Geochemistry and U/Pb geochronology of the Williams Brook area, Tobique-Chaleur zone, New Brunswick: stratigraphic and geotectonic setting of gold mineralization

2021 ◽  
Author(s):  
Dennis Sánchez-Mora ◽  
Christopher R.M. McFarlane ◽  
James A Walker ◽  
David R. Lentz
Keyword(s):  
New Brunswick ◽  
Gold Mineralization ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Volcanic Belt ◽  
Temporal Variations ◽  
Lower Percentage ◽  
Oblique Convergence ◽  
Felsic Volcanic

Gold mineralization at Williams Brook in northern New Brunswick is hosted within the Siluro-Devonian, bimodal, volcano-sedimentary rocks of the Tobique-Chaleur Zone (Wapske Formation). Gold mineralization occurs in two styles: 1) as disseminations (refractory gold) in rhyolite, and 2) in cross-cutting quartz veins (free gold). Dating of the felsic volcanic host rocks by in situ LA-ICP-MS zircon U-Pb geochronology returned ages of 422 ± 3, 409 ± 2, 408 ± 3, 405 ± 2, 401 ± 9 Ma. Zr/Y of subvolcanic felsic intrusion (<8 for syn-mineralization and >8 for post-mineralization) suggests evolution from transitional to more alkalic affinities. Two mineralizing events are recognized; the first is a disseminated mineralization style formed at ~422–416 Ma and the second consists of quartz vein-hosted gold emplaced at 410–408 Ma. Felsic rocks from Williams Brook and elsewhere in the Tobique Group (i.e. Wapske, Costigan Mountain, and Benjamin formations), and the Coastal Volcanic Belt have similar Th/Nb ratios of ~0.1 to 1, reflecting similar levels of crustal contamination, and similar Nb and Y content, suggesting A-type affinities. These data indicate a similar environment of formation. Regionally, mafic rocks show similar within-plate continental signatures and an E-MORB mantle source that formed from partial melts of 10–30%. Mafic volcanic rocks from Williams Brook have a more alkaline affinity (based on Ti/V), and derivation from lower percentage partial melting (~5%). The chemical and temporal variations in the Williams Brook rocks suggest that they were erupted in an evolving transpressional tectonic setting during the oblique convergence of Gondwana and Laurentia.

Evolution of 3.1 and 3.0 Ga volcanic belts and a new thermotectonic model for the Hopedale Block, North Atlantic craton (Canada)

2002 ◽  
Vol 39 (5) ◽  
pp. 687-710 ◽  
Author(s):  
D T James ◽  
S Kamo ◽  
T Krogh
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Tholeiitic Basalt ◽  
Amphibolite Facies ◽  
Metasedimentary Rocks ◽  
Rock Types ◽  
Metavolcanic Rocks ◽  
Block Based ◽  
Felsic Volcanic

A new model for evolution of the Archean Hopedale Block, based on mapping and supporting U–Pb geochronological and geochemical studies, is highlighted by (i) ca. 3.25 Ga emplacement of igneous precursors of Maggo Gneiss; (ii) &gt3.1 Ga, high-grade Hopedalian metamorphism and attendant deformation; (iii) emplacement of the Hopedale mafic dykes; (iv) 3.1 Ga deposition of Hunt River volcanic rocks; (v) ca. 3.0 Ga deposition of Florence Lake volcanic rocks; (vi) 2.88–2.96 Ga, greenschist- to amphibolite-facies Fiordian metamorphism and formation of penetrative, northeast-striking Fiordian structures; and (vii) emplacement of a suite of 2.89–2.83 Ga tonalite to granite intrusions, which partially overlap and locally postdate Fiordian metamorphism and deformation. The Hunt River and Florence Lake volcanic sequences are different in age but similar in most other respects. The former consists mainly of amphibolite-facies mafic metavolcanic rocks and lesser amounts of komatiite flows and metasedimentary and 3105 ± 3 Ma felsic volcanic rocks. The Florence Lake volcanic belt consists mainly of greenschist- to amphibolite-facies mafic metavolcanic rocks, lesser amounts of felsic metavolcanic rocks, dated at 2979 ± 1 and 2990 ± 2 Ma, komatiite flows, and rare metasedimentary rocks. The similarity of rock types, field relationships between different rock types, such as the common association of ultramafic and felsic metavolcanic rocks, and the chemistry of volcanic rocks in both belts suggest a common tectonic setting for each belt. A model involving episodic volcanism, separated by 100 Ma, in ensialic basins is consistent with the dominance of tholeiitic basalt and an abundance of pre-volcanic basement.

