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Współczesne głębokomorskie budowle węglanowe - nieznany świat podmorskich oaz

Jakubowicz M.

Przegląd Geologiczny

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2012

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Vol. 60, nr 6

325-332

EN

Deep-marine carbonate buildups constitute one of the most spectacular and enigmatic features found on modern seafloors. Despite some characteristics shared by all the deep-marine carbonate buildups, they represent, in fact, several distinct types, which differ in terms of their geneses, as well as sedimentary, biotic and geochemical features. These structures can be roughly divided into hydrocarbon seep limestones, carbonate-built hydrothermal vents and deep-water coral reefs. The former group include carbonate concretions, lenses, mud mounds and mud volcanoes forming as a result of decrease in alkalinity, caused by an activity of methane-oxidizing microbes. The rare examples of hydrothermal-derived limestone columns, in turn, grow in response to mixing of ambient, cold seawater and warm, Ca2+-rich fluids originating from peridotite massifs. In contrast, growth of the deep-water coral reefs appears to be stimulated largely by hydrological and bathymetric constraints, whereas a potential input of fluid seepage is rather of subordinate importance in diagenetic lithification of these structures. Surprisingly, studies on deep-water carbonates may turn out to be relevant also for understanding the shallow-water carbonate factories, providing evidence, that abiotic factors are more important in marine limestone precipitation than previously thought.

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Microbial laminites with coprolites from Upper Jurassic carbonate buildups (Kraków-Częstochowa Upland, Poland)

Kochman A., Matyszkiewicz J.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 4

331–-347

EN

The Upper Oxfordian microbial-sponge agglutinated to open-frame reef complex of the Zegarowe Crags in the Kraków-Częstochowa Upland originated upon an elevation of the Late Jurassic stable northern shelf of the Tethys. This elevation was formed, owing to a local decrease in subsidence rate during Jurassic time, induced by the presence of a Palaeozoic granitoid intrusion in the shelf substratum, and Late Jurassic, synsedimentary tectonics, which controlled the topography of the sea bottom. The Zegarowe Crags (Skały Zegarowe) complex at the top contains microbial laminites, composed of peloidal and agglutinated stromatolites, and intercalations of grainstones with indeterminable, favrenoid coprolites, occurring in large numbers. The development of stromatolites was associated with low nutrient availability. In contrast, the periodic activity of crabs, the main producers of the coprolites, forming the coprolitic grainstone intercalations, indicates periods, when nutrients were abundant in the sea water. The nutrinets most likely were associated with the occurrence of clouds of suspended matter, induced by gravity flows, generated by active, synsedimentary tectonics. The results of isotopic studies do not support the presence of warm, mineralizing solutions, connected with synsedimentary tectonics during development of the Zegarowe Crags complex in the Late Jurassic.

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The Ordovician-Silurian boundary beds between Saaremaa and Gotland, Baltic Sea, based on high resolution seismic data

Tuuling I., Flodén T.

Geological Quarterly

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2007

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Vol. 51, No 3

217-229

EN

New seismic profiles have been used to revise earlier interpretations of the Ordovician-Silurian bound ary beds be tween Saaremaa and Gotland. Atrans-Baltic reflector with erosional fea ures (S2) above the erosional Ordo vician-Silurian boundary reflector (S1) correlates with the bound ary between the Raikküla and Adavere stages. The sporadic reflector or2 below the S1 reflector off shore from Gotland represents the erosional boundary between the Pirgu and Porkuni stages. Three stratigraphic gaps occur in the Ordovician-Silurian boundary beds off shore from Gotland. The amount of eroded rocks between the Pirgu and Porkuni stages, the Ordovician and Silurian systems and the Raikküla and Adavere stages can change rapidly. Consequently, the thick ness and stratigraphy of the Ordovician-Silurian boundary beds around Gotland can change considerably across short distances. The O4-5-S1 unit off shore from Gotland, including carbonate build ups and erosional incisions infilled with Porkuni strata, belongs facially to the transi ional belt between the Estonian Shelf and the Livonian Tongue. The thick ness changes in the S1-S2 unit (Juuru and Raikküla stages) indicate an extensive subma rine erosional channel, streching from north of Estonia across the Baltic Sea and central Gotland, which developed in the Baltic Basin along a shelf to deep-basin transect dur ng Llandovery time.

