Epigenetic silicification of the Upper Oxfordian limestones in the Sokole Hills (Kraków-Częstochowa Upland): relationship to facies development and tectonics

Abstract

ABSTRACT:Matyszkiewicz, J., Kochman, A., Rzepa, G., Gołębiowska, B., Krajewski, M., Gajdzik, K. and Żaba, J. 2015. Epigenetic silicification of the Upper Oxfordian limestones in the Sokole Hills (Kraków-Częstochowa Upland): relationship to facies development and tectonics. Acta Geologica Polonica, 65 (2), 181-203. Warszawa.A spectacular epigenetic silicification was encountered in the Oxfordian bedded limestones exposed in the Sokole Hills situated in the Kraków-Częstochowa Upland. The main epigenetic mineral is microcrystalline quartz accompanied by minor goethite, hematite, barite, galena and sphalerite. Locally, the mineralized limestones reveal Pb and Cu contents exceeding over 150 times the background values of these metals in unmineralized limestones.The epigenetic mineralization of the bedded limestones was probably a two-stage process. During the first, Early Cretaceous stage, silicified limestones formed at the erosional surface of a denuded carbonate complex. Such silicification greatly limited the progress of the first karstification phase of the Upper Jurassic carbonates initiated in the Hauterivian. The sources of silica accumulated in the limestones were descending solutions enriched in silica derived from the weathering zone. This silicification affected the topmost part of the Upper Jurassic massive limestones and the deeper portions of the bedded limestones along the fracture systems and stylolites.Early Cretaceous tectonic activity generated new dislocations and re-opened the existing faults, which were subsequently filled with permeable Albian quartz sands. These openings became the migration pathways for ascending, warm, relict, sulphide-carrying hydrothermal solutions at the second formation stage of the epigenetic mineralization. The newly supplied silica from the Albian sands precipitated on the silicified limestones and, as concentric rims, on brecciated, early diagenetic cherts. The second-stage mineralization proceeded under phreatic conditions, presumably close to a fluctuating mixing zone of ascending, warm hydrothermal solutions and descending cold groundwaters. The brecciated cherts acting as silica crystallization nuclei indicate that the last mineralization stage probably followed the final phase of Cenozoic faulting.

Oxfordian neptunian dykes with brachiopods from the southern part of the Kraków-Częstochowa Upland (southern Poland) and their links to hydrothermal vents

“…In a sample of unaltered Upper Oxfordian limestone from the northern part of KCU, the ε Nd(T = 155 Ma) value is −6.6 (Matyszkiewicz et al 2015a). This value seems to correspond to the paleogeographic position of the studied fragment of shelf from the northern margin of the Tethys (cf.…”

“…We interpret second stage of silicification as an effect of the invasion of hydrothermal solutions triggered by episodes of tectonic activity in the Cenozoic (Fig. 14), during which silica-enriched hydrothermal solutions migrated along the reactivated faults (Gołębiowska et al 2010;Kochman and Matyszkiewicz 2012;Matyszkiewicz et al 2015a). In the second stage, inclusion-free quartz crystallized in the still-empty centers of cavities and in the interiors of brachiopod shells (Figs.…”

“…Subsequent Early Cretaceous tectonic activity (cf. Matyszkiewicz et al 2015a) was related to the action of hydrothermal solutions, which migrated along the rejuvenated fault zone (cf. Matyszkiewicz et al 2015a).…”

“…Matyszkiewicz et al 2015a) was related to the action of hydrothermal solutions, which migrated along the rejuvenated fault zone (cf. Matyszkiewicz et al 2015a). It was connected with crystallization of dogtooth cement in meteoric-phreatic environment (cf.…”

Electrical resistivity tomography (ERT) and sedimentological analysis applied to investigation of Upper Jurassic limestones from the Krzeszowice Graben (Kraków Upland, southern Poland)

“…Pochat and Van Den Driessche, 2007;Quiquerez et al, 2013). In the re search area, tec tonic ac tiv ity was ac com pa nied by the re ju ve na tion of older Pa leo zoic struc tures in the homocline base ment, in par ticu lar the Kraków-Lubliniec Fault Zone (e.g., BrochwiczLewiñski et al, 1984;¯aba, 1999;Matyszkiewicz et al, 2006Matyszkiewicz et al, , 2012Matyszkiewicz et al, , 2015a.…”