Collapse, infilling, and postimpact deformation at the Mjølnir impact structure, Barents Sea

Abstract

Research Article| May 01, 1998 Collapse, infilling, and postimpact deformation at the Mjølnir impact structure, Barents Sea Filippos Tsikalas; Filippos Tsikalas 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Search for other works by this author on: GSW Google Scholar Steinar Thor Gudlaugsson; Steinar Thor Gudlaugsson 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Search for other works by this author on: GSW Google Scholar Jan Inge Faleide Jan Inge Faleide 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Search for other works by this author on: GSW Google Scholar Author and Article Information Filippos Tsikalas 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Steinar Thor Gudlaugsson 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Jan Inge Faleide 1Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (5): 537–552. https://doi.org/10.1130/0016-7606(1998)110<0537:CIAPDA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Filippos Tsikalas, Steinar Thor Gudlaugsson, Jan Inge Faleide; Collapse, infilling, and postimpact deformation at the Mjølnir impact structure, Barents Sea. GSA Bulletin 1998;; 110 (5): 537–552. doi: https://doi.org/10.1130/0016-7606(1998)110<0537:CIAPDA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A dense composite grid of high-resolution single-channel, shallow multichannel, and conventional multichannel seismic reflection profiles defines in detail the structures and stratigraphy associated with impact-induced tectonics, and the postimpact evolution of the Mjølnir impact structure, Barents Sea. Clear seismic images of the well-preserved 40-km-diameter structure reveal that the primary, impact-induced deformation is bounded on top by discernible structural relief. At this stratigraphic level the structure exhibits a distinct radial zonation pattern composed of a 12-km-wide complex outer zone, including a marginal fault zone and a modestly elevated ring, a 4-km-wide annular depression, and an uplifted central high, 8 km in diameter. Key features of the Mjølnir structure are similar to the majority of large terrestrial complex craters. Sharp boundary faults form an ∼150-m-high, near-circular rim wall and separate highly deformed strata within the crater from intact platform strata. A 45–180-m-thick layer of disturbed and incoherent seismic reflectivity caused by the impact is confined by prominent fault blocks and the postimpact strata. The seismic data also provide evidence of crater-influenced sedimentation, and extensive secondary, postimpact deformation expressed by structural reactivation and differential subsidence. Reconstruction of the original crater relief reveals a subtle structure that has average depth variations of only ∼30–40 m. When compared to the current morphology of the crater floor, this demonstrates substantial enhancement of structural features by postimpact burial and deformation. We infer that impact in a shallow-marine sedimentary basin led to an atypically shallow crater depth, resulting from gravitational collapse on an apparent low-angle decollement at the crater periphery, and considerable infilling of the crater. The extensive postimpact deformation is closely related to the instability and lateral changes in physical properties within the impact-affected rock volume, triggered by prograding postimpact sediments. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.