DOCSLIB.ORG

Provenance of the Meguma Terrane, Nova Scotia: Rifted Margin of Early Paleozoic Gondwana

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Provenance of the Meguma Terrane, Nova Scotia: Rifted Margin of Early Paleozoic Gondwana Provenance of the Meguma terrane, Nova Scotia: rifted margin of early Paleozoic Gondwana John W.F,Waldron, Chris E. White, SandraM. Barr, Antonio Simonetti,and Larry M. Heaman Abstract: Detrital zircon ages from the lower part of the Late Proterozoic(?)to Middle Cambrian Goldenville Group in the Meguma te(ane of Nova Scotia suggestderivation from local sourcesin the Avalonian and Pan-African orogenson the margins of Early Cambrian Gondwana. Samplesfrom near the top of the group show a brcader distribution, including ages back to Archean. The eNddata show a correspondingtrend, from slightly positive in the lower Coldenville Group to highly negative in the upper Goldenville Group and overlying Upper Cambrian to Lower Ordovician Halifax Group. The trends are consistentwith deposition of the lower part of the Meguma successionin a rift, in which uplifted rift-flanks werc the main source of the early basin fill, whereassubsequent themal subsidenceof rift margins allowed for more wide- spread sedimentsourcing in younger units. The dft was possibly located between Gondwana and Avalonia, and may have been the locus for separationof Avalonia from Gondwana to form pafi of the Rheic Ocean. R6sum6: Les 6gesdes zircons d6tritiques du Groupe de Goldenville (Protdrozoiquetardif(?) i Cambrien moyen) dans le terrane de Meguma de la Nouvelle-Ecossesuggdrent une provenancede sourceslocales dans les orogEnesavalonien et pan-atricain sur les bordures du continent de Gondwana au Cambrien pr6coce.Des 6chantillonspr6levds prds du sommet du groupe montrent une distribution plus vaste, incluant des dges arch6ens.Les donn6eseNd montrent une tendancecorre- spondante,de l6garernentpositive dans le Grcupe de Goldenville infdrieur d hautementn6gative dans le Grcupe de Gold- enville sup6deur et dans le Groupe de Halifax susjacent (Cambrien sup6rieure Ordovicien inf6rieur). Les tendances concordent avec la ddposition de la partie inf6rieure de la successionde Meguma dans une fosse d'effondrement; les flancs soulev6sde cette fosse auraient constitu6 la source principale de mat6del de remplissagedu bassin pdmitif alors qu'une subsidencethermique subs6quentedes borduresde la fosse aurait conduit i une source de s6dimentsplus 6tenduepour les unit6s plus jeunes. La fosse d'effondrement 6tait possiblementsitu6e entre le Gondwana et I'Avalonie et elle constitue pos- siblement le lieu de la s6parationde I'Avalonie du Gondwana pour la formation d'une partie de I'oc€an Rh6ique. [Traduit par la R6daction] Introduction adiacent to northwest Africa and was transferTed to Lauren- tia during the Acadian orogeny, whereas others have pro- Meguma, the most outboard terrane of the Canadian Ap- posed an origin juxtaposed with westem Amazonia (e.g., palachians (Fig. la), has no clear conelative elsewhere in Keppie 1977) and (or) that Meguma travelled with Avalonia the Appalachian-Caledonideorogen. Although generally re- during the early Paleozoic (Muryhy et al. 2OO4a). garded as a peri-Gondwanan terane, Meguma shows marked contrasts with adjaqent Avalonia, and its origin has We report here the results of U-Pb dating of detrital zircon been controversial. Some authors (e.g., Schenk 1997 and and Sm-Nd isotopic analyses from Cambrian-Ordovician referencestherein) have proposed that Meguma odginated metasedimentaryunits in Meguma that are relevant to this conboversy. The data demonstxatethat sedimentprovenance changedrapidly from a restrictedand juvenile sourceto more Received 6 October 2008. Accepted 27 Jan!aty 2009. Published diverse and isotopically evolved sourceswith abundantPale- on the NRC ResearchPress Web site at cies.nrc.caon 2 March 