Search for dissertations about: "Early Middle Ordovician"

Showing result 1 - 5 of 10 swedish dissertations containing the words Early Middle Ordovician.

2. 1. Trilobites from the Middle and Upper Ordovician Andersön Shale Formation in Jämtland and the equivalent Killeröd Formation in Skåne, Sweden

   Author : Kristina Månsson; Berggrundsgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; fysisk geografi; Geologi; physical geography; Geology; Sweden; Jämtland; Skåne; Upper Ordovician; Middle Ordovician; Killeröd Formation; Andersön Shale Formation; ontogeny; biostratigraphy; Trilobita; taxonomy; trilobite associations; Systematic zoology; zoogeography; Zoologisk systematik; djurgeografi; Development biology; growth animal ; embryology; Utvecklingsbiologi; ontogeni; embryologi;

   Abstract : Trilobites from the Middle and Upper Ordovician Andersön Shale Formation in Jämtland, central Sweden, and the Middle Ordovician Killeröd Formation in Skåne (Scania), southern Sweden, are revised and discussed. These formations have several genera and a few species in common, e.g. READ MORE

4. 2. Cambro-Ordovician microorganisms: acritarchs and endoliths

   Author : Martin Stockfors; Malgorzata Vidal-Moczydlowska; John S. Peel; Kenneth John Dorning; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Cambrian; Ordovician; acritarch; endolith; Kolguev Island; North Greenland; Stratigraphy; Geovetenskap; Earth sciences; Geovetenskap;

   Abstract : Organic-walled microfossils are abundant and taxonomically diverse in Cambrian-Ordovician strata; some are important for biostratigraphy and for the correlation of geological successions. New assemblages of Cambrian-Ordovician acritarchs from Kolguev Island, Arctic Russia and Middle Cambrian ichnofossils of endoliths from Peary Land, North Greenland are studied. READ MORE

5. 3. Conodont biostratigraphy, taxonomy and palaeoecology in the Darriwilian (Middle Ordovician) of Baltoscandia - with focus on meteorite and extraterrestrial chromite-rich strata

   Author : Johanna Mellgren; Berggrundsgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Conodonts; biostratigraphy; taxonomy; palaeoecology; morphometrics; extraterrestrial chromite; meteorites; Darriwilian; Middle Ordovician; Baltoscandia;

   Abstract : This thesis deals with conodont biostratigraphy and palaeoecology in the Darriwilian (Middle Ordovician) of Baltoscandia, with focus on limestone strata showing traces of the ~ 470 Ma L-chondrite parent body break-up. The evidence for this cosmic event includes abundant centimeter to decimeter-sized fossil meteorites and elevated levels of sediment-dispersed extraterrestrial L-type chromite found in a stratigraphical interval corresponding to the uppermost Lenodus antivariabilis, the L. READ MORE

6. 4. Ordovician (Billingen and Volkhov stages) Brachiopod Faunas of the East Baltic

   Author : Eva Egerquist; Lars Holmer; John S. Peel; Michael G. Bassett; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Early Middle Ordovician; Billingen Regional Stage; Volkhov Regional Stage; Diversity; Brachiopoda; Conodonta; Ostracoda; Estonia; Russia; Geovetenskap; Earth sciences; Geovetenskap;

   Abstract : Lower-Middle Ordovician (Arenig) successions in the East Baltic have been investigated for more than one hundred and fifty years. Nevertheless detailed sampling still yields new species and better knowledge of the environment in which these organisms lived. READ MORE

7. 5. Traces in Earth's geological record of the break-up of the L-chondrite parent body 470 Ma

   Author : Carl Alwmark; Berggrundsgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; L chondrite; Middle Ordovician; extraterrestrial material; meteorite flux; Sweden;

   Abstract : This thesis deals with signatures in sediments on Earth related to the L-chondrite parent body break-up event at 470 Ma. The aim of this thesis is twofold: (1) investigate if the increased flux of extraterrestrial material to Earth, following the disruption of the L-chondrite parent body included larger, asteroid-sized bodies (2) try to develop new methods and tools for finding and classifying relict cosmic material in sediments. READ MORE