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The middle-upper Cenomanian of Zilly (Sachsen-Anhalt, northern Germany) with remarks on the Pycnodonte Event

Wilmsen M., Voigt T.

Acta Geologica Polonica

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2006

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Vol. 56, no. 1

17-31

EN

A detailed stratigraphic log of the 28 m thick Cenomanian succession at Zilly (Sachsen-Anhalt) is presented. The succession is composed of 11 m of middle Cenomanian hemi-pelagic marl-limestone alternations ("Planer Limestones") grading into 15 m of upper Cenomanian calcareous pelagites ("Poor rhotomagense Limestones") unconformably overlain by 1,5 m of red-coloured marly clays and limestones ("Rotplaner"). The proof of the interregional marker beds of the Pycnodonte Event at the 11 m level, the Facies Change at 26 m, and the base of the plenus Bed at 26,9 m allow a bio-/chronostratigraphic correlation of these levels with the middle/upper Acanthoceras jukesbrownei Zone (upper middle Cenomanian), the Calycoceras (Proeucalycoceras) guerangeri/Metoicoceras geslinianum Zone transition, and the lower Metoicoceras geslinianumZone, respectively (middle upper Cenomanian).Litho-/microfacies and sequence stratigraphic analyses indicate an overall increase of pelagic influence up to the Facies Change. This retrogradational trend was shortly interrupted by the Pycnodonte Event, the base of which correlates with the late middle Cenomanian sequence boundary SB Ce IV and the succeeding transgressive surface. The Facies Change indicates a significant mid-late Cenomanian sea-level fall (sequence boundary SB Ce V), followed by more shallow water Rotplaner deposition. The Pycnodonte Event is very thick and proximal in character at Zilly. Its monospecific oyster fauna consists of small pycnodonteines assigned to Pycnodonte (Phygraea) vesicularis (LAMARCK) vesiculosa (J. SOWERBY), a secondarily free-lying oyster which lived as a "cup-shaped recliner".The patchy occurrence of the oysters, the sorting and partial damage of valves prior to final burial along with significant supply of terrigenous materials suggest episodically elevated water energy and strong environmental stress during deposition of the Pycnodonte Event. This situation promoted colonization of the sea-floor by, and reproductive success of the inferred eurytopic oyster. The Pycnodonte Event is a classic example of an "onlapping bioevent", the formation of which was controlled by different factors such as sea-level rise, terrigenous influx, environmental stress, and preferential preservation.

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Event stratigraphy of the Badenian selenite evaporites (Middle Miocene) of the northern Carpathian Foredeep

Bąbel M.

Acta Geologica Polonica

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2005

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Vol. 55, no. 1

9-29

EN

The Middle Miocene (Badenian) evaporites of the northern Carpathian Foredeep were deposited in a salina-type basin. Calcium sulphate sediments were deposited mainly on the broad northern margins of the basin, on vast evaporite shoals (mainly as fine-grained microbialite gypsum) and in large shallow saline pans (as coarse-crystalline selenites). 125 sections of these primary deposits, exposed from Moldova, Ukraine, Poland to the Czech Republic, were subjected to stratigraphic analysis based principally on the methodology of event and high-resolution stratigraphy. Due to an extremely gentle relief and a predominantly aggradational type of deposition, typical of a salina basin, the environmental changes or events were recorded nearly instantaneously in the whole area. Some events, such as water-level or brine-level fluctuations (emersions and floods, which can be very rapid in a salina basin),fluctuations in the average pycnocline level, aeolian dust or ash falls, accretion of specific gypsum microbialites, produced sets of marker beds which are perfectly correlated over distances of tens to hundreds of kilometres. Some thin grass-like selenite beds, representing deposits of shallow flat-bottomed saline pans, were correlated precisely over such great distances and are interpreted as isochronous or near-isochronous. Each bed was presumably deposited during the average pycnocline level highstands in the saline pan. The thick-bedded selenite units do not show long-distance bed-by-bed correlation, presumably because they were deposited in deeper pans in which the pycnocline fluctuations were recorded by bedding planes (i.e. by intercalations of fine-grained gypsum or dissolution surfaces) only on the shallow slopes or swells. However some apparent growth zones in the gypsum crystals from such selenite units were correlated throughout the basin, proving that the selenite growth However some apparent growth zones in the gypsum crystals from such selenite units were correlated throughout the basin, proving that the selenite growth was isochronous.

