Jhon Meyer Munoz Barrera

Structural configuration of the southern Klakk Fault Complex, mid-Norway. Crustal-scale fault geometry and interaction in basement rift shoulders.

The thinning of continental crust from ~ 30 km to ~ 10 km characterises the necking domain of passive margins. In this domain, crustal-scale faults, denominated as inner and outer necking breakaway, bound this domain from the proximal and distal domains. Growth and interaction of those faults control the regional configuration of the basin, just as sediment generation, routing and deposition for tens of millions of years. We investigate the southernmost part of the Klakk Fault Complex (KFC), which formed during the late Middle Jurassic to earliest Cretaceous, and separated the Frøya High from the Rås Basin in the Mid-Norwegian Continental Shelf. Although there are no studies related to the Klakk fault in this area, the necking domain has been represented as a single necking breakaway complex. We analysed 2D/3D seismic data and well data to identify the fault geometries, their variation along strike and map the syn-rift deposits.

Interaction of 10-35 km long fault plains with NE-SW, N-S and NW-SE trends define the structural configuration of the Southern Klakk Fault Complex. Three fault geometries have been identified, (i) a low-angle concave downward shape that follow a roughly ramp-flat-ramp geometry, (ii) a low-angle concave upward, and (iii) a series of rider blocks with a common abandon detachment, which is cut by a steep fault segment that bounds the Rås basin. BCU marker shows a vertical separation of approximately 5 km in a highly degraded fault scarp. In addition, fault interaction creates a slope with a series of canyons that transported sediments from the uplifted footwall to the Rås basin. The syn-rift sediments were accumulated in mini-basins in the slope and the Rås Basin. Four hydrocarbon plays can be associated with the geometry and interaction of those crustal faults. (i) syn-rift sediments associated with middle Jurassic to lower Cretaceous rift (Fenja Oilfield), (ii) Basement fracture reservoirs (analogue of Utsira High), (iii) Shallow marine sediments in the footwall’s passive flank (Draugen Field), (iv) Sandy Lower Cretaceous post-rift sediments located next to the fault scarp.