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The North-Subducting Rheic Ocean During the Devonian: Consequences for the Rhenohercynian Ore Sites
Published in "International Journal of Earth Sciences 106(7): 2279–2296, 2017" which should be cited to refer to this work. The north-subducting Rheic Ocean during the Devonian: consequences for the Rhenohercynian ore sites Jürgen F. von Raumer1 · Heinz-Dieter Nesbor2 · Gérard M. Stampfli3 Abstract Base metal mining in the Rhenohercynian Zone activated Early Devonian growth faults. Hydrothermal brines has a long history. Middle-Upper Devonian to Lower Car- equilibrated with the basement and overlying Middle-Upper boniferous sediment-hosted massive sulfide deposits Devonian detrital deposits forming the SHMS deposits in the (SHMS), volcanic-hosted massive sulfide deposits (VHMS) southern part of the Pyrite Belt, in the Rhenish Massif and and Lahn-Dill-type iron, and base metal ores occur at sev- in the Harz areas. Volcanic-hosted massive sulfide deposits eral sites in the Rhenohercynian Zone that stretches from the (VHMS) formed in the more eastern localities of the Rheno- South Portuguese Zone, through the Lizard area, the Rhen- hercynian domain. In contrast, since the Tournaisian period ish Massif and the Harz Mountain to the Moravo-Silesian of ore formation, dominant pull-apart triggered magmatic Zone of SW Bohemia. During Devonian to Early Carbonif- emplacement of acidic rocks, and their metasomatic replace- erous times, the Rhenohercynian Zone is seen as an evolv- ment in the apical zones of felsic domes and sediments in ing rift system developed on subsiding shelf areas of the the northern part of the Iberian Pyrite belt, thus changing the Old Red continent. A reappraisal of the geotectonic setting general conditions of ore precipitation. -
Structural and Tectonic Evolution of the Acatlán Complex, Southern Mexico
TECTONICS, VOL. 28, TC4008, doi:10.1029/2007TC002159, 2009 Click Here for Full Article Structural and tectonic evolution of the Acatla´n Complex, southern Mexico: Its role in the collisional history of Laurentia and Gondwana Ricardo Vega-Granillo,1 Thierry Calmus,2 Diana Meza-Figueroa,1 Joaquı´n Ruiz,3 Oscar Talavera-Mendoza,4 and Margarita Lo´pez-Martı´nez5 Received 24 May 2007; revised 22 January 2009; accepted 10 March 2009; published 25 July 2009. [1] Correlation of deformational phases and thermal opening. Citation: Vega-Granillo, R., T. Calmus, D. Meza- events in the Acatla´n Complex permits definition of Figueroa, J. Ruiz, O. Talavera-Mendoza, and M. Lo´pez-Martı´nez nine major tectonic events. Seven events are related to (2009), Structural and tectonic evolution of the Acatla´n Complex, the evolution of the Iapetus and Rheic oceans. By the southern Mexico: Its role in the collisional history of Laurentia Early Ordovician, the Xayacatla´n suite of Laurentian and Gondwana, Tectonics, 28, TC4008, doi:10.1029/ affinity was metamorphosed to eclogite facies and 2007TC002159. exhumed before colliding with the El Rodeo suite. From the Late Ordovician to Silurian, the Upper 1. Introduction Ordovician Ixcamilpa suite with peri-Gondwanan affinity was metamorphosed to blueschist facies, [2] The Acatla´n Complex basement of the Mixteco exhumed, and subsequently was overthrust by the terrane contains the largest exposure of eclogites, high-P Xayacatla´n–El Rodeo block. Part of the Esperanza garnet amphibolites, blueschists and eclogitized granitoids of Paleozoic age in Mexico. In a strict sense, the Mixteco suite is an Early Silurian intra-Iapetian continental arc terrane must be considered a superterrane composed of that collided with and subducted beneath continental thrust sheets containing Mesoproterozoic to Paleozoic pet- crust, generating a Silurian eclogitic event. -
Mapping a Hidden Terrane Boundary in the Mantle Lithosphere with Lamprophyres
ARTICLE DOI: 10.1038/s41467-018-06253-7 OPEN Mapping a hidden terrane boundary in the mantle lithosphere with lamprophyres Arjan H. Dijkstra 1 & Callum Hatch1,2 Lamprophyres represent hydrous alkaline mantle melts that are a unique source of information about the composition of continental lithosphere. Throughout southwest Britain, post-Variscan lamprophyres are (ultra)potassic with strong incompatible element enrich- 1234567890():,; ments. Here we show that they form two distinct groups in terms of their Sr and Nd isotopic compositions, occurring on either side of a postulated, hitherto unrecognized terrane boundary. Lamprophyres emplaced north of the boundary fall on the mantle array with εNd −1 to +1.6. Those south of the boundary are enriched in radiogenic Sr, have initial εNd values of −0.3 to −3.5, and are isotopically indistinguishable from similar-aged lamprophyres in Armorican massifs in Europe. We conclude that an Armorican terrane was juxtaposed against Avalonia well before the closure of the Variscan oceans and the formation of Pangea. The giant Cornubian Tin-Tungsten Ore Province and associated batholith can be accounted for by the fertility of Armorican lower crust and mantle lithosphere. 