Sökning: "Early Proterozoic"

Visar resultat 6 - 10 av 16 avhandlingar innehållade orden Early Proterozoic.

1. 6. Evolution of the rifted and subducted Late Proterozoic to Early Paleozoic Baltoscandian margin in the Torneträsk section, northern Swedish Caledonides

   Författare :Benno Kathol; Stockholms universitet; []
   Nyckelord :;

   Sammanfattning : .... LÄS MER

3. 7. Unlocking the hidden diversity of organic-walled microfossils from the early Cambrian of North Greenland

   Författare :Elise Wallet; Sebastian Willman; Ben Slater; Graham Budd; Charles H. Wellman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cambrian; acritarchs; organic-walled microfossils; small carbonaceous fossils; Greenland; diversity; disparity; taxonomy; taphonomy; Crustacea; plankton; Historical Geology and Paleontology; Historisk geologi och paleontologi;

   Sammanfattning : The early Cambrian Buen Formation of North Greenland is celebrated for hosting one of the oldest Cambrian Burgess Shale-type deposits known to date – the Sirius Passet Lagerstätte. Further south in a shallower shelf facies belt, the Buen Formation yielded organic-walled microfossils (OWMs) that were originally described with a focus on acritarchs. LÄS MER

4. 8. Disturbance of Pb, Sr, and Nd isotope systems related to medium and low grade metamorphism illustrated with data from the polymetamorphic Early Proterozoic (Rombak) - Sjangeli basement window of the Caledonides of Northern Sweden

   Författare :Rolf Romer; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

   Sammanfattning : The Sjangeli supracrustal belt forms the easternmost belt of a series approximately N-S striking, steeply dipping Early Proterozoic belts of the Rombak-Sjangeli basement window, which formed in an island arc setting. The volcanic units of the Sjangeli area consist of metatuffs, which contain abundant Cu-mineralizations, metalava flows and pillowed metalavas and are intercalated with banded carbonatesilicate rocks and micaschists, which contain various amounts of volcanic material. LÄS MER

5. 9. Vaikijaur, a palaeoproteroic Cu-Au porphyry style mineralization in the Jokkmokk granitoid at the archaean-proterozoic boundary in northern Sweden

   Författare :Christina Lundmark; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Malmgeologi; Ore Geology;

   Sammanfattning : The Jokkmokk granitoid is exposed in a plutonic massif northwest of Jokkmokk in northern Norrbotten. It is light grey to white, fine-grained, with megacrysts of feldspar and glomeroporphyritic hornblende and biotite. Small enclaves of mafic rocks and synplutonic mafic dykes are products of mingling with a coeval and possibly cogenetic mafic magma. LÄS MER

7. 10. Evolution of the earliest molluscs

   Författare :Alexander P. Gubanov; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Geovetenskap; Earth sciences; Geovetenskap; Historical Geology and Paleontology; historisk geologi och paleontologi;

   Sammanfattning : The first helcionelloid molluscs appeared in the late Vendian and were forerunners ofthe sudden molluscan diversification of the Cambrian explosion. The diversification ofMollusca coincided with global changes in the lithosphere, hydrosphere, atmosphere,and biosphere coincident with the break-up of the Late Proterozoic supercontinentRodinia, a distinct shift in oceanic water geochemistry, and the sudden abundance ofshelled multicellular organisms. LÄS MER