Lithostratigraphy and geochemistry of the Cottrells Cove Group, Buchans – Roberts Arm volcanic belt: new constraints for the paleotectonic setting of the Notre Dame Subzone, Newfoundland Appalachians

1997 ◽  
Vol 34 (1) ◽  
pp. 86-103 ◽  
Author(s):  
Tomasz Dec ◽  
H. Scott Swinden ◽  
R. Greg Dunning
Keyword(s):  
Tectonic Setting ◽  
Volcanic Belt ◽  
Island Arc ◽  
Upper Ordovician ◽  
Sedimentary Sequences ◽  
History Of ◽  
Laurentian Margin ◽  
Uplift And Erosion ◽  
Back Arc ◽  
Volcaniclastic Deposits

New sedimentological, geochemical, and geochronological data from the Cottrells Cove Group in central Newfoundland provide important constraints on the nature of the Notre Dame Subzone, its tectonic setting, and the history of the Laurentian margin during the Early Ordovician. The Cottrells Cove Group forms the eastern extension of the Roberts Arm Group and correlates with the Chanceport Group on New World Island. It is represented by two volcano-sedimentary formations that occur in a complex thrust stack. The Fortune Harbour Formation consists of calc-alkalic, island-arc lavas, followed by a 1250 m thick succession of volcaniclastic deposits, radiolarian cherts, and calc-alkalic, mafic flows, which were deposited in a back-arc, basin-plain setting. The volcaniclastic deposits include felsic tuff, which has a U–Pb zircon age of 484 ± 2 Ma and an inheritance component of 2517 ± 26 Ma. These new U–Pb and Nd-isotope data suggest that the island-arc–back-arc volcanism and sedimentation in the Notre Dame Subzone developed in the vicinity of continental margin and approximately 10 Ma earlier than has previously been established. The Moores Cove Formation is undated but contains boulders of calc-alkalic basalt and is presumed to be at least in part younger than the Fortune Harbour Formation. Tholeiitic lavas, together with associated radiolarian cherts and volcaniclastic deposits, constitute the basal part of the Moores Cove Formation and may have been deposited in a back-arc environment synchronously with some parts of the Fortune Harbour Formation. They are conformably followed by an over 1200 m thick, coarsening-upward succession of lower-slope and submarine-fan deposits. The polymictic flysch, containing clasts of island-arc basalt, accompanied by other volcanic, plutonic, ultramafic, and sedimentary detritus, may record Middle or Upper Ordovician uplift and erosion of obducted arc–back-arc, volcano-sedimentary sequences and their ophiolitic substrate.

Depositional and geotectonic history of the Gala area, eastern Southern Uplands, Scotland

1993 ◽  
Vol 84 (2) ◽  
pp. 161-173 ◽  
Author(s):  
A. M. Kassi ◽  
J. A. Weir
Keyword(s):  
Late Stage ◽  
Large Scale ◽  
Strike Slip ◽  
Upper Ordovician ◽  
Volcanic Arc ◽  
History Of ◽  
Back Arc

AbstractThe Ordovician and Silurian successions between Falahill and Galashiels encompass six flysch-dominated formations: the Upper Ordovician Portpatrick and Shinnel Formations representing the Leadhills Group, the Llandovery Mindork, Garheugh, and Buckholm Formations together comprising the Gala Group, and a formation indeterminate of age within the Hawick Group. Southward ensialic andesitic volcanic arc and northward low- to medium-grade sialic sources contributed sediment, whilst ophiolitic and subduction-related sources made minor contributions. Deposition took place firstly, in a SE-migrating back-arc basin bordering the northerly source, the Laurentian continent. Subsequent NW-directed underthrusting led to formation out of the back-arc basin of an imbricate thrust stack which migrated southeastwards. Ultimately a foreland successor basin formed ahead of the rising thrust stack.Flysch units are typically associated with linear outcrops of Moffat Shales which are the loci of major steep SE-translating reverse faults, two of which participate in a late-stage sinistral strike–slip duplex with large-scale imbrication. The faults divide the succession into a sequence of tectonostratigraphic blocks, successively younger to the SE. At least six of the ten blocks customarily recognised in the Southern Uplands, Blocks 3–8, are represented, some of which coincide with single or complete formations.

scholarly journals Petrological and Tectonostratigraphic Evidence for a Mid Ordovician Rift Pulse on the Arabian Peninsula

GeoArabia ◽  
1999 ◽  
Vol 4 (4) ◽  
pp. 467-500 ◽  
Author(s):  
W. Heiko Oterdoom ◽  
Mike A. Worthing ◽  
Mark Partington
Keyword(s):  
Tectonic Setting ◽  
Late Ordovician ◽  
Mafic Rocks ◽  
Early Ordovician ◽  
Sedimentary Sequences ◽  
Field Investigations ◽  
Clastic Sediments ◽  
Step Heating ◽  
Well Data ◽  
Uplift And Erosion

