Partitioning pre-, syn- and post-Variscan deformation in the Holy Cross Mountains, eastern Variscan foreland

Abstract

In this study we demonstrate how a combined structural, sedimentological and palaeomagnetic approach provides a new perspective on the tectonic evolution of the Holy Cross Mountains. In the field, we performed a structural and sedimentological analysis of Palaeozoic rocks. Our analysis was complemented by a palaeomagnetic study and by the restoration of balanced cross sections in Palaeozoic and Mesozoic rocks. Different steps of deformation were restored for a c.350 Ma period. (1) The extensional tectonics of the Devonian basin was unravelled: the resulting normal fault system constituted the fundamental structural control for the later Variscan tectonic inversion and Alpine deformations. (2) The style of Variscan folding is characterized and quantified by way of a cross section across the Holy Cross Mountains. (3) The role of the reactivation of Variscan faults during the Permo-Triassic initiation of the Polish Basin was examined. (4) The localized Alpine compressive deformation was quantified and shown to contribute only to a minor degree to the present-day state of deformation in the Holy Cross Mountains. The Holy Cross Fault zone is the product of the interplay of changing transtensional and transpressional settings during the Variscan diastrophic cycle, with the final effect of the Variscan evolution being the flower-like structure of the Holy Cross Fault zone.

Basement structure of the Paleozoic Platform in Poland

“…The Variscan (late Car bon if er ous) fore land com pres sion partly over printed Early Pa leo zoic struc tures by gen er at ing reverse faults or mi nor thrusts and hor i zon tal de tach ments commonly formed due to transpressive re ac ti va tion of the pre-ex isting tec tonic dis con ti nu ities (Po¿aryski et al, 1992;Po¿aryski and Tomczyk, 1993;Lamarche et al, 2003;Krzywiec, 2009;aba, 1999; sum ma rized by Narkiewicz, 2007). Given such an over print vis i ble in the De vo nian-Car bon if er ous strata the orig inal pre-Variscan ge om e try of the base ment block bound aries can be in ter preted pri mar ily from deep geo phys i cal ev i dence, in clud ing seis mic re sults in par tic u lar.…”

Late Silurian deformation in the Łysogóry Region of the Holy Cross Mountains revisited: restoration of a progressive Caledonian unconformity in the Klonów Anticline and its implications for the kinematics of the Holy Cross Fault (Central Poland)

“…The Pa leo zoic core is sur rounded from the north, west and south-west by the Me so zoic mar gin that com prises less deformed Perm ian-Me so zoic sed i men tary rocks. The Pa leo zoic core of the HCM was ex humed dur ing the Late Cre taceous-Paleocene in ver sion of the Ger man-Pol ish Ba sin (e.g., A -tec tonic sketch; note the po si tion of the Holy Cross Moun tains astride the con tact of the Łysogóry and Małopolska blocks; B -POLCRUST-01 deep re flec tion seis mic (Malinowski et al, 2013); re in ter preted; HCF -Holy Cross Fault Kutek and Głazek, 1972;Lamarche et al, 2002Lamarche et al, , 2003. In the Mio cene, the Pa leo zoic core and the Me so zoic mar gin were cov ered by transgressive sed i ments of the Carpathian fore land ba sin that com pleted the en cir cle ment of the Pa leo zoic core from the south (Fig.…”

“…This Pa leo zoic inlier ex poses a con tact be tween the Łysogóry and Małopolska blocks, which is de fined by the Holy Cross Fault (HCF). The HCM is the only win dow into the structure of the Pol ish seg ment of the TESZ and has there fore been the sub ject of nu mer ous stud ies (e.g., Lewandowski, 1993;Mizerski, 1995;Żelaźniewicz, 1998;Lamarche et al, 1999Lamarche et al, , 2003Nawrocki, 2000;Porębska, 2002;Belka et al, 2002;Konon, 2006Konon, , 2007Nawrocki and Poprawa, 2006;Poprawa, 2006a, b;Schätz et al, 2006;Nawrocki et al, 2007;Żylińska and Masiak, 2007;Kozłowski, 2008;Kozłowski et al, 2014).…”

Tracing tectonic deformation using the sedimentary record: an overview

“…Thrust wedge advance and the corresponding loading resulted in basin flexure and sediment infill. Similar work from the Variscan succession of Poland (Lamarche et al 2003) has demonstrated the complexity of orogenic activity in this region. It has also been possible to subdivide the various tectonic episodes into pre-, syn-and post-orogenic phases, thus clarifying the tectonic evolution of this important region.…”