Seismic-Scale Evidence of Thrust-Perpendicular Normal Faulting in the Western Outer Carpathians, Poland

Jan Barmuta,Krzysztof Starzec,Wojciech Schnabel

doi:10.3390/min11111252

Abstract

Based on the interpretation of 2D seismic profiles integrated with surface geological investigations, a mechanism responsible for the formation of a large scale normal fault zone has been proposed. The fault, here referred to as the Rycerka Fault, has a predominantly normal dip-slip component with the detachment surface located at the base of Carpathian units. The fault developed due to the formation of an anticlinal stack within the Dukla Unit overlain by the Magura Units. Stacking of a relatively narrow duplex led to the growth of a dome-like culmination in the lower unit, i.e., the Dukla Unit, and, as a consequence of differential uplift of the unit above and outside the duplex, the upper unit (the Magura Unit) was subjected to stretching. This process invoked normal faulting along the lateral culmination wall and was facilitated by the regional, syn-thrusting arc–parallel extension. Horizontal movement along the fault plane is a result of tear faulting accommodating a varied rate of advancement of Carpathian units. The time of the fault formation is not well constrained; however, based on superposition criterion, the syn -thrusting origin is anticipated.

Highlights

The Outer Carpathians (OC) are a well-known example of a thrust and fold belt formed during the Alpine orogeny as a result of the Alpine–Carpathian (Alcapa) and the Tisa blocks collision with the North European Platform (e.g., [1,2,3])
In this article, based on seismic data interpretation, geological mapping and highresolution digital elevation model (DEM) analysis supported by field observations, we describe a seismic-scale, thrust-perpendicular fault, here referred to as the Rycerka Fault (RF)
The structure of the western side of the RF involves several north-vergent thrust related folds (Figures 3 and 7), in which the forelimbs are composed of the oldest lithostratigraphic units known from the Rača Subunit, i.e., the Upper Cretaceous Szczawina and Ropianka formations

Summary

Introduction

The Outer Carpathians (OC) are a well-known example of a thrust and fold belt formed during the Alpine orogeny as a result of the Alpine–Carpathian (Alcapa) and the Tisa blocks collision with the North European Platform (e.g., [1,2,3]). This young, Miocene in age, thrust and fold belt encircles inner units and forms an arcuate geometry, (e.g., [1,4,5]). It is assumed that the effects of such forces should be recorded as extension-related structures like roughly thrust-perpendicular normal faults. Such structures were comprehensively studied for example in the area of Alps (e.g., Simplon and Brenner faults) [6,7,8,9]

Results

Discussion

Conclusion