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Storm-influenced deposition and cyclicity in a shallow-marine mudstone succession - example from the Middle Jurassic ore-bearing clays of the Polish Jura (southern Poland)

Leonowicz P. M.

Geological Quarterly

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2015

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Vol. 59, No. 2

325--344

EN

Sedimentological analysis of bioturbated mudstones from the Middle Jurassic ore-bearing Częstochowa Clay Formation has revealed common relics of sedimentary structures, such as thin silt/sand laminae, bedding-plane accumulations of shell debris, small and medium silt-sand lenses, as well as silt-, sand- and shell-debris-rich levels, accompanied by erosion surfaces and minor scours. These features document periodical high-energy conditions of mud deposition, including storm stirring, event sedimentation and the activity of storm-generated bottom currents, which were responsible for seafloor erosion and sediment supply from shallower parts of the basin. The sea bottom was prevalently below the storm wave base, but it rose above it during exceptionally strong storms and in the Early Bathonian zigzag chron when the basin experienced considerable shallowing. The shallowest and highest energy conditions occurred in the late macrescens subchron, when the bottom was close to, or above the fair-weather wave base. The estimated depth of the sea did not exceed several tens of metres, but in some periods it could be even less than 20 m. Based on the vertical variation of the sand, silt and clay contents, seven transgressive-regressive cycles have been distinguished in the approximately 75-m thick succession spanning the Upper Bajocian - Upper Bathonian. Cycles TR1, TR2+3, TR5 and TR6+7 correlate with those distinguished in the coeval succession from central Poland, although the stratigraphic position of cycle boundaries is slightly shifted. These cycles record relative sea-level changes that affected the entire Polish Basin. Regressions R2 and R6 were smaller-scale-events, generated in response to a local tectonic activity and autocyclic shoreline progradation.

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The significance of mudstone fabric combined with palaeoecological evidence in determining sedimentary processes - an example from Middle Jurassic of southern Poland

Leonowicz P. M.

Geological Quarterly

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2013

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Vol. 57, No. 2

243–-260

EN

Analysis of the fabric of laminated black mudstones of the Ore-Bearing Częstochowa Clay Formation (Bathonian, southern Poland) is used for reconstruction of sedimentary processes and conditions. Small-scale sedimentary features indicate that ore-bearing clays were deposited below storm-wave base in a shallow epicontinental sea, but structures reflecting quiet settling from suspension are not common. Most of recognized lamina types record the activity of bottom currents generated by storms. The benthic faunal association indicates that suboxic conditions prevailed on the seafloor, restricting infaunal activity to cryptobioturbation. Recurrent short-lived reoxygenetion events, linked probably to storms, resulted in the development of dysoxic conditions, recorded by a more diverse trace fossil association (consisting of Chondrites, Trichichnus, pyritized burrows, Palaeophycus and Protovirgularia) and colonization of the seafloor by epifaunal bivalves (Bositra). Truly anoxic conditions might have been briefly established, leading to mass mortality of Bositra.

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Sedimentary facies, ichnofossils and storm deposits in the Lower Permian Taiyuan Formation, Jiaozuo city, Henan Province, central China

Hu B., Song H., Liu S., Zhang L.

Acta Geologica Polonica

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2010

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Vol. 60, no. 1

45-52

EN

Five sedimentary facies - neritic carbonate platform, lagoon, tidal flat, swamp and barrier island facies - are recorded in the Lower Permian Taiyuan Formation along with abundant ichnofossils. Common ichnofossils in this formation include Zoophycos villae, Zoophycos brianteus, Nereites cf. missouriensis, Chondrites isp., Gordia marina, Taenidium isp., Thalassinoides isp., Palaeophycus isp., Planolites isp. and a kind of bifurcation trail. From observations of the morphology of Zoophycos spreiten in approximately vertical sections, at least three kinds of spreite laminae are distinguished: ligular, crescentic and rectangular forms. Four types of storm deposits (coded as A, B, C, D) are recognised in the carbonates of the Taiyuan Formation and can be explained forming in shallow marine environments, which are distributed in order from near storm wave base to near fair weather wave base respectively.

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Storm deposits: evidence of event sedimentation in the Bajocian of the Central High Atlas, Morocco

Alt Addi A.

Volumina Jurassica

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2008

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Vol. 6, no. 1

23-32

EN

Storm beds interbedded with marls, claystones and beds of nodular to undulose bioclastic limestones have been recognized in the Central High Atlas of Morocco. These provide the first evidence of event sedimentation in the Bajocian of the area. The outcrops studied are included in the Agoudim and Tazigzaout formations in the center of the basin, and are parts of the Bin El Ouidane Group at the margins of the basin. The storm deposits comprise calcarenites and bioclastic packstones-grainstones. These beds have symmetrical wave-ripples at their tops and an internal structure of hummocky cross-stratification. They are considered to have been formed by tropical storms and hurricanes. Multiple reworking and winnowing of siliciclastic or bioclastic material by oscillatory currents related to storm and to currents resulting from storm/tide interactions is inferred. Bed features are the most important evidence in favour of a palaeobathymetric interpretation of related pelagic sediments, with calcareous tempestites representing episodic resedimentation, mainly coincident with relative sea-level falls during which major storm waves affected the sea bottom. This interpretation is in agreement with the regional palaeogeography and is further supported by evidence of Jurassic storm-controlled sedimentation in adjacent Mediterranean basins.

