Repeated large-scale slope failures associated with a rapidly prograding shelf margin from the Plio-Pleistocene of the Deepwater Taranaki Basin, New Zealand
Presented by Dr. Suzanne BULL on 23 Sep 2013 from 17:15 to 19:15
Type: Poster presentation
Session: Poster session
Track: Poster presentations
A series of large-scale, stacked and locally amalgamated mass transport complexes (MTC’s) have been identified using 2D seismic reflection lines in the deepwater area of the Taranaki Basin, offshore Western New Zealand. The MTC’s represent a significant proportion (c. 40 %) of the Plio-Pleistocene succession and cover a combined area in the excess of 40,000 km2, with individual examples showing run out distances of over 200 km and thicknesses of approx. 300 m. In a stratigraphic context, the MTC’s form a series of stacked bodies, some interbedded with undisrupted background sedimentation, while others directly overlie one another, and in some examples, merge laterally to form amalgamated complexes. Key kinematic information is derived from the identification of primary constraining features such as headwall scarps and lateral margins, indicating a gross general transport direction to the north-west. In addition, a range of internal features and deformational fabrics including basal shear surface ramps and flats, slide blocks and imbricate thrusts are imaged. Slope failure is believed to be linked to rapid northward progradation of the shelf margin from Late Miocene to recent times, during which over 2km of sediment was deposited as outward building stacked clinoforms. The rapid development of clinoforms has had a significant impact on the thermal regime of the basin, which is currently New Zealand’s only hydrocarbon producing region. Correlation with two exploration wells suggests that some failed sediments predominantly comprise unconsolidated mud rich facies, while seismic reflection lines indicate that headwall scarps developed along the bounding surfaces of progradational foresets,and that slope instability may have been triggered by over-steepening of sediments. This work aims to evaluate the impact of the repeated large scale slope failure on the petroleum system of the deepwater Taranaki Basin, which is receiving increased interest as a site of potential future exploration.