Provenance of Cretaceous clastics in the Subhercynian Basin: constraints to exhumation of the Harz Mountains and timing of inversion tectonics in Central Europe

Abstract

The Harz Mountains and the adjacent Subhercynian Cretaceous Basin figure as the most prominent surface representative for Late Cretaceous inversion structures in Central Europe. Facies, depositional architecture and provenance of the basin fill reflect mechanisms and timing of the exhumation of the Harz. From Hauterivian to Early Santonian there is no evidence for detrital input from the nearby Harz area. Sediments are mature quartzarenites derived from Paleozoic basement rocks and/ or recycled Permian to Mesozoic sedimentary rocks. This situation changed drastically in Middle to Late Santonian when freshly exhumed and eroded Mesozoic sedimentary cover rocks of the Harz were delivered into the basin. Feldspar and lithoclasts reflect erosion of Triassic and, in places, Jurassic to Turonian strata. Apatite and garnet in heavy mineral spectra are derived from largely unweathered Lower Triassic Buntsandstein as indicated by apatite and garnet chemistry. In Early Campanian, Paleozoic lithoclasts indicate erosion cutting down into the basement of the Harz. Simultaneous strong decrease of feldspar, garnet and apatite suggest an almost complete removal of the 2-3 km thick Mesozoic cover of the Harz within only 2-4 Myr. This translates into an exhumation rate of approximately 1 mm/a consistent with apatite fission track data from granitoid rocks of the Harz Mountains.

Thermochronological constraints on the long-term erosional history of the Karkonosze Mts., Central Europe

“…(AFT ages: 73-83 Ma with generally long mean track lengths; Thomson et al, 1997), Ruhla Crystalline Complex (AFT ages: 69-81 Ma with generally long mean track lengths; Thomson and Zeh, 2000), Lower Saxony Basin (AFT ages: 89-72 Ma; Senglaub et al, 2005), Fichtelgebirge in the western border of the Bohemian Massif Hejl et al, 1997), and along the Franconian Line (Bischoff, 1993;Wagner et al, 1989). Petrographic and geochemical data from stratigraphically wellcalibrated sediments of 82-86 Ma age (von Eynatten et al, 2008) precisely constrain the erosion record in the Harz Mts. Collectively, they suggest that the Late Cretaceous was a period of major environmental change, with topographic relief forming and decaying fairly rapidly.…”

Gold-bearing ferroselite (FeSe2) from Trogtal, Harz, Germany, and significance of its Co/Ni ratio

“…The Trogtal ferroselite, predominantly of Co/Ni > 1, could thus be interpreted to have formed from oxidizing, Kupferschiefer-like brines. It is important to note here that the selenide vein-hosting Carboniferous greywacke was primarily overlain by the Zechstein evaporitic sequences (i.e., Late Permian; e.g., Ziegler 1978), which were eroded during rapid uplift of the Harz in Late Cretaceous times (e.g., von Eynatten et al 2008). The Zechstein could explain the existence of such highly saline fluids.…”

Stability assessment of sandstones from the St. Servatius Church in Quedlinburg (UNESCO’s World Heritage Site, Germany)

“…Most of the samples are fine-to medium-grained friable and porous sandstones that contain nearly pure quartz grains (ca. 99.9% quartz), typical for the Lower Cretaceous quartz-arenites (Tröger 1955;von Eynatten et al 2008). The grains are sub-angular to sub-rounded and consist mostly of clear monocrystalline quartz (Fig.…”

“…2). In the Quedlinburg anticline, the Lower Cretaceous Hauterivian to Barremian sediments are mainly quartz arenites that reach a thickness of up to 400 m. In contrast, Upper Cretaceous sediments are widely distributed and attain a thickness of more than 2,000 m mainly as the result of a tectonically induced subsidence, which is controlled by the uplift of the Variscan basement unit of the Harz block (Voigt et al 2004(Voigt et al , 2006von Eynatten et al 2008).…”

“…125 Ma old (Barremian) sediments cropping out on the castle hill consist mainly of monotonous, well sorted, fine-to medium-grained shallow marine quartz arenitic sandstones (Neokom-Sandstones) intercalated with some claystone layers and conglomerate beds (Voigt and von Eynatten 2008). The conglomerate beds and parts of the sandstones were more or less infiltrated by iron ore-bearing fluids (limonite), yielding a yellow to red colour of the originally light to greyish coloured rocks.…”