Sökning: "crustal structure"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden crustal structure.

  1. 1. Geochronology of impact structures - constraining syn- and post-impact processes using the 40Ar/39Ar and U-Pb techniques

    Författare :Maria Herrmann; Berggrundsgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Impact structure; Dating impact events; 40Ar 39Ar dating; U-Pb dating; Siljan impact structure; Mien impact structure; Hummeln impact structure; Puchezh-Katunki impact structure;

    Sammanfattning : The discovery, at the beginning of the 20th century, that elements can transform into other elements, due to the spontaneous decay of an instable to a stable atomic nuclei, gave rise to a powerful source for age information in many fields of earth science. For impact structures, it is crucial to establish well-defined and precise ages in order to understand how impact events affect the Earth’s geo and biosphere and also with regard to possible future events that can have devastating effects on our civilization. LÄS MER

  3. 2. Seismicity and crustal structure in Iceland

    Författare :Claudia Abril; Ólafur Gudmundsson; Vala Hjörleifsdóttir; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earthquake relocation; local earthquake tomography;

    Sammanfattning : The main goal of this Ph.D. thesis is to improve locations of earthquake hypocenters and to resolve heterogeneous crustal structure and its effects on travel times. The data and case studies are drawn from the Icelandic national SIL network and the temporary NICE project deploy-ment in the Tjörnes Fracture Zone. LÄS MER

  4. 3. Seismic Studies of Paleozoic Orogens in SW Iberia and the Middle Urals

    Författare :Artem Kashubin; Christopher Juhlin; Lars Nielsen; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reflection seismics; Traveltime tomography; Uralian orogeny; Variscan orogeny; Crustal structure; Geophysics; Geofysik;

    Sammanfattning : Controlled source seismic methods were employed in this study to investigate the reflectivity and velocity structure of two Hercynian orogens – the Uralides and Variscides. Conventional common depth point (CDP) sections from five reflection seismic campaigns and a velocity model obtained from tomographic inversion of wide-angle observations were the main datasets studied from the Middle Urals. LÄS MER

  5. 4. Geophysical Studies Bearing on the Origin of the Arctic Basin

    Författare :Nina Lebedeva-Ivanova; Christopher Juhlin; David Gee; Ruth Jackson; Uppsala universitet; []
    Nyckelord :refraction seismic; reflection seismic; crustal structure; Arctic Ocean; Amerasia Basin.; Geofysik med inriktning mot seismologi; Geophysics with specialization in Seismology;

    Sammanfattning : Deep troughs and ridges of the Arctic Basin are some of the least known features of the Earth's crust. Some of the ridges, eg. Chukchi and Nordwind, are connected directly to the continental shelves and are certainly submarine promontories of the latter. LÄS MER

  7. 5. Some aspects of body-wave spectra in crustal structure studies

    Författare :Lap Sau Leong; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : .... LÄS MER