2009. oproterozoic zircon, consistentwith formation on the Gond- wanan margin in an evolving dft that subsequentlybecame Paper handled by Associate Editor B. Muryhy. inactive and underwentthermal subsidence. J.W.F, Waldronr and L.M. Heaman. Departmentof Eafth and Atmospheric Sciences,University of Alberta, Edmonton, AB Stratigraphic context T6G 2E3. Canada. C.E. White. NS Departmentof Natural Resources,PO Box 698, Meguma is charactedzedby unique stratigraphy, includ- Halifax. NS B3J 2T9. Canada. ing a thick (>10 km) Cambrian (and possibly older) to Early S.M, Barr. Department of Earth and Environmental Science, Ordovician turbiditic clastic succession,historically assigned Acadia Unive$ity, Wolfvi e, NS B4P 2R6, Canada. to the Meguma Group, and divided into a lower, coarser A. Simonetti. Department of Earth and Atmospheric Sciences, grained Goldenville Formation and an upper, dominantly Univenity of Alberta, Edmonton, AB T6G 2E3, Canada;Present fine-grained Halifax Formation. Shatigraphic work (O'Brien address:Department of Civil Engineering & Geological 1988; Waldron 1992) and recent mapping (e.g., White 2007) Sciences,156 Fitzpatrick Hall, University Dame, of Notre Notre resulted in subdivision of thesethick formations and their el- Dame. IN 46556. USA. evation to group status. The entire package now is termed lConesponding author (e-mail: [email protected]). the Meguma Supergroup(White 2008). Can.J. EarthSci.46: 1-8 (2009) doi:10.1139/E09004 Publishedby NRC Researchkess Can.J. EadhSci. Vol.46,2009 Fig. 1. (a) Meguna Terrane showing units and sample locations. Paleocunent rose diagrams rcprcsentflutes and cunent ipples, corrected for tectonic distortion and rotated to horizontal (Waldron and Jensen 1985; waldron 1988). Inset: Location in Appalachial orogen, afler Hibbard et al. (2006). Fm., Formation; Gp., Group; L.. Lower; U., Upper. (r) Schematic stratigraphiccolumns for Meguma, showing sample bcations. (.) Values of ex6 at 540 Ma, against straligraphicposition, west and easl of ChebogucPoint shear zone (CPSZ). Red line on both plots shows the trend west of the CPSZ. for compffison. Data fiom this study and Clarke and Halliday (1985). Clarke et al. (1988), and Currieet ai. (1998). b Yarmouth-Digby 12 .#,^,; Easlof CheboouePoinl Halifax-Canso shearione 29 18 ^^25 CunadFm r'zla 23 -o 2215 JU,C\ t-- )^ o- "church x PoinlFm. B 38 , F$t tNd at 540t a Publishedby NRC ResearchPress Waldronet al. The Goldenville Group is dominated by psammite (meta- Results sandstone), with subordinate pelitic rocks (metasiltstone, slate, argillite). A locality close to tre top of the group U-Pb detrital zircon dating (Figs. la, lb) yielded a Middle Cambrian trilobite faunule Sample 1, from the lowest point in the exposedstuatigraphy (Pratt and Waldron 1991). Nearer the base of the exposed west of the CPSZ (Fig. lb), shows a strongly clustered age Goldenville Group (Fig. 1b), the trace fossil Oklhamia indt- distribution; 7l of 76 grains lie between 750 and 540 Ma. cates an Early Cambrian or possibly late Neoproterozoicage The density distribution has a strong peak at -640 Ma, with (White et al. 2005). The overlying Halifax Group is domi- subsidiary peaks at 560,585, and possibly 700 Ma. The nated by pelite, associatedwith fine- and very fine-grained youngestgrain, at 544 t 18 Ma, representsthe maximum dep- metasandstone.Rare graptolites high in the Halifax Group ositional age of the sampleand henceof the exposedGolden- (Fig. lb) indicate an Early Ordovician age (e.g., Cumming ville Group. Of the remaining grains,two are Neoproterozoic, r985). and three are Paleoproterozoic. -4 Northwest of the Chebogue Point shear zone (CPSZ; Sample 2, from a metasandstonebed km higher in the section, Fig. la), the Halifax Group is overlain unconformably by an Oldhamia-beaing interval of fine-grained meta- sedimentaryrocks Silurian volcanic and sedimentary rocks assigned