scholarly journals Avalonian proximity of the Ordovician Miramichi Terrane, northern New Brunswick, northern Appalachians: Paleomagnetic evidence for rifting and back-arc basin formation at the southern margin of Iapetus

1993 ◽  
Vol 227 (1-4) ◽  
pp. 17-30 ◽  
Author(s):  
Margo J. Liss ◽  
Ben A. van der Pluijm ◽  
Rob Van der Voo
Keyword(s):  
New Brunswick ◽  
Southern Margin ◽  
Basin Formation ◽  
Back Arc

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.

Baltica-Laurentia link during the Mesoproterozoic: 1.27 Ga development of continental basins in the Sveconorwegian Orogen, southern Norway

2002 ◽  
Vol 39 (9) ◽  
pp. 1425-1440 ◽  
Author(s):  
Bernard Bingen ◽  
Joakim Mansfeld ◽  
Ellen MO Sigmond ◽  
Holly Stein
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Active Continental Margin ◽  
Dyke Swarm ◽  
Quartz Porphyry ◽  
Extensional Tectonic ◽  
Basin Formation ◽  
Sveconorwegian Orogen ◽  
Southern Norway ◽  
Back Arc ◽  
Secondary Ion

Recent models suggest that Laurentia and Baltica were contiguous during the Mesoproterozoic and shared a long-lived active continental margin, subsequently reworked during the Grenvillian orogeny. Around 1.25 Ga, the geological record is dominated by dyke-swarm intrusion, continental rift basin formation, A-type felsic magmatism, and arc – back-arc basin development. It points to a dominantly extensional tectonic regime over most of the craton and the Grenvillian margin, suggesting a retreating subduction boundary at that time. In the westernmost allochthonous domain of the Sveconorwegian Orogen, southern Norway, the Sæsvatn–Valldal supracrustal sequences are interpreted as rift or pull-apart basins. They formed at and after 1.27 Ga, in a continental setting, at the margin of Baltica. This interpretation is based on geological, geochemical, and new secondary ion mass spectrometry (SIMS) zircon U–Pb data. A subvolcanic quartz porphyry at the base of the Sæsvatn sequence yields a 1275 ± 8 Ma intrusion age. Metarhyolite samples in the lower part of the sequences yield equivalent extrusion ages of 1264 ± 4 Ma (Sæsvatn sequence) and 1260 ± 8 Ma (Valldal sequence). The metarhyolite units are overlain by sequences of metabasalt and metasandstone. An angular unconformity between the metarhyolites and overlying rocks is locally observed and possibly reflects rift tectonics during formation of the basin. A sample of arkosic metasandstone at the top of the exposed Sæsvatn sequence yields a few Archaean detrital zircon grains and a large spectrum of 2.2–1.2 Ga Proterozoic grains. These data point to a varied continental provenance and constrain sedimentation to later than 1211 ± 18 Ma.

scholarly journals U-Pb (zircon) age for the Beaver Harbour Porphyry, New River belt, southern New Brunswick, Canada

2014 ◽  
Vol 50 ◽  
pp. 155
Author(s):  
Sandra M. Barr ◽  
Cameron J. Bartsch ◽  
Brent V. Miller ◽  
Chris E. White
Keyword(s):  
New Brunswick ◽  
Continental Margin ◽  
Active Continental Margin ◽  
Chemical Data ◽  
Volcanic Arc ◽  
Zircon Age ◽  
Isotopic Signatures ◽  
Southern Margin ◽  
High Level

The Beaver Harbour Porphyry is a high-level intermediate to felsic granitoid and locally tuffaceous unit with quartz and less abundant feldspar phenocrysts. It forms a fault-bound sliver along the southern margin of the New River belt in southern New Brunswick. A concordant TIMS U-Pb (zircon) age of 551 ± 1.2 Ma shows that the porphyry is of the same age as other high-level plutonic and volcanic units that form most of the New River belt. Chemical data show that these units likely formed in a volcanic-arc environment at an active continental margin. One sample from the porphyry has ƐNd(t) of -0.5, within the range of other samples from the New River belt and consistent with the interpretation that the belt is part of Ganderia, rather than Avalonia, which generally has more juvenile isotopic signatures.