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Cenomanian through Lower Coniacian events in the Upper Cretaceous of Saxony, Germany

Troger K.

Acta Geologica Polonica

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2004

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Vol. 54, no. 4

629-638

EN

The event sequence recognised in the Cenomanian through basal Coniacian (Late Cretaceous) of the Elbe Valley is compared with the event stratigraphic scheme worked out in NW Germany. The following events, recognised originally in Lower Saxony, and subsequently in other Cretaceous areas of north-western Europe, were found in Saxony: Schloenbachia / virgatus eustatoevent (Lower Cenomanian); Chondrites ecoevent, Puzosia eustatoevent and plenus eustatoevent (Upper Cenomanian); hattini ecoevent, Mytiloides ecoevents, hercynicus ecoevent, Hyphantoceras ecoevent, Didymotis ecoevents and waltersdorfensis ecoevent (Turonian); erectus ecoevent, hannovrensis ecoevent, and incostans ecoevent (Lower Coniacian). Both the oxic/anoxic Cenomanian/Turonian boundary event and the facies change at the base of the Metoicoceras geslinianum Zone are recognisable. With the exception of the Mytiloides ecoevents, recorded in all facies types, all the events are well developed only in the marly-silty facies.Local events, specific to the Cretaceous of Saxony are: the Late Cenomanian Pennrich event, known from the Sudetic area, and the Middle Turonian rhynchonellid events, occurring in sandy and transitional facies between Pirna and Bad Schandau.

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20 years of event stratigraphy in NW Germany; advances and open questions

Wiese F., Wood Ch. J., Kaplan U.

Acta Geologica Polonica

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2004

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Vol. 54, no. 4

639--656

EN

The application of event stratigraphy in the Cenomanian to Lower Coniacian (Upper Cretaceous) Plńnerkalk Gruppe of northwestern Germany has advanced stratigraphic resolution considerably. For a short interval in the Upper Turonian, various genetically variable events (bioevents, tephroevents, stable isotope marker, eustatoevents) are reviewed and new data are partly added. In addition, the lateral litho and biofacies changes within individual events are discussed and provide a basis for a tentative high-resolution correlation between distal and proximal settings. The dense sequence of events permits a stratigraphic resolution of 50 - 100ky for some intervals. Beyond stratigraphic purposes, the alternation of fossil barren intervals with thin fossil beds still demands explanations. As taphonomic processes are considered to be play only a minor role, other explanations are required. It appears that trophic aspects and a calibration of planktic and benthic faunal assemblages may result in a better understanding of this biosedimentary system and its faunal characteristics.

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GIS based map of glaciotectonic phenomena in Denmark

Jakobsen P. R.

Geological Quarterly

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2003

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Vol. 47, No 4

331-338

EN

An ArcView-based map of glaciotectonic phenomena in Denmark has facilitated correlation of glaciotectonic features with particular ice advances and enabled creation of an event-stratigraphic map. Well log data was used to map the intensity of glaciotectonic deformation on a large scale. The highest intensities of glaciotectonic deformation is seen in the regions underlain by pre-Quaternary marine clays and chalk or interglacial marine clays.

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Early Cenomanian (Cretaceous) inoceramid bivalves from the Kronsberg Syncline (Hannover area, Lower Saxony, Germany) : stratigraphic and taxonomic implications

Wilmsen M., Niebuhr B., Wood C.

