Wyniki wyszukiwania - BazTech

1

The proposal of a GSSP for the Berriasian Stage (Cretaceous System): Part 1

Wimbledon William A.P., Reháková Daniela, Svobodová Andrea, Elbra Tiiu, Schnabl Petr, Pruner Petr, Šifnerová Krýstina, Kdýr Šimon, Dzyuba Oksana, Schnyder Johann, Galbrun Bruno, Košťák Martin, Vaňková Lucie, Copestake Philip, Hunt Christopher O., Riccardi Alberto, Poulton Terry P., Bulot Luc G., Frau Camille, De Lena Luis

Volumina Jurassica

|

2020

|

Vol. 18, no. 1

53--106

EN

Here in the first part of this publication we discuss the possibilities for the selection of a GSSP for the Berriasian Stage of the Cretaceous System, based on the established methods for correlation in the Tithonian/Berriasian interval. This will be followed, in the second part, by an account of the stratigraphic evidence that justifies the locality of Tré Maroua (Hautes-Alpes, SE France) as the proposed GSSP. Here we discuss the possibilities for correlation in the historical J/K boundary interval, and the evolution of thinking on the positioning of the boundary over recent generations, and in relation to research in the last ten years. The Tithonian/Berriasian boundary level is accepted as occurring within magnetosubzone M19n.2n. The detailed distribution of calpionellids has been recorded at numerous sites, tied to magnetostratigraphy, and the base of the calpionellid Alpina Zone is taken to define the base of the Berriasian Stage. This is at a level just below the distinctive reversed magnetic subzone M19n.1r (the so-called Brodno reversal). We discuss a wide range of magnetostratigraphic and biostratigraphic data from key localities globally, in the type Berriasian areas of France and wider regions (Le Chouet, Saint Bertrand, Puerto Escaño, Rio Argos, Bosso, Brodno, Kurovice, Theodosia etc.). The characteristic datums that typify the J/K boundary interval in Tethys and its extensions are detailed, and the correlative viability of various fossil groups is discussed. The boundary level is correlated to well-known J/K sections globally, and a series of secondary markers and proxies are indicated which assist wider correlation. Particularly significant are the primary basal Berriasian marker, the base of the Alpina Subzone (marked by dominance of small Calpionella alpina, Crassicollaria parvula and Tintinopsella carpathica) and secondary markers bracketing the base of the Calpionella Zone, notably the FOs of the calcareous nannofossil species Nannoconus wintereri (just below the boundary) and the FO of Nannoconus steinmannii minor (just above). Notable proxies for the boundary are: 1) the base of the A rctoteuthis tehamaensis Zone in boreal and subboreal regions, 2) the dated base of the Alpina Subzone at 140.22 ±0.14 Ma, which also gives a precise age estimate for the system boundary; and 3) the base of radiolarian “unitary zone” 14, which is situated just above the base of the Alpina Subzone.

2

Additional Tithonian and Berriasian ammonites from the Vaca Muerta Formation in Pampa Tril, Neuquén Basin, Argentina

Parent H., Schweigert G., Scherzinger A., Garrido A. C.

Volumina Jurassica

|

2017

|

Vol. 15, no 1

139--154

EN

The ammonite fauna of the Tithonian–Berriasian of the Vaca Muerta Formation in Pampa Tril has been recently described in detail. New important specimens and additional information are presented in this paper. The phyletic evolution of Choicensisphinctes, passing from C. platyconus to C. erinoides is confirmed, as well as the sexual dimorphic correspondence of this latter with C. mendozanus. A microconch of the genus Krantziceras is described for the first time. New specimens of Substeueroceras koeneni identical to the paralec¬totype, along with material already described from the koeneni Hz. (Koeneni Zone), point to the fixation of this horizon as the type horizon of the species. New specimens of Subthurmannia boissieri from the Damesi Zone match clearly the range of variation of this species in Spain, thus providing an element for time-correlation with the Tethyan standard scale. Additional material from the internispinosum alpha Hz. confirms the origin of W. internispinosum from C. proximus by the inception of an evolutionary innovation in the juvenile ontogeny.

3

Middle Jurassic-Early Cretaceous foraminiferal biozonation of the Amran Group, eastern Sana’a Basin, Yemen

Al-Wosabi M., El-Anbaawy M., Al-Thour K.

Geologos

|

2017

|

Vol. 23, No. 2

75--87

EN

Two sections of strata assigned to the Amran Group at Jabal Salab and Jabal Yam in the eastern Sana’a governorate were sampled and correlated. These sections are part of a carbonate platform that extends from the city of Marib in the east to Naqil Ibn Ghailan, 20 km east of the city of Sana’a to the west. Palaeontological analysis of samples recovered has resulted in identification of 123 foraminiferal species, which are used to subdivide the sequence of the Amran Group into five biostratigraphic zones, aged between Bathonian (Middle Jurassic) and Berriasian (Early Cretaceous). The proposed biozones are those of Riyadhella rotundata, Kurnubia jurassica, Ammomarginulina sinaica, Alveosepta jaccardiand Pseudocyclammina sulaiyana/Furitilla caspianseis. These biozones were constructed and correlated with the equivalent zones reported from several localities.

4

Remarks on the Tithonian-Berriasian ammonite biostratigraphy of west central Argentina

Riccardi A. C.

Volumina Jurassica

|

2015

|

Vol. 13, no. 2

23--52

EN

Status and correlation of Andean ammonite biozones are reviewed. Available calpionellid, nannofossil, and radiolarian data, as well as radioisotopic ages, are also considered, especially when directly related to ammonite zones. There is no attempt to deal with the definition of the Jurassic–Cretaceous limit. Correlation of the V. mendozanum Zone with the Semiforme Zone is ratified, but it is open to question if its lower part should be correlated with the upper part of the Darwini Zone. The Pseudolissoceras zitteli Zone is characterized by an assemblage also recorded from Mexico, Cuba and the Betic Ranges of Spain, indicative of the Semiforme–Fallauxi standard zones. The Aulacosphinctes proximus Zone, which is correlated with the Ponti Standard Zone, appears to be closely related to the overlying Windhauseniceras internispinosum Zone, although its biostratigraphic status needs to be reconsidered. On the basis of ammonites, radiolarians and calpionellids the Windhauseniceras internispinosum Assemblage Zone is approximately equivalent to the Suarites bituberculatum Zone of Mexico, the Paralytohoplites caribbeanus Zone of Cuba and the Simplisphinctes/Microcanthum Zone of the Standard Zonation. The C. alternans Zone could be correlated with the uppermost Microcanthum and “Durangites” zones, although in west central Argentina it could be mostly restricted to levels equivalent to the “Durangites Zone”. The Substeueroceras koeneni Zone ranges into the Occitanica Zone, Subalpina and Privasensis subzones, the A. noduliferum Zone could be equivalent to the Dalmasi Subzone, Occitanica Zone, to lower part of the Boissieri Zone, and the S. damesi Zone could range through the upper part of the Boissieri Zone to the lower part of the Pertransiens Zone. Division of the Substeueroceras koeneni Zone and a precise correlation between the Andean ammonite zones and the international standard require new systematic and stratigraphic studies.