st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland Geological and architectural delights of the Kraków-Częstochowa Upland L. Marynowski, M. Rybicki, J. Smolarek Faculty of Earth Sciences, University of Silesia, Będzińska 60, PL-41-200 Sosnowiec, Poland [email protected]; [email protected]; [email protected] Stop 1. The Ojców National Park: Hercules Club rock and Pieskowa Skała castle Ojców National Park Ojców National Park (Fig. 1), a national park in the Lesser Poland Voivodeship in southern Poland, was established in 1956. It takes its name from the village of Ojców where it also has its headquarters. With an area of 2145,62 ha, it is Poland's smallest national park Fig. 1. Simplified geological map of the Kraków-Silesia Monocline (after Gedl & Kaim, 2012) with marked field trip stops. 129 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland Geological structure Exposed geological strata in the area of the Ojców National Park are Upper Jurassic (mainly Oxfordian) limestones reaching about 200 m in thickness. In the Ojców area, two major types of limestones are observed – massive and bedded. Monadnocks are mainly built from massive limestones which are characterized by their hardness, coherence, systematic fracture and the absence of flints. The most common fossils are sponges. Areas located between the monadnocks are formed by bank limestones lithologically similar to the massive rocks but their bedding is different and, in addition, they contain flint nodules. Fossils include brachiopods and rare ammonites (http://www.ojcowskiparknarodowy.pl/). Geomorphological origin During the Paleogene, the area was subjected to long-term denudation which led to the creation of a vast, slightly wavy plateau raised an average about 450 meters above sea level - the Paleogene surface of leveling. In the vicinity of the park, mainly in the north-west, the plateau is dotted with numerous rocks monadnocks of massive Jurassic limestone that resisted the denudation processes. Initiated in the Pliocene, the current network of rivers flowing from north to south progressively cut a series of ravines and, at the same time, karstic processes formed many caves. Glaciation which only once affected the edge of the Carpathian Mountains covered the area of the plateau with clays, sands and gravels. By this time, the valleys had already been deeply eroded. During the younger glaciations (Middle Polish Glaciation and the Last Glacial Period), the area of the park experienced a cool climate. Aeolian loess from the north, deposited at the end of the Ice Age, reaches up to 8m in thickness. In the relief of the Ojców National Park, two main groups of forms are characteristic – valleys and plateaus. The first includes valleys of ravine character (indented approximately 100 m) and small karst valleys with terraces and alluvial fans. The second group comprises the monadnocks scattered on the plateau and surrounded by Quaternary strata. Pieskowa Skała castle Pieskowa Skała castle (Fig. 2a&b), built by King Kazimierz the Great (Kazimierz Wielki), is one of the best-known examples of a defensive structure in Polish Renaissance architecture. In the first half of the 14th century, it was erected as part of the chain of fortified castles called Orle Gniazda (Eagles Nests) along the highland plane of the Polish Jura extending north-west from Kraków to the city of Częstochowa. The castle was an important link in the fortifications defending the trade route from Kraków to Silesia. Today, it belongs to the small extant group of Polish Renaissance monuments and is a major tourist attraction on the Eagles' Nests Trail. 130 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland a Fig. 2. Pieskowa Skała castle: a - The southern keep of the castle with the observation loggia, b - the northern keep of b the castle. 131 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland Hercules Club rock – “Maczuga Herkulesa” “Maczuga Herkulesa” (Fig. 3) is a tall (30 meters) limestone monadnock situated in the Ojców National Park near Pieskowa Skała, north of Kraków. Its name, in Polish meaning the "cudgel of Hercules", derives from its distinctive shape (http://www.ojcowskiparknarodowy.pl/). Fig. 3. Hercules Club rock. 132 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland Stop 2. Gnaszyn clay pit In the Gnaszyn area (Fig. 1), there are 5 active and 2 inactive clay pits from which Middle Jurassic clays are and were exploited for brick production (Fig. 4). The largest is the Gnaszyn- Winerberger brick pit (Fig. 5). The brownish and grey clays are part of a widespread facies – the so-called ore-bearing clays. The sedimentation of these epicontinental marine Middle Jurassic deposits is associated with a transgression which started in the Early Aalenian and lasted, with short regressive episodes, throughout the whole of the Dogger (Gedl & Kaim, 2012). Fig. 4. a - Jurassic palaeogeography of the Polish part of the Mid-European Epicontinental Basin (adapted from Marynowski et al., 2007a); b - Geological map of the