King C.,16a Park Road
Stratigraphy | Year: 2012
The Paleocene interval of the Dababiya Quarry Corehole (DQC) (at Dababiya, near Luxor, Egypt) comprises mainly hemipelagic sediments (calcareous claystone, marl and chalk), deposited in outer neritic to upper bathyal environments on the southern margin of Tethys. The earliest Danian is however represented by dark gray claystone deposited in shallower, mid neritic environments. The greatest water depths were reached in the mid-Thanetian. The principles of identifying sequences and sequence tracts in hemipelagic settings are summarised. Nine depositional sequencesare tentatively differentiated at Dababiya, based mainly on sedimentology, gamma-ray and magnetic susceptibility logs and foraminiferid assemblages. Comparisons are made with depositional sequences differentiated in other low and mid-latitude areas.
Thomsen E.,University of Aarhus |
Abrahamsen N.,University of Aarhus |
Heilmann-Clausen C.,University of Aarhus |
King C.,16a Park Road |
Nielsen O.B.,University of Aarhus
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2012
The cored 154.5. m deep Kysing-4 borehole in central Jutland is unique for high northern latitudes because it comprises an almost complete Middle Eocene to lowermost Oligocene succession mostly in a highly calcareous facies with abundant well preserved microfossils and from an upper bathyal environment. It has therefore been possible to carry out biostratigraphical analyses of calcareous nannofossils, benthic and planktonic foraminifera as well as dinoflagellate cysts. In order to correlate the section to the geomagnetic polarity time scale a detailed palaeomagnetic analysis has been performed. The magnetobiostratigraphic calibration allowed a well constrained identification of nearly all magnetochrons between Chron C21n and Chron C13n. The Eocene deposits consist mostly of calcareous ooze (Søvind Marl Formation with three new members formally defined), whereas the Oligocene Viborg Formation consists of moderately calcareous mud. Overall, the lithology of the deposits is in agreement with previous interpretations of a British provenance for the Eocene deposits and a Scandinavian provenance for the Oligocene deposits. Cyclic shifts in the clay/carbonate content during the Middle Eocene (chrons C19-C17) are attributed to orbitally controlled climate shifts. Obliquity seems to have been the dominating factor, but intervals dominated by precession end eccentricity signals also occur. A 10. m thick hitherto unknown black mud (Moesgaard Member) of Scandinavian provenance and deposited very rapidly during the late Eocene Chron C16n.1n is interpreted as a precursor event to the Oligocene mode of sedimentation. Both the Moesgaard Member and the Lower Oligocene Viborg Formation are associated with sea-level falls. © 2012 Elsevier B.V.
Underwood C.J.,Birkbeck College |
Ward D.J.,Crofton Court |
King C.,16a Park Road |
Antar S.M.,Egyptian Environmental Affairs Agency |
And 2 more authors.
Proceedings of the Geologists' Association | Year: 2011
The Eocene rocks exposed in the Fayum Area, Egypt, are well known for their fossil vertebrates but in recent times the sharks and rays have been largely neglected. Extensive surface collecting, supplemented with bulk samples, has produced large collections from the Midawara, Gehannam, Birket Qarun and Qasr el-Sagha formations, spanning the Bartonian and Priabonian stages and from palaeoenvironments varying from open muddy shelf to very shallow estuarine systems. In total about 90 species of sharks and rays are recorded, many of them previously unrecognised, resulting in some of the most diverse fossil chondrichthyan assemblages known from the Tertiary. Teeth of these species suggest that they occupied a wide range of ecological niches from top predator to tiny benthic invertebrate feeder to planktivore. Many of the species are limited in their stratigraphical range and show potential to be used, at least locally, as biostratigraphical indicators for stratigraphically poorly constrained vertebrate sites elsewhere in North Africa. Distinctly different faunas from different sedimentary environments indicate a strong environmental control on the distribution of many species. © 2010.
Royse K.R.,British Geological Survey |
De Freitas M.,First Steps Ltd |
De Freitas M.,Imperial College London |
Burgess W.G.,University College London |
And 8 more authors.
Proceedings of the Geologists' Association | Year: 2012
The population of London is around 7 million. The infrastructure to support this makes London one of the most intensively investigated areas of upper crust. However construction work in London continues to reveal the presence of unexpected ground conditions. These have been discovered in isolation and often recorded with no further work to explain them. There is a scientific, industrial and commercial need to refine the geological framework for London and its surrounding area. This paper reviews the geological setting of London as it is understood at present, and outlines the issues that current research is attempting to resolve. © 2011 NERC.
Underwood C.J.,Birkbeck |
King C.,16a Park Road |
Steurbaut E.,Royal Belgian Institute Of Natural Sciences
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2013
The Late Eocene and Early Oligocene sedimentary succession in the Fayum, Egypt records the progressive development of northerly flowing Nile-type African drainage. New biostratigraphic dating of these units allows the calibration of the paleomagnetic record, the combination of dating methods enabling a detailed chronology of events to be studied. Between about 38 and 35. Ma there was a dramatic change in sedimentary regime and vast quantities of clastic material were transported into the area, smothering the underlying carbonate platform and initiating a stepwise progradation of clastic units. The sudden change in sediment availability coincides with the beginning of uplift and volcanic activity in the Turkana region of East Africa, cutting off preexisting easterly drainage from the middle of the continent. The Fayum succession therefore records the initiation of northerly drainage of central and eastern Africa, and the origins of the modern Nile watershed. The development of the current route of the Nile, with the incision of the current Nile Valley, was slightly later and related to mid Oligocene uplift of the Red Sea margins and Messinian base level fall. © 2013.