to the known as the High Head member (White et al- 2005), shows White Rock Formation and equivalent units, deposited in a an even more restricted detrital aee range:all 124 grains give shallow-madne rift environment (MacDonald et al. 2002, ages berween740 and 540 Mi, with distinct peaks at and referencestherein). The overlying Early Devonian Tor- 560,580, and 620 Ma. A grain at 537 t 15 Ma provides brook Formation records shelf conditions (Jensen 1975). In the most reliable ma"ximumdepositio, nal age. addition to the contrast in stratigraphy (Fig. 1b), this part of Meguma is characterizedby abundantmafic sills (White and Sample 5, from the statigraphically highest metasand- Barr 2004; White et al. 2006). Furthermore,our limited pa- stone unit in the Goldenville Group northwest of the CPSZ (Figs. leocurrentdara from rhe area indicatesou(hward paleoflow 1a, 1b), shows a much more diverse age spectrum.A (Fig. 1a), in contrast with northwestward to northeastward large Neoproterozoiccluster (78 of 125 grains) has peats at -550, flow reported elsewhere in the terrane (Schenk 1970; Wal- 590, and possibly 620 Ma. A concordant grain at dron and Jensen1985; Waldron 1988). 529 i 19 Ma representsthe best constraint on depositional age. A second large peak occurs at 2060 Ma. Scattered The basementof Meguma is poorly known. Sm-Nd data grains show Mesoproterozoic and older Paleoproterozoic from mafic and felsic volcanic rocks in the White Rock For- ages. Seven Archean grains range from 2620 to 3036 Ma. mation are mainly positive, suggestingcrustal contamination Sample 13 is from an equivalent stratigraphiclevel east of of mainly mantle-derived magmas (MacDonald et al. 2002) the CPSZ (Fig. lb), adjacentto a fossiliferous Middle Cam- but also consistent with sources in Avalonian basement brian bed (Pratt and Waldron 1991). Of 47 grains (Keppie et al. 1991). Greenoughet a1. (1999) recorded con- with <10% discordance,12 arc late Neoproterozoic,grouped cordant and slightly discordant zircons with Avalonian and at -560,
Load more

Recommended publications
  • The Acadian Fold Belt in the Meguma Terrane, Nova Scotia: Cross Sections, Fold Mechanisms, and Tectonic Implications
    TECTONICS, VOL. 25, TC3007, doi:10.1029/2004TC001752, 2006 The Acadian fold belt in the Meguma Terrane, Nova Scotia: Cross sections, fold mechanisms, and tectonic implications Nicholas Culshaw1 and Sharon K. Y. Lee1 Received 6 October 2004; revised 10 January 2006; accepted 20 February 2006; published 20 May 2006. [1] Structural data and cross sections from the eastern from the Avalon Terrane (Figure 1). An Acadian fold belt part of the Devonian-Carboniferous fold belt of the affects its sedimentary component, the Cambrian–Early Meguma Terrane give insight into its structural Ordovician Meguma Group and latest Ordovician-Devonian development and crustal tectonics. The sandy White Rock, Kentville, and Torbrook formations. The fold Goldenville Formation, the active competent member belt is notable for its apparent simplicity: the locally during buckling, formed a multilayer several kilometers periclinal folds have mostly upright axial surfaces and horizontal hinges, with kilometric spacing between axial thick that lay beneath the denser, softer muds and silts of traces that are up to several tens of kilometers in length. the Halifax Formation. Cross sections reveal 2 orders of Given the external position of the Meguma Group relative folds: 11–18 km wavelength folds are interpreted as to the Appalachian orogen, the simple geometry of the resulting from buckling under the influence of gravity; Acadian fold belt is of interest, for, although resembling 4–6 km wavelength folds reflect the thickness of the an external foreland fold and thrust belt, thrusts are absent at multilayer with buckle shortening in the range 32– the present level of exposure. Also, the presence or absence 44%.