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Upper Jurassic chalky limestones in the Zakrzówek Horst, Kraków, Kraków-Wieluń Upland (South Poland)

Krajewski M.

Annales Societatis Geologorum Poloniae

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2001

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Vol. 71, No 1

43-51

EN

Chalky limestones in the Zakrzówek Horst were laid down in small sponge-microbolite biostromes that provided stable foundation for the growth of extensive sponge- ’’Tubiphytes ” biostromes forming the nodular limestones in the Zakrzówek area. The ammonites occurred in chalky limestones indicate that the studied deposits belong to the youngest palaentologically documented Upper Jurassic limestones in the Kraków area (Planula zone). The vertical succession of fauna and facies characteristics indicate progressive shallowing of the environment at the end Oxfordian, from deeper shelf to shallower water.

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Depositional setting of the Devonian/Carboniferous biohermal Bol'shaya Nadota Carbonate Complex, Subpolar Urals

Skompski S.

Acta Geologica Polonica

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2001

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Vol. 51, nr 3

217-235

EN

Multi-stage development of carbonate buildups has been recognised in the Bol'shaya Nadota Carbonate Complex, in the vicinity of the town of Inta (Subpolar Urals). The growth of typical stromatoporoid-coral bioherms, characteristic of the Middle-Late Devonian stage, was terminated by the appearance of the shallow water oolitic facies, most probably at the beginning of the Famennian. During the Visean stage the carbonate platform was reconstructed, but algarbrachiopod-coral bioherms were characterized by relatively small dimensiones and an interfingering with organodetrital-oolitic facies. Sporadically, the inter-mound facies is represented by goniatite-bivalve coquinas with two new goniatite species: Goniatites olysya sp.nov. and Lusitanoceras kusinae sp.nov. The persistence of biohermal sedimentation in the Bol'shaya Nadota area is most probably caused by the specific position of the region on the boundary of two sedimentary-structural units: Lemva and Elets Zones, which corresponded to a basinal and a tectonically-active elevated part of a platform margin respectively. The overall biotic composition of the Carboniferous bioherms from Bol'shaya Nadota, situated in the northern periphery of Laurussia, falls generally within the diversity spectrum of Lower Carboniferous mounds described from the southern margin of the continent.

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Lithology and morphology of Upper Jurassic carbonate buildups in the Będkowska Valley. Kraków region, Southern Poland

Krajewski M.

Annales Societatis Geologorum Poloniae

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2000

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Vol. 70, No. 2

151-163

EN

Upper Jurassic limestones exposed in the Będkowska Valley form an extensive complex of carbonate buildups of microbolite-sponge and microbolite-Tubiphytes reef-like bioherms, in which the main rock-building material are packstone and grainstone bound by microbolite structures. Horizontal discontinuity surfaces locally found in massive limestones are of sedimentary origin and are related to sediment gravity flows from the higher parts of the buildups. Two basic morphological types of carbonate buildups are distinguished in the vertical sequence of studied sediments: (i) one or a couple of large buildups forming a continuous biolitite cover with one type of sediment prevailing over a wide area in the lower part and passing upwards to (ii) numerous small buildups separated by depressions filled with packstone and grainstone formed from erosion of the buildups. The smaller, younger buildups were subject to early cementation which led to formation of extensive constructions.

PL

Górnojurajskie wapienie Doliny Będkowskiej tworzą rozległy kompleks budowli węglanowych typu bioherm mikrobolitowo-gąbkowych i mikrobolitowo-Tubiphytesowych bioherm rafopodobnych, w których podstawową rolę skałotwórczą odgrywają ziarnity wiązane przez struktury mikrobolitowe. Poziome powierzchnie nieciągłości obserwowane niekiedy w wapieniach masywnych posiadają genezę sedymentacyjną związaną z drobnodetrytycznymi spływami z wyższych partii budowli. W badanych osadach można wydzielić dwa podstawowe typy morfologiczne budowli: (i) rozwinięte jako jedna lub kilka dużych budowli tworzących zwartą pokrywę biolitytową charakteryzującą się szerokim rozprzestrzenieniem jednego typu sedymentacji, (ii) oraz liczne ale niewielkie budowle, między którymi, w nieckach, osadzały się ziarnity pochodzące z erozji tych budowli. Budowle te wraz z otaczającymi je ziarnitami uległy wczesnej cementacji tworząc większe, złożone konstrukcje.