Paleocene sea‐level fluctuations recorded in benthic foraminiferal assemblages from gebel oweina (Esna, Egypt): Local, regional or global patterns?

Abstract

Stratotype Points (GSP) is that they represent reference points where both geological time and rock are defined. Traditionally, geological history has been perceived in two ways, one rock-related and one time-related. This is manifested in the conventional twosplit stratigraphic (time) scale where chronostratigraphical units (system, series, stage) are matched against geochronological units (period, epoch, age). One principal reason why this divided perception originally evolved, were the uncertainties in correlation that arouse because (immaterial) time boundaries were not satisfactorily defined in relation to (material) rock boundaries. The GSP represents the base of a rock unit as well as the beginning of a time unit, which both continue up to the next asp, and the conventional, divided perception of Earth history will be oflimited practical value after GSSP-standardization (at least in global stratigraphic studies; in regional studies, however, it may still be important to distinguish between time and rock units). Harland et al. (1989) states that, with time and rock deriving from the same standard reference point, "the two apparent! y distinct disciplines geochronology and chronostratigraphy will be different aspects of a single procedure". These authors suggest that the terms period, epoch, and stage shall be used for the different hier- Meeting proceedings "Stratigraphy of the Paleocene" 63archies of time-rock subunits in a GSSP-standardized scale. The terms period and epoch, they adopt from the traditional~eochrono-logic scale, but for the next lower-in-rank time-rock unit, the geochronologic concept "age" is abandoned in favor of the chronostratigraphic concept "stage". The term "age" is dismissed in order to avoid ambiguity because of its general reference to time. However, if traditional geochronologic nomenc1ature, and including also the tenn "age", was used for the GSP-bounded time-rock subunits, the concept "Selandian Age" would refer to such a unit, whereas "Selandian Stage" could be used in a chronostratigraphic sense with reference to the historical stratotype sections. The double meaning of "age" is a minor problem (cf. "period" and "epoch" that refer also to time intervals in general) compared with introducing two stratjgraphic meanings of the term "stage".

Campanian‐Maastrichtian intermediate‐ to deep‐water changes in the high latitudes: Benthic foraminiferal evidence

“…The genus Pullenia contains species which are typical for high latitudes dominated by cold water masses during the latest Cretaceous [ Widmark , 1995]. In Maastrichtian sediments of Spain and the South Atlantic, Pullenia indicates increasing bottom water oxygenation [ Coccioni et al , 1993; Speijer , 1994], a pattern somehow contradicting the dominance of recent Pullenia in high productivity areas of the South Atlantic [ Mackensen et al , 1993]. Nuttallides truempyi is assumed to be a highly oligotrophic species preferring well‐oxygenated bottom waters [ Schönfeld and Burnett , 1991; Widmark and Speijer , 1997; Thomas et al , 2000; Widmark , 2000].…”

High resolution planktonic foraminiferal biostratigraphy of the Gurpi Formation, K/Pg boundary of the Izeh Zone, SW Iran

“…The relative abundance of species was noted as abundant, >10%; common, 5-10%; few, 2-5%; and rare, <2%. Species identifi cation and zonal scheme ( Figure 3) were primarily based on the studies of Caron (1985); Keller (1988) ;Berggren & Miller (1988); Sliter (1989);Speijer (1994); Robaszynski & Caron (1995); Berggren & Norris 1997;Olsson et al (1999); Premoli Silva & Verga (2004); Berggren & Pearson (2005); Gallala et al (2009) and Gallala & Zaghbib-Turki (2010). Thus, 53 species belonging to 24 genera of planktonic foraminifera from 11 biozones were identifi ed.…”