Geochemistry of Carboniferous peralkaline felsic volcanic rocks, central New Brunswick, Canada: examination of uranium potential

Abstract

Felsic volcanic rocks from the ca. 335 Ma Cumberland Hill Formation of southern New Brunswick consist of peralkaline rhyolite and trachyte. These rocks are interpreted to have undergone extensive fractional crystallization from an alkali basaltic magma, although their different geochemical signatures indicate that the rhyolite was not derived from the trachyte via continuous fractional crystallization. The rhyolite is highly enriched in incompatible trace elements including uranium (up to ca. 20 ppm). Cumberland Hill peralkaline rhyolite suggests that a potentially economic source of uranium exists in the basin, based on the elevated uranium concentrations and high potential for remobilization into surrounding sedimentary units. RÉSUMÉLes roches volcaniques felsiques de la Formation de Cumberland Hill, au sud du Nouveau-Brunswick, dont l'origine remonte à quelque 335 Ma se composent de rhyolite et de trachyte hyperalcalines. On estime que ces roches ont subi une cristallisation fractionnée intense à partir d'un magma de basalte alcalin, même si leurs diverses signatures géochimiques indiquent que la rhyolite n'est pas issue de la trachyte par un processus permanent de cristallisation fractionnée. La rhyolite est fortement enrichie d'éléments traces incompatibles, au nombre duquel se trouve de l'uranium (concentration qui peut atteindre environ 20 ppm). Si l'on se fie aux fortes concentrations d'uranium et à la grande possibilité de remobilisation dans les unités sédimentaires environnantes, la présence de la rhyolite hyperalcaline dans la Formation de Cumberland Hill porte à croire que le bassin pourrait contenir une source d'uranium vraisemblablement rentable. [Traduit par la redaction]

Granodiorites of the South Mountain Batholith (Nova Scotia, Canada) derived by partial melting of Avalonia granulite rocks beneath the Meguma terrane: Implications for the heat source of the Late Devonian granites of the Northern Appalachians

“…If that was the case then the underplated rocks could have acted either directly or indirectly as a source for younger volcanic and plutonic rocks (i.e. plutons of the Cobequid highlands, Maritimes basin basalts) throughout Atlantic Canada (Ayuso et al, 1988;Barr et al, 1994;Dorais and Paige, 2000;Dunning et al, 2002;Giles, 2008;Gray et al, 2010;La-Fleche et al, 1998;Ross 2010). The fact that there may not be a spatial-temporal evolution of the magmatic rocks in the region is of little concern because the heat source is relatively stationary and melting will occur over a wide area.…”

Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications

“…This bedrock palaeovalley was bordered on either side by slates and lavas that formed subdued topographical highs with a palaeoelevation of a few tens of metres above base level (Hacquebard & Barss ; Gray et al . ; Fig. A).…”

The Litchfield Pluton in South-Central Maine: Carboniferous Alkalic Magmatism in northern New England, USA

“…These rocks are dominated by fine-grained terrestrial clastic rocks and the subordinate aforementioned alkaline volcanic rocks of the Cumberland Hill Formation (ca. 335 Ma; Gray et al 2010). In southern New England, Carboniferous strata are preserved in the Narragansett and Norfolk, and Worcester basins of Rhode Island and Massachusetts (Hermes et al 1994;Zen et al 1983).…”

“…Similarly, magmatism in adjacent Atlantic Canada seems to have also been limited during this time span with a notable exception being ca. 335 Ma peralkaline felsic volcanic rocks in the Cumberland Hill Formation in central New Brunswick (Gray et al 2010;see Fig. 1 for location).…”