An integrated paleomagnetic and magnetic anisotropy study of the Oligocene flysch from the Dukla nappe, Outer Western Carpathians, Poland

Abstract

Abstract:The Dukla Nappe belongs to the Outer Western Carpathians, which suffered considerable shortening due to the convergence and collision of the European and African plates. In this paper we present new paleomagnetic and magnetic anisotropy results from the Polish part of the Dukla Nappe, based on 102 individually oriented cores from nine geographically distributed localities. Susceptibility measurements and mineralogy investigations showed that paramagnetic minerals are important contributors to susceptibility anisotropy (AMS). The AMS fabrics are related to deposition/ compression (foliation) and weak tectonic deformation (lineation). The AARM fabric, that of the ferrimagnetic minerals, seems to be a less sensitive indicator of tectonic deformation than the AMS fabric. The inclination-only test points to the pre-folding age of the remanent magnetizations. Seven localities exhibit CCW rotation, a single one shows CW rotation. The CCW rotated paleomagnetic directions form two groups, one showing large, the other moderate CCW rotation. Previously published paleomagentic directions from the Slovak part of the same nappe exhibit smeared distribution between them. The declination of the overall-mean paleomagnetic direction for the Dukla nappe is similar to those observed in the neighbouring Magura and Silesian nappes, but it is of poorer quality. The AMS lineations at several localities are deviating more to the west from the present north than that of the local tectonic strikes. A possible explanation for this is that the AMS lineations were imprinted first, probably still in the Oligocene, while the sediments were soft (ductile deformation) and the folding and tilting took place during the CCW rotation.

Anisotropy of Full and Partial Anhysteretic Remanence Across Different Rock Types: 2—Coercivity Dependence of Remanence Anisotropy

“…Similarly, the AMS in Devonian black shales of the Appalachian Plateau relates to vertical compaction whereas the AARM does not (Hirt et al, ). In the Dukla Nappe, Outer Western Carpathians, Poland, the AARM is less sensitive to tectonic overprints than the AMS, indicating that the magnetite grains were less affected by this deformation than the rock‐forming paramagnetic minerals (Kiss et al, ). If AMS and AARM fabrics are coaxial, they can either both be carried by the same mineral, that is, magnetite (Kissel et al, ), or by different minerals that record the same deformation (Biedermann et al, ; Yokoyama et al, ).…”

Anisotropy of magnetic susceptibility as an indicator for palaeocurrent analysis in folded turbidites (Outer Western Carpathians, Poland)

“…However, primary sedimentary fabrics are often omitted in AMS studies, since AMS lineations correlate well over large areas and are coherent with inferred tectonic deformations (e.g. Márton et al , 2009; Kiss et al , 2016; Nawrocki et al , 2016; Szaniawski et al , 2017). In orogenic belts where rocks underwent folding and thrusting, increasing deformation causes the reorientation or recrystallization of new constituent minerals, and thus may lead to changes in the shape of its magnetic fabric.…”

“…1B; Hrouda & Stráník, 1985; Stráník et al , 2007) or mainly represent the first stage of tectonic overprinting, characterized by sedimentary foliation accompanied by tectonic lineations (Fig. 1E; Hrouda & Potfaj, 1993; Hrouda et al , 2009; Márton et al , 2009; Márton et al , 2010; Szaniawski et al , 2013; Kiss et al , 2016; Nawrocki et al , 2016; Szaniawski et al , 2017). In the latter case, a phenomenon widespread in areas where folding and thrusting were significant (e.g.…”

Last scene in the large scale rotations of the Western Carpathians as reflected in paleomagnetic constraints

“…No positive results were acquired from the Skola Nappe, although several points were tested. Concerning the other nappes, good results were obtained from the Western, Central and Eastern segments, respectively of the Silesian Nappe (Márton et al 2009a), the Dukla Nappe (Koráb et al 1981, Kiss et al 2016, and the Magura Nappe (Márton et al 2009a).…”

“…The paleomagnetic results, which serve as the basis for the interpretation, have been published along with the documentation of their quality (Márton et al 1999, 2009a, 2009b, Kiss et al 2016 or submitted for publication (Turiec Basin, Márton et al in prep.). Exceptions are those from the Nowy Sącz Intramontane Basin, which is a Neogene basin developed over the Magura Nappe.…”