Geological relationships and laser ablation ICP-MS U-Pb geochronology of the Saint George Batholith, southwestern New Brunswick, Canada: implications for its tectonomagmatic evolution

Mohammadi, Nadia; Fyffe, L. R.; McFarlane, Christopher R.M.; Thorne, Kathleen G.; Lentz, David R.; Charnley, Brittany; Branscombe, Laurin; Butler, Sheena

doi:10.4138/atlgeol.2017.008

Cited by 22 publications

(30 citation statements)

References 47 publications

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“…11, right column). Finally, the detrital zircon age spectrum for Kendall Mountain quartz arenite (KM-1) differs significantly from that of the adjacent Digdeguash Formation (Dokken et al 2018) from which it is separated by a terrane-bounding fault (Ludman 1990;Mohammadi et al 2017), but is similar to those of the Miramichi basement units, confirming the basement rock status of the Kendall Mountain.…”

Section: St Croix Terranementioning

confidence: 69%

SHRIMP U–Pb zircon evidence for age, provenance, and tectonic history of early Paleozoic Ganderian rocks, east-central Maine, USA

Ludman

Aleinikoff

Berry

et al. 2018

atgeol

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SHRIMP U–Pb zircon ages from Ganderia in eastern Maine clarify the ages and provenance of basement units in the Miramichi and St. Croix terranes and of cover rocks in the Fredericton trough and Central Maine/Aroostook-Matapedia basin (CMAM). These new data constrain timing of orogenic events and help understand the origin of the cover rock depocenters.Detrital zircon data generally confirm suggested ages of the formations sampled. Zircon grains with ages of ca. 430 Ma in both depocenters, only slightly older than their host rocks, were probably derived from the earliest volcanic eruptions in the Eastport-Mascarene belt. Their presence indicates that unnamed CMAM sandstone units may be as young as Pridoli and their absence from the Appleton Ridge and Digdeguash formations suggests that these formations are older than initial Eastport-Mascarene volcanism. Detrital and volcanic zircon ages confirm a Late Cambrian to Middle Ordovician age for the Miramichi succession and date Miramichi volcanism at 469.3 ± 4.6 Ma. In the St. Croix terrane, zircon grain with an age of 477.4 ± 3.7 Ma from an ashfall at the base of the Kendall Mountain Formation and age spectra and fossils from overlying quartz arenite suggest that the formation may span Floian to Sandbian time. The main source of CMAM and Fredericton sediment was recycled Ganderian basement from terranes emergent after Late Ordovician orogenesis, supplemented by Silurian tephra. Zircon barcodes and lithofacies and tectonic models suggest little, if any, input from Laurentia or Avalonia.Zircon- and fossil-based ages indicate coeval Upper Ordovician deformation in the St. Croix (ca. 453 to 442 Ma) and Miramichi (ca. 453 to 446 Ma) terranes. Salinic folding in the southeastern Fredericton trough is bracketed between the 421.9 ± 2.4 Ma age of the Pocomoonshine gabbro-diorite and 430 Ma detrital zircons in the Flume Ridge Formation. Zircon ages, lithofacies analysis, and paleontological evidence support the origin of the Fredericton trough as a Salinic foredeep. The CMAM basin cannot have been an Acadian foreland basin, as sedimentation began millions of years before Acadian subduction.

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Section: St Croix Terranementioning

confidence: 69%

SHRIMP U–Pb zircon evidence for age, provenance, and tectonic history of early Paleozoic Ganderian rocks, east-central Maine, USA

Ludman

Aleinikoff

Berry

et al. 2018

atgeol

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“…The highly fractionated peraluminous Mount Douglas Granite (MDG), composed of three units (Dmd1, Dmd2, and Dmd3; Figures 1 and 2), has characteristic features of High Heat Production (HHP) Granites, in which the granites have elevated concentrations of K 2 O, Rb, LREE, U, and Th. They [22] and Mohammadi et al [29]). The MDG is divided into units Dmd1, Dmd2, and Dmd3 (modified after McLeod [17]).…”

Section: Introductionmentioning

confidence: 91%

“…Monazite grains were analyzed using a Resonetics S-155-LR 193 nm ArF Excimer laser ablation (LA) system coupled to an Agilent 7700X quadrupole inductively coupled plasma-mass spectrometer (ICP-MS) (see [29,[32][33][34][35]) using a laser beam with a diameter of 17 µm (a few microns depth). Measurements were performed on monazite grains following SEM-BSE imaging to determine any internal textural variations of the grains.…”

