Basement-involved reactivation in foreland fold-and-thrust belts: the Alpine–Carpathian Junction (Austria)

Abstract

-The late Eocene -early Miocene Alpine-Carpathian fold-and-thrust belt (FTB) lies in the transition between the Eastern Alps and the Western Carpathians, SE of the Bohemian crystalline massif. Our study shows the involvement of crystalline basement from the former European Jurassic continental margin in two distinct events. A first extensional event coeval with Eggerian-Karpatian (c. 28-16 Ma) thin-skinned thrusting reactivated the rift basement fault array and resulted from the large degree of lower plate bending promoted by high lateral gradients of lithospheric strength and slab pull forces. Slab break-off during the final stages of collision around Karpatian times (c. 17-16 Ma) promoted large-wavelength uplift and an excessive topographic load. This load was reduced by broadening the orogenic wedge through the reactivation of the lower-plate deep detachment beneath and ahead of the thin-skinned thrust front (with the accompanying positive inversion of the basement fault array) and ultimately, by the collapse of the hinterland summits, enhanced by transtensional faulting. Although this work specifically deals with the involvement of the basement in the AlpineCarpathian Junction, the main conclusions are of general interest to the understanding of orogenic systems.

Cooling and Vertical Motions of Crustal Wedges Prior to, During, and After Lateral Extrusion in the Eastern Alps: New Field Kinematic and Fission Track Data from the Mur‐Mürz Fault System

“…Therefore, we propose that D1 predates the segmentation of the Alpine nappe stack and thus the formation of the Styrian block. D1 kinematics are consistent with shortening directions deduced from the Northern Calcareous Alps (Peresson & Decker, ) and thin‐skinned thrusting at the transition of the Eastern Alps and Western Carpathians (Granado et al, ). NNW‐SSE contraction was associated with ENE‐WSW extension, leading to rapid exhumation of the Penninic units exposed in the Rechnitz window since 23 Ma (Cao et al, ; Dunkl & Demény, ).…”

Stretching and Contraction of Extensional Basins With Pre-Rift Salt: A Numerical Modeling Approach

“…It is well known that the inherited structural framework and the distribution of décollement-prone units have a strong influence on the structural style of fold-and-thrust belts and their kinematic evolution (Ruh et al, 2012;Granado et al, 2016;Lacombe and Bellahsen, 2016;Tavani et al, 2021). A significant leap in the understanding of fold-and-thrust belts (Boyer and Elliot, 1982) came with the incorporation of thrust tectonics involving the positive inversion of rift basins and passive margins (e.g., Gillcrist et al, 1987;Granado and Ruh, 2019;Ruh, 2019).…”

The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran

“…Basement-involved structures characterized by highangle uplift are common in the foreland fold-andthrust belts of many orogens. These structures commonly contain significant hydrocarbon accumulations with most major fields located on the crests of these structures [e.g., Mitra and Mount, 1998, Cooper et al, 2006, Granado et al, 2016, Mohammadrezaei et al, 2020. Basement-involved structures such as faults, fractures, and shear zones can have a strong influence on the development of brittle and ductile structures and the structural style of a geologic setting.…”