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

• Main Author: Forbes Halldén, Malvina
• Format: Bachelor Thesis
• Language: English
• Published: Stockholms universitet, Institutionen för geologiska vetenskaper 2019
• Subjects: geology; geochemistry; spinel; Cr-spinel; chromite; SEM; scanning electron microscope; electron microprobe; EMP; electron probe microanalyzer; EPMA; electron micro probe analyzer; EMPA; petrogenetic indicator; microscopy; alteration; Franklinian Mobile Belt; Kulutingwak Formation; Clements Markham fold belt; Pearya; Paleozoic; suprasubduction zone; SSZ; island arc; IA; Arctic Canadian Archipelago; Ellesmere Island; Canada; 2017 Circum-Arctic Structural Events Expedition 19; Memorial University of Newfoundland; geologi; geokemi; spinell; Cr-spinell; kromit; svepeletronmikroskopi; elektronmikrosondanalys; petrogenetisk indikator; mikroskopi; Kulutingwak-formationen; Paleozoikum; suprasubduktionszon; Arctic; Clements Markham; Markham; Canadian Archipelago; University of Newfoundland
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-178470

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.