Erosional history of the Karkonosze Granite Massif – constraints from adjacent sedimentary basins and thermochronology

Abstract

Ero sional his tory of the Karkonosze Gran ite Mas sif -con straints from ad ja cent sed i men tary bas ins and thermochronologyThe long-term ero sional his tory of the Karkonosze Gran ite Mas sif is re vised and re con structed us ing dif fer ent sources of in for ma tion, includ ing the sed i men tary re cord of ad ja cent bas ins, pre vi ously pub lished low-tem per a ture thermochronological data and geomorphic features. Al though the ev i dence is still in com plete, this work has iden ti fied a num ber of in ter vals, of un equal du ra tion, char ac ter ized by dif fer ent de nu da tion re gimes and rates. Sev eral ma jor phases of rapid ex hu ma tion are in ferred -in the Perm ian and the Early Tri as sic as seen in the sed i men tary re cord, and in the Late Cre ta ceous as shown by both the thermochronological and sed i men tary re cords. Neotectonic up lift of the Karkonosze Mts. in the late Ce no zoic is not re corded in the thermochronological re cord and there is no ev i dence of any ac cel er ated de nu da tion close to the mas sif. Ap a tite fis sion track data show that >~3.6 km of rock must have been eroded since the Turonian, while the re sults of zir con (U-Th)/He anal y sis sug gest that in places ero sion of >~6 km of rock must have taken place. This picture dif fers from pre vi ous es ti mates of de nu da tion which sug gested that only 2-2.5 km has been eroded from the ax ial part of the Karkonosze dome since the ex po sure of gran ite batholith in the Perm ian. Piotr Migoñ, De part ment of Ge og ra phy and Re gional De vel op ment, Uni ver sity of Wroc³aw,

Post-Variscan cooling history of the central Western Sudetes (NE Bohemian Massif, Poland) constrained by apatite fission-track and zircon (U-Th)/He thermochronology

“…500 m during the Early Carboniferous to 50 m/Ma in the Late Permian times. However, these are based on mathematically unconstrained stable paleo-geothermal gradient of 40°C km − 1 assumed both for syn-and post-Variscan times, what makes these calculations highly speculative (see also for comments Migoń and Danišík, 2012).…”

Post-Variscan thermal history of the Intra-Sudetic Basin (Sudetes, Bohemian Massif) based on apatite fission track analysis

“…1), is still a matter of debate, particularly due to the sparsely preserved post-Variscan geological record (e.g. Maluski et al 1995;Migoń and Danišík 2012;Danišík et al 2012;Sobczyk et al 2015;Botor et al 2017a, b). Previous low-temperature thermochronological studies, mostly based on apatite fission track (AFT) data, suggest that the Bohemian Massif experienced a complex post-orogenic thermal evolution that may have been influenced by burial under Mesozoic sediments, Late Cretaceous inversion-related exhumation and inception of the European Cenozoic Rift System (Jarmołowicz-Szulc 1984;Wagner et al 1997;Hejl et al 1997Hejl et al , 2003Thomson and Zeh 2000;Glasmacher et al 2002;Ventura and Lisker 2003;Aramowicz et al 2006;Ventura et al 2009;Vamvaka et al 2014;Wolff et al 2015).…”

Architecture of thrust faults with alongstrike variations in fault-plane dip: anatomy of the Lusatian Fault, Bohemian Massif

“…The relative position of the two wall blocks separated by the LF is compatible with reverse faulting showing a vertical displacement in excess of 1000 m. The real displacement is possibly much higher as suggested by the summary of apatite fission-track data from the granitic rocks of the Krkonoše Mts. : over c. 3.6 km could have been eroded from the hangingwall block of the LF since the Turonian (Migoń and Danišík 2012).…”