Section: Analytical Proceduresmentioning

confidence: 99%

“…Mount Pleasant's molybdenite Re-Os geochronology was taken from Thorne et al [22]. LA ICP-MS U-Pb zircon and monazite geochronology of the Utopia Granite, Jake Lee Mountain Granite, Wellington Lake Granite, John Lee Brook Granite, and Magaguadavic Granite were taken from Mohammadi et al [29]. LA ICP-MS U-Pb zircon and monazite crystallization ages of the MDG were taken from Mohammadi [15].…”

Section: Introductionmentioning

confidence: 99%

“…LA ICP-MS U-Pb zircon and monazite crystallization ages of the MDG were taken from Mohammadi [15]. [22] and Mohammadi et al [29]). The MDG is divided into units Dmd1, Dmd2, and Dmd3 (modified after McLeod [17]).…”

Section: Introductionmentioning

confidence: 99%

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U–Pb Geochronology of Hydrothermal Monazite from Uraniferous Greisen Veins Associated with the High Heat Production Mount Douglas Granite, New Brunswick, Canada

2019

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A combination of in situ laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS) analyses guided by Scanning Electron Microscope-Back-Scattered Electron imaging (SEM-BSE) was applied to hydrothermal monazite from greisen veins of the Late Devonian, highly evolved, uraniferous Mount Douglas Granite, New Brunswick, Canada. Understanding the uraniferous nature of the suite and characterizing the hydrothermal system that produced the associated mineralized greisen veins were the main goals of this study. The uraniferous nature of the Mount Douglas Granite is evident from previous airborne radiometric surveys, whole-rock geochemical data indicating high U and Th (2-22 ppm U; 19-71 ppm Th), the presence of monazite, zircon, xenotime, thorite, bastnaesite, and uraninite within the pluton and the associated hydrothermal greisen veins, as well as anomalous levels of U and Th in wolframite, hematite, and martite within greisen veins. New U-Pb geochronology of hydrothermal monazite coexisting with sulfide and oxide minerals yielded mineralization ages ranging from 344 to 368 Ma, with most of them (90%) younger than the crystallization age of the pluton (368 ± 3 Ma). The younger mineralization age indicates post-magmatic hydrothermal activities within the Mount Douglas system that was responsible for the mineralization. The production of uraniferous greisen veins by this process is probably associated with the High Heat Production (HHP) nature of this pluton, resulting from the radioactive decay of U, Th, and K. This heat prolongs post-crystallization hydrothermal fluid circulation and promotes the generation of hydrothermal ore deposits that are younger than the pluton. Assuming a density of 2.61 g/cm 3 , the average weighted mean radiogenic heat production of the Mount Douglas granites is 5.9 µW/m 3 (14.1 HGU; Heat Generation Unit), in which it ranges from 2.2 µW/m 3 in the least evolved unit, Dmd1, up to 10.1 µW/m 3 in the most fractionated unit, Dmd3. They are all significantly higher than the average upper continental crust (1.65 µW/m 3 ). The high radiogenic heat production of the Mount Douglas Granite, accompanied by a high estimated heat flow of 70 mW/m 2 , supports the assignment of the granite to a 'hot crust' (>7 HGU) HHP granite and highlights its potential for geothermal energy exploration.

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Using magmatic biotite chemistry to differentiate barren and mineralized Silurian–Devonian granitoids of New Brunswick, Canada

Azadbakht

Lentz

McFarlane

et al. 2020

Contrib Mineral Petrol

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Geological relationships and laser ablation ICP-MS U-Pb geochronology of the Saint George Batholith, southwestern New Brunswick, Canada: implications for its tectonomagmatic evolution

Abstract: The Late

Cited by 22 publications

References 47 publications

SHRIMP U–Pb zircon evidence for age, provenance, and tectonic history of early Paleozoic Ganderian rocks, east-central Maine, USA

SHRIMP U–Pb zircon evidence for age, provenance, and tectonic history of early Paleozoic Ganderian rocks, east-central Maine, USA

U–Pb Geochronology of Hydrothermal Monazite from Uraniferous Greisen Veins Associated with the High Heat Production Mount Douglas Granite, New Brunswick, Canada

Using magmatic biotite chemistry to differentiate barren and mineralized Silurian–Devonian granitoids of New Brunswick, Canada

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