Stratigraphy, paleogeography, and tectonic setting of the Coldbrook Group in the Caledonia Highlands of southern New Brunswick

1977 ◽  
Vol 14 (6) ◽  
pp. 1263-1275 ◽  
Author(s):  
P. S. Giles ◽  
A. A. Ruitenberg
Keyword(s):  
New Brunswick ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Fine Grained ◽  
Arc Model ◽  
Basement Rocks ◽  
Northwestern Margin ◽  
Intracratonic Basin ◽  
Volcanic Belts

The late Precambrian Coldbrook volcanic sequence and stratigraphic equivalents in southern New Brunswick can be divided into three distinct belts. These have been named the Eastern, Central and Western Volcanic Belts.The Eastern Volcanic Belt, along the Bay of Fundy coast, is characterized by intensely deformed mafic and felsic flows, tuffs, and abundant related volcanogenic sediments. Two thick arkosic sedimentary units in this belt reflect extensive intervals of volcanic quiescence. Fine-grained siliceous siltstone and conglomerate, locally intercalated with these rocks, have probably been derived from erosion of older Precambrian basement rocks to the northwest.The Central Volcanic Belt is composed of generally weakly deformed felsic and lesser mafic flows, and coarse lithic tuffs (including ignimbrites), and very minor intercalated sediments. The almost complete lack of water-lain sediments and presence of ignimbrites suggests subaerial deposition for most of these volcanic rocks. The relationship between rocks of the Central and Eastern Volcanic Belts is one of facies equivalence. The Western Volcanic Belt is also composed of felsic and minor mafic flows and tuffs that resemble those of the Central Volcanic Belt, but they are intensely deformed. Minor volcanogenic sedimentary rocks are intercalated with the volcanic rocks along the northwestern margin of this belt.The nature and distribution of major lithofacies belts in the Coldbrook Group and stratigraphic equivalents appear to be consistent with deposition along the margin of an intracratonic basin. It is possible, however, that further work may prove an ensialic island arc model to be a viable alternative.

Age, chemistry, and tectonic setting of Miramichi terrane (Early Paleozoic) volcanic rocks, eastern and east-central Maine, USA

2021 ◽  
Vol 57 ◽  
pp. 239-273
Author(s):  
Allan Ludman ◽  
Christopher McFarlane ◽  
Amber T.H. Whittaker
Keyword(s):  
New Brunswick ◽  
Subduction Zone ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Calc Alkaline ◽  
East Central ◽  
Arc Volcanism ◽  
Middle Ordovician ◽  
Volcanic Suite ◽  
Back Arc

Volcanic rocks in the Miramichi inlier in Maine occur in two areas separated by the Bottle Lake plutonic complex: the Danforth segment (Stetson Mountain Formation) north of the complex and Greenfield segment to the south (Olamon Stream Formation). Both suites are dominantly pyroclastic, with abundant andesite, dacite, and rhyolite tuffs and subordinate lavas, breccias, and agglomerates. Rare basaltic tuffs and a small area of basaltic tuffs, agglomerates, and lavas are restricted to the Greenfield segment. U–Pb zircon geochronology dates Greenfield segment volcanism at ca. 469 Ma, the Floian–Dapingian boundary between the Lower and Middle Ordovician. Chemical analyses reveal a calc-alkaline suite erupted in a continental volcanic arc, either the Meductic or earliest Balmoral phase of Popelogan arc activity. The Maine Miramichi volcanic rocks are most likely correlative with the Meductic Group volcanic suite in west-central New Brunswick. Orogen-parallel lithologic and chemical variations from New Brunswick to east-central Maine may result from eruptions at different volcanic centers. The bimodal Poplar Mountain volcanic suite at the Maine–New Brunswick border is 10–20 myr younger than the Miramichi volcanic rocks and more likely an early phase of back-arc basin rifting than a late-stage Meductic phase event. Coeval calc-alkaline arc volcanism in the Miramichi, Weeksboro–Lunksoos Lake, and Munsungun Cambrian–Ordovician inliers in Maine is not consistent with tectonic models involving northwestward migration of arc volcanism. This >150 km span cannot be explained by a single east-facing subduction zone, suggesting more than one subduction zone/arc complex in the region.

scholarly journals Multivariate Analysis, Mass Balance Techniques, and Statistical Tests as Tools in Igneous Petrology: Application to the Sierra de las Cruces Volcanic Range (Mexican Volcanic Belt)

2014 ◽  
Vol 2014 ◽  
pp. 1-32 ◽  
Author(s):  
Fernando Velasco-Tapia
Keyword(s):  
Multivariate Analysis ◽  
Mass Balance ◽  
Magma Mixing ◽  
Statistical Tests ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Cocos Plate ◽  
Igneous Petrology ◽  
Mexican Volcanic Belt

