Sökning: "granulite facies metamorphism"

Hittade 4 avhandlingar innehållade orden granulite facies metamorphism.

1. 1. Sveconorwegian orogenesis in the southwestern Baltic Shield - Zircon geochronology and tectonothermal setting of orthogneisses in SW Sweden

   Författare :Jenny Andersson; Berggrundsgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Petrology; Geologi; fysisk geografi; physical geography; Geology; structural markers; augen gneiss; orthogneiss; migmatite; ion microprobe; Pb-Pb evaporation; U-Pb; geochronology; zircon; Sweden; Mylonite Zone; Western Segment; Sveconorwegian orogen; Eastern Segment; mineralogy; geochemistry; Petrologi; mineralogi; geokemi;

   Sammanfattning : The Mylonite zone (MZ) is a prominent late-Sveconorwegian lithological terrane boundary in the SW Baltic Shield along which large-scale crustal block movements took place during the Sveconorwegian orogeny. The southern section of the MZ also defines a conspicuous metamorphic break separating upper amphibolite and high-pressure granulite facies rocks in the parautochthonous Eastern Segment (ES), from middle amphibolite facies rocks in the overlying Western Segment (WS). LÄS MER

3. 2. 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

4. 3. Chemical and isotopic records of polycyclic histories in a subducted continental crust (Dora-Maira Massif, Western Alps)

   Författare :Francesco Nosenzo; Paola Manzotti; Alasdair Skelton; Charlotte Möller; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Subduction; continental crust; polycyclic; garnet; metamorphic petrology; Geology; geologi;

   Sammanfattning : At convergent plate margin, part of the continental crust can be subducted and exhumed. During continental subduction a pre-existing crust is reworked. Remnants of an older orogen are recycled and subjected to (ultra)-high-pressure metamorphism. LÄS MER

5. 4. Mesoproterozoic crustal evolution in Southern Africa

   Författare :Åsa Pettersson; Göteborgs universitet; []
   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