Structural Analysis of the Troms-Finnmark Fault Complex, SW Barents Sea

• Main Author: Ahmed, Waqas
• Other Authors: Roy Helge Gabrielsen, Jan Inge Faleide & Michael Heeremans
• Format: Master Thesis
• Language: English
• Published: 2012
• Subjects: VDP::450; Barents Sea; Finnmark; Troms
• Online Access: http://hdl.handle.net/10852/12636; http://urn.nb.no/URN:NBN:no-30715

Detailed structural analysis of the Troms-Finnmark Fault Complex is implemented in order to understand the associated structural configuration and the stress apparatus responsible for the present day architecture of the area under investigation. The en-echelon array of the fault complex is composed of three constituent, softly-linked fault strands named as MF1, MF2 & MF3. This fault complex registers repeated episodes of reactivation since its inception in the late Paleozoic. Late Paleozoic fault dating is constrained by making use of “Expansion Index” analysis which indicates growth of strata belonging to this age. Stratigraphic dating provides control on the age-bracketing of the fault movement during the middle-late Mesozoic. The master fault strands MF2 and MF3, on the basis of stratigraphic age dating reveals a bicyclic kinematic behavior. The profile view of these fault strands (MF1, MF2 & MF3) display a wide variety of the master fault geometries which range from the planar through the slightly curved to the typical listric normal fault, which all show a down-to-the-North displacement. On the basis of the basement-involvement and degree of reactivation, the three fault strands are termed as “First-Class” faults. The maximum fault displacement is associated with the central fault strand MF2 where the displacement values surpass 2.7 km towards the central part, while the greatest displacement values for the fault segment MF3 are slightly above 1.5 km at the intra Permian level. Several instances of positive structural inversion are documented in the study area. The analysis of kinematic indicators of such features suggests that the compressive stress system acting perpendicular to the master faults is responsible for their development. Their analysis further yields information on the age of inversion structures and this episodic event is placed in the mid-late Jurassic to the late Cretaceous. The first order estimate of the paleo-stress orientations is carried out. During the Permian, the WNW-ESE oriented σ3 is interpreted to have influenced the study area. The stress regime shifted to the NE-SW oriented σ3 during the mid-Jurassic and the orientation of minimum principal stress direction is interpreted to be NW-SE for the early Cretaceous. These local stress vectors do not conform to the regional stress orientations determined by previous workers, however, the NW-SE oriented σ3 during the Tertiary, shows agreement with the regional interpretations.