Sökning: "late Eocene"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden late Eocene.

  1. 1. Late Eocene through Oligocene calcareous nannofossils from the paleo-equatorial Pacific Ocean – taxonomy, preservation history, biochronology and evolution

    Författare :Teodora Blaj; Jan Backman; Jorijntje Henderiks; Isabella Raffi; Paul Bown; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; marine sediments; calcareous nannofossils; late Eocene; Oligocene; biochronology; evolution; morphometry; taxonomy; ODP Leg 199 Site 1218; paleo-equatorial Pacific Ocean; Historical geology and palaeontology; Historisk geologi och paleontologi; Marine Geoscience; marin geovetenskap;

    Sammanfattning : This study aims to unravel the ecological and evolutionary dynamics within the calcareous nannofossil communities at the Eocene/Oligocene (E/O) transition and during the Oligocene time when Cenozoic 'icehouse' conditions were established. The main question this study aims to answer is whether the changes in the nannofossil assemblages were controlled by intrinsic evolutionary trends or if the changes were controlled by environmental factors such as changes in temperature and nutrient availability in the surface water. LÄS MER

  2. 2. The Greenhouse - Icehouse Transition : a dinoflagellate perspective

    Författare :Caroline A. van Mourik; Henk Brinkhuis; Malgorzata Moczydlowska-Vidal; Stockholms universitet; []
    Nyckelord :Eocene - Oligocene; dinoflagellate cysts; biostratigraphy; paleoecology; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : Through the analysis of the stratigraphic and spatial distribution of organic walled dinoflagellate cysts (dinocysts) from climatologically and oceanographically key sites, this project aims to contribute to a better understanding of the Eocene-Oligocene (E/O) environmental changes and their timing. A central issue is to identify the global environmental changes which are responsible for the Eocene cooling and its underlying mechanisms with the focus on the Oligocene isotope-1 (Oi-1) event, thought to mark the onset of major Antarctic glaciation. LÄS MER

  3. 3. Evolutionary Progression of the Iconic Australasian Kangaroos, Rat-Kangaroos, and their Fossil Relatives (Marsupialia: Macropodiformes)

    Författare :Wendy den Boer; Benjamin Kear; Christine Janis; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; macropodiforms; kangaroos; rat-kangaroos; fossil ancestors; post-cranial; eco-morphology; systematic; phylogeny; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    Sammanfattning : The exceptionally diverse macropodiform’s (kangaroos, rat-kangaroos and their fossil allies) currently have a fossil record that spans from the late Oligocene to the Holocene with an Australasian widespread fossil occurence. The origins of the macropodiforms are believed to have been during the Eocene possibly having split from the Phalangeridae. LÄS MER

  4. 4. Geological development of the East African coastal basin of Tanzania

    Författare :Samson Mpanda; Ole Veibaeck; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; Marine Geology; seismic methods; seismic stratigraphy; multichannel seismic recordings; tectonic development; Karoo; Mesozoic; Tertiary; East Africa; Tanzania; Earth sciences; Geovetenskap; allmän och historisk geologi; General and Historical Geology;

    Sammanfattning : The East African coastal basin of Tanzania, which is characterised by an extensional tectonic style, is located along the passive continental margin of the western Indian Ocean. The present study is concerned with the Mafia Island and the Mafia Channel which together form a subbasin within the north-south elongated coastal sedimentary basin of Tanzania. LÄS MER

  5. 5. Cenozoic landscape evolution in northern Sweden : Geomorphological interpretation within a GIS-framework

    Författare :Karin Ebert; Clas Hättestrand; Paul Bishop; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Long-term geomorphology; northern Sweden; base-level surface; inselbergs; digital elevation models; field observations; Physical geography; Naturgeografi; naturgeografi; Physical Geography;

    Sammanfattning : The large-scale bedrock landscape in northern Sweden has a complex evolution history of planation, uplift, transgression, burial, weathering, and erosion. The aim of this thesis is to examine the long-term development of the area. Terms for base-level surfaces in the area are defined. LÄS MER