Sökning: "Eocene"

Visar resultat 1 - 5 av 25 avhandlingar innehållade ordet 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 :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

3. 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

4. 3. Atmospheric dynamics and the hydrologic cycle in warm climates

   Författare :Henrik Carlson; Rodrigo Caballero; Johan Nilsson; Jonathan L. Mitchell; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; superrotation; early Eocene; warm climates; Madden-Julian Oscillation; the hydrologic cycle; vegetation sensitivity; large-scale circulation; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

   Sammanfattning : Past warm climates represent one extreme of Earth's known climate states. Here, we study warm climates in both idealized simulations and full-complexity general circulation model (GCM) simulations of the early Eocene epoch, approximately 50 million years ago. LÄS MER

5. 4. How were high-pressure rocks exhumed in Naxos, Greece?

   Författare :Alexandre Peillod; Uwe Ring; Johannes Glodny; Alasdair Skelton; Joakim Mansfeld; Jaroslaw Majka; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; extrusion wedge Naxos petrology metamorphism; Mineralogy; Petrology and Geochemistry; mineralogi; petrologi och geokemi;

   Sammanfattning : Combining petrological and geochronological data we were able to show that rocks in south Naxos completed a full blueschist-/greenschist-facies metamorphic loop in about 10 Myr, distinctly faster than hitherto believed. We show that the high-pressure rocks reached peak pressure (16.3±0.9 kbar - 619 ±32°C) between 40. LÄS MER

7. 5. Depositional environments and processes across regressive to transgressive turnarounds, examples from the Devonian Baltic Basin and the Eocene Central Basin of Spitsbergen

   Författare :Anna Pontén; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : .... LÄS MER