Magmatic processes have usually been identified and evaluated using qualitative or semiquantitative geochemical or isotopic tools based on a restricted number of variables. However, a more complete and quantitative view could be reached applying multivariate analysis, mass balance techniques, and statistical tests. As an example, in this work a statistical and quantitative scheme is applied to analyze the geochemical features for the Sierra de las Cruces (SC) volcanic range (Mexican Volcanic Belt). In this locality, the volcanic activity (3.7 to 0.5 Ma) was dominantly dacitic, but the presence of spheroidal andesitic enclaves and/or diverse disequilibrium features in majority of lavas confirms the operation of magma mixing/mingling. New discriminant-function-based multidimensional diagrams were used to discriminate tectonic setting. Statistical tests of discordancy and significance were applied to evaluate the influence of the subducting Cocos plate, which seems to be rather negligible for the SC magmas in relation to several major and trace elements. A cluster analysis following Ward’s linkage rule was carried out to classify the SC volcanic rocks geochemical groups. Finally, two mass-balance schemes were applied for the quantitative evaluation of the proportion of the end-member components (dacitic and andesitic magmas) in the comingled lavas (binary mixtures).

Chapter 3 Archean (>2.6 Ga) and Paleoproterozoic (2.5–1.8 Ga), pre- and syn-orogenic magmatism, sedimentation and mineralization in the Norrbotten and Överkalix lithotectonic units, Svecokarelian orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 27-81 ◽  
Author(s):  
Stefan Bergman ◽  
Pär Weihed
Keyword(s):  
Variable Temperature ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Ductile Deformation ◽  
Fe Oxide ◽  
Ductile Shear Zones ◽  
Three Stages ◽  
Felsic Volcanic

AbstractTwo lithotectonic units (the Norrbotten and Överkalix units) occur inside the Paleoproterozoic (2.0–1.8 Ga) Svecokarelian orogen in northernmost Sweden. Archean (2.8–2.6 Ga and possibly older) basement, affected by a relict Neoarchean tectonometamorphic event, and early Paleoproterozoic (2.5–2.0 Ga) cover rocks constitute the pre-orogenic components in the orogen that are unique in Sweden. Siliciclastic sedimentary rocks, predominantly felsic volcanic rocks, and both spatially and temporally linked intrusive rock suites, deposited and emplaced at 1.9–1.8 Ga, form the syn-orogenic component. These magmatic suites evolved from magnesian and calc-alkaline to alkali–calcic compositions to ferroan and alkali–calcic varieties in a subduction-related tectonic setting. Apatite–Fe oxide, including the world's two largest underground Fe ore mines (Kiruna and Malmberget), skarn-related Fe oxide, base metal sulphide, and epigenetic Cu–Au and Au deposits occur in the Norrbotten lithotectonic unit. Low- to medium-pressure and variable temperature metamorphic conditions and polyphase Svecokarelian ductile deformation prevailed. The general northwesterly or north-northeasterly structural grain is controlled by ductile shear zones. The Paleotectonic evolution after the Neoarchean involved three stages: (1) intracratonic rifting prior to 2.0 Ga; (2) tectonic juxtaposition of the lithotectonic units during crustal shortening prior to 1.89 Ga; and (3) accretionary tectonic evolution along an active continental margin at 1.9–1.8 Ga.

scholarly journals Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia

2016 ◽  
Vol 53 (1) ◽  
pp. 10-33 ◽  
Author(s):  
Lijuan Liu ◽  
Jeremy P. Richards ◽  
S. Andrew DuFrane ◽  
Mark Rebagliati
Keyword(s):  
British Columbia ◽  
Gold Deposit ◽  
Late Cretaceous ◽  
Gold Mineralization ◽  
Volcanic Rocks ◽  
Fluid Inclusion Study ◽  
Epithermal Gold ◽  
Epithermal Gold Deposit ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Newton is an intermediate-sulfidation epithermal gold deposit related to Late Cretaceous continental-arc magmatism in south-central British Columbia. Disseminated gold mineralization occurs in quartz–sericite-altered Late Cretaceous felsic volcanic rocks, and feldspar–quartz–hornblende porphyry and quartz–feldspar porphyry intrusions. The mineralization can be divided into three stages: (1) disseminated pyrite with microscopic gold inclusions, and sparse quartz–pyrite ± molybdenite veins; (2) disseminated marcasite with microscopic gold inclusions and minor base-metal sulfides; and (3) polymetallic veins of pyrite–chalcopyrite–sphalerite–arsenopyrite. Re–Os dating of molybdenite from a stage 1 vein yielded an age of 72.1 ± 0.3 Ma (published by McClenaghan in 2013). The age of the host rocks has been constrained by U–Pb dating of zircon: Late Cretaceous felsic volcanic rocks, 72.1 ± 0.6 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013); feldspar–quartz–hornblende porphyry, 72.1 ± 0.5 Ma; quartz–feldspar porphyry, 70.9 ± 0.5 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013). The mineralized rocks are intruded by a barren diorite, with an age of 69.3 ± 0.4 Ma. Fluid inclusions in quartz–pyrite ± molybdenite ± gold veins yielded an average homogenization temperature of 313 ± 51 °C (number of samples, n = 82) and salinity of 4.8 ± 0.9 wt.% NaCl equiv. (n = 46), suggesting that a relatively hot and saline fluid likely of magmatic origin was responsible for the first stage of mineralization. Some evidence for boiling was also observed in the veins. However, the bulk of the gold mineralization occurs as disseminations in the wall rocks, suggesting that wall-rock reactions were the main control on ore deposition.

