Search for dissertations about: "geochronology"

Showing result 1 - 5 of 53 swedish dissertations containing the word geochronology.

  2. 1. The evolution of lunar breccias : U-Pb geochronology of Ca-phosphates and zircon using Secondary Ion Mass Spectrometry

    Author : Fiona Karen Thiessen; Martin Whitehouse; Alexander Nemchin; Victoria Pease; Barbara Cohen; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Moon; impact breccias; Apollo missions; impact event; Late Heavy Bombardment; zircon; Ca-phosphates; U-Pb; SIMS; geochronology; Geology; geologi;

    Abstract : Planetary bodies in our Solar System, including the Moon, were exposed to an intense asteroid bombardment between ~4.5-3.8 Ga, shaping their surfaces and leaving visible “footprints” in the form of large impact basins. The end of this period (~4. READ MORE

  4. 2. New constraints on paleoreconstructions through geochronology of mafic dyke swarms in North Atlantic Craton

    Author : Mimmi Nilsson; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; baddeleyit; U-Pb; geokronologi; large igneous province; mantelplym; superkontinent; paleorekonstruktion; North Atlantic craton; baddeleyite; Large Igneous Province; Mantle plume; supercontinent; paleoreconstruction; U-Pb; geochronology; North Atlantic craton;

    Abstract : Earth history is punctuated by a series of events of supercontinent amalgamation and break-up. Fragments of old continents display rifted margins and orogenic sutures that testify their involvement in supercontinent cycles. READ MORE

  5. 3. Constraining the timing of veins, faults and fractures in crystalline rocks by in situ Rb-Sr geochronology

    Author : Mikael Tillberg; Henrik Drake; Mats E. Åström; Thomas Zack; Johan Hogmalm; Bjarne Almqvist; Linnéuniversitetet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; geochronology; brittle deformation; crustal fluids; mineral precipitation; ancient microbial activity; Precambrian craton; Scandinavia; Natural Science; Naturvetenskap;

    Abstract : Precambrian cratons are continent cores archiving the oldest crustal histories on Earth. The crystalline basement of cratons is typically characterized by complex arrays of multiple fracture and fault generations hosting minerals formed by fluids flowing through fracture networks. READ MORE

  6. 4. Geochronology of Tectonothermal Events in the Parautochthonous Eastern Segment of the Sveconorwegian (Grenvillian) Orogen, Southwestern Sweden

    Author : Ulf Söderlund; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Sveconorwegian; SW Sweden; Eastern Segment; geochronology; U-Pb; zircon; titanite; polymetamorphic; high-grade; Geology; exhumation; physical geography; Geologi; fysisk geografi;

    Abstract : Timing of deformation and metamorphism yield important information for understanding the development of orogenic processes and correlation of mobile belts and continents. This thesis adds new geochronological data constraining the age of protoliths and events of reworking in the frontal region of the c. 1.2-0. READ MORE

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

    Author : Jenny Andersson; Berggrundsgeologi; []
    Keywords : 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;

    Abstract : 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). READ MORE