The Ordovician volcanics of the Elmtree–Belledune inlier and their relationship to volcanics of the northern Miramichi Highlands, New Brunswick

1992 ◽  
Vol 29 (7) ◽  
pp. 1430-1447 ◽  
Author(s):  
J. A. Winchester ◽  
C. R. van Staal ◽  
J. P. Langton
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Late Ordovician ◽  
Igneous Rocks ◽  
Volcanic Arc ◽  
Middle Ordovician ◽  
Marginal Basin ◽  
Tectonic Mélange ◽  
Back Arc

An investigation of the geology and chemistry of the basic igneous rocks in the Elmtree and Belledune inliers in northern New Brunswick shows that the bulk of the Middle Ordovician rocks of the ophiolitic Fournier Group are best interpreted as the products of volcanism and sedimentation in an extensive ensimatic back-arc basin southeast of a volcanic arc. The oceanic back-arc-basin igneous rocks form the basement to renewed arc-related basaltic volcanism in late Middle to Late Ordovician time. The Fournier Group is separated from the structurally-underlying, shale-dominated Elmtree Formation of the Tetagouche Group by an extensive tectonic melange, which incorporates lenses of serpentinite, mafic volcanic rocks, and sedimentary rocks of both the Tetagouche and Fournier groups. The mafic volcanic rocks in the Elmtree Formation correlate best with those intercalated with the lithologically similar sediments of the Llandeilian–Caradocian Boucher Brook Formation in the northern Miramichi Highlands. The melange and the present structural amalgamation of the Tetagouche and Fournier groups result from closure of the marginal basin by northward-directed subduction at the end of the Ordovician. Most mafic suites in the Elmtree and Belledune inliers can be chemically correlated with similar suites in the northern Miramichi Highlands, showing that the two areas are not separated by a terrane boundary.

U–Pb ages, geochemistry, and tectonomagmatic history of the Cambro-Ordovician Annidale Group: a remnant of the Penobscot arc system in southern New Brunswick?1This article is one of a series of papers published in this CJES Special Issue: In honour of Ward Neale on the theme of Appalachian and Grenvillian geology.

2012 ◽  
Vol 49 (1) ◽  
pp. 166-188 ◽  
Author(s):  
Susan C. Johnson ◽  
Leslie R. Fyffe ◽  
Malcolm J. McLeod ◽  
Gregory R. Dunning
Keyword(s):  
New Brunswick ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Conclusive Evidence ◽  
The Past ◽  
Late Cambrian ◽  
Suprasubduction Zone ◽  
History Of ◽  
Group A ◽  
Back Arc

The Penobscot arc system of the northeastern Appalachians is an Early Cambrian to early Tremadocian (ca. 514–485 Ma) ensialic to ensimatic arc–back-arc complex that developed along the margin of the peri-Gondwanan microcontinent Ganderia. Remnants of this Paleozoic arc system are best preserved in the Exploits Subzone of central Newfoundland. Correlative rocks in southern New Brunswick are thought to occur in the ca. 514 Ma Mosquito Lake Road Formation of the Ellsworth Group and ca. 497–493 Ma Annidale Group; however in the past, the work that has been conducted on the latter has been of a preliminary nature. New data bearing on the age and tectonic setting of the Annidale Group provides more conclusive evidence for this correlation. The Annidale Group contains subalkaline, tholeiitic to transitional, basalts to basaltic andesites, picritic tuffs and calc-alkaline to tholeiitic felsic dome complexes that have geochemical signatures consistent with suprasubduction zone magmatism that was likely generated in a back-arc basin. New U–Pb ages establish that the Late Cambrian to Early Tremadocian Annidale Group and adjacent ca. 541 Ma volcanic rocks of the Belleisle Bay Group in the New River belt were affected by a period of younger magmatism ranging in age from ca. 479–467 Ma. This provides important constraints on the timing of tectonism in the area. A ca. 479 Ma age for the Stewarton Gabbro that stitches the faulted contact between the Annidale and Belleisle Bay groups, demonstrates that structural interleaving and juxtaposition occurred during early Tremadocian time, which closely coincides with the timing of obduction of Penobscottian back-arc ophiolites onto the Ganderian margin in Newfoundland.

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.

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