    [Show full text]
  • ES 2000 Bsc Muir Catherine.Pdf (5.221Mb)
    An 40 Ar/39 Ar Study of the Goldenville, Halifax, White Rock, and Torbrook formations of the Digby Area, Southwest Nova Scotia by Catherine Margaret Muir Undergraduate Honours Thesis Department of Earth Sciences Dalhousie University Halifax, Nova Scotia Dalhousie University Department of Earth Sciences HJiii"'· ~O\.l Sco1i.1 C~nada BJH Jlj t901l 49"'·1358 F.-U t9011 49"'·6889 DATE APRIL 27, 2000 I AUTHOR CATHERINE MARGARET MUIR ) TITLE AN 40AR/39AR STUDY OF THE GOLDENVILLE, HALIFAX. WHITE ROCK AND I TORBROOK FO~~TIONS OF THE DIGBY AREA, SOUTHWEST NOVA SCOTIA l ) Degree BSC HO~OURS Convocac::io:-. MAY·=:.;=-..::.::;___;_ 23 __ _ . Year 2000 Permission is her~with granted :o Dalhousie Uni?erslty to circulate and to have copied for non-commercial pu=?oses, at its discretion, the above title upon the request of individuals or i~stitu:ions. THE AUT~OR RESERVES OTHER P~BL!CATION RIGHTS, AND NEITHER THE THESIS NOR EXTE..~S IVE E.XTRACTS FROM IT XAY BE PR!Y!ED OR OTHER'JISE REPRODUCED 'JITHOUT THE A~!HOR ' S ~~ITT~~ P~~ISSION. THE AUTHOR ATTESTS THAT P~~ISS!ON HAS BE£..~ OBTAI~ED FOR THE USE OF &~ COPYRIGHTED ~TERIAL APPEARI~G I~ THIS THESIS (OTHER THAN BRIEF EXCERPTS REQUIRING ONLY PROPER ACKNOWLEDGE..~£..~ IN SCHOL\RLY w~ITING) AND THAT ALL SUCH USE IS CLEARLY ACKNOYLEDCED . ABSTRACT Cambrian to early-Devonian meta-sedimentary rocks of the Halifax and Goldenville formations of the Meguma Group and the overlying White Rock and Torbrook formations form the rart of the Meguma Terrane that underlies southwest Nova Scotia in the Digby area.
    [Show full text]
  • Assessment of Geothermal Resources in Onshore Nova Scotia
    FINAL REPORT Assessment of geothermal resources in onshore Nova Scotia Setting the stage, demonstrating value, and identifying next steps Félix-Antoine Comeau1 Stephan Séjourné 2 Jasmin Raymond1 1Institut national de la recherche scientifique (INRS), Centre Eau Terre Environnement 2Enki GeoSolutions inc. Rapport de recherche R2002 Prepared for the account of: Offshore Energy Research Association (OERA) December 1st, 2020 © INRS, Centre - Eau Terre Environnement, 2020 Tous droits réservés ISBN : 978-2-89146-939-5 (version électronique) Dépôt légal - Bibliothèque et Archives nationales du Québec, 2020 Dépôt légal - Bibliothèque et Archives Canada, 2020 Table of Contents ACKNOWLEDGEMENTS.................................................................................................................. 13 FOREWORD ......................................................................................................................................... 15 EXECUTIVE SUMMARY ................................................................................................................... 17 1. OVERVIEW OF THE GEOTHERMAL RESOURCE TYPES ............................................... 21 1.1 Geothermal systems ............................................................................................................... 21 1.1.1 Magmatic .......................................................................................................................... 25 1.1.2 Sedimentary basins ..........................................................................................................