Polish Jura with clay-pit locations (asterisks); c - Kawodrza and Gnaszyn areas with location of the major brick-pits (shaded). PJ = Polish Jura. Fig. 5. a - General view on the Gnaszyn-Winerberger brick-pit; b - NE wall of the clay-pit. Since the Middle Ages, siderite concretions and siderite beds occurring as intercalations in the clays were exploited in underground mines for iron. Though this exploitation was definitely finished by the second part of the 20th century, carbonate concretions and massive siderites are still frequently observed in all outcrops in the Częstochowa area (e.g. Matyja & Wierzbowski 2000, Marynowski et al. 2007a, Krzykawski 2012, Witkowska 2012). These concretions are of interest to palaeontologists and mineralogists due to the excellent preservation of marine fossils such as ammonites, gastropods, bivalves, belemnites, 133 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland echinoderm ossicles and crabs (e.g. Różycki 1953, Majewski 2000, Zatoń & Marynowski 2006, Krobicki & Zatoń 2008, Zatoń 2010a &b, 2011, Kaim 2012) and the occurrence of beautiful mineral specimens, e.g., aragonite, calcite, sphalerite, barite, pyrite and chalcopyrite (Galuskin et al. 1996, Krzykawski 2012). In the clays and concretions, anatomically well-preserved fossil wood fragments frequently occur (Fig. 6a; Philippe et al. 2006, Marynowski et al. 2007a&b, 2013, Kaim et al. 2011). Interestingly, this wood is also chemically excellently preserved, containing some of the oldest biomolecules identified in sedimentary rocks, e.g., ferruginol or sugiol (Marynowski et al., 2007b). This excellent chemical preservation is possibly due to the very low thermal maturation of the Middle Jurassic clays from the Kraków – Wieluń upland; vitrinite reflectance values range from 0.2-0.45% (Marynowski et al., 2007b; 2011). Moreover, the clays and concretions acted as perfect protective shields against secondary processes such as water washing or weathering. Some wood fragments are completely gelified and resemble highly fractured jets (Fig. 6b). Fig. 6. Examples of fossil wood from the Gnaszyn-Winerberger clay-pit: a - partially mineralized wood fragment; b - gelified, jet-like wood. Some specific carbonate concretions from Middle Jurassic siliciclastics are bored- and encrusted “hiatus concretions” with variable morphologies and distinct traces of bioerosion and encrustation due to exhumation on the sea floor during intervals of low sedimentation and/or erosion. Taphonomic- and ecologic evidence indicates that these concretions were 134 st 65 Annual Meeting of the ICCP’ 2013, Sosnowiec, Poland repeatedly overturned and transported by episodic high-energy bottom currents, probably in a shallow sub-tidal environment (Zatoń et al. 2011). The ore-bearing clay succession was deposited in relatively well oxygenated oxic- to suboxic conditions; there is no evidence of anoxia/euxinia in the whole water column (Szczepanik et al. 200,; Marynowski et al. 2007a, Zatoń et al. 2009). Clays contain low to moderate (0.2-5%) amounts of total organic carbon (TOC) and and characterized by III/IV kerogen type being a mixture of terrestrial- and marine organic matter (Marynowski et al. 2007a, Szczepanik et al. 2007, Gedl et al. 2012). Leonowicz (2012) located the depositional setting of the Middle Jurassic clays in the offshore zone below the wave base. However, the occurrence of some hiatus concretion levels may indicate occasional storms reaching the sea floor (Zatoń et al. 2011). Generally, palaeontological interpretations show that bottom water conditions during the main phase of ore-bearing clay sedimentation were below the photic zone (Gedl et al. 2012). Sea-water temperature estimates suggest vertical ranges of ca 4-9.5˚C for bottom waters and ca 16-22˚C for surface waters (Wierzbowski & Joachimski 2007). Stop 3. Castle ruins in Olsztyn Olsztyn castle is another example of a fortification built by King Kazimierz the Great and now part of the Trail of the Eagles’ Nests (Orle Gniazda). Its main task was to protect the south-western Polish boundaries against onslaughts from Silesia and the Czech Republic. In addition to being a powerful border protection, the castle also served as a prison for the nobility. The castle was destroyed during the Swedish invasion of 1655-1660 when it was captured, robbed of valuable equipment and finally abandoned. During 1722-1726, large parts of the stronghold were demolished, and the material thus obtained used to rebuild the burned church and surrounding buildings. In the nineteenth century, the castle was already the romantic ruin of today (http://www.zamkipolskie.com/olsz/olsz.html). Stop 4. Silver mine in Tarnowskie Góry The Tarnowskie Góry ore district is a NW part of the Silesian-Cracovian Zn-Pb ore region (Fig. 7) extending from Tarnowskie Góry and Bytom in the west to Zawiercie and Olkusz in the east. The deposits occur mainly in ore-bearing dolomites of the Middle Triassic (Muschelkalk) and are classified as Mississippi Valley-type deposits by most authors (e.g.