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Charakterystyka sedymentologiczna górnej części warstw szydłóweckich

Vierek A.

Przegląd Geologiczny

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2008

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Vol. 56, nr 9

848-856

EN

The Givetian to Frasnian boundary interval in the N part of the Kielce region (Holy Cross Mts.) consists of dark-coloured shales, marls and micritic limestones defined as Szydłówek Beds. The upper parts of the Szydłówek Beds are well exposed in the Kostomłoty-Mogiłki and Górno-Józefka quarries. These sections are situated in Kostomłoty transitional facies zone between the shallow-water carbonate platform and the deeper Łysogóry basin. The uppermost parts of the Szydłówek Beds comprise many fine-grained intercalations: laminated calcisiltites, calcarenites, calcirudites and coquinas beds. The shales, marls and micritic limestones are hemipelagic deposits of deep, quiet and oxygen-depleted basin, whereas grained limestones correspond with shallower water and higher energy environment. Laminated calcisiltites and finer calcarenites originated in the environment below storm wave base and are interpreted as surge-like turbidity flows deposits. Thicker calcarenites, calcirudites, and coquinas beds were deposited about storm wave base and are interpreted as tempestites.

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Storm deposits: evidence of event sedimentation in the Bajocian of the Central High Atlas, Morocco

Ait Addi A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

75-75

EN

During Bajocian time, the Central High Atlas of Morocco received several hundred meters of marls, shaly marls and carbonate deposits. These are spread out in two main domains: southern and northern platforms, situated N of Errachidia and S of Midelt cities, respectively, where shallow marine carbonates corresponding to the group of Bin El Ouidane formations dominate (Monbaron 1981); and central basin, presently forming the centre of High Atlas, where hemipelagic facies to shallow marine carbonates represent Agoudim (members II, III and IV) and Tazigzaout formations (Ait Addi 2000, Ait Addi 2002). The first evidence of event sedimentation in the Middle Jurassic of central High Atlas of Morocco has been provided by Ait Addi (2002). These deposits are Middle Jurassic (Bajocian) in age and are included in Agoudim and Tazigzaout formations in the central basin; and parts of Bin El Ouidane Group in the borders. The storm deposits are calcarenite beds of bioclastic packstone-grainstone character. These beds present symmetrical wave-ripples at their tops and show an internal structure with hummocky cross-stratification. The deposits are considered to be formed by tropical storms and hurricanes. The above characteristics are the effects of multiple reworking and winnowing of siliciclastic or bioclastic and/or carbonate material by oscillatory currents related to storm and to storm/tide currents interaction. Palaeobathymetric interpretation of related pelagic sediments indicates that the sedimentation occurred fairly deep, and that calcareous tempestites resulted from episodic resedimentation, mainly coincident with relative sea-level falls, in which major storm waves and tsunamis affected the sea bottom. This interpretation is in agreement with the regional palaeogeography and is further evidence of Jurassic storm-controlled sedimentation in adjacent Mediterranean basins.

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Zechstein (Ca1) limestone-marl alternations from the North-Sudetic Basin, Poland: depositional or diagenetic rhythms?

Biernacka J., Borysiuk K., Raczyński P.

Geological Quarterly

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2005

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Vol. 49, No. 1

1--14

EN

Limestone-marl alternations constitute a characteristic rock facies within the Zechstein Limestone (Ca1) deposits of the North-Sudetic Basin, Poland. Rhythmites of this type are exposed in a 10-metres section at Nowy Kooeciół, which from the beginning of the last century has been considered representative for this part of the Zechstein basin, and were formerly interpreted as calcareous storm sediments alternating with marls deposited during more quiet conditions. Our results of sedimentological, petrographical and chemical studies suggest that the Nowy Kościół section is a record of distal storm deposits, but that the present-day layering does not precisely reflect the depositional rhythm. Post-depositional changes have overprinted and blurred the original pattern.We propose a model of diagenetic alteration in which dissolution and reprecipitation of calcium carbonate in the shallow subsurface formed new layer boundaries; subsequent modifications during deeper burial followed these early diagenetic changes.

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Sedimentological record of changing hydrodynamic conditions in the upper Tremadoc deposits of the Holy Cross Mountains, Poland

Trela W.

Geological Quarterly

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2001

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Vol. 45, No 2

131-142

EN

In the upper Tremadoc, in the Kielce region of the Holy Cross Mountains, siltstones and fine-grained sandstones are interbedded with chalcedonites and claystones. The deposits were probably laid down when the late Tremadoc transgression reached its maximum. Storm currents influenced deposition at times while, during calm periods, sedimentation of chalcedonites, clayey cherts and clays took place. Weak bottom currents affected the deposition of siliceous layers. The deposits accumulated on a distal shelf.