    [Show full text]
  • Possible Evidence for a Protracted Gold-Forming System
    Further Re-Os Arsenopyrite Geochronology from Selected Meguma Au Deposits, Meguma Terrane, Nova Scotia: Possible Evidence for a Protracted Gold-forming System by Lin Chen A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Earth and Atmospheric Sciences University of Alberta ©Lin Chen, 2015 Abstract The Meguma terrane, Nova Scotia, is dominated by two rock types; regionally deformed and metamorphosed Cambro-Ordovician metasedimentary rocks and ca. 380-370 Ma meta- to peraluminous granites. The metasedimentary rocks host numerous orogenic-type, vein-hosted gold deposits which occur throughout the metasandstone-dominated Goldenville Group rather than the overlying metasiltstone- and metamudstone-dominated Halifax Group. These mineralized veins are dominated by quartz-carbonate-sulfide assemblages and occupy structures consistent with emplacement during late-stage fold tightening of the regional, northeast-trending, upright folds that formed during the Acadian orogenic event at ca. 410-400 Ma. From previous work, vein formation, hence gold emplacement, spanned 30-40 Ma, as constrained from field observations and radiometric dating. The former indicates veins post-date cleavage formation given that cleaved wall-rock fragments occur in some veins, and that rarely; veins post-date hornfels related to 380 Ma granites. Existing absolute age dating indicates two events at 408 Ma (Re-Os Arsenopyrite; 40Ar/39Ar whole rock) and 380-362 Ma (Re-Os Arsenopyrite; 40Ar/39Ar Muscovite, Biotite, whole rock). Here we report new Re-Os geochronological data generated from arsenopyrite in gold-bearing veins for two deposits sampled, all of which lie in the same stratigraphic-structural position in the lower part of the Goldenville Group.
    [Show full text]
  • Variscan Accretionary Complex of Northwest Iberia: Terrane Correlation and Succession of Tectonothermal Events
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by EPrints Complutense Variscan accretionary complex of northwest Iberia: Terrane correlation and succession of tectonothermal events Jose R. Martlnez Catalan Departamento de Geologia, Unlversldad de Salamanca, 37008 Salamanca, Spain Ricardo Arenas Departamento de Petroiogia y Geoquimlca, Unlversldad Complutense, 28040 Madrid, Spain Florentino Diaz Garcia Departamento de Geologia, Unlversldad de OVledo, 33005 OVledo, Spain Jacobo Abati Departamento de Petroiogia y Geoquimlca, Unlversldad Complutense, 28040 Madrid, Spain ABSTRACT The allochthonous terranes of northwest Iberia can be correlated with specific pale ogeo­ graphic realms of the continental masses and intervening oceans involved in the Variscan colli­ sion. Assuming that the existing ophiolites represent the suture formed by the closure of the Rheic ocean, the units in the fo otwall to the suture correspond to the outer edge of the Good­ waDa continentalmargin, and the units in the hanging waD are interpreted as fragments of the conjugate margin, represented by the Me guma terrane. This correlation establishes a precise link betweencircum-Atlantic terranes, and makes it possible to draw a relatively simple sce­ nario of the successive tectonothermal events recorded. Following the amalgamation of Avalon to LaUl'entia, the remaining outboard terranes underwent a progressive accretion to this conti­ nent that ended with the collision between Laurentia and Gondwana. INTRODUCTION position in the nappe pile: basal, intermediate, granulite, amphibolite and greenschist facies. The allochthonousterranes of northwest Iberia and upper units. Because the intermediate units The ophiolitic nappes were stacked during the outcrop in five synforms or structural basins as show clear oceanicaffinities, they are referred to closure of the Rheic ocean.