ABSTRACT During late Early Ordovician times an increase in the rate of subsidence in the Ghaba Salt Basin and western South Oman Salt Basin is suggested by the thick sequence of continental clastics of the Ghudun Formation. After a phase of rift-shoulder uplift and erosion, related to a renewed pulse of extension which may have initiated diapiric growth of salt structures in the Ghaba Salt Basin, sedimentation resumed again in the Mid Ordovician. During this period, the center of deposition shifted to the Saih Hatat area in North Oman. This paper documents seismic and well data, field investigations and petrological study of potassic mafic rocks from the Huqf area which were intruded in the eastern side of the Ghaba Salt Basin. A Mid Ordovician age of 461 ± 2.4 million years has been established for these rocks by the Argon-Argon step heating method. Analogy with the petrology and setting of similar potassic mafic rocks from the Rio Grande Rift in the western United States of America suggests that they were intruded into the shoulder of an intra-continental rift. The data provide the first clear evidence of a pulse of rift-shoulder uplift in the Huqf area during the Mid Ordovician. The 3-kilometer-thick Mid to Late Ordovician clastic sediments of the Amdeh Formation in North Oman, together with the occurrence of abnormally thick sedimentary sequences and volcanics in the Tabas Graben in Iran, are consistent with a period of break-up of eastern Gondwana. Together, the Ghaba-Saih Hatat and Tabas Basins are considered to be part of a failed rift arm. These observations further improve our regional knowledge of the Early to Late Ordovician tectonic setting of Oman and will assist in unlocking the hydrocarbon potential of classical rift-related structures consisting of early-rift Early Ordovician sand-prone reservoirs sealed by syn-rift Mid to Late Ordovician marine shales.

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.

Geochemical aspects of back-arc spreading in the Scotia Sea and western Pacific

1981 ◽  
Vol 300 (1454) ◽  
pp. 263-285 ◽  
Keyword(s):  
Island Arc ◽  
Calc Alkaline ◽  
Volcanic Arc ◽  
Scotia Sea ◽  
Marginal Basin ◽  
Early Stages ◽  
Enriched Mantle ◽  
Mantle Sources ◽  
History Of ◽  
Back Arc

The results of recent geochemical investigations of several island arc - marginal basin systems in the Scotia Sea area and in the western Pacific are outlined. Marginal basins in different stages of evolution are represented, from those in the initial stages of formation to those with an extensive and multiple history of back-arc spreading. Some are completely intraoceanic, others have developed at continental margins. Basalts erupted at back-arc spreading centres seem to be as geochemically varied as those from normal mid-ocean ridges, and record evidence for similar processes of partial melting, fractional crystallization and magma mixing in their genesis. They appear to have been derived from mantle sources with incompatible trace element characteristics ranging from ‘depleted’ to ‘enriched’, but with the ‘enriched’ mantle sources being sampled during the earlier stages of back-arc spreading. Submarine back-arc basalts are more vesicular than their normal ocean ridge equivalents, and their corresponding glasses have higher water contents. This, together with other geochemical features such as the higher ratios of lithophile to high field strength elements in some back-arc basalts, suggests that a component from the subducted slab may be involved in their petrogenesis. The chemistry of the corresponding arc volcanics is described in relation to the subduction and extensions history of marginal basin development. In intraoceanic arcs the early stages of arc magmatism are dominated by the eruption of large volumes of island arc tholeiites and subsidiary high-Mg andesites. In the Mariana region, after the initial volcanic arc is split and separated by back-arc spreading, the later frontal arc volcanics have calc-alkaline characteristics. Basalts erupted during the early stages of back-arc spreading more commonly have arc-like geochemical features when the marginal basin has developed through splitting of a calc-alkaline volcanic arc. The secular variation in the geochemistry of the arc volcanics may be related to the progressive development of a lithophile element enriched mantle source beneath the arc. This source contributes to the basalts produced during the early stages of arc rifting and back-arc spreading. Ophiolite complexes which represent marginal basin floor may well carry these arc-like geochemical features.

