Geochronology and lithogeochemistry of granitoid rocks from the central part of the Central plutonic belt, New Brunswick, Canada: implications for Sn-W-Mo exploration

Abstract

The central part of the Central plutonic belt in New Brunswick is underlain by numerous plutons of calc-alkaline, foliated and unfoliated granite that intrude Cambrian to Early Ordovician metasedimentary rocks. U-Pb (zircon) dating demonstrates that granites range in age from Middle Ordovician to Late Devonian, although most are late Silurian to Early Devonian. An age of 467 ± 7 Ma has been obtained on the foliated McKiel Lake Granite, whereas unfoliated intrusions yield ages of 423.2 ± 3.2 Ma (Bogan Brook Granodiorite), 420.7 +1.8/-2.0 Ma (Nashwaak Granite), 419.0 ± 0.5 Ma (Redstone Mountain Granite), 416.1 ± 0.5 Ma (Beadle Mountain Granite), 415.8 ± 0.3 Ma (Juniper Barren Granite), 409.7 ± 0.5 Ma (Lost Lake Granite), and 380.6 ± 0.3 Ma (Burnthill Granite). All plutons exhibit mixed arc-like and within-plate geochemical signatures, although the Redstone Mountain and Burnthill granites are dominantly of within-plate type. Trace element data reveal a close overall geochemical similarity between Ordovician and Silurian – Devonian plutons, indicating that all were generated by partial melting of the same crustal source. Late Silurian to Early Devonian plutons mainly comprise biotite and/or muscovite-bearing, peraluminous granite and are considered prospective for granophile-element mineralization. All plutons contain Sn well in excess of the granite global average abundance, and several contain average tin values comparable to productive stanniferous granites elsewhere. The Burnthill, Lost Lake, Beadle Mountain, and Nashwaak granites are geochemically most evolved and enriched in Sn and W. The Burnthill Granite in particular has experienced late-stage hydrothermal processes that have resulted in local enrichments of these elements.

U-Pb (zircon) age, petrology, and tectonic setting of the Canaan River pluton, southeastern New Brunswick, Canada

“…The arrival of the leading edge of Ganderia at the Laurentian margin and subsequent inversion of the Fredericton Trough during the terminal Salinic orogeny coincided with the arrival of Avalonia at its trailing edge and the onset of the Acadian orogeny, resulting in a highly complex geodynamic setting (e.g., van Staal et al 2009;van Staal and Barr 2012). The mechanism by which the Pokiok Batholith and other plutons in the Central Plutonic belt were generated has been ascribed to crustal thickening following Salinic orogenesis and/or underthrusting of Ganderia's trailing edge by the leading edge of Avalonia (van Staal et al 2009;Wilson and Kamo 2016). The Early Devonian units of the Pokiok Batholith (e.g., Hawkshaw) and Saint George Batholith (e.g., John Lee Brook), as well and the Canaan River pluton (Fig.…”

Detrital U-Pb and 40Ar/39Ar geochronology of the Connecticut Valley-Gaspé trough, southern Quebec and northern Vermont – Transitional tectonism from Salinic to Acadian orogenic cycles

“…Ma plutons (Whalen et al, 1994;Wilson and Kamo, 2016), which also represent a probable source of detrital mica. However, the coexistence of Middle-Ordovician and Lower-Devonian 39 Ar/ 40 Ar ages in the same muscovite grains is also consistent with metamorphic ages found in the Bathurst Supergroup in New Brunswick, an Ordovician volcanic and sedimentary sequence that yielded 477 to 468 Ma detrital white micas which have been affected by three events of deformation/metamorphism attributed to the Salinic orogeny, among which the D2 event yielded 427 to 418 Ma 40 Ar/ 39 Ar ages (Kellett et al, 2017).…”

Apatite Chemical Compositions from Acadian-Related Granitoids of New Brunswick, Canada: Implications for Petrogenesis and Metallogenesis

“…The plutonic belt extends from Chaleur Bay in northeastern New Brunswick and extends toward the southwest of the province passing the American border into adjacent Maine (Azadbakht et al [43]). The belt encloses many calc-alkaline, non-foliated and foliated Silurian-Devonian felsic intrusions, which intrude the Cambrian to Early Ordovician rocks of the Woodstock, Miramichi, and Meductic groups, Bathurst Supergroup, and the Trousers Lake metasedimentary Suite (Wilson and Kamo [44]). The plutonic belt cuts three out of four (excluding Humber zone) lower Paleozoic tectonomagmatic zones including Dunnage, Gander, and Avalon from northwest to southeast.…”

“…This Early Devonian heterogeneous granitic body (U-Pb zircon age of 409.7 ± 0.5 Ma; Wilson and Kamo [44]) covers an area of 120 km 2 in central New Brunswick. It is composed mainly of medium-grained equigranular biotite-muscovite granite (WX85NB-161), with minor muscovite granite and pegmatite in southern portion (Whalen [42]; Whalen et al [57]).…”

“…Walker et al[47]; 2 Whalen[42];3 Azadbakht et al[43];4 Shinkle[48];5 MacLellan et al[49];6 Wilson and Kamo[44];7 Bevier and Whalen[50];8 Beal et al[51];9 Yang et al[52];10 White[53];11 Mohammadi et al[54];12 McLeod [55];13 Yang[56].…”