    [Show full text]
  • Preliminary Bedrock Geology of the New Germany Map Area (NTS 21A/10), Southern Nova Scotia
    Report of Activities 2007 113 Preliminary Bedrock Geology of the New Germany Map Area (NTS 21A/10), Southern Nova Scotia C. E. White Introduction to produce a 1:50 000-scale bedrock map (White and Kaul, 2007) showing the distribution of units and mineral occurrences. The Nova Scotia Department of Natural Resources continued bedrock mapping through the summer of 2007 in the New Germany map area (NTS Stratigraphy 21A/10). This work completes the northernmost part of the area covered by the South Shore Introduction Bedrock Mapping Project (Fig. 1). The project has provided a greater understanding of the The earliest regional geological mapping at a stratigraphy, structure, metamorphism and mineral reasonable scale (1 inch to 1 mile) in the current deposits of southwestern Nova Scotia. map area was done by Faribault et al. (1939a, b). As with previous map sheets in the project area They subdivided the stratified rocks into an older (e.g. White, 2005, 2006, 2007), geological data grey or blue-grey quartzite (Goldenville Formation) were collected at a scale of 1:10 000 and complied and a younger grey, green, and black slate (Halifax Figure 1. Simplified geological map of the Meguma Terrane, Nova Scotia, showing location of the New Germany map area in relation to the Southwest Nova and South Shore mapping projects (red box). White, C. E. 2008: in Mineral Resources Branch, Report of Activities 2007; Nova Scotia Department of Natural Resources, Report ME 2008-1, p. 113-124. 114 Mineral Resources Branch Formation), and placed both formations in the Meguma or “Gold-bearing” Series, which they considered to be Precambrian.
    [Show full text]
  • The Meguma Terrane of Southern Nova Scotia
    atlantic geology . volume 47 . 2011 50 The Meguma terrane of southern Nova Scotia: The gap in age between the Halifax Group and the overlying insights on its pre-Carboniferous stratigraphy Rockville Notch Group confirms that a major unconformity exists between the two groups. C.E. WHite1, T. Palacios2, S. Jensen2, and S.M. Barr3 1. Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia B3J 2T9, Canada <[email protected]> ¶ 2. Area de Paleontologia, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s/n, 06006 Badajoz, Spain ¶ 3. Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada The Meguma terrane of southern Nova Scotia includes the Neoproterozoic-Ordovician Goldenville and Halifax groups and the younger Silurian to early Devonian Rockville Notch Group, intruded by mainly Devonian plutons and overlain by Carboniferous and younger rocks. The Goldenville Group con- sists of metasandstone with minor interbeds of metasiltstone and slate (Moses Lake, Church Point, Green Harbour, Tangier, and Taylor Head formations), and locally grades upwards into thinly bedded metasandstone, metasiltstone, and silty slate (Government Point formation). The uppermost unit, which includes the laterally equivalent Moshers Island, Bloomfield, Beaverbank, and Tupper Lake Brook formations, is character- ized by numerous Mn-rich laminations and concretions. The Church Point formation contains a distinctive metasiltstone unit (High Head Member) that contains a deep-water Lower Cambrian trace fossil assemblage, including the ichnofossil Oldhamia. The upper part of the Government Point formation has yielded early Middle Cambrian Acado-Baltic trilobite fos- sils and the overlying Tupper Lake Brook formation yielded an acritarch species consistent with middle Cambrian age.
    [Show full text]
  • Late Devonian Peraluminous Granitic Plutons in the Canso Area, Eastern Meguma Terrane, Nova Scotia*
    LATE DEVONIAN PERALUMINOUS GRANITIC PLUTONS IN THE CANSO AREA, EASTERN MEGUMA TERRANE, NOVA SCOTIA* J.D. Hill Geological Survey of Canada 601 Booth Street, Ottawa, Ontario K1A 0E8 present address: Department of Mining Engineering Technical University of Vova Scotia P.O. Box 1000, Halifax, N o v a Scotia B3J 2X4 Date Received October 10, 1987 Date Accepted January 10, 1988 Late Devonian granitic rocks are well exposed in coastal outcrops near Canso in the eastern part of the Meguma Terrane. They form numerous, relatively homogeneous plutons of peraluminous biotite-muscovite granite and minor granodiorite which are enriched in muscovite, aluminum and alkalis and depleted in biotite and cafemic components relative to comparable rocks in other Meguma Terrane granites such as the South Mountain and Musquodoboit Batholiths. Individual plutons, which crystallized between 371 and 373 Ma based on U-Pb isotopic data, show a variable relationship between composition and relative age of intrusion. This implies crystallization from two or more separate batches of slightly different magma supplied from below the current level of exposure. Highly felsic, peraluminous compositions and initial °'Sr/B°Sr ratios ranging from 0.703 to 0.709 favour magma derivation from heterogenous intermediate to felsic continental crust containing some pelitic material. Intrusions were emplaced syntectonically during the early part of a ductile shearing event related to dextral transcurrent movements in the Cobequid-Chedabucto Fault System. Des roches granitiques tardiddvoniennes forment de vastes affleurements littoraux prAs de Canso, dans la partie orientale de la LaniAre de MAguma, oil elles dAterminent des plutons nombreux, relativement homogAnes, constituAs surtout de granites pAralumineux A biotite et muscovite avec.quelque granodiorite, qui sont enrichis en muscovite, aluminium, alcalis et ddficitaires en biotite et composants cafAraiques par rapport aux roches semblables des autres granites de la LaniAre de MAguma tels que les batholites de South Mountain et de Musquodoboit.
