A transpressional origin for the West Spitsbergen fold‐and‐thrust belt: Insight from analog modeling

Abstract

[1] The West Spitsbergen fold-and-thrust belt formed along the transform plate boundary between Greenland and the western Barents Sea during Paleocene-Eocene breakup in the northern North Atlantic. Approximately 20-40 km margin-perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head-on collision. We have applied scaled analog tectonic modeling to test the former hypothesis. A pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15°convergence angle by movement of a basal plate. The kinematics was quantified by means of digital particle image velocimetry. The result was a doubly vergent transpressional wedge, consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike-slip zone and an adjacent low-taper thin-skinned fold-and-thrust belt. The doubly vergent wedge evolved through several kinematic phases. Three main stages were identified, namely, (1) initial distributed deformation, (2) development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones, and, finally, (3) a stage of full strain partitioning between a central strike-slip zone and reverse displacement along marginal shear zones, with folding and thrusting in a thin-skinned belt on the proside. The analog model convincingly reproduced the geometry and the kinematic evolution of the West Spitsbergen fold-and-thrust belt, supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement.

Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

“…The geometry of the structures observed in the Isfjorden area is in accordance with results of analogue tectonic modelling, supporting the hypothesis that the WSFTB was related to low-angle transpression (Leever, Gabrielsen, Faleide et al 2011;Leever, Gabrielsen Sokoutis et al 2011).…”

“…An alternative hypothesis is that the fold-and-thrust belt reflects the contractional component of strain in a transpressional setting (Harland 1969;Lowell 1972;Faleide et al 1988;Maher & Craddock 1988). The latter has been supported by analogue modelling performed by Leever and co-workers (Leever, Gabrielsen, Faleide et al 2011;Leever, Gabrielsen, Sokoutis et al 2011). Hence, the fold-andthrust belt was related to the evolution of a dextral transform fault system between Greenland and Svalbard (Harland 1969;Birkenmajer 1972;Srivastava 1978;Birkenmajer 1981;Faleide et al 1993;Lundin & Dore 2002;Mosar et al 2002;Faleide et al 2008;Gaina et al 2009).…”

Lineament Domain of Regional Strike-Slip Corridor: Insight from the Neogene Transtensional De Geer Transform Fault in NW Spitsbergen

“…Since the 1960s, this fold-and-thrust belt was regarded as reflecting the contraction component of strain in a transpressional setting (HARLAND 1969;LOWELL 1972;FALEIDE et al 1988;MAHER and CRADDOCK 1988). This has been supported by analogue modeling performed by Leever and co-workers (LEEVER et al 2011). Hence, the fold-and-thrust belt was related to the evolution of the dextral transform fault system between Greenland and Svalbard (HARLAND 1969;SRIVASTAVA 1978;BIRKENMAJER 1981;FALEIDE et al 1993FALEIDE et al , 2008LUNDIN and DORE 2002;MOSAR et al 2002;GAINA et al 2009).…”

Applying the anisotropy of magnetic susceptibility technique to the study of the tectonic evolution of the West Spitsbergen Fold-and-Thrust Belt

“…Indeed, the evidence for the proposal that the SEDL (Maher et al 1997) lineament represents such an onshore fault zone is questionable in light of extensive field data presented by Manby & Lyberis (1996) and Tessensohn (2001). Leever et al (2011), on the other hand, disregard the latter field-based studies and favour instead the SEDL as representing a major onshore strikeÁslip fault in their analogue modelling of the WSFTB.…”