The provenance of tills overlying the eastern part of the South Mountain Batholith, Nova Scotia
DOI :
https://doi.org/10.4138/1640Résumé
Happing of quarternary deposits on the South Mountain Batholitb (SMB) has resulted in a four-fold subdivision of tills, divided primarily on the basis of clast lithology, texture, stratigraphic position and morphology. Three tills have clast lithologies characterized by granites eroded from the South Mountain Batholih. The oldest granite till is a compact till of restricted distribution, mianly observed In drumlin cores. Two younger granite tills dominate the surficial deposits of portions of the SMB and have textural properties ascribed to melt-out tills. The fourth till represents a farther-travelled till with a variable clast provenance typified by pebbles derived from both the SMB and regions to the north. Clast dispersal evidence suggests that all tills were transported in a general southward direction. Detailed clast examinations allow reliable conclusions concerning direction of Ice flow and lithologic relationship between till and bedrock of the SMB. The SMB is an area of multiple glaciatlon where till prospecting cannot be successful unless the direction of till transport and source areas are established. RÉSUMÉ Dn levé cartographique des dépôts quaternaires recouvrant le Batholite de South Mountain à permis de mettre en évidence quatre varlétés de tills en fonctlon de la lithologie des clastes, la texture, la position stratlgraphlque et la morphologic Dana trola tills, les clastes nontrent des lithologles caractérisées par des granites arrachés au Batholite de South Mountain (BSM). Le plus vleux till de granite est un till tasse. de faible étendue, observe surtout dans les noyaux de drumlins. Dans certaines portions du BSM, les dépôts de surface sont dominés par deux tills de granite plus recents qui possedent des caractéristlques texturales rapportées aux tills d'ablation. Le quatriéme till a parcouru une plus grande distance; la source de ses clastes est variable et comprend typiquement des galets provenant tant du BSM que des régions plus au nord. La dispersion des blocaux suggère un direction générale de transport des tills vers le sud. Un exanen approfondi des clastes permet de tirer de solides conclusions à propos de la direction de l’écouleroent glacialre et de la relation lithologique entre le till et le socle du BSM. Le BSM a subi de multiples glaciatlons et la prospection du till n'y est done guère profitable à molns de déterminer la direction de transport et la source du till. [Traduit par le journal]Téléchargements
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