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

2018 ◽  
pp. 389-408
Author(s):  
Susan Johnson ◽  
Sandra M. Barr ◽  
Deanne Van Rooyen ◽  
Chris E. White
Keyword(s):  
New Brunswick ◽  
Tectonic Setting ◽  
Leading Edge ◽  
Borehole Data ◽  
Zircon Age ◽  
Early Devonian ◽  
Icp Ms ◽  
Laurentian Margin ◽  
Radiometric Data

 The Canaan River pluton comprises megacrystic monzogranite and quartz diorite to monzodiorite that is exposed in several small inliers on the Carboniferous New Brunswick Platform west of Moncton in southeastern New Brunswick. Its distinct geophysical signature and borehole data suggest that the Canaan River pluton is part of a large buried felsic to mafic intrusive body that lies at relatively shallow depths beneath flat-lying Pennsylvanian sandstone on the platform. New laser ablation ICP-MS in situ analysis of the megacrystic monzogranite yielded a U-Pb zircon concordia age of 412.6 ± 2.1 Ma, indicating that the intrusion is of Early Devonian (upper Lochkovian) age.The new radiometric data along with lithological, geochemical, and isotopic data suggest that the Canaan River pluton is most like the megacrystic Hawkshaw Granite of upper Lochkovian age in the Pokiok Batholith in southwestern New Brunswick. The similarities shown by these granites suggests that they may have been generated in the same complex tectonomagmatic setting related to the successive arrival of the leading edge of Ganderia and Avalonia at the composite Laurentian margin during the Salinic and Acadian orogenies. 

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

2017 ◽  
Vol 53 ◽  
pp. 207-240 ◽  
Author(s):  
Nadia Mohammadi ◽  
Les Fyffe ◽  
Christopher R.M. McFarlane ◽  
Kay G. Thorne ◽  
David R. Lentz ◽  
...  
Keyword(s):  
New Brunswick ◽  
Geochemical Data ◽  
Late Devonian ◽  
Magmatic Evolution ◽  
Early Devonian ◽  
Tectonic Environment ◽  
Icp Ms ◽  
Zircon Crystallization ◽  
Two Samples

  The Late Silurian to Late Devonian Saint George Batholith in southwestern New Brunswick is a large composite intrusion (2000 km2) emplaced into the continental margin of the peri-Gondwanan microcontinent of Ganderia. The batholith includes: (1) Bocabec Gabbro; (2) equigranular Utopia and Wellington Lake biotite granites; (3) Welsford, Jake Lee Mountain, and Parks Brook peralkaline granites; (4) two-mica John Lee Brook Granite; (6) Jimmy Hill and Magaguadavic megacrystic granites; and (6) rapakivi Mount Douglas Granite. New LA ICP-MS in situ analyses of six samples from the Saint George Batholith are as follows: (1) U-Pb monazite crystallization age of 425.5 ± 2.1 Ma for the Utopia Granite in the western part of the batholith (2) U-Pb zircon crystallization ages of 420.4 ± 2.4 Ma and 420.0 ± 3.5 Ma for two samples of the Utopia Granite from the central part of the batholith; (3) U-Pb zircon crystallization age of 418.0 ± 2.3 Ma for the Jake Lee Mountain Granite; (4) U-Pb zircon crystallization age of 415.5 ± 2.1 Ma for the Wellington Lake Granite; and (5) U-Pb monazite crystallization age of 413.3 ± 2.1 Ma for the John Lee Brook Granite. The new geochronological together with new and existing geochemical data suggest that the protracted magmatic evolution of the Late Silurian to Early Devonian plutonic rocks is related to the transition of the Silurian Kingston arc-Mascarene backarc system from an extensional to compressional tectonic environment during collision of the Avalonian microcontinent with Laurentia followed by slab break-off. 

