Hassan Khozyem

Palaeoenvironmental and climatic changes during the Palaeocene–Eocene Thermal Maximum (PETM) at the Wadi Nukhul Section, Sinai, Egypt

The Palaeocene–Eocene Thermal Maximum (PETM) interval at the Wadi Nukhul section (Sinai, Egypt) is represented by a 10 cm thick condensed clay-rich layer corresponding to the NP9a–NP9b nannofossil subzone boundary. The Wadi Nukhul Palaeocene–Eocene boundary (PEB) is characterized by (1) an abrupt negative excursion in carbonate and organic carbon isotope ratios (−6‰ in δ13Ccarb and −2‰ δ13Corg), (2) an abrupt persistent negative shift in organic nitrogen isotope values (δ15Norg), (3) a significant increase in phosphorus concentrations just above the carbon isotope excursion, (4) a decrease in carbonate content and significant increase in kaolinite and (5) high vanadium and low manganese contents coincident with the occurrence of framboidal pyrite. The abrupt correlative isotopic excursions of δ13Ccarb, δ13Corg and δ15N suggest that the lowermost part of the PETM is missing. The decrease in carbonate content indicates dilution by high detrital input triggered by acid weathering and carbonate dissolution in response to increased atmospheric CO2 resulting from the oxidation of methane. The sudden increase in kaolinite content reflects a short-lived change to humid conditions. The δ15N values close to 0‰ above the PEB suggest a bloom of N2-fixing cyanobacteria. Increased bacterial activity may be either the cause or the result of the anoxia locally associated with the PETM.

Chicxulub impact spherules in the North Atlantic and Caribbean: age constraints and Cretaceous–Tertiary boundary hiatus

The Chicxulub impact is commonly believed to have caused the Cretaceous–Tertiary boundary mass extinction and a thin impact spherule layer in the North Atlantic and Caribbean is frequently cited as proof. We evaluated this claim in the seven best North Atlantic and Caribbean Cretaceous–Tertiary boundary sequences based on high-resolution biostratigraphy, quantitative faunal analyses and stable isotopes. Results reveal a major Cretaceous–Tertiary boundary unconformity spanning most of Danian subzone P1a(1) and Maastrichtian zones CF1–CF2 (~400 ka) in the NW Atlantic Bass River core, ODP Sites 1049A, 1049C and 1050C. In the Caribbean ODP Sites 999B and 1001B the unconformity spans from the early Danian zone P1a(1) through to zones CF1–CF4 (~3 Ma). Only in the Demerara Rise ODP Site 1259B is erosion relatively minor and restricted to the earliest Danian zone P0 and most of subzone P1a(1) (~150 ka). In all sites examined, Chicxulub impact spherules are reworked into the early Danian subzone P1a(1) about 150–200 ka after the mass extinction. A similar pattern of erosion and redeposition of impact spherules in Danian sediments has previously been documented from Cuba, Haiti, Belize, Guatemala, south and central Mexico. This pattern can be explained by intensified Gulf stream circulation at times of climate cooling and sea level changes. The age of the Chicxulub impact cannot be determined from these reworked impact spherule layers, but can be evaluated based on the stratigraphically oldest spherule layer in NE Mexico and Texas, which indicates that this impact predates the Cretaceous–Tertiary boundary by about 130–150 ka.

Response of terrestrial environment to the Paleocene-Eocene Thermal Maximum (PETM), new insights from India and NE Spain

The late Paleocene - Early Eocene boundary (56Ma) is marked by the warmest climate period of the Cenozoic, known as the Paleocene-Eocene Thermal Maximum (PETM). Most notably, the culprit behind it was a massive injection of heattrapping greenhouse gases into the atmosphere and oceans, comparable in volume to what our persistent burning of fossil fuels could deliver in coming centuries. The response of the oceanic and continental environments to the PETM is different. Many factors might control the response of the environments to the PETM such as paleogeography, paleotopography, paleoenvironment, and paleodepth. Herein, we present two different examples from terrestrial environment, their correlation with the marine record and their response to the PETM warming. In northwestern India, the establishment of wetland conditions and related thick lignite accumulations reflect the response of the continental environments to the PETM. This continental climatic shift towards more humid conditions led to migration modern mammals northward following the migration of the climatic belts. What remains uncertain is the timing and tempo of this mammal migration event and whether it originated in Asia or more specifically out of India. Biostratigraphy and carbon isotope analyses in three lignite mines located in NW India reveal the presence of both PETM and ETM2 organic carbon isotope negative excursions and demonstrate that modern mammals appeared in India after the PETM. Relative ages of this mammal event based bio-chemoand paleomagnetic stratigraphy support a migration path originating from Asia into Europe and North America, followed by later migration from Asia into India.

Mineralogy and Geochemistry of the Numidian Formation (Central-Northern Sicily): intra-formation variability and provenance evaluation

Mudrocks and sandstones of Numidian Formation in Sicily have been analysed for mineralogical, petrographic, major element and selected trace element compositions to constrain the intraformational variability and the sediment provenance. The mudrocks are characterized by a kaolinite-rich signature while the sandstones have a quartz-arenitic composition. The high Chemical Index of Alteration and Plagioclase Index of Alteration strongly suggest that recycling processes have been responsible for the present compositions. The mudrocks geochemical data suggested a compositional variability function of the paleogeographic depositional environments. In particular, the Numidian Formation of the more external Serra Del Bosco Unit is affected by the terrigenous contribution of epicontinental-type sediments. With regard to provenance, the geochemical data indicate a derivation from post-Archean sedimentary siliciclastic rocks. The contribution of African cratonic sediments was confirmed by the trace elements ratios and by the end-member modelling processed on mudrocks compositional data. In particular the suitability of the Nubian sediments as one of the sources of sediment supply is also attested.

Toward a better understanding of Paleocene-Eocene Thermal Maximum: A multidisciplinary record from Dababiya GSSP, Luxor, Egypt

The Paleocene-Eocene thermal maximum (PETM) shows an extraordinary drop in both δ 13 Ccarb and δ 13 Corg values, suggesting that a massive amount of 12 C-rich carbon dioxide was released into the atmosphere in a very short time (on the order of few hundred ky). The Dababiya GSSP (Luxor, Egypt) is thought to be the most complete known PETM section. The expanded sedimentary record of the Dababiya GSSP improves our understanding of the processes leading to the PETM events. Our multiproxy dataset, which includes geochemistry, mineralogy, micropaleontology and sedimentology, provided the following crucial clues for the PETM interval at Dababiya GSSP (Fig. 1). The Dababiya GSSP is deposited in the deepest part of an asymmetric submarine channel as indicated by the paleotopography, and absence of uppermost Paleocene and lowermost Eocene sediments from the Eastern section located 25m away from the main GSSP outcrop (Fig.1). At 50 m to the NW, the sediment beds thin out and finally disappear at about 150 m from the main GSSP outcrop. Thus, the Dababiya GSSP represents a localized expanded PETM sequence with a maximum extent of about 200m. At the GSSP, the PaleoceneEocene boundary (PEB) coincides therefore with a sequence Toward a better understanding of Paleocene-Eocene Thermal Maximum: A multidisciplinary record from Dababiya GSSP, Luxor, Egypt