|Titre||Detrital-zircon provenance of a Torridonian fluvial-aeolian sandstone: the 1.2 Ga Meall Dearg Formation, Stoer Group (Scotland)|
|Auteur||Lebeau, L E; Ielpi, A; Krabbendam, M; Davis, W J|
|Source||Precambrian Research vol. 346, 0301-9268, 2020 p. 1-19, https://doi.org/10.1016/j.precamres.2020.105822|
|Séries alt.||Ressources naturelles Canada, Contribution externe 20200105|
|Document||publication en série|
|Media||papier; en ligne; numérique|
|Région||Scotland; Northern Highlands|
|Lat/Long OENS|| -7.7161 -4.5608 58.6483 56.7044|
|Sujets||datation radiométrique; datation au uranium-plomb; datations au zircon; minéraux détritiques; zircon; origine; régions émettrices; transfert des sédiments; dépôts fluviaux; dépôts éoliens; géologie du
substratum rocheux; lithologie; grès; analyses par microsonde électronique; paléocourants; paléogéographie; cadre tectonique; décrochement horizontal; evolution du bassin; Archéen; Groupe de Stoer ; Complexe de Lewisian Gneiss ; géochronologie;
sédimentologie; Sciences et technologie; Nature et environnement; Précambrien; Protérozoïque|
|Illustrations||cartes de localisation; graphiques; diagrammes|
|Diffusé||2020 06 10|
|Résumé||(disponible en anglais seulement)|
The Meall Dearg Formation is a 1.2 Ga fluvial-aeolian sandstone exposed in the northwestern Highlands of Scotland, and represents one of the least studied rock
units in the Torridonian succession, especially in terms of sedimentary provenance. Three hundred and nine detrital zircon grains were analysed from four samples of the Meall Dearg Formation using sensitive high-resolution ion microprobe, allowing
for its provenance to be resolved at the terrane scale. Ages range from c. 3,100 to c. 1,750 Ma, with dominant proportions between c. 2,900 and c. 2,650 Ma, and subordinate fractions of c. 2,500 Ma and c. 1,900 Ma. U-Pb protolith-zircon ages from
eight previous studies across the Lewisian Gneiss Complex were compiled and compared to detrital-age distributions of the Meall Dearg Formation. Strong similarities in age trends and palaeocurrent data corroborates the hypothesis of sedimentary
provenance from the Lewisian Gneiss Complex. Detritus was prevalently derived from the Rhiconich and Gruinard terranes, and subordinately from the Assynt, Gairloch (including the Loch Maree Group and Ard Gneiss), and Ialltaig terranes. Age
distributions from the fluvial and aeolian samples show near-matching distributions, indicating sediment transfer between adjacent depositional environments, and possibly derivation from similar source regions. The Meall Dearg Formation, part of the
Stoer Group, is postulated to record the overfilling stage of a rift basin near the eastern flank of the Columbia Supercontinent at c. 1.2 Ga. Critical comparisons can be drawn between the Stoer Group and Gardar Rift of southern Greenland, based on
their age, palaeogeography, and patterns of rift-basin development.
|Sommaire||(Résumé en langage clair et simple, non publié et disponible en anglais seulement)|
This research delves into the origins of a rock formation known as the Meall Dearg Formation, located in the
northwestern Highlands of Scotland, which is about 1.2 billion years old. This rock layer has been poorly studied when it comes to understanding where its sediments originated.
To uncover its provenance, the scientists analyzed 309 zircon grains
from the Meall Dearg Formation. These tiny grains, which are incredibly durable and can survive for billions of years, hold clues about the rock's history. The ages of the grains ranged from about 3.1 billion to 1.75 billion years, with the majority
falling within the range of 2.9 billion to 2.65 billion years.
By comparing these zircon ages to ages from previous studies of the Lewisian Gneiss Complex, the researchers discovered that the Meall Dearg Formation likely originated from this
complex. The detritus primarily came from the Rhiconich and Gruinard terranes, with smaller contributions from other regions.
This study helps us understand the geological history of this region, revealing details about ancient rift basins and the
Columbia Supercontinent. It also enables comparisons with similar geological features in southern Greenland, offering insights into Earth's past.