High-resolution LA-ICP-MS trace-element mapping of magmatic biotite: A new approach for studying syn- to post-magmatic evolution

2020 ◽  
Vol 58 (3) ◽  
pp. 293-311 ◽  
Author(s):  
Zeinab Azadbakht ◽  
David R. Lentz
Keyword(s):  
New Brunswick ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Fluid Phase ◽  
New Approach ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Magma Crystallization ◽  
Topaz Granite

ABSTRACT Biotite grains from 22 felsic intrusions in New Brunswick were mapped in situ using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). We investigated the extent to which biotite can retain its magmatic zoning patterns and, where zoning does exist, how it can be used to elucidate early to late stage, syn-magmatic to post-crystallization processes. Although the major element and halogen contents of the examined biotite phenocrysts are homogeneous, two-thirds of the grains display trace-element zoning for Ba, Rb, and Cs. The results also indicated that zoning is better retained in larger grains (i.e., > 500 × 500 μm) with minimal alteration and mineral inclusions. An exceptionally well-zoned Li-rich siderophyllite from the Pleasant Ridge topaz granite in southwestern New Brunswick shows Ti, Ta, Sn, W, Cs, Rb, and V (without Li or Ba) zoning. Cesium values increase from 200 to 1400 ppm from core to rim. Conversely, Sn and W values decrease toward the rim (50 to 10 and 100 to 10 ppm, respectively). Tantalum and Ti values show fewer variations but drop abruptly close to the rim of the grain (100 to 20 and 2000 to 500 ppm, respectively). These observations may indicate crystallization of mineral phases with high partition coefficients for these highly incompatible elements (except Ti) (e.g., cassiterite and rutile) followed by fractionation of a fluid phase at a later stage of magma crystallization. The preservation of zoning may indicate rapid cooling post-crystallization of the parent magma.

High spatial resolution in situ U–Pb dating using laser ablation multiple ion counting inductively coupled plasma mass spectrometry (LA-MIC-ICP-MS)

2017 ◽  
Vol 32 (5) ◽  
pp. 975-986 ◽  
Author(s):  
Lie-Wen Xie ◽  
Jin-Hui Yang ◽  
Qing-Zhu Yin ◽  
Yue-Heng Yang ◽  
Jing-Bo Liu ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Inductively Coupled Plasma ◽  
High Spatial Resolution ◽  
Zircon Age ◽  
Analytical Technique ◽  
Inductively Coupled ◽  
Rapid Measurement ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

A new LA-MIC-ICP-MS analytical technique has been developed for the rapid measurement of 206Pb/238U zircon age (<1%, 2s) at a high spatial resolution. We show that this technique can be routinely employed to date U–Pb in small and/or complex zircons, providing a powerful tool for geochronology.

scholarly journals U-Pb, Ar-Ar, and Re-Os Geochronological Constraints on Multiple Magmatic–Hydrothermal Episodes at the Lake George Mine, Central New Brunswick

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 566 ◽  
Author(s):  
Carlin Lentz ◽  
Kathleen Thorne ◽  
Christopher R. M. McFarlane ◽  
Douglas A. Archibald
Keyword(s):  
New Brunswick ◽  
Zircon Geochronology ◽  
Weighted Mean ◽  
Metasedimentary Rocks ◽  
Quartz Veins ◽  
Icp Ms ◽  
Step Heating ◽  
Geochronological Constraints ◽  
Lake George

The Lake George antimony mine was at one time North America’s largest producer of antimony. Despite being widely known for the antimony mineralization, the deposit also hosts a range of styles of mineralization such as multiple generations of W-Mo bearing quartz veins as well as a system of As-Au bearing quartz–carbonate veins. In situ U-Pb zircon geochronology, using LA ICP-MS, of the Lake George granodiorite yielded a weighted mean 206Pb/238U age of 419.6 ± 3.0 Ma. Step heating of phlogopite separated from the lamprophyre dykes produced a 40Ar/39Ar plateau segment date of 419.4 ± 1.4 Ma. Single molybdenite crystal analysis for Re-Os geochronology was conducted on two W-Mo-bearing quartz veins, which cross-cut altered granodiorite and altered metasedimentary rocks and yielded two dates of 415.7 ± 1.7 Ma and 416.1 ± 1.7 Ma respectively. 40Ar/39Ar geochronology of muscovite from alteration associated with Au-bearing quartz–carbonate veins yielded one representative plateau segment date of 414.1 ± 1.3 Ma. The dates produced in this study revealed that the different magmatic–hydrothermal events at the Lake George mine occurred over approximately a 10-million-year period at the end of the Silurian and the start of the Devonian following the termination of the Acadian orogeny.

