Neo-Alpine uplift and subsidence zones in the Western Carpathians: Product of kinematic activity on Cenozoic AnD3 (NW-SE and NE-SW) and AnD4 (E-W – subequatorial and N-S – submeridian) regional faults

Abstract

Article presents the role of disjunctive (brittle and brittle-ductile) regional faults of two Cenozoic Neo-Alpine orogenic phases in the Western Carpathians: The AnD3 phase, producing conjugate systems of NW-SE (dominantly dextral shearing) as well as NE-SW (dominantly sinistral shearing), and younger AnD4 phase manifested with regional faults of subequatorial (E-W) and submeridian (N-S) courses (with dominantly uplift and subsidence kinematics). The disintegration of upper crust by kinematic activity on both (AnD3 and AnD4) fault systems produces the origin of block-shaped setting with lateral offsets, eventual rotation (in AnD3), as well as mutual uplifts or subsidences (in AnD4) of individual blocks. This tectonic setting represents the most striking morphological feature at the end of Cenozoic Neo-Alpine orogenic cycle, frequently overprinting or re-activating older tectonic structures. Article provides an interpretation that parallel with the applied global stress field, the AnD4 subequatorial (E-W) and submeridian (N-S) coursing faults can originate also by merging of individual segments of synthetic (oriented N-S) and antithetic (oriented E-W) megashears between parallel AnD3 shear faults of both systems (NW-SE or NE-SW). Merging of individual segments of antithetic shears arranged naturally in one line creates a predisposition for the origin of equatorial (E-W) trending faults, while merging of synthetic segments produces meridian (N-S) trending faults, both being principal in later AnD4 phase.