Sökning: "U-Pb"

Visar resultat 21 - 25 av 41 avhandlingar innehållade ordet U-Pb.

  1. 21. Geochronology of the Oklo and Bangombé fossil natural fission reactors : tracing the effects of geological events

    Författare :Lena Zetterström Evins; Ian Williams; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Historisk geologi; Geology; geologi; geokemi; Geochemistry;

    Sammanfattning : Thesis to be publicly defended for the degree of Doctor of Philosophy, in lecture room De Geersalen, Svante Arrhenius väg 8a, Stockholm, Friday February 1, 2002 at 10.00 am. Two billion years ago, natural fission reactions took place in the Oklo and Bangombé uranium ores in Gabon, West Equatorial Africa. LÄS MER

  3. 22. Paleoproterozoic deformation in the Kiruna‑Gällivare area in northern Norrbotten, Sweden : Setting, character, age, and control of iron oxide-apatite deposits

    Författare :Joel Andersson; Tobias Bauer; Olof Martinsson; Nicholas Oliver; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kiruna; Gällivare; structural geology; Paleoproterozoic; deformation; Malmgeologi; Ore Geology;

    Sammanfattning : This thesis covers the structural evolution of the Kiruna‑Gällivare area in the northern Norrbotten ore province, Sweden. The study area hosts several economically significant iron oxide-apatite (IOA) deposits and includes the type locality for this ore type. LÄS MER

  4. 23. Pressure, temperature and time constraints on tectonic models for southwestern Sweden

    Författare :Eric Austin Hegardt; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sveconorwegian; Gothian; Hallandian; U‐Pb zircon ion probe dating; Sm-Nd garnet dating; thermobarometry; continental subduction; Eastern Segment; Median Segment; Western Segment;

    Sammanfattning : In this work, a number of key localities have been investigated in detail in order to provide precise constraints on models for the tectonic evolution of southern Sweden. The new data presented in this thesis show that there are large differences in terms of pre-Sveconorwegian tectonic evolution between the Eastern and Median-Western Segments situated on either side of the Mylonite Zone, a major shear zone as well as a structural and lithological boundary. LÄS MER

  5. 24. Provenance of late Paleozoic and Mesozoic clastic sediments of Taimyr and their significance for understanding Arctic tectonics

    Författare :Xiaojing Zhang; Victoria Pease; Arne Willner; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geology; geologi;

    Sammanfattning : The Taimyr Peninsula is a key element in the circum-Arctic region and represents the northern margin of the Siberian Craton. The Taimyr Peninsula preserves late Paleozoic through Mesozoic clasitic sedimentary successions in its Mesozoic fold belt, providing an ideal location to investigate the Mesozoic tectonic evolution associated with the opening of Amerasia Basin within a circum-Arctic framework. LÄS MER

  7. 25. 3D structural framework and constraints on the timing of hydrothermal alteration and ore formation at the Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen, Sweden

    Författare :Tobias Christoph Kampmann; Pietari Skyttä; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Malmgeologi; Ore Geology;

    Sammanfattning : The Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base and minor precious metal sulphide deposits in Sweden. LÄS MER