Biostratigraphy of the Danian/Selandian transition: A case study from Kamestan anticline section, northwest of Izeh city in Khuzestan province, Southern Iran

The planktonic foraminifera turnover across the Danian-Selandian boundary (early to late Paleocene, ~60 Ma) has been studied in the Kamestan anticline section. The studied interval span planktonic foraminifera zones P2-P3. In this section Danian-Selandian boundary is located in Pabedeh – Gurpi Formations transition. Here, the boundary of Pabeh and Gurpi Formations is a transitional one and identified by with color change of from grey shale to purple shale of Gurpi Formation to Pabdeh Formation .

&#xa

Evidence of volcanic ash at a K-T boundary section: Ocean drilling program hole 690 C, Maud Rise, Weddell Sea off East Antarctica

Rare vitric volcanogenic ash but more abundant clay minerals considered volcanogenic in origin are associated with an expanded and essentially complete K-T boundary sequence from Ocean Drilling Project (ODP) Hole 690 C on Maud Rise in the Weddell Sea off East Antarctica. Results at this writing are preliminary and are still based to some extent on shipboard descriptions. Further shore-based studies are in progress. It would appear, however, that the presence of volcanic ash and altered ash in the Danian section beginning at the biostratigraphically and paleomagnetically determined K-T boundary on Maud Rise can be cited as evidence of significant volcanic activity within the South Atlantic-Indian Ocean sector of the Southern Ocean coincident with the time of biotic crises at the end of the Maestrichtian. This is a postulated time of tectonic and volcanic activity within this Southern Hemisphere region, including possible initiation of the Reunion hot spot and a peak in explosive volcanism on Walvis Ridge (1) among other events. A causal relationship with the biotic crisis is possible and volcanism should be given serious consideration as a testable working hypothesis to explain these extinctions

A latest Cretaceous to earliest Paleogene dinoflagellate cyst zonation of Antarctica, and implications for phytoprovincialism in the high southern latitudes

The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary succession in the world is exposed on southern Seymour Island (65° South) in the James Ross Basin, Antarctic Peninsula. This fossiliferous shallow marine sequence, which spans the Cretaceous–Paleogene boundary, has allowed a high-resolution analysis of well-preserved marine palynomorphs. Previous correlation of Cretaceous–Paleogene marine palynomorph assemblages in the south polar region relied on dinoflagellate cyst biozonations from New Zealand and southern Australia. The age model of the southern Seymour Island succession is refined and placed within the stratigraphical context of the mid to high southern palaeolatitudes. Quantitative palynological analysis of a new 1102 m continuous stratigraphical section comprising the uppermost Snow Hill Island Formation and the López de Bertodano Formation (Marambio Group) across southern Seymour Island was undertaken. We propose the first formal late Maastrichtian to early Danian dinoflagellate cyst zonation scheme for the Antarctic based on this exceptional succession. Two new late Maastrichtian zones, including three subzones, and one new early Danian zone are defined. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a new South Polar Province based on Maastrichtian to Danian dinoflagellate cysts is proposed, which excludes most southern South American marine palynofloras. This interpretation is supported by models of ocean currents around Antarctica and implies an unrestricted oceanic connection across Antarctica between southern South America and the Tasman Sea