1 School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL4 8AA, UK. 2 Department of Core Research Laboratories, Natural History Museum, Cromwell Road, London, SW7 5BD UK. Correspondence and requests for materials should be addressed to A.H.D. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3770 | DOI: 10.1038/s41467-018-06253-7 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-06253-7 ilson’s cycle1 of the opening and closing of ocean typically form 10 cm to m-wide dykes and other types of minor Wbasins throughout Earth history was based on the intrusions cutting across Variscan foliations in Carboniferous and similarity of Early Palaeozoic faunal assemblages in Devonian rocks. -
Suprasubduction Zone Setting for the Youngest Rheic Ocean Floor
CORE Metadata, citation and similar papers at core.ac.uk Provided by EPrints Complutense Care6n ophiolite, NW Spain: Suprasubduction zone setting for the youngest Rheic Ocean floor Sonia Sanchez Martfnez "" Departamento de Petrologla y Geoqulmlca, Unlversldad Complutense, 28040 Madrid, Spain R·Icar d 0 Arenas } Florentino Dfaz Garcfa Departamento de Geologia, Unlversldad de OVledo, 33005 OVledo, Spain Jose Ram6n Martfnez Catalan Departamento de Geologia, Unlversldad de Salamanca, 37008 Salamanca, Spain Juan G6mez-Barreiro Department of Earth & Planetary SCiences, University of California at Berkeley, Berkeley, California 94720, USA Julian A. Pearce School of Earth, Ocean and Planetary SCiences, Cardiff University, CFto 3YE Cardiff, UK ABSTRACT included in the GSA Data Repository.l The The Careon ophiolite (Galicia, NW Iberian MassiO shows lithological and geochemical geochemical features of these samples (Fig. 2; features suggestive of an origin in a suprasubduction zone setting. As with other Devonian Fig. DRI [see footnote I]) show that most of the ophiolites in the European Variscan belt, it was generated within a contracting Rheic Ocean. studied metabasites have compositions equiva This setting and the general absence of large Silurian-Devonian volcanic arcs on both of the lent to tholeiitic basalts (Fig. DRIA). Average Rheic Ocean margins strongly suggest that this ocean was closed by intraoceanic subduction rare earth element (REE) contents (Rg. DRl B) directed to the north. This subduction removed the older normal (N) mid-oceanic-ridge basalt of most rock types have concentrations around (MORB) oceanic lithosphere and gave rise to a limited volume of new suprasubduction zone ten times the chondrite abundances and ahnost oceanic lithosphere. -
(Acadian) Orogenic Events in Scotland John R Mendum British Geological Survey, Edinburgh
Late Caledonian (Scandian) and Proto-Variscan (Acadian) orogenic events in Scotland John R Mendum British Geological Survey, Edinburgh Abstract The later tectonic phases of the Caledonian Orogeny reflect the collision of Baltica and Laurentia. The result was the Scandian event in Silurian times, and the oblique docking of Eastern Avalonia with Scotland, generating deformation and metamorphism in the Southern Uplands. The exhumation of the Caledonide Orogen was then accompanied by sinistral transtensional faulting and emplacement of granitoid plutons. The Iapetus Ocean was finally closed, and subduction activity had migrated south to the Rheic Ocean by early Devonian times. Continental rifting and deposition of the Lower Old Red Sandstone fluvial-lacustrine succession, accompanied by basaltic-andesitic volcanism, occurred across Scotland. Deposition commenced in the late Silurian and continued through to Emsian times, when it was interrupted by the short-lived, northward-directed Acadian event. The resultant deformation and folding, a product of sinistral transpression, were focussed along the major pre-existing faults and shear zones. Evidence for Acadian transpressional movements along the Great Glen Fault (GGF) is found near Rosemarkie, where Moine psammites and semipelites are interleaved with Lewisianoid gneisses in a structural inlier. These lithologies are intruded by pink leucogranite veins that themselves show evidence of two phases of ductile deformation and folding. U-Pb monazite and zircon ages show that the leucogranites were emplaced at c. 399 Ma. Leucogranite intrusion and subsequent deformation are interpreted to have occurred during oblique extrusion of the inlier as an elongate ‘pip’, generated at a northwestward step-over that developed on the GGF during the Acadian Event. -
