Glacially induced faulting along the NW segment of the Sorgenfrei-Tornquist Zone, northern Denmark: Implications for neotectonics and Lateglacial fault-bound basin formation

Autor: Holger Steffen, Jutta Winsemann, Peter B.E. Sandersen, Christian Brandes, Patrick Wu
Rok vydání: 2018
Předmět:
Dewey Decimal Classification::500 | Naturwissenschaften::550 | Geowissenschaften
Archeology
Younger Dryas
earthquake magnitude
010504 meteorology & atmospheric sciences
Denmark
Lacustrine sediments
Fault (geology)
010502 geochemistry & geophysics
Fault scarp
01 natural sciences
ddc:551
ddc:550
Stresses
Lithospheric structure
Atlantic Ocean
Holocene
Neotectonics
Global and Planetary Change
deformation mechanism
geography.geographical_feature_category
Structural geology
Geology
Børglum fault
Strike-slip tectonics
Deformation
Finite element modelling
Dewey Decimal Classification::500 | Naturwissenschaften::551 | Geologie
Hydrologie
Meteorologie
North Sea
Finite element method
Coulomb stress changes
Baltic Sea
Glacially induced faulting
Finite element simulations
tectonic structure
Soft-sediment deformation structures
Sediments
Paleontology
Earthquakes
Ecology
Evolution
Behavior and Systematics
0105 earth and related environmental sciences
Coulomb failure stress
Fault slips
geography
Sorgenfrei-Tornquist Zone
glacial deposit
Glacial geology
Allerod
Teisseyre-Tornquist Zone
Strike-slip faults
faulting
strike-slip fault
Zdroj: Quaternary Science Reviews 189 (2018)
ISSN: 0277-3791
DOI: 10.1016/j.quascirev.2018.03.036
Popis: The Sorgenfrei-Tornquist Zone (STZ) is the northwestern segment of the Tornquist Zone and extends from Bornholm across the Baltic Sea and northern Denmark into the North Sea. It represents a major lithospheric structure with a significant increase in lithosphere thickness from south to north. A series of meter-scale normal faults and soft-sediment deformation structures (SSDS) are developed in Lateglacial marine and lacustrine sediments, which are exposed along the Lønstrup Klint cliff at the North Sea coast of northern Denmark. These deformed deposits occur in the local Nørre Lyngby basin that forms part of the STZ. Most of the SSDS are postdepositional, implying major tectonic activity between the Allerød and Younger Dryas (∼14 ka to 12 ka). The occurrence of some syn- and metadepositional SSDS point to an onset of tectonic activity at around 14.5 ka. The formation of normal faults is probably the effect of neotectonic movements along the Børglum fault, which represents the northern boundary fault of the STZ in the study area. The narrow and elongated Nørre Lyngby basin can be interpreted as a strike-slip basin that developed due to right-lateral movements at the Børglum fault. As indicated by the SSDS, these movements were most likely accompanied by earthquake(s). Based on the association of SSDS these earthquake(s) had magnitudes of at least Ms ≥ 4.2 or even up to magnitude ∼ 7 as indicated by a fault with 3 m displacement. The outcrop data are supported by a topographic analysis of the terrain that points to a strong impact from the fault activity on the topography, characterized by a highly regular erosional pattern, the evolution of fault-parallel sag ponds and a potential fault scarp with a height of 1–2 m. With finite-element simulations, we test the impact of Late Pleistocene (Weichselian) glaciation-induced Coulomb stress change on the reactivation potential of the Børglum fault. The numerical simulations of deglaciation-related lithospheric stress build-up additionally support that this neotectonic activity occurred between ∼14.5 and 12 ka and was controlled by stress changes that were induced by the decay of the Scandinavian ice sheet. In the Holocene, the stress field in the study area thus changed from GIA-controlled to a stress field that is determined by plate tectonic forces. Comparable observations were described from the central STZ in the Kattegat area and the southeastern end of the STZ near Bornholm. We therefore interpret the entire STZ as a structure where glacially induced faulting very likely occurred in Lateglacial times. The fault reactivation was associated with the formation of small fault-bound basins that provided accommodation space for Lateglacial to Holocene marine and freshwater sediments. © 2018 The Authors
Databáze: OpenAIRE
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