Sökning: "crustal reworking"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden crustal reworking.

  1. 1. Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems

    Detta är en avhandling från Department of Geology, Lund University

    Författare :Andreas Petersson; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; crustal reworking; Proterozoic; O-isotopes; Lu–Hf; U–Pb; zircon; Crustal growth;

    Sammanfattning : To understand the growth of continental crust, the balance between juvenile mantle derived extraction, infracrustal reworking and crustal recycling, needs to be estimated. Since the beginning of the century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address these questions have increased exponentially. LÄS MER

  2. 2. Crustal evolution of the Arabian–Nubian Shield Insights from zircon geochronology and Nd–Hf–O isotopes

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Fitsum Girum Yeshanew; Victoria Pease; Martin J. Whitehouse; Robert J. Stern; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Gondwana; Arabian–Nubian Shield; Azania; zircon U–Pb–O–Hf isotopes; Nd isotopes; Cambrian Sandstones; juvenile; pre–Neoproterozoic; reworking; Geology; geologi;

    Sammanfattning : The Arabian–Nubian Shield (ANS) represents a major site of juvenile Neoproterozoic crustal addition on Earth and documents Neoproterozoic tectonics bracketed by two supercontinent cycles, namely the fragmentation of Rodinia and the amalgamation of Gondwana. There is general consensus that the ANS formed by juvenile magmatic arc accretion and subsequent shield–wide post–tectonic magmatism. LÄS MER

  3. 3. Mesoproterozoic crustal evolution in Southern Africa

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Åsa Pettersson; Göteborgs universitet.; Gothenburg University.; [2008]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Namaqua-Natal province; Mezoproterozoic; geochronology; U-Pb zirkon dating; Sm-Nd model ages; Ar-Ar dating; Southern Africa;

    Sammanfattning : The objects of this thesis were to use geochronology to investigate crustal evolution of part of Southern Africa that formed during a global event, resulting in the ~1 Ga supercontinent Rodinia. The timing of assembly by continent-continent collisions and the position of the individual continental blocks of this ancient landmass is still largely unknown. LÄS MER

  4. 4. Proterozoic crustal evolution in southcentral Fennoscandia

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Karin Appelquist; Göteborgs universitet.; Gothenburg University.; [2010]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Transscandinavian Igneous Belt; TIB; Eastern Segment; Habo Volcanic Suite; Malmbäck Formation; U-Pb zircon ion probe dating; Nd isotopes; geochemistry; Hallandian; Danopolonian;

    Sammanfattning : The Transscandinavian Igneous Belt (TIB) and the Eastern Segment of the Southwest Scandinavian Domain reflect advanced stages of continental growth within the Fennoscandian Shield. The relationship between the two units is not clear, mainly because N-S trending shear zones of the Protogine Zone transect the border zone. LÄS MER

  5. 5. The Mesoproterozoic Hallandian event - a region-scale orogenic event in the Fennoscandian Shield

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Linus Brander; Göteborgs universitet.; Gothenburg University.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fennoscandian Shield; Hallandian orogeny; Eastern Segment; Protogine Zone; U-Pb geochronology; zircon; baddeleyite; Nd-isotopes; Hf-isotopes; tectonic model;

    Sammanfattning : The Sveconorwegian Province occupies the southwestern part of the Fennoscandian Shield. The easternmost tectonic unit of the Province is the 1710-1660 Ma parautochthonous Eastern Segment, which bears the imprint of at least two metamorphic events; the 1460-1380 Ma Hallandian and the 1150-970 Ma Sveconorwegian. LÄS MER