An effective palynological preparation procedure using hydrogen peroxide

Most pre-Quaternary palynology samples are currently prepared by demineralization of the sediment/sedimentary rock matrix using hydrochloric and hydrofluoric acids (HCl and HF respectively). If a consistently effective alternative to this procedure can be developed, palynological processing will be made significantly less hazardous to both laboratory personnel, and to the wider environment. Furthermore, most non-acid processing methods are normally quicker and cheaper than matrix dissolution using acid. Some authors have previously used hydrogen peroxide (H2O2) to extract palynomorphs by the physico–chemical disaggregation of the clay fraction. However, H2O2 is a powerful oxidizing agent and hence can potentially destroy sedimentary organic material, including palynomorphs. A new method using hot H2O2, where exposure of the sample material to the H2O2 is minimized, has been developed. Crushed sample material in a suitable vessel is placed on a hot plate for one minute, treated with 15–30% H2O2 for 10 minutes, then the residue is diluted with cold distilled water. Disaggregated sample material tends to float, and is decanted into a large vessel containing distilled water to further dilute the H2O2. If any undisaggregated sample remains, the procedure is repeated several times if necessary. Relatively indurated sedimentary lithotypes normally require several treatments. The reason for this stepwise treatment is that the organic material is not exposed to H2O2 for sustained periods, thereby reducing the possibility of palynomorph damage/degradation due to oxidation. When the sample matrix has been fully disaggregated, the residue can be further processed as appropriate. In this study, eight samples of Carboniferous, Jurassic, Paleogene, and Quaternary age were prepared quantitatively using the new H2O2 method. These were all prepared using 30% H2O2. For comparison, they were also prepared quantitatively using HCl/HF and/or sodium hexametaphosphate [(NaPO3)6]. Quantitative preparations allow the concentration of palynomorphs extracted to be determined, and therefore the effectiveness of the techniques used can be compared objectively. The palynomorph residues derived from these three techniques varied markedly. The H2O2 method does not consistently disaggregate all the sample material, particularly the older and more indurated lithotypes. Some evidence of oxidation effects was observed. Two samples of Mississippian mudstone from the U.S.A. were prepared using H2O2 and (NaPO3)6. Both methods produced abundant miospores, however the H2O2 procedure yielded far higher palynomorph concentrations than the (NaPO3)6 technique. Minor degradation of palynomorphs in the H2O2 preparation was noted. The H2O2 and HCl/HF methods were compared directly on a palynomorph-rich sample of Upper Carboniferous mudstone from offshore Scotland. Both preparations produced abundant miospores. The HCl/HF method had significantly higher recovery levels than the H2O2 procedure. It appears that the H2O2 method simultaneously macerates the matrix, and oxidizes any amorphous organic material (AOM) present. In this sample, the HCl/HF residue was relatively rich in AOM. By contrast, the H2O2 preparation is virtually clear of this phytoclast type, which partially obscures palynomorphs. Two samples of the Middle Jurassic Grantham Formation of eastern England were processed using H2O2 and HCl/HF. The two methods produced abundant palynofloras of similar palynomorph concentrations. Two dinoflagellate cyst acmes within the Danian (Paleogene) part of the López de Bertodano Formation of Seymour Island, Antarctica were also tested using H2O2, (NaPO3)6, and HCl/HF. TheH2O2 preparation completely destroyed the dominant taxon, Palaeoperidinium pyrophorum, in one sample. By contrast, the (NaPO3)6 and HCl/HF preparations produced abundant, fully representative palynofloras. In the other sample, the acme of Spinidinium spp. is completely unaffected by the H2O2 preparation procedure. The final sample of this study is an unconsolidated clay of Late Pleistocene age from offshore Scotland. Both the H2O2 and HCl/HF preparations proved similar in both taxonomic content and overall palynomorph yield. The new method of preparation using hot H2O2 has proved to be extremely effective. In particular, it appears to be superior to the (NaPO3)6 procedure for indurated lithotypes. However care should be taken because H2O2 can destroy certain dinoflagellate cysts and kerogen macerals which are especially susceptible to oxidation. Further development work, and more comparative testing of the H2O2, (NaPO3)6, and HCl/HF procedures, should be undertaken

Paleoecology of the Maastrichtian and Danian sediment at North of Central Alborz, Iran, based on Planktonic foraminifera

In order to study the fossil contents of the Ziarat-kola section for biostratigraphical purposes the 212 meters was sampled at Central Alborz. The sequence is mainly made up of monotonous grey- green to light grey marl. Based on Planktonic foraminifera age of Maastrichtian-Danian is determined to the section.

Four zones were determined by the benthic foraminifera morphogroup for showing oxygen and productivity change. The approximate low oxygen and high food supply has been indicates zone of one that increase infauna to epifauna morphotype percent is low (nearness 60% infouna, 40% epifauna). In zone two, with due attention to equal percent of Epifauna ratio to infauna, intermediate oxygen and food supply is anticipated. The decrasing epifauna foraminifera and increasing infauna demonstrates low oxygen and high food supply condition at zone of three. In zone four, increasing epifauna (approximate 90 percent) that are indicated high oxygen condition and low food supply. Analysis of planktonic foraminifera assemblage at this section with Cretaceous biostratigraphical provinces is indicating a close similarity with Tethyan provinces