    [Show full text]
  • Meguma Terrane Revisited: Stratigraphy, Metamorphism, Paleontology, and Provenance Chris E
    Document generated on 09/27/2021 5:58 a.m. Geoscience Canada Meguma Terrane Revisited: Stratigraphy, Metamorphism, Paleontology, and Provenance Chris E. White and Sandra M. Barr Volume 39, Number 1, 2012 URI: https://id.erudit.org/iderudit/geocan39_1fgs03 See table of contents Publisher(s) The Geological Association of Canada ISSN 0315-0941 (print) 1911-4850 (digital) Explore this journal Cite this document White, C. E. & Barr, S. M. (2012). Meguma Terrane Revisited:: Stratigraphy, Metamorphism, Paleontology, and Provenance. Geoscience Canada, 39(1), 8–12. All rights reserved © The Geological Association of Canada, 2012 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/ This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ 8 GAC–MAC 2012: FIELD GUIDE SUMMARY Meguma Terrane Revisited: phosed (greenschist to amphibolite stratigraphic differences. The forma- facies) during the Early to Middle tions of the Rockville Notch Group, as Stratigraphy, Devonian Neoacadian orogeny (ca. well as two distinct suites of mafic sills Metamorphism, 405–365 Ma), and intruded by numer- and dykes (White and Barr 2004), ous, late syntectonic to post-tectonic, occur only northwest of the shear Paleontology, and mainly Middle to Late Devonian, pera- zone (Figs. 1, 2). Provenance luminous, granitic plutons (Figs. 1, 2).
    [Show full text]
  • Paleocontinental Setting for the Catskill Delta
    Downloaded from specialpapers.gsapubs.org on June 30, 2014 Geological Society of America Special Paper 201 1985 Paleocontinental setting for the Catskill Delta Dennis V. Kent Lamont-Doherty Geological Observatory and Department of Geological Sciences Columbia University Palisades, New York 10964 ABSTRACT Paleomagnetic data confirm geological evidence for tropical paleolatitudes for dep- osition of the Catskill Delta and related Old Red deposits in Europe. A tectonic model constrained by paleomagnetic data suggests that the Catskill deposits are the product of the Acadian orogeny of the Northern Appalachians as a complex continent-continent collision between Armorica (Hercynian Europe), Laurentia (cratonic North America) and possibly Gondwana, with the Traveler terrane (central New England and New Brunswick) rotated and compressed in between. INTRODUCTION A low latitude setting for deposition of the mid- to late- approximately 20° farther south at this time. For example, meta- Devonian Catskill Delta has been inferred from geologic evi- volcanics in the Boston basin have magnetizations that were reset dence. The evidence indicates a depositional environment with during the Devonian and indicate a southern hemisphere paleo- warm to hot temperatures, geographically variable rainfall pat- latitude of about 23° (Schutts and others 1976). This difference in terns, relatively high evaporation rates, and generally easterly paleomagnetic directions led to the concept of the Acadia winds (Woodrow and others 1973). Paleomagnetic data confirm displaced-terrane (Kent and Opdyke 1978; 1979), one of three low paleolatitudes for eastern North America in the Devonian middle to late Paleozoic terranes now recognized in the Northern and place additional constraints on the paleocontinental configu- Appalachians on the basis of paleomagnetic data.
