Commune: Kielce (pow. Kielce, woj. świętokrzyskie)
Framework element or context represented:
Abnormal, tectonic occurrence of the Cambrian over Ordovician, sequence of the Lower Ordovician of the Kielce subregion of the Świętokrzyskie (Holy Cross) Mts.
Primary geological/geomorphological interest:
Tectonics and lithostratigraphy of Lower Paleozoic rocks.
Comparative assessment justification:
Unique outcrop of the most probably Caledonian compression – reversed fault formed in the Lower Paleozoic sedimentary rocks, illustrating scale of tectonic movements in the Małopolska Caledonian massif (comprising Kielce subregion).
Protection status and accessibility:
Nature reserve “Biesak-Białogon” (since 1981), relatively well accessible, situated in the forest of peripherial part of the town Kielce.
Character of site: Abandoned quarry.
Area: 13 ha
Altitude: 265-315 m a.s.l.
Lithology: sandstones, conglomerates, breccias, other siliceous rocks, shales, silstones, claystones
Discipline: Stratigraphy of Phanerozoic, Tectonics
Process Age: *all periods
Bedrock Age: Ordovician, Cambrian, *all periods
Description of primary interest:
The Cambrian and Ordovician rocks of northern limb of the Dyminy anticline crop out in the western part of the abandoned quarry. The Cambrian is represented with a) grey, reddish-grey quartzitic sandstones interbedded with shales – Ociesęki Fm, b) light grey-beige, weakly lithified siltstones. The Ordovician represent grey to greenish-grey, mainly thick-bedded sandstones (ca 25 m thick) of the Miedzygórze Fm and thin-bedded sandstones with chalcedonites. Inarticulate brachiopods and insert of bentonite were found in the sandstones of lower section. Cambrian-Ordovician unconformity, lack of the lowermost Ordovician and occurrence of basal conglomerates in the bottom of Ordovician strata (now not accessible, below water table) document old-Caledonian tectonic movements of the Sandomierz phase. Structure of the Dyminy anticline was modelled due to the Caledonian, Variscian and Alpine orogeneses. Main folding are supposed to develop due to the Caledonian orogenesis and to be modified during the Variscian movements. Also faults are referred to all three stages of tectogenesis. Essential role in the anticline formation played large longitudinal, reversed faults of compression nature. They likely developed during the Caledonian stage, but their later renovation is not excluded. Outcrop of this type fault in the northern part of Biesak quarry represents illustrative example of the tectonics. In the downthrown flank of this fault block of the Ordovician sandstones was squeezed into the soft Cambrian siltstones, what caused their abnormal occurrence above the Ordovician. Uplifted, northern flank of the fault is formed of Cambrian quartzitic sandstones.
Literature:
BEDNARCZYK W. 1971–Stratigraphy and palaeogeography of the Ordovician in the Holy Cross Mts. Acta Geol. Pol., 21: 573-616. BEDNARCZYK W., CHLEBOWSKI R., KOWALCZEWSKI Z. 1971–The geological structure of the northern wing of the Dyminy anticline in Świętokrzyskie Mts (English sum.). Biul. Geol. Wydz. Geol. UW, 12: 197-223. MIZERSKI W. 1996–The Caledonides in the Holy Cross Mts – do they exist? (English sum.). Przegl. Geol. 44, 4: 381-185. MODLIŃSKI Z., SZYMAŃSKI B. 2001–The Ordovician stratigraphy and palaeogeography of the Nida-Holy Cross Mts area, Poland – a rewiev. Geol. Qater. 45, 4: 417-433. ORŁOWSKI S. 1988–Stratigraphy of the Cambrian system in the Holy Cross Mts, Central Poland. Kwart. Geol., 32: 525-532. URBAN J., WRÓBLEWSKI T. 1999–Representative geosites of the Góry Świętokrzyskie (Holy Cross Mts.) and the Nida Basin, Central Poland. Pol. Geol. Inst., Special Papers, 2: 61-70. WRÓBLEWSKI T. 2001–Geodiversity conservation in the Góry Świętokrzyskie region (English sum.). Min. Środ., Państw. Inst. Geol., Warszawa, 88 pp.