Geochemical Characteristics and Tectonic Implications of the early Permian Volcanic Rocks from Ongniud Banner, Inner Mongolia

2013 ◽  
Vol 734-737 ◽  
pp. 344-351 ◽  
Author(s):  
Deng Liu ◽  
Dai Yong Cao ◽  
Yi Wu Wang ◽  
Zhong Yuan Liu
Keyword(s):  
North China ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Island Arc ◽  
Early Permian ◽  
Sedimentary Sequences ◽  
High K ◽  
North China Plate ◽  
Plate Subduction

The Early Permian volcanic-sedimentary sequences of Ongniud Banner consist mainly of andesite, rhyolite, perlite, volcanic breccia, tuff, tuffaceous sandstone, siliceous rock. Rock assemblage and sedimentary formations indicate that are of fore-arc basin sedimentary feature between subduction zone and island arc in Early Permian. The volcanic rocks from Elitu Formation have SiO2=50.23%~74.83%, Mg#=6.21~49.54, Na2O+K2O=5.27%~10.73%, Na2O/K2O=0.36~4.17, belonging to high-K cal-alkaline (HKCA)~shoshonite (SHO) series. The volcanic rocks are characterized with (La/Yb)N=5.52~9.89, moderate - intense negative Eu anomalies, LILE enrichment such as Ba, Ra, K, Th and HFSE depletion such as Ta, Nb, P, Ti, and indicating that magma could be formed in the tectonic setting of the island arc and active continental margin related to the plate subduction. R1-R2 diagram also indicates that volcanic rocks were generated at syn-collision or post-orogenic period, perhaps representing the mid-later subduction stage of the Palaeo-Asian Ocean Plate and North China Plate. Taken together, the authors suggest that the region was located still in the Palaeo-Asian Ocean, rather than the intracontinental taphrogenic trough in Early Permian.

scholarly journals Discovery of Ancient Volcanoes in the Okhotsk Sea (Russia): New Constraints on the Opening History of the Kurile Back Arc Basin

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 442
Author(s):  
Reinhard Werner ◽  
Boris Baranov ◽  
Kaj Hoernle ◽  
Paul van den Bogaard ◽  
Folkmar Hauff ◽  
...  
Keyword(s):  
Trace Element ◽  
Island Arc ◽  
Kurile Island ◽  
Geochemical Data ◽  
Magma Source ◽  
Published Data ◽  
Kurile Island Arc ◽  
History Of ◽  
Spreading Rates ◽  
Back Arc

Here we present the first radiometric age and geochemical (major and trace element and isotope) data for samples from the Hydrographer Ridge, a back arc volcano of the Kurile Island Arc, and a newly discovered chain of volcanoes (“Sonne Volcanoes”) on the northwestern continental slope of the Kurile Basin on the opposite side of the arc. The 40Ar/39Ar age and geochemical data show that Hydrographer Ridge (3.2–3.3 Ma) and the “Sonne Volcanoes” (25.3–25.9 Ma) have very similar trace element and isotope characteristics to those of the Kurile Island Arc, indicating derivation from a common magma source. We conclude that the age of the “Sonne Volcanoes” marks the time of opening of the Kurile Basin, implying slow back arc spreading rates of 1.3–1.8 cm/y. Combined with published data from the Kurile fore arc, our data suggest that the processes of subduction, Kurile Basin opening and frontal arc extension occurred synchronously and that extension in the rear part and in the frontal part of the Kurile Island Arc must have been triggered by the same mechanism.

Anatomy and orogenic history of a Paleoproterozoic accretionary belt: the Makkovik Province, Labrador, Canada

2002 ◽  
Vol 39 (5) ◽  
pp. 711-730 ◽  
Author(s):  
John W.F Ketchum ◽  
Nicholas G Culshaw ◽  
Sandra M Barr
Keyword(s):  
Island Arc ◽  
Amphibolite Facies ◽  
Mobile Belt ◽  
Localized Deformation ◽  
Facies Metamorphism ◽  
History Of ◽  
Archean Crust ◽  
Arc Setting ◽  
Back Arc ◽  
Over Time

