Sökning: "Early Proterozoic"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Early Proterozoic.

  1. 1. Phosphate and Arsenic Cycling under Experimental Early Proterozoic Marine Conditions

    Detta är en avhandling från Stockholm : Stockholm University

    Författare :Christoffer Hemmingsson; Stockholms universitet.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; DIP; Early Proterozoic; coprecipitation; adsorption; Iron formations; BIF; geokemi; Geochemistry;

    Sammanfattning : Nutrient dynamics in the Archean-Paleoproterozoic oceans strongly influenced primary productivity and the rise of atmospheric O2. Reconstructing the cycling of key nutrients such as dissolved inorganic phosphate (DIP) at this time is important for our understanding of the timing, rate and extent of atmospheric oxygenation at this time. LÄS MER

  2. 2. Palaeobiology and taphonomy of early problematic fossils

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Mónika Marti Mus; Uppsala universitet.; [2001]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Geovetenskap; NATURAL SCIENCES Earth sciences; NATURVETENSKAP Geovetenskap; Historical Geology and Paleontology; Historisk geologi och paleontologi;

    Sammanfattning : Extinct organisms that cannot be accommodated in any extant phylum are generally referred to as "problematic fossils". They are more numerous in progressively older strata and constitute an important part of the late Proterozoic and early Palaeozoic biota. LÄS MER

  3. 3. Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Heda Agić; Uppsala universitet.; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; microfossils; eukaryotes; Mesoproterozoic; Neoproterozoic; Cambrian; Ordovician; palaeobiology; biostratigraphy; phylogeny; China; Estonia; Siberian Platform; prasinophytes; microstructure; Raman spectroscopy; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

    Sammanfattning : One of the most important events in the history of life is the evolution of the complex, eukaryotic cell. The eukaryotes are complex organisms with membrane-bound intracellular structures, and they include a variety of both single-celled and multicellular organisms: plants, animals, fungi and various protists. LÄS MER

  4. 4. Single fluid inclusion analysis using ToF-SIMS Implications for ancient Earth biodiversiy and paleoenvironment studies

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

    Författare :Sandra Siljeström; Stockholms universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ToF-SIMS; time-of-flight secondary ion mass spectrometry; fluid inclusions; biomarkers; hopanes; steranes; early life; paleoenvironment; oil; eukaryotes; NATURAL SCIENCES Earth sciences; NATURVETENSKAP Geovetenskap; Geochemistry; geokemi;

    Sammanfattning : When and how life first emerged on the Earth is an area of intense research. Signs of the first life on Earth, including morphological fossils, are scarce and hard to interpret. An alternative approach is to study organic biomarkers, which are molecular fossils commonly considered as bona fide biosignatures. LÄS MER

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

    Detta är en avhandling från Stockholm : Almqvist & Wiksell International [distributör]

    Författare :Benno Kathol; Stockholms universitet.; [1989]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : .... LÄS MER