Sökning: "late Eocene"

Visar resultat 6 - 10 av 12 avhandlingar innehållade orden late Eocene.

1. 6. Provenance of the pre-Quaternary aeolian dust deposits of East Asia

   Författare :Katja Bohm; Thomas Stevens; Anu Kaakinen; Alex Pullen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chinese Loess Plateau; Red Clay; mineral dust; sediment provenance; detrital zircon; detrital rutile; Neogene; Paleogene; Earth Science with specialization in Physical Geography; Geovetenskap med inriktning mot naturgeografi;

   Sammanfattning : Atmospheric mineral dust is a key component in the climate system, but its effect on and response to climate changes are poorly understood, especially over long timescales. This thesis investigates the sources of late Paleogene and Neogene dust deposits that formed under warmer-than-present global climates in the northern Chinese Loess Plateau (CLP) region in mid-latitude East Asia. LÄS MER

3. 7. Cryptic Orogeny : uplift of the Al Hajar Mountains at an alleged passive margin

   Författare :Reuben Johannes Hansman; Ring Uwe; Joachim Jacobs; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; uplift; mountains; structural; low-temperature; thermochronology; dating; fission-track; U-Th He; U-Pb; calcite; structure-from-motion; photogrammetry; UAV; trishear; fault-propagation; Hafit; Al Hajar Mountains; United Arab Emirates; Oman; Geology; geologi;

   Sammanfattning : Mountains evolve and grow because of the large forces that occur from the collision of tectonic plates. Plate boundaries change and move through time, and regions that were once stable, shallow-marine environments can be dragged into subduction zones and get transformed into vast mountain ranges. LÄS MER

4. 8. The flux of extraterrestrial spinels to Earth associated with He-3 anomalies in Cenozoic and Ordovician sediments

   Författare :Samuele Boschi; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Chromite; He-3 anomaly; Cenozoic; mid-Ordovician; asteroid breakup; ordinary chondrites; Popigai ejecta; iridium anomaly; Zircons; ice age;

   Sammanfattning : The main goal of this thesis is to reconstruct the flux of extraterrestrial matter to Earth in specific time intervals of our past in order to add an astronomical dimension to the understanding of Earth's history. To accomplish this, extraterrestrial chrome-spinel grains have been extracted and analysed. LÄS MER

5. 9. An attempt based on an interpretation of multichannel reflection seismic data to delineate sedimentary sequences, structures and evolution in the part of the Western Barents Sea 72° - 74°N and 10° - 17°E

   Författare :Lars Ole Boldreel; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Tillämpad geofysik; Applied Geophysics;

   Sammanfattning : This thesis is an attempt to throw further light on the structural development of the passive continental margin of the Western Barents Sea in the area from 72000'N to 74000'N and from 17000'E to 10000'E. It is based mainly on multichannel reflection seismics but available aeromagnetic, shipborne magnetic and free-air gravimetric data have also been analyzed. LÄS MER

7. 10. Systematics and assessment of the chemosynthetic bivalve family Vesicomyidae

   Författare :Frida Hybertsen; Steffen Kiel; Helen Coxall; Elizabeth Harper; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Cenozoic; deep sea; hydrocarbon seeps; chemosynthetic; Bivalvia; Vesicomyidae; maringeologi; Marine Geology;

   Sammanfattning : The deep ocean has fascinated researchers for centuries with discoveries of new ecosystems and species, yet there are still many biogeographic and evolutionary questions unanswered. Along active and passive tectonic margins, specialized ecologies thrive in a symbiosis between chemosynthesizing bacteria and their host animals. LÄS MER