The Makkovik Province is a segment of a Paleoproterozoic accretionary belt (the Makkovik–Ketilidian orogen) that developed on the southern margin of Laurentia at 1.9–1.7 Ga. In contrast to coeval Laurentian orogenic belts that mainly resulted from collision of Archean plates, Makkovikian–Ketilidian orogenesis was dominated by active-margin processes including continental margin arc plutonism and juvenile terrane accretion, both of which were accompanied by regional transpression. In the Makkovik Province, earliest deformation and amphibolite-facies metamorphism of Paleoproterozoic rift–drift assemblages (Post Hill and Moran Lake groups) and the Archean foreland (Nain Province) occurred at 1.9 Ga in response to accretion of a Paleoproterozoic island arc. Following this collision, cratonward-dipping subduction was established, resulting in the formation of the 1895–1870 Ma Island Harbour Bay Plutonic Suite, a calc-alkaline magmatic arc built on reworked Archean crust. Crust formation continued between ca. 1860 and 1850 Ma with deposition of the Aillik Group on a largely juvenile basement in a rifted-arc or back-arc setting. Sometime before 1802 Ma this depositional basin was tectonically inverted, with resultant northwestward thrusting of the Aillik Group over reworked Archean crust. This phase of deformation may have been driven by accretion of a second island arc potentially represented by the Cape Harrison Metamorphic Suite. Regional transpression and amphibolite-facies metamorphism at ca. 1815–1780 Ma were accompanied by widespread granitoid plutonism. These events were mainly concentrated in the juvenile domains and are thought to reflect processes in a broad continental back-arc setting. A final orogenic pulse, marked by regional greenschist-facies transpression and emplacement of A-type granitoid plutons, occurred between 1740 and 1700 Ma, with deformation and plutonism potentially linked to crust–mantle detachment and incursion of mafic magmas at the base of the crust, respectively. The record of crustal development suggests that the coeval themes of spatially and temporally linked structural and plutonic activity, oceanward migration of this activity over time, and a trend toward increasingly more localized deformation occurred throughout the orogenic history of the Makkovik Province. These characteristics are thought to broadly reflect oceanward crustal growth of the orogen over time. In the correlative Ketilidian mobile belt of southern Greenland, these themes were also operative but appear to have been less pronounced, most likely due to minimal or a complete absence of accretion of island-arc material.

Sr, Y, Zr, Nb, Ti, and REE in Grenville amphibolites at Montauban-les-Mines, Quebec

1982 ◽  
Vol 19 (4) ◽  
pp. 633-644 ◽  
Author(s):  
W. H. MacLean ◽  
K. St. Seymour ◽  
M. K. Prabhu
Keyword(s):  
Tectonic Setting ◽  
Island Arc ◽  
The Other ◽  
Ocean Floor ◽  
Grenville Province ◽  
Ree Distribution ◽  
Back Arc ◽  
Ore Deposition

Distribution of Ti, Sr, Y, Zr, Nb, and REE in Proterozoic amphibolites and a rarely preserved pillowed metabasalt in the vicinity of Pb–Zn mineralization at Montauban-les-Mines in the Grenville Province of Quebec are used to assess the tectonic setting of the volcanism and, hence, the environment of ore deposition. Absolute abundances of Ti, Sr, Y, Zr, and Nb are close to those reported for modem island-arc and back-arc basalts. The flat patterns of the chondrite-normalized REE distribution and the discrimination plots of the other elements indicate a tholeiitic affinity for the volcanism. Specifically, plots of Ti against Zr and Ti–Zr–Y are mostly in the fields reported for ocean-floor (MOR and back-arc) basalts, but overlap with arc tholeiites. Cr and Ni are, however, higher than for most arc tholeiites. Overall, the data are most compatible with tholeiitic volcanism in an island-arc (including back-arc) environment.

U–Pb geochronology of the eastern Abitibi Subprovince. Part 2: Noranda – Kirkland Lake area

1993 ◽  
Vol 30 (1) ◽  
pp. 29-41 ◽  
Author(s):  
J. K. Mortensen
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Rapid Onset ◽  
Detrital Zircons ◽  
Lake Area ◽  
Sedimentary Sequences ◽  
South Central ◽  
Abitibi Subprovince ◽  
History Of ◽  
Main Period

U–Pb zircon ages for 15 volcanic and plutonic units in the Noranda and Kirkland Lake areas help constrain the history of volcanism, plutonism, sedimentation, and deformation in the south-central part of the Abitibi belt. Volcanism occurred over an interval of at least 50 Ma, beginning with the deposition of the volcanic and volcaniclastic units within the Pacaud Structural Complex at 2747 Ma. Following a period of apparent quiescence, magmatism resumed at 2730–2725 Ma with the eruption of volcanic rocks in the Normétal and Lac Abitibi area. From 2715 until about 2698 Ma, volcanism occurred sporadically throughout much of the area, culminating in the eruption of the Blake River Group from 2703 to 2698 Ma. Several large intrusive bodies yield ages that indicate that they are plutonic equivalents of the Blake River Group. Plutons that are considered to have been emplaced during the Kenoran orogeny give ages that are only slightly younger than the youngest volcanic units of the Blake River Group, emphasizing the very rapid onset of Kenoran deformation following the cessation of volcanic activity.The Cléricy syenite, dated at 2682 ± 3 Ma, postdates the main period of Kenoran deformation in this area and intrudes sedimentary rocks of the Kewagama Group which contain detrital zircons as young as 2687 Ma. These data suggest that the Kewagama Group is the same age as late sedimentary sequences such as the Timiskaming Group and may have been deposited in a similar tectonic setting.

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