Commune: Raków (pow. kielecki, woj. świętokrzyskie)
Framework element or context represented:
Ordovician and partly Silurian sequence of the Kielce subregion, Świętokrzyskie (Holy Cross) Mts, northern part of the Małopolska Caledonian massif.
Primary geological/geomorphological interest:
Stratotype of Zalesie Formation, sequence of Ordovician and Silurian, fossils.
Comparative assessment justification:
Concentrated in the small area one of the most complete sequence of sedimentary rocks (with volcanic intrusions) of Caledonian cycle outcropped in Poland.
Protection status and accessibility:
Two nature monuments (since 1954, 1987) and area proposed for protection, well accessible - located close to the road Łagów-Raków.
Character of site: Geological outcrops.
Area: 10 ha
Altitude: 300-315 m a.s.l.
Lithology: hydrotermal veins, sandstones, other siliceous rocks, dolostones, shales, silstones, claystones
Discipline: Palaeobiology, Palaeoenvironment, Stratigraphy of Phanerozoic
Process Age: *all periods
Bedrock Age: Silurian, Ordovician, Cambrian, *all periods
Description of primary interest:
The sequence is exposed in some outcrops scattered on a slope of the valley. The section of the Ordovician was entirely exposed (total thickness 67 m) in the past. The stratigraphy of the Ordovician bases on conodonts but other fossils: trilobites, brachiopods have been found here. Now just above the Cambrian-Ordovician unconformity Upper Tremadoc-Arenig rocks crop out: a) Wysoczki Chalcedonite Fm (or Zbilutka Member of Międzygórz Sandstone Fm) – sandstones and siltstones with chacedonite inserts; b) Międzygórz Fm (or Kleczanów Sandstone Member of Międzygórz Fm) – grey-greenish, glauconitic sandstones; c) Bukówka Sandstone Fm (or Dyminy Orthid Sandstone Member of Międzygórz Fm). In the next outcrop the Upper Ordovician (Llandvirn-Ashgill) and Lower Silurian (Llandovery) rocks are exposed: a) Mójcza Limestones Fm – dolomitic limestones and marls bearing inserts of bentonite; b) Zalesie Fm (type section) – brownish-grey shales with inserts of marls, limestones and dolomites. Shales of the Zalesie Fm pass to dark graptolitic shales with chalcedonites of the Lower Silurian Bardo Fm. Sedimentary structures and trace fossils in the Tremadoc rock indicate that sedimentation took place on distal shelf and was influenced by storms and tectonically generated flows. Deposition of chalcedonites was related to hydrothermal or volcanic activity. Diabase intrusion crops out in the bed of the stream 0.4 km to the north, forming thick vein (ca 15 m). Late-Caledonian intrusions of diabases occur mainly in the lower part of the Upper Silurian greywackes. Niewachlów Greywackes (Ludlow) crop out 0.3 km to the north.
Literature:
BEDNARCZYK W. 1971–Stratigraphy and palaeogeography of the Ordovician in the Holy Cross Mts. Acta Geol. Pol., 21: 573-616. BEDNARCZYK W. 1996–Stop. 2. Zalesie. In: Szulczewski M., Skompski S. eds., 6th European conodont Symp. ECOS VI. Exc. Guide, 30.06-3.07.1996. Warszawa: 18-21. DZIK J. 1999–Excursion I, day 1, stop 2: Zalesie Nowe. In: Dzik J., Linnemann U., Heuse T. eds., Intern. Symp. on the Ordovician System, ISOS Prague 1999, Pre-Conf. Fieldtrip, Excurs. Guide Poland and Germany: 11-13. CZARNOCKI J. 1928–Coupe de l’Ordovicien à Zalesie (French sum.). Zabyt. Przyr. Nieożyw. 1: 47-50. KARDYMOWICZ I 1957–On the petrography of the diabase of the Święty Krzyż Mts (English sum.). Kwart. Geol. 1, 1: 136-154. KOWALCZEWSKI Z. 1974–Geological and structural aspects of magmatism in the Góry Świętokrzyskie Mts against the background of recent research (English sum.). Biul. Inst. Geol. 275: 11-62. MODLIŃSKI Z., SZYMAŃSKI B. 2001–The Ordovician stratigraphy and palaeogeography of the Nida-Holy Cross Mts area, Poland – a review. Geol. Qater. 45, 4: 417-433. MODLIŃSKI Z., SZYMAŃSKI B. 2001–The Silurian of the Nida, Holy Cross Mts and Radom areas, Poland – a review. Geol. Qater. 45, 4: 435-454. TRELA W. 2001–Sedimentological record of changing hydrodynamic conditions in the Upper Tremadoc deposits of the Holy Cross Mts, Poland. Geol. Quat. 45, 2: 117-130. 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.