    [Show full text]
  • Late Devonian Peraluminous Granitic Plutons in the Canso Area, Eastern Meguma Terrane, Nova Scotia J
    Document generated on 09/26/2021 1:57 a.m. Atlantic Geology Late Devonian peraluminous granitic plutons in the Canso area, eastern Meguma Terrane, Nova Scotia J. D. Hill Volume 24, Number 1, April 1988 Article abstract Late Devonian granitic rocks are well exposed In coastal outcrops near Canso URI: https://id.erudit.org/iderudit/ageo24_1art02 In the eastern part of the Meguma Terrane. They form numerous, relatively homogeneous plutons of peralumlnous biotite-muscovite granite and minor See table of contents granodlorlte which are enriched In muscovite, aluminum and alkalis and depleted in biotite and cafemic components relative to comparable rocks in other Meguma Terrane granites such as the South Mountain and Publisher(s) Musquodoboit Batholiths. Individual plutons. which crystallized between 371 and 373 Ha based on U-Pb isotopic data, show a variable relationship between Atlantic Geoscience Society composition and relative age of intrusion. This Implies crystallization from two or more separate batches of slightly different magma supplied from below the ISSN current level of exposure. Highly felsic, peralumlnous compositions and initial Sr/ Sr ratios ranging from 0.703 to 0.7O9 favour magma derivation from 0843-5561 (print) heterogenous intermediate to felsic continental crust containing some pelitic 1718-7885 (digital) material. Intrusions were emplaced syntectonlcally during the early part of a ductile shearing event related to dextral transcurrent movements in the Explore this journal Cobequid-Chedabucto Fault System. Cite this article Hill, J. D. (1988). Late Devonian peraluminous granitic plutons in the Canso area, eastern Meguma Terrane, Nova Scotia. Atlantic Geology, 24(1), 11–19. All rights reserved © Atlantic Geology, 1988 This document is protected by copyright law.
    [Show full text]
  • Late Paleozoic Motions of the Meguma Terrane,Nova Scotia: New Paleomagnetic Evidence
    Geodynamics Series Plate Reconstruction From Paleozoic Paleomagnetism Vol. 12 LATE PALEOZOIC MOTIONS OF THE MEGUMA TERRANE,NOVA SCOTIA: NEW PALEOMAGNETIC EVIDENCE Dann J. Spariosu and Dennis V. Kent Lamont-Doherty Geological Observatory and Department of Geological Sciences, Columbia University, Palisades, New York 10964 J. Duncan Keppie Nova Scotia Department of Mines and Energy, 1690 Hollis Street, Halifax, Nova Scotia, Canada B3J 2Xl Abstract. Three rock units from southern Nova Introduction Scotia were sampled for a paleomagnetic study of the relationship of the Meguma terrane to the Differing paleomagnetic signatures of adjacent Atlantic-bordering continents during the Paleo­ geologic provinces have provided evidence for the zoic. These include the Si lure-ordovician White existence of terranes in the northern Appala­ Rock Formation volcanics, sandstones of the Lower chians that were exotic to cratonic North America Devonian Torbrook Format ion and red beds of the for portions of Paleozoic time, including Acadia Lower Carboniferous Cheverie Formation. Pro­ [Kent and Opdyke, 1978, 1979, 1980], Armorica gressive thermal and alternating field demagneti­ [Vander Voo, 1982], and the Traveler terrane zation of the White Rock basalts and rhyolites [Spariosu and Kent, 1981, in press, 1983]. Recen­ reveal a single component magnetization with a tly, plate tectonic models of the Appalachians mean direction of D • 149.10, I "' 24.3°, a 95 = have been constructed with the incorporation of 10°, for N = 13 sites. Rotation of the site mean the concept of "exotic" or "suspect" terranes in directions about the axis of the Torbrook the Paleozoic evolution of the orogen [Williams Syncline suggest a post-folding (post Middle and Hatcher, 1982; Keppie, in press, 1983].
    [Show full text]