scholarly journals Early Cambrian U-Pb zircon age and Hf-isotope data from the Guasayán pluton, Sierras Pampeanas, Argentina: implications for the northwestern boundary of the Pampean arc

2016 ◽  
Vol 43 (1) ◽  
pp. 137 ◽  
Author(s):  
Juan A. Dahlquist ◽  
Sebastián O. Verdecchia ◽  
Edgardo G. Baldo ◽  
Miguel A.S. Basei ◽  
Pablo H. Alasino ◽  
...  
Keyword(s):  
Central Area ◽  
Magma Source ◽  
Western Boundary ◽  
Low Grade ◽  
Early Cambrian ◽  
Zircon Age ◽  
Sierras Pampeanas ◽  
Metasedimentary Rocks ◽  
Icp Ms

An Early Cambrian pluton, known as the Guasayán pluton, has been identified in the central area of Sierra de Guasayán, northwestern Argentina. A U-Pb zircon Concordia age of 533±4 Ma was obtained by LA-MC-ICP-MS and represents the first report of robustly dated Early Cambrian magmatism for the northwestern Sierras Pampeanas. The pluton was emplaced in low-grade metasedimentary rocks and its magmatic assemblage consists of K-feldspar (phenocrysts)+plagioclase+quartz+biotite, with zircon, apatite, ilmenite, magnetite and monazite as accessory minerals. Geochemically, the granitic rock is a metaluminous subalkaline felsic granodiorite with SiO2=69.24%, Na2O+K2O=7.08%, CaO=2.45%, Na2O/ K2O=0.71 and FeO/MgO=3.58%. Rare earth element patterns show moderate slope (LaN/YbN=8.05) with a slightly negative Eu anomalies (Eu/Eu*=0.76). We report the first in situ Hf isotopes data (εHft=-0.12 to -4.76) from crystallized zircons in the Early Cambrian granites of the Sierras Pampeanas, helping to constrain the magma source and enabling comparison with other Pampean granites. The Guasayán pluton might provide a link between Early Cambrian magmatism of the central Sierras Pampeanas and that of the Eastern Cordillera, contributing to define the western boundary of the Pampean paleo-arc.

scholarly journals Geochronology and petrogenesis of granitoid rocks from the Goryczkowa Unit, Tatra Mountains (Central Western Carpathians)

2013 ◽  
Vol 64 (6) ◽  
pp. 419-435 ◽  
Author(s):  
Jolanta Burda ◽  
Aleksandra Gawęda ◽  
Urs Klötzli
Keyword(s):  
Tectonic Setting ◽  
Regional Metamorphism ◽  
Source Material ◽  
Tatra Mountains ◽  
Volcanic Arc ◽  
Zircon Age ◽  
Icp Ms ◽  
Crystalline Core ◽  
Granitoid Rocks ◽  
Central Western Carpathians

Abstract The geochemical characteristics as well as the LA-MC-ICP-MS U-Pb zircon age relationship between two granitoid suites found in the Goryczkowa crystalline core in the Western Tatra Mountains were studied. The petrological investigations indicate that both granitoid suites were emplaced at medium crustal level, in a VAG (volcanic arc granites) tectonic setting. However, these suites differ in source material melted and represent two different magmatic stages: suite 1 represents a high temperature, oxidized, pre-plate collision intrusion, emplaced at ca. 371 Ma while suite 2 is late orogenic/anatectic magma, which intruded at ca. 350 Ma. These data are consistent with a period of intensive magmatic activity in the Tatra Mountain crystalline basement. The emplacement of granitoids postdates the LP-HT regional metamorphism/ partial melting at ca. 387 Ma and at 433-410 Ma, imprinted in the inherited zircon cores.

Lower Silurian subduction-related volcanic rocks in the Chaleurs Group, northern New Brunswick, CanadaGeological Survey of Canada, Contribution No. 2008-0166.Contribution to Natural Resources Canada’s Targeted Geoscience Initiative 3 (2005–2010).

