Upper Jurassic mass flow deposits. Linking tectonic evolution to
deposition on seismic and field scale
Background and objectives
The yet to find resources on the Norwegian Continental Shelf (NCS) is estimated and published by the
NPD every other year. In the last publication (2013) the yet to find resource potential in the Upper
Jurassic play model is considered to be interesting. There are several recent discoveries within the
Upper Jurassic play model. Examples are the Snilehorn (2013) and Pil (2014) discoveries in the south
eastern part of the Norwegian Sea, the Skarfjell (2012) discovery in the northern North Sea, and the
J. Sverdrup (2010) and E. Grieg (2007) discoveries in the central North Sea. The similar play model is
also explored for in the southern North Sea and the Barents Sea.
The main purposes of this project will be to investigate the depositional character and distribution of
Upper Jurassic deposits, substantiate the sediment provenance areas, relate sedimentary sequences
to tectonic events, and compare and distinguish the development of mass flow deposits in different
regions of the NCS. The work will mainly be based on offshore seismic and well data, but mapping of
onshore field analogues will be an important part of the project. The results of this project will be
used to document exploration and reservoir risks related to Upper Jurassic mass flow deposits.
Introduction
The interplay between mass flow deposits and tectonic events during the Upper Jurassic has been
thoroughly described by several authors (e.g. Mitchener et al., 1992; Milton, 1993). In general, two
major basinal processes operated during this time. Firstly, the onset of rift-related faulting with initial
propagation from north to south along the axis of the Viking Graben, and, secondly, a regional rise in
relative sea level associated with the “Mid Cimmerian” unconformity. An important consequence of
the sea level rise was the development of an extensive coastal-shelf depositional system
characterised by the deposition of shallow-marine sands around the basin margins (e.g. Heather
Formation sands). Subsequent tectonic events during the uppermost Jurassic led to uplift of margin
highs, erosion and re-deposition of sandstone (and shale) sequences as proximal to distal submarine
fan successions. Some of these successions form long and narrow conglomerate and sand-prone
belts along the hangingwall of basin bounding faults. Two main types of fans are recognized; slopeapron fans and basin-floor fans. However, both may display rapid lateral facies changes both
perpendicular and parallel to the fault scarps.
Methodology/methods
Investigation of the Upper Jurassic depositional systems will be the main focus of this project both on
semi-regional and local (prospect) scale. The study will need to be based on a literature review of the
latest Jurassic to earliest Cretaceous epochs in the North and Norwegian seas. Mapping and
characterisation of Upper Jurassic sequences will be based on good-quality seismic data covering key
areas to be defined early in the project. Well data shall be utilized in order to correlate intra-Upper
Jurassic events, boundaries and unconformities (e.g. logs, biostratigraphy, and chemostratigraphy).
An important part of the project will be to work out a field analogue in which individual sedimentary
sequences can be mapped and linked to tectonic events or sea-level fluctuations. The main purpose
of the field analogue part will be to establish and describe the inter-relationship between fault
movements and depositional events, sediment provenance and transport mechanisms, as well as the
characteristics of the resulting facies development (e.g. lateral and vertical variations).
The field analogue work and the literature/seismic/well part of the project shall aim at concluding on
similarities and variations between Upper Jurassic depositional systems identified in different
geographical areas on the NCS.
Organisation and Time schedule
The project will be led by the University of Stavanger (UiS) and sponsored by Bayerngas Norge AS.
UiS supervisor will be Dr. A. Escalona. An additional supervisor will be provided by Bayerngas. Due to
the relevance of the project to Bayerngas, as well as guidance and data availability during the work, it
is highly recommended that the project executing member will spend part of his/her project in
Bayerngas’ premises in Oslo.
The project is scheduled to start during autumn 2014. The duration of the project is estimated to four
years.