Faunal and erosional events in the Eastern Tethyan Sea across the K/T boundary

A regional pattern of three closely spaced erosional events at and above the K/T boundary was determined from six Cretaceous/Tertiary boundary sections in the Negev of Israel. The sections were collected from locations throughout the central and northern Negev. All sections are lithologically similar. The Maastrichtian consists of a sequence of limestone beds intercalated with thin marly beds. In some sections, the last limestone bed is followed by 1 to 2 m of calcareous marls grading upwards into several meters of grey shale. In other sections the limestone bed is followed directly by grey shale with the contact containing particles of limestone and marl. A 5 to 20 cm thick dark grey organic-rich clay layer is present about 1.5 to 2.5 m above the base of the grey shale. The grey shale grades upwards into increasingly carbonate rich marls. No unconformities are apparent in field outcrops. During field collection the dark grey clay layer was believed to represent the K/T boundary clay. Microfossil analysis however identified the boundary at the base of the grey shale. The black shale represents a low productivity anoxic event similar to, but younger than, the K/T boundary clay in other K/T boundary sections. High resolution planktic foraminiferal and carbonate analysis of these sections (at 5 to 10 cm intervals) yield surprising results. The K/T boundary is marked by an erosional event which removed part or all of the uppermost Maastrichtian marls above the last limestone bed. Percent carbonate data for four Negev sections are illustrated and show the regional similarities in carbonate sedimentation. Faunal and carbonate data from the Negev sections thus show three closely spaced short erosional events at the K/T boundary and within the first 50,000 to 100,000 years of the Danian. These K/T boundary erosional events may represent global climatic or paleoceanographic events

Palinología e importancia paleoambiental de la Formación Tunal (Daniano) en su localidad tipo, Quebrada el Chorro (Salta, Argentina).

The palynologic investigation of samples from the Tunal Formation at El Chorro creek (Salta, Argentina) resulted in the recovery of terrestrial assemblages of pollen and spores associated with freshwater algae (Pediastrum spp. and Scenedesmus sp.). Of the 43 species of sporomorphs identified for the Tunal Formation so far, 28 species are cited here for the first time. The spores and pollen indicate a Danian age at the type locality. Sedimentary proxidata including abundant evaporites suggest intervals of at least seasonal arid environmental conditions. In contrast, the palynologic assemblages recovered from the organic rich dark shales indicate the presence of swampy areas and forests surrounding them. The dominance of Verrustephanoporites simplex Leidelmeyer (corresponding to the modern Phyllostylon, Ulmaceae) indicates abundant seasonal rainfalls, warm humid conditions and subtropical climate.La investigación palinológica de muestras extraídas de la Formación Tunal en la quebrada El Chorro (Salta, Argentina) resultó en la recuperación de una asociación de polen y esporas, juntamente con algas de agua dulce (Pediastrum spp. y Scenedesmus sp.). De las 43 especies de esporomorfos identificadas hasta el momento para la Formación Tunal, 28 se citan aquí por primera vez. Las esporas y polen indican edad Daniana en la localidad tipo. Los proxidata sedimentarios incluyendo abundantes evaporitas, sugieren intervalos al menos estacionales de condiciones ambientales áridas. Por otro lado, las asociaciones palinológicas recuperadas de las pelitas oscuras ricas en materia orgánica indican la presencia de áreas anegadas y selvas en sus alrededores. En las últimas, el predominio de Verrustephanoporites simplex Leidelmeyer (que se corresponde con el actual Phyllostylon, Ulmaceae) indica abundantes lluvias estacionales, condiciones cálido-húmedas y clima subtropicalFil: Volkheimer, Wolfang. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Novara, Martin Guillermo. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Narvaez, Paula Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Marquillas, Rosa Argentina. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentin

Lake sedimentological and ecological response to hyperthermals : Boltysh impact crater, Ukraine

Acknowledgements Initial drilling of the Boltysh meteorite crater was funded by Natural Environment Research Council (NERC) grant NE/D005043/1. The authors are extremely grateful to the valuable scientific contributions of S. Kelley and I. Gilmour. The constructive and critical reviews by M. Schuster and an anonymous reviewer greatly helped to improve this manuscript.Peer reviewedPostprin