Universität zu Köln

Biermanns, Peter, Schmitz, Benjamin, Mechernich, Silke ORCID: 0000-0003-3684-040X, Weismueller, Christopher, Onuzi, Kujtim, Ustaszewski, Kamil and Reicherter, Klaus (2022). Aegean-style extensional deformation in the contractional southern Dinarides: incipient normal fault scarps in Montenegro. Solid Earth, 13 (6). S. 957 - 975. GOTTINGEN: COPERNICUS GESELLSCHAFT MBH. ISSN 1869-9529

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Abstract

We describe two 5-7 km long normal fault scarps (NFSs) occurring atop fault-related anticlines in the coastal ranges of the Dinarides fold-and-thrust belt in southern Montenegro, a region under predominant contraction. Both NFSs show well-exposed, 6-9 m high, striated, and locally polished fault surfaces, cutting uniformly northeastward-dipping limestone beds at high angles and documenting active faulting. Sharply delimited ribbons on free rock faces show different colors, varying karstification, and lichen growth and suggest stepwise footwall exhumation, which is typical of repeated normal faulting during earthquake events. Displacements, surface rupture lengths, and geometries of the outcropping fault planes imply paleoearthquakes with M-w approximate to 6 +/- 0.5 and slip rates of similar to 0.5-1.5 mm yr(-1) since the Last Glacial Maximum. This is well in line with (more reliable, higher-resolution) slip rates based on cosmogenic Cl-36 data from the scarps for which modeling suggests 1.5 +/- 0.1 mm yr(-1) and 6-15 cm slip every 35-100 years during the last similar to 6 kyr. The total throw on both NFSs - although poorly constrained - is estimated to similar to 200 m and offsets the basal thrust of a regionally important tectonic unit. The NFSs are incipient extensional structures cutting (and postdating emplacement of) the uppermost Dinaric thrust stacks down to an unknown depth. To explain their existence in a region apparently under pure contraction, we consider two possibilities: (i) syn-convergent NFS development or - less likely - (ii) a hitherto undocumented propagation of extensional tectonics from the hinterland. Interestingly, the position of the extensional features documented here agrees with geode- tic data, suggesting that our study area is located broadly at the transition from NE-SW-directed shortening in the northwest to NE-SW-directed extension to the southeast. While the contraction reflects ongoing Adria-Europe convergence taken up along the frontal portions of the Dinarides, the incipient extensional structures might be induced by rollback of the Hellenic slab in the southeast, whose effects on the upper plate appear to be migrating along-strike of the Hellenides towards the northwest. In that sense, the newly found NFSs possibly provide evidence for a kinematic change of a thrust belt segment over time. However, with a significantly higher probability, they can be regarded as second-order features accommodating geometrical changes in the underlying first-order thrust faults to which they are tied genetically.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Biermanns, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmitz, Benjamin UNSPECIFIED UNSPECIFIED UNSPECIFIED Mechernich, Silke UNSPECIFIED orcid.org/0000-0003-3684-040X UNSPECIFIED Weismueller, Christopher UNSPECIFIED UNSPECIFIED UNSPECIFIED Onuzi, Kujtim UNSPECIFIED UNSPECIFIED UNSPECIFIED Ustaszewski, Kamil UNSPECIFIED UNSPECIFIED UNSPECIFIED Reicherter, Klaus UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-679502
DOI:	10.5194/se-13-957-2022
Journal or Publication Title:	Solid Earth
Volume:	13
Number:	6
Page Range:	S. 957 - 975
Date:	2022
Publisher:	COPERNICUS GESELLSCHAFT MBH
Place of Publication:	GOTTINGEN
ISSN:	1869-9529
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MT CHELMOS; APENNINES; EARTHQUAKE; HISTORY; SLIP; PELOPONNESUS; KINEMATICS; TECTONICS; BASINS; MOTION Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/67950