2008 ◽  
Vol 45 (9) ◽  
pp. 981-998 ◽  
Author(s):  
R. A. Wilson ◽  
C. R. van Staal ◽  
S. Kamo
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Zircon Age ◽  
Mafic Rocks ◽  
Fine Grained ◽  
Lower Silurian ◽  
Narrow Width ◽  
Basaltic Flow ◽  
Back Arc

Early Silurian volcanic and subvolcanic rocks are preserved in the lower part of the Chaleurs Group at two locations in northern New Brunswick. At Quinn Point, mafic to intermediate rocks are hosted by sedimentary rocks of the Weir Formation, and at Pointe Rochette, a bed of felsic tuff occurs near the base of the Weir. These rocks are interpreted as the first evidence in New Brunswick of magmatism associated with Late Ordovician – Early Silurian subduction of Tetagouche–Exploits back-arc oceanic crust. At Quinn Point, mafic rocks include a thick basaltic flow or sill and intermediate to mafic cobbles in overlying conglomerate beds. The in situ mafic rocks and the conglomerate clasts are chemically alike and display subduction-related affinities on tectonic discrimination diagrams. At Pointe Rochette, fine-grained felsic tuff contains elevated Th and U and depleted high-field-strength elements, consistent with a subduction-influenced setting, although rare-earth element (REE) abundances are low and the REE profile is relatively flat. A U–Pb (zircon) age of 429.2 ± 0.5 Ma was obtained from the tuff, consistent with the late Llandovery to early Wenlock age of the overlying La Vieille Formation and coinciding with the latter stages of development of the Brunswick subduction complex. Volcanic rocks were emplaced in the arc to arc-trench gap region, probably reflecting local step-back of the magmatic axis due to accretion of continental back-arc ribbons. The low volume of Early Silurian subduction-influenced rocks is probably related to the relatively narrow width of the back-arc basin and the young, “warm” character of back-arc crust.

Unraveling potential biases in U-Pb detrital zircon record induced by high-temperature metamorphism (> 850 ºC)

2021 ◽  
Author(s):  
Mahyra Tedeschi ◽  
Humberto Reis ◽  
Laura Stutenbecker ◽  
Matheus Kuchenbecker ◽  
Bruno Ribeiro ◽  
...  
Keyword(s):  
High Temperature ◽  
Detrital Zircon ◽  
Metamorphic Event ◽  
Sediment Provenance ◽  
Metamorphic Rocks ◽  
Zircon Age ◽  
Icp Ms ◽  
Depositional Age ◽  
High Temperature Metamorphism

&lt;p&gt;Detrital zircon records are prone to several sources of bias that can compromise sediment provenance investigations based on U-Pb ages. High-temperature metamorphism (&gt;850 &amp;#186;C) is herewith addressed as a natural cause of bias since U-Pb zircon data from rocks submitted to these extreme, often prolonged conditions, frequently display protracted apparent concordant geochronological U-Pb records. The resulting spectrum can originate from disturbance of the primary U-Pb zircon system, likewise from subsequent recrystallization and crystallization processes during multiple and/or prolonged metamorphic events. Consequently, a high-grade metamorphosed igneous rock can exhibit a zircon age spectrum similar to that produced by polymict sedimentary rocks, thereby inducing provenance misinterpretations if this rock becomes a source for a sediment. A polymict sedimentary source that undergoes such high temperatures could potentially generate an even more intricate spectrum. Archean, Neoproterozoic and Paleozoic metamorphic rocks from the literature, dated by different techniques (SIMS and LA-ICP-MS), are employed as examples to demonstrate the resulting complications.&amp;#160; The compilation shows that (1) high-temperature metamorphism may generate age peaks of unclear or lacking geological meaning, and (2) the interpretation of detrital zircon age spectra depends on the timing of the metamorphic event (pre- or post-depositional). When high-temperature metamorphic rocks are eroded in uplifted areas, the youngest population of a detrital spectrum represents the maximum depositional age through metamorphic zircon from the source. If a sedimentary succession was subjected to high-temperature metamorphic conditions after deposition, its youngest zircon population more likely records the metamorphism, and the maximum depositional age, as well as older sources cannot be directly accessed. To evaluate the presence of high-temperature metamorphism-related bias in a given detrital zircon sample, we suggest a workflow for data acquisition and interpretation, combining a multi-proxy approach with: in situ U-Pb dating coupled with Hf analyses to retrieve the isotopic composition of the sources, and the integration of a petrochronological investigation to typify fingerprints of the (ultra)high-temperature metamorphic event.&lt;/p&gt;

scholarly journals Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

2014 ◽  
Vol 41 (4) ◽  
pp. 459 ◽  
Author(s):  
Sébastien Castonguay ◽  
Cees R. Van Staal ◽  
Nancy Joyce ◽  
Thomas Skulski ◽  
James P. Hibbard
Keyword(s):  
Leading Edge ◽  
Amphibolite Facies ◽  
Subduction Channel ◽  
Zircon Age ◽  
Ophiolitic Rocks ◽  
Eclogite Facies ◽  
Radiometric Ages ◽  
Geochronological Evidence ◽  
Structural Base

