|Titre||New U-Pb baddeleyite ages for Neoarchean and Paleoproterozoic mafic dyke swarms of the southern Nain Province, Labrador: Implications for possible plate reconstructions involving the North Atlantic
|Auteur||Sahin, T; Hamilton, M A|
|Source||Precambrian Research vol. 329, SI, 2019 p. 44-69, https://doi.org/10.1016/j.precamres.2019.02.001|
|Séries alt.||Ressources naturelles Canada, Contribution externe 20200273|
|Document||publication en série|
|Media||papier; en ligne; numérique|
|Lat/Long OENS|| -60.1667 -59.8333 55.5000 55.3333|
|Sujets||tectonique de plaques; filons mafiques; filons rocheux; uranium; datation au uranium-plomb; plomb; baddeleyïte; Craton de l'Atlantique du Nord; géochronologie; paléontologie; Sciences et technologie;
|Illustrations||cartes de localisation; tableaux; diagrammes Concordia; images; diagrammes de distribution des éléments; graphiques|
|Diffusé||2019 02 04|
|Résumé||(disponible en anglais seulement)|
We present ten new ID-TIMS U-Pb baddeleyite ages for late Neoarchean to Paleoproterozoic dyke swarms cutting Archean gneisses of the Hopedale block (North
Atlantic craton, NAC). An age of 2505 +/- 4 Ma for a NNE trending pyroxenite dyke represents the first date for extension-related mafic magmatism of this antiquity in the Labrador portion of the NAC. Four samples of N-S to NNE-trending Kikkertavak
dykes yield ages between 2238 +/- 6 Ma and 2216 +/- 2 Ma, defining a minimum age range and distribution for this extensive swarm. A single NNE-trending dyke is dated at 2169 +/- 13 Ma, representing a new magmatic event at this age in Nain Province,
but is equivalent in timing to the well-known Biscotasing dykes in the southern Superior craton. Three NW-trending dykes (termed Ellen Island dykes) yield ages of 2051 +/- 6 Ma, 2051 +/- 1 Ma and 2050 +/- 2 Ma, and represent part of a
newly-recognized but important swarm in southern Nain craton. The 2.05 Ga dykes better define a vast radiating fan of dykes that include Kangamiut and MD3 dykes of southern West and South-West Greenland, respectively. A U-Pb baddeleyite age of 1800
+/- 4 Ma has been obtained for a fourth, NW-trending ("Ussiranniak Lake") dyke, which also represents a newly-revealed mafic magmatic event, both in the Labrador and Greenland portions of the NAC. The results presented here are unique for Labrador,
but invite comparison with other Neoarchean and Paleoproterozoic mafic dykes elsewhere in the North Atlantic craton and other Archean cratons (e.g., Superior, Kola-Karelia, Zimbabwe). Multiple precise age matches, dyke geochemistry, and dyke
geometries for several swarms allow a preliminary level testing of possible reconstructions involving the North Atlantic and eastern Superior cratons.
|Sommaire||(Résumé en langage clair et simple, non publié et disponible en anglais seulement)|
This publication is about dating rocks in the Hopedale block, part of the North Atlantic craton (NAC), which
is a piece of Earth's ancient crust. The researchers used a method called ID-TIMS U-Pb baddeleyite dating to figure out the ages of various rock formations called dyke swarms.
They found rocks in this area that are between 2.5 billion and 1.8
billion years old. This information helps us understand when these rocks formed and the geological history of the NAC.
One significant finding is the discovery of a pyroxenite dyke with an age of 2.5 billion years, which is a first for this region
in Labrador. The study also dated several other dykes in the NAC, which gives us insights into the timing of magmatic events in this ancient part of the Earth's crust.
The scientific impact of this publication is that it contributes to our
knowledge of the geological history of the North Atlantic craton. It helps us understand how and when certain rock formations formed, which is essential for studying the Earth's ancient past and the processes that shaped our planet. The research also
suggests possible connections between different cratons, which can provide insights into the Earth's tectonic history.