The Mesoarchaean Akia terrane, West Greenland, revisited: New insights based on spatial integration of geophysics, field observation, geochemistry and geochronology
نویسندگان
چکیده
The northern part of the North Atlantic Craton (NAC) in southern West Greenland comprises a large tract exposed Meso-Neoarchaean continental crust, divided into ca 3300–2900 Ma Akia and 2900–2500 Tuno terranes. We combine aeromagnetic, stream sediment geochemical, new litho-chemical zircon geochronological data with previously published to re-evaluate crustal architecture evolution terrane its boundary towards terrane. recognised, but overlooked, Alanngua complex, situated between terranes is bounded by aeromagnetic lineaments interpreted as Neoarchaean shear zones has distinct spectrum magmatic metamorphic ages that are rare complex components derived from both tectonic melange created during assembly NAC. Within terrane, chemistry orthogneiss samples indicate percentage too mafic classify TTG s.s., implying not only partial melting also some yet unaddressed mantle involvement necessary their formation. Previous models for generation ca. 3015–2990 quartz-dioritic Finnefjeld Taserssuaq complexes conflict geochemical variation. argue may be genetically linked buried gabbro-dioritic rocks indicated strong response. Formed at same time carbonatite, high-Mg gabbro tonalite-trondhjemite, we propose this wide was formed lithospheric response asthenospheric upwelling possibly an extensional setting. Periods extensive magmatism were recognised 3220–3180 3070–2970 Ma. now subdivide latter period three episodes: juvenile basaltic-andesitic volcanism 3070–3050 Ma; tonalitic dioritic plutonism 3050–3020 Ma, gabbroic-dioritic plus tonalitic-trondhjemitic 3020–2985 This last episode immediately followed reworking collision 2980–2950
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ژورنال
عنوان ژورنال: Precambrian Research
سال: 2021
ISSN: ['1872-7433', '0301-9268']
DOI: https://doi.org/10.1016/j.precamres.2020.105958