The Baie Verte Peninsula, western Newfoundland Appalachians, preserves evidence for Early to Mid Ordovician closure of the Taconic seaway, which led to obduction of the Baie Verte oceanic tract (BVOT) ophiolites onto the Laurentian (Humber) margin and Taconic orogenesis. The scarcity of Taconic radiometric ages (and predominance of Silurian (Salinic) data) from the Humber margin rocks (down-going plate) has been problematic, calling into question the intensity and existence of Taconic collisional orogenesis. 40Ar/39Ar and in situ U–Pb geochronology was undertaken on metamorphosed units from the Laurentian basement (Mesoproterozoic East Pond Metamorphic Suite), from the ca. 560 Ma Birchy Complex forming the leading edge of the Humber margin, and from the ca. 490 Ma ophiolitic rocks of the BVOT (Advocate Complex) in order to address this question. Our results confirm evidence of Taconic metamorphism along the Humber margin and at the base of the ophiolites. Ages obtained from the structural base of the Advocate Complex (481–465 Ma) are interpreted to reflect the timing of accretion and internal thickening of the ophiolite, whereas data from the underlying Birchy Complex (467–461 Ma) record the underthrusting and exhumation of the leading edge of the Humber margin along a subduction channel, penecontemporaneously with final obduction of the BVOT. A concordant ca. 465 Ma zircon age and REE data obtained from retrogressed eclogite of the East Pond Metamorphic Suite suggest that the parautochthonous Humber margin was locally subducted to eclogite-facies conditions during the Taconic collision and partly exhumed to amphibolite-facies conditions prior to a strong Silurian (Salinic) tectonometamorphic overprint.SOMMAIRELa péninsule de Baie Verte dans les Appalaches de l’ouest de Terre-Neuve a conservé des indices de la fermeture du bras de mer taconique, qui a mené à l’obduction des ophiolites de la bande océanique de Baie Verte (BOBV) sur la marge laurentienne (Humber) et à l’orogénèse taconique. La rareté des âges radiométriques taconiques (et la prédominance des données siluriennes (saliniques)) provenant des roches de la marge de Humber (i.e. la plaque subductée) a été problématique, mettant en question l’intensité et l’existence de la collision orogénique taconique. De la géochronologie 40Ar/39Ar et U–Pb in situ a été réalisée sur des unités métamorphisés provenant du socle laurentien (la Suite Métamorphique d’East Pond d’âge Mésoprotérozoïque), du Complexe de Birchy daté à ca. 560 Ma formant la partie frontale de la marge de Humber, and des roches ophiolitiques de la BOBV (Complexe d’Advocate) datée à ca. 490 Ma afin de confronter ce questionnement. Nos résultats confirment les indices de métamorphisme taconique le long de la marge de Humber et à la base des ophiolites. Les âges obtenus à la base structurale du Complexe d’Advocate (481–465 Ma) sont interprétés comme reflétant la période d’accrétion et d’épaississement interne de l’ophiolite, tandis que les données du Complexe de Birchy sous-jacent (467–461 Ma) enregistrent le sous-charriage et l’exhumation de la partie frontale de la marge de Humber au sein d’un chenal de subduction, de façon pénécontemporaine à l’obduction finale de la BOBV. Un âge concordant de ca. 465 Ma d’un zircon et les données de terres rares provenant d’une éclogite rétromorphosée de la suite métamorphique d’East Pond suggèrent que la marge de Humber parautochtone a été localement subductée à des conditions du faciès éclogitique durant la collision taconique et partiellement exhumée à des conditions du faciès des amphibolites précédant la forte surimposition tectonométamorphique silurienne (salinique).

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