Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

3 Acta Geologica Polonica

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: mastrycht

Sortuj według:

Ogranicz wyniki do:

The Upper Campanian - lower Maastrichtian cephalopod fauna of Botellos, Nuevo León: a key to understand faunal turnover across the Campanian-Maastrichtian boundary in NE Mexico

100%

Ifrim C. , Lara de la Cerda J. E. , Peña Ponce V. H. , Stinnesbeck W.

tom Vol. 67, no. 1

145--162

A new cephalopod collection from the Campanian-Maastrichtian boundary interval of NE Mexico, consisting of 1076 individuals assigned to 29 species and 22 genera is presented. This collection is a mix of ammonoids, one coleoid and one nautilid, which originate from at least three ammonoid biozones: The upper Campanian Exiteloceras jenneyi and Nostoceras (Nostoceras) hyatti zones, and the lower Maastrichtian Pachydiscus (Pachydiscus) neubergicus Zone. The age of the collection is thus middle late Campanian to late early Maastrichtian, and it closes a stratigraphic gap between faunas described formerly from this region. The specimens are nuclei collected from the desert pavement. The abundance of specimens allows for a comparison to other Campanian-Maastrichtian ammonoid records from Mexico, North America and Europe.

The phymosomatid echinoid Trochalosoma taeniatum from the Maastrichtian (Upper Cretaceous) of southeast Poland

100%

Jagt J. , Kin A.

tom Vol. 60, no. 3

429-435

The phymosomatid Trochalosoma taeniatum (von Hagenow, 1840) is recorded for the first time from upper Maastrichtian strata exposed at Piotrowice, near Lublin, southeast Poland. Although fragmentary, the single, moderately preserved test is of note in representing one of the larger individuals of this species on record (estimated diameter > 60 mm), and in displaying crenulate ambulacral and interambulacral tubercles, at least adapically. Previous records of T. taeniatum include the lower and upper Maastrichtian of Denmark, northern Germany (Rugen), Alava (northern Spain) and Mangyshlak (Kazakhstan). Trochalosoma corneti (Cotteau, 1875), from the upper Maastrichtian of southern and northeast Belgium (Mons and Liege basins, respectively) and the southeast Netherlands (type area of the Maastrichtian Stage), synonymised by some authors with T. taeniatum, is considered to be distinct.

Integrated stratigraphy of the Kronsmoor section (northern Germany), a reference point for the base of the Maastrichtian in the Boreal Realm

80%

Niebuhr B. , Hampton M. , Gallagher L. , Remin Z.

tom Vol. 61, no. 2

193-214

Results of detailed multistratigraphic analyses of the Campanian.Maastrichtian boundary section at Kronsmoor in northern Germany are summarised and calibrated with the GSSP at Tercis les Bains, southwest France. Additional markers for the definition of the boundary in the Boreal Realm are proposed, and a detailed carbon isotope curve around the Campanian.Maastrichtian boundary in the chalk facies of the Boreal epicontinental sea is presented. The C isotopic GSSP marker for global correlation is the markedly abrupt decrease of c. 0.7 [per mil] [delta^13]C directly at the Campanian.Maastrichtian boundary as dated by ammonites. In electronic borehole measurements the Kronsmoor section covers the SP peaks 53 to 64 and the base of the Maastrichtian being situated just below SP peak 60. The first occurrence (FO) of the ammonite Pachydiscus neubergicus, which corresponds to biohorizon 1 at Tercis, falls in the upper part of nannofossil Zone UC15, at both localities. Biohorizon 3 is the FO of the ammonite Diplomoceras cylindraceum, which first appears in the Upper Campanian of Tercis and at Kronsmoor enters significantly above the FO of Belemnella lanceolata, the conventional Boreal belemnite marker for the base of the Maastrichtian Stage. Based on ammonite evidence, the internationally accepted base of the Maastrichtian at Kronsmoor is located between the FOs of Diplomoceras cylindraceum (Upper Campanian) and Pachydiscus neubergicus (Lower Maastrichtian) c. 11 m above flint layer F 600, at which the first representatives of the belemnite genus Belemnella, in particular Bn. lanceolata occur. The latter thus is a Late Campanian species, appearing c. 450 ky prior to the ammonite-based boundary. The FOs of Belemnella pseudobtusa (sensu Schulz) resp. Belemnella obtusa (sensu Remin) directly at the boundary can be use as the coleoid proxy for the definition of the base of the Maastrichtian in the Boreal Realm. To define the boundary by benthic foraminifera the last occurrence (LO) of Neoflabellina praereticulata is suitable. Biohorizon 12, as defined at Tercis, involves the nannofossil Uniplanarius trifidus, however, at Kronsmoor this species is rare, occurs only sporadically and also significantly lower in comparison to Tercis. It is possible though to compare and correlate nannofossil events between Kronsmoor and Tercis using cosmopolitan taxa such as Broinsonia parca constricta and Eiffellithus eximius. The LO of the latter appears to be situated just above the boundary in both sections; it follows from this that the top of nannofossil Zone UC15 is of Early Maastrichtian age.