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- Title
Devonian-Mississippian faulting controlled by WNW-ESE-striking structural grain in Proterozoic basement rocks in Billefjorden, central Spitsbergen.
- Authors
Koehl, Jean-Baptiste P.; Christophersen, Gard; Collombin, Maxime; Taule, Christoffer; Stokmo, Eirik M. B.; Allaart, Lis
- Abstract
In Billefjorden, central Spitsbergen, Devonian collapse and Carboniferous rift-related sedimentary strata were deposited unconformably over Proterozoic basement rocks displaying well developed N-S-trending Caledonian grain. Caledonian structures and fabrics are thought to have controlled the location and trend of subsequent Devonian and Carboniferous basin-bounding faults like the Billefjorden fault zone and Lemströmfjellet--Løvehovden fault. However, fieldwork and interpretation of aerial photographs in Proterozoic basement rocks reveal the existence of steep, abundant, WNW-ESE-striking brittle faults that are sub-orthogonal to known major Caledonian and post- Caledonian structures in Billefjorden, but that do not extend into adjacent-overlying, rift-related, Pennsylvanian rocks of the Gipsdalen Group. Structural analysis of field data and aerial photographs suggest that WNW-ESE-striking faults in basement rocks in Billefjorden formed as (sinistral) strike-slip and normal faults during Devonian- Mississippian extension in agreement with previously inferred models of sinistral transtension. The abundance of these faults suggests that their formation was controlled by analogously trending, preexisting structural grain (planar anisotropies) at depth, and their pronounced WNW-ESE strike suggests that the strike of preexisting anisotropies were comparable to recently identified, crustal-scale, WNW-ESE-striking Timanian thrust systems in Svalbard and the northern Barents Sea.
- Subjects
SPITSBERGEN Island (Norway); PROTEROZOIC Era; BASEMENTS; AERIAL photographs; FAULT zones; DATA analysis
- Publication
Geologica Acta, 2023, Vol 21, p1
- ISSN
1695-6133
- Publication type
Article
- DOI
10.1344/GeologicaActa2023.21.7