Geochemistry of Siluro-Devonian Tobique volcanic belt in northern and central New Brunswick (Canada): tectonic implications

1989 ◽  
Vol 26 (6) ◽  
pp. 1282-1296 ◽  
Author(s):  
J. Dostal ◽  
R. A. Wilson ◽  
J. D. Keppie
Keyword(s):  
New Brunswick ◽  
Mantle Source ◽  
Upper Mantle ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Continental Rift ◽  
Basaltic Rocks ◽  
Incompatible Elements ◽  
Tectonic Implications

Siluro-Devonian volcanic rocks of the northwestern mainland Appalachians are found mainly in the Tobique belt of New Brunswick where they consist predominantly of bimodal mafic–felsic suites erupted in a continental-rift environment. The axis of the Tobique rift trends north-northeast – south-southwest, obliquely to the regional northeast–southwest trend of the Appalachians. These geometric relationships are interpreted as being the result of rifting in a sinistral shear regime produced during emplacement of the Avalon terrene. The basaltic rocks are continental tholeiites and transitional basalts derived from a heterogeneous upper-mantle source that was enriched in incompatible elements relative to the primordial mantle. The mantle source was probably affected by the subduction processes.

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

2010 ◽  
Vol 46 (0) ◽  
pp. 173-184 ◽  
Author(s):  
Taryn R. Gray ◽  
Jaroslav Dostal ◽  
Malcolm McLeod ◽  
Duncan Keppie ◽  
Yuanyuan Zhang
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Geochemistry and uranium-lead isotopic ages of volcanic rocks associated with Ladakh batholith, western Himalaya: Implications for petrogenesis and tectonic evolution

2020 ◽  
Author(s):  
Nongmaithem Lakhan Singh ◽  
Athokpam Krishnakanta Singh
Keyword(s):  
Oceanic Crust ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Primary Source ◽  
Western Himalaya ◽  
Mature Stage ◽  
Northern Margin ◽  
Felsic Volcanic ◽  
Compositional Diversity ◽  
Felsic Volcanic Rocks

&lt;p&gt;We present zircon U-Pb ages and whole-rock geochemistry along with mineral chemistry of the Khardung volcanic rocks outcropped in the northern margin of the Ladakh batholith in order to constrain their origin and tectono-magmatic history. These volcanic rocks are sandwiched between the Ladakh batholith in the south and the Shyok suture zone in the north and span a continuous compositional range from basalt to rhyolite, although mafic rocks are minor and intermediate to felsic rocks are volumetrically predominant. New zircon U-Pb dating for andesite coupled with two rhyolitic rocks yield 69.71 Ma, 62.49 Ma, and 66.55 Ma, defining the probable span of their magmatism from Late Cretaceous to Palaeogene. Based on their mineralogical and geochemical compositional diversity, the Khardung volcanic rocks are categorized as intermediate volcanic rocks (basaltic andesite-andesite) and felsic volcanic rocks (dacite-rhyolite). The intermediate volcanic rocks are marked by low SiO&lt;sub&gt;2&lt;/sub&gt; (52.80-61.31 wt.%), enriched LREEs, and negative HFSEs (Nb, Ti, Zr) anomalies whereas,&amp;#160; felsic volcanic rocks are characterized by high SiO&lt;sub&gt;2&lt;/sub&gt; (64.52-79.19 wt.%), pronounced negative Eu anomalies, enriched LREE and concave-downward HREE&amp;#8217;s and negative HFSE&amp;#8217;s (Nb, Ti) anomalies. Both the intermediate and felsic volcanic rocks exhibit quartz, sanidine, albite, bytownite, and diopside as their dominant mineral phases. Geochemical signatures indicate that the fractional crystallization and crustal contamination played a significant role in the evolution of the Khardung volcanic rocks and their geochemical diversity probably resulted from the partial melting of the common primary source, which had been metasomatized by variable contributions of fluids released from down going Neo-Tethyan oceanic crust. Thus, the Khardung volcanic rocks could be considered as a product of mature stage of arc magmatism during the subduction of the Neo-Tethyan oceanic crust, which occurred during Early Cretaceous to Palaeogene, prior to the main collision between the Indian and Asian plates.&lt;/p&gt;

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