Cr-spinels in the Franklinian Mobile Belt : a geochemical record of Paleozoic tectonics

Detta är en Kandidat-uppsats från Stockholms universitet/Institutionen för geologiska vetenskaper

Sammanfattning: The chemical compositions of Cr-spinel extracted from mafic and ultramafic rocks collected on Ellesmere Island in the Arctic Canadian Archipelago were obtained through electron microprobe analyses. The extensively altered rocks are sampled from rock units in the Franklinian MobileBelt, which is representative of a Paleozoic tectonically active oceanic regime of which little is presently known. The evolutionary trend of the ocean basin may have changed when the exotic crustal fragments now called the Pearya terrane were accreted to the North American margin through poorly understood tectonic processes sometime prior to the Devonian. The results of the analysis are used to determine the tectonic setting associated with the rock units. The results reveal that the Cr-spinels predominantly have a supra-subduction zone geochemical signature, suggesting an island arc origin.

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