. Inversion movements are identified in at least six separate pulses starting in Hauterivian times and continuing into the seventh tectonic phase, that of thermal subsidence initiated in mid-Cretaceous times. These seven phases are largely superimposed on one another, and affect different structural elements within the Central Trough to differing degrees.