Acta Geologica Polonica

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2001

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Vol. 51, nr 2

121-136

EN

An Early Cenomanian inoceramid bivalve assemblage collected from material excavated from a temporary exposure in the Kronsberg Syncline east of Hannover (northern Germany) is described. It consists of "Inoceramus" crippsi MANTELL, 1822, "I" hoppenstedtensis TROGER, 1967, Inoceramus virgatus scalprum BOHM, 1914 and I. virgatus virgatus SCHLUTER, 1877, as well as transitional forms between I. virgatus virgatus and I. virgatus scalprum and an apparently undescribed sulcate form. The inoceramid fauna is well preserved and very rich in individuals. Many of the inoceramids occur either as double-valved individuals or with the valves in close association and appear to be cocentrated in distinct layers. Co-occurring ammonites are Mantelliceras dixoni SPATH, Mantelliceras sp., Schloenbachia varians (J. SOWERBY), Hypoturrilities gravesianus (D'ORBIGNY) and Scaphites obliquus J. SOWERBY. Using event stratigraphy, the stratigraphic interval of the collected fauna can be assigned to the lower part of the Lower Cenomanian Mantelliceras dixoni ammonite Zone. It predominantly comprises material from the Inoceramus virgatus acme-event (the Schloenbachia/virgatus event of German event stratigraphy) at the top of the lower subzone (Mantelliceras dixoni & M. saxbii Subzone) of the dixoni Zone, which is known from the Lower Saxony, Cleveland (eastern England) and Anglo-Paris basins, where it invariably occurs in carbonate-rich rocks with low diversity faunas. The lithofacies and geochemistry of the strata are documented and the "Inoceramus" crippsi and Inoceramus virgatus groups are discussed, including the problematic provenance of the type series of Inoceramus virgatus scalprum.

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Upper Cretaceous of the Barranca (Navarra, northern Spain); integrated litho-, bio- and event stratigraphy.Part 2, Campanian and Maastrichtian

Kuchler T.

Acta Geologica Polonica

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2000

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Vol. 50, no. 4

441-499

EN

Campanian to Lower Maastrichtian strata of the eastern Barranca (Navarra, northern Spain), based on 11 exposures near Irurzun, were investigated in detail and correlated with coeval strata of the western Barranca and the Oroz-Betelu Massif (Navarra). The Sarasate Formation exposed in the Barranca in divided into ten members. Deposition was influenced by uplift of the Anoz-Ollo salt structure during the latest Santonian and Early Campanian. The Campanian-Maastrichtian of Navarra is characterised by thick and relatively complete successions containing biostratigraphically significant fossil groups (ammonites, inoceramids, echinoids). Detailed bed-by-bed collecting has enabled the establishment of an integrated zonal scheme with potential for interbasinal correlation. In addition to local peak, partial range and assemblage zones, based on echinoids and ammonite-echinoid assemblages, an ammonite zonation, based on an unnamed interval and the following 10 partial range (PRZ) and assemblage zones (AZ) of Scaphites hippocrepis III, S. hippocrepis III/Menabites spp., Hoplitoplacenticeras marroti, Trachyscaphites spiniger, Pseudoxybeloceras phaleratum, Nostoceras (Bostrychoceras) polyplocum, Trachyscaphites pulcherrimus, N. (didymoceras) archiacianum, N. (Nostoceras) hyatti and Pachydiscus neubergicus/Pachydiscus epiplectus, is presented. The ammonite zonation markedly refines both the existing regional and the so-called European standard zonal schemes. Correlation with other Spanish areas (Cantabria, Burgos and Guipuzcoa), the Aquitaine (France), Westphalia and Lower Saxony (Germany) and the Vistula valley (Poland) is discussed. Twelve of the recognised bio-events, characterised by mass-occurrences of irregular echinoids and of monospecific, or taxonomically more variable, mostly heteromorph ammonite assemblages, are significant for regional correlation. Three Offaster maxima are of interbasinal importance as they can be correlated to Germany, Great Britain and Northern Ireland. The origin of these bio-events is closely related to the transgressive and regressive pulses recognised in Navarra, of which the pomeli Transgression I and the hippocrepis, subglobosa and polyplocum regressions are the most pronounced. The tectonic phase at the Santonian/Campanian boundary is related to the Wernigerode Phase. The onset of the second phase is placed in the lower Upper Campanian marotti Zone, the onset of a third phase (UCTE) in theUpper Campanian polyplocum Zone.