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Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Pangea B and the Late Paleozoic Ice Age ⁎ D.V. Kenta,b, ,G.Muttonic a Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA b Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA c Dipartimento di Scienze della Terra 'Ardito Desio', Università degli Studi di Milano, via Mangiagalli 34, I-20133 Milan, Italy ARTICLE INFO ABSTRACT Editor: Thomas Algeo The Late Paleozoic Ice Age (LPIA) was the penultimate major glaciation of the Phanerozoic. Published compi- Keywords: lations indicate it occurred in two main phases, one centered in the Late Carboniferous (~315 Ma) and the other Late Paleozoic Ice Age in the Early Permian (~295 Ma), before waning over the rest of the Early Permian and into the Middle Permian Pangea A (~290 Ma to 275 Ma), and culminating with the final demise of Alpine-style ice sheets in eastern Australia in the Pangea B Late Permian (~260 to 255 Ma). Recent global climate modeling has drawn attention to silicate weathering CO2 Greater Variscan orogen consumption of an initially high Greater Variscan edifice residing within a static Pangea A configuration as the Equatorial humid belt leading cause of reduction of atmospheric CO2 concentrations below glaciation thresholds. Here we show that Silicate weathering CO2 consumption the best available and least-biased paleomagnetic reference poles place the collision between Laurasia and Organic carbon burial Gondwana that produced the Greater Variscan orogen in a more dynamic position within a Pangea B config- uration that had about 30% more continental area in the prime equatorial humid belt for weathering and which drifted northward into the tropical arid belt as it transformed to Pangea A by the Late Permian. -
Paleozoic Evolution of Pre-Variscan Terranes: from Gondwana to the Variscan Collision
Geological Society of America Special Paper 364 2002 Paleozoic evolution of pre-Variscan terranes: From Gondwana to the Variscan collision Gérard M. Stamp×i Institut de Géologie et Paléontologie, Université de Lausanne, CH-1015 Lausanne, Switzerland Jürgen F. von Raumer Institut de Minéralogie et Pétrographie, Université de Fribourg, CH-1700 Fribourg, Switzerland Gilles D. Borel Institut de Géologie et Paléontologie, Université de Lausanne, CH-1015 Lausanne, Switzerland ABSTRACT The well-known Variscan basement areas of Europe contain relic terranes with a pre-Variscan evolution testifying to their peri-Gondwanan origin (e.g., relics of Neo- proterozoic volcanic arcs, and subsequent stages of accretionary wedges, backarc rift- ing, and spreading). The evolution of these terranes was guided by the diachronous subduction of the proto-Tethys oceanic ridge under different segments of the Gond- wana margin. This subduction triggered the emplacement of magmatic bodies and the formation of backarc rifts, some of which became major oceanic realms (Rheic, paleo- Tethys). Consequently, the drifting of Avalonia was followed, after the Silurian and a short Ordovician orogenic event, by the drifting of Armorica and Alpine domains, ac- companied by the opening of the paleo-Tethys. The slab rollback of the Rheic ocean is viewed as the major mechanism for the drifting of the European Variscan terranes. This, in turn, generated a large slab pull force responsible for the opening of major rift zones within the passive Eurasian margin. Therefore, the µrst Middle Devonian Variscan orogenic event is viewed as the result of a collision between terranes detached from Gondwana (grouped as the Hun superterrane) and terranes detached from Eurasia. -
Pannotia to Pangaea: Neoproterozoic and Paleozoic Orogenic Cycles in the Circum-Atlantic Region: a Celebration of the Career of Damian Nance
Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 Pannotia to Pangaea: Neoproterozoic and Paleozoic Orogenic Cycles in the Circum-Atlantic Region: A celebration of the career of Damian Nance J. Brendan Murphy1,2*, Robin A. Strachan3 and Cecilio Quesada4 1Department of Earth Sciences, St Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, Canada 2Earth Dynamics Research Group, the Institute for Geoscience Research (TIGeR), School of Earth and Planetary Sciences, Curtin University, WA 6845, Australia 3School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth PO1 3QL, UK 4Instituto Geológico y Minero de España (IGME), C/Ríos Rosas, 23, 28003 Madrid, Spain JBM, 0000-0003-2269-1976 *Correspondence: [email protected] Special Publication 503 celebrates the career of between tectonic events and biogeochemical cycles, R. Damian Nance. It features 27 articles, with more as exemplified in the late Neoproterozoic–Early than 110 authors based in 18 different countries. Cambrian by the amalgamation of Gondwana span- The wide range of topics presented in this volume ning a time interval characterized by dramatic climate mirrors the breadth and depth of Damian’s contribu- swings, profound changes in the chemistry of the tions, interests and expertise. Like Damian’s papers, oceans and atmosphere, and the evolution of multi- the contributions range from the predominantly con- cellular animals (see Hoffman 1991; Hoffman et al. ceptual to detailed field work, but all are targeted at 1998; Narbonne 2010; Knoll 2013). understanding important tectonic processes. Their As reconstructions became more refined, scope not only varies in scale from global to regional several authors proposed that Gondwana was part to local, but also in the range of approaches required of a larger entity called Pannotia that included Lau- to gain that understanding. -
A History of Supercontinents on Planet Earth
By Alasdair Wilkins Jan 27, 2011 2:31 PM 47,603 71 Share A history of supercontinents on planet Earth Earth's continents are constantly changing, moving and rearranging themselves over millions of years - affecting Earth's climate and biology. Every few hundred million years, the continents combine to create massive, world-spanning supercontinents. Here's the past and future of Earth's supercontinents. The Basics of Plate Tectonics If we're going to discuss past and future supercontinents, we first need to understand how landmasses can move around and the continents can take on new configurations. Let's start with the basics - rocky planets like Earth have five interior levels: heading outwards, these are the inner core, outer core, mantle, upper mantle, and the crust. The crust and the part of the upper mantle form the lithosphere, a portion of our planet that is basically rigid, solid rock and runs to about 100 kilometers below the planet's surface. Below that is the asthenosphere, which is hot enough that its rocks are more flexible and ductile than those above it. The lithosphere is divided into roughly two dozen major and minor plates, and these plates move very slowly over the almost fluid-like asthenosphere. There are two types of crust: oceanic crust and continental crust. Predictably enough, oceanic crust makes up the ocean beds and are much thinner than their continental counterparts. Plates can be made up of either oceanic or continental crust, or just as often some combination of the two. There are a variety of forces pushing and pulling the plates in various directions, and indeed that's what keeps Earth's crust from being one solid landmass - the interaction of lithosphere and asthenosphere keeps tearing landmasses apart, albeit very, very slowly. -
What's in a Name? the Columbia (Paleopangaea/Nuna) Supercontinent
Gondwana Research 21 (2012) 987–993 Contents lists available at SciVerse ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR Letter What's in a name? The Columbia (Paleopangaea/Nuna) supercontinent Joseph G. Meert ⁎ University of Florida, Department of Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States article info abstract Article history: Supercontinents play an important role in Earth's history. The exact definition of what constitutes a super- Received 4 December 2011 continent is difficult to establish. Here the argument is made, using Pangæa as a model, that any superconti- Received in revised form 6 December 2011 nent should include ~75% of the preserved continental crust relevant to the time of maximum packing. As an Accepted 8 December 2011 example, Rodinia reached maximum packing at about 1.0 Ga and therefore should include 75% of all conti- Available online 14 December 2011 nental crust older than 1.0 Ga. In attempting to ‘name’ any supercontinent, there is a clear precedent for Handling Editor: M. Santosh models that provide a name along with a testable reconstruction within a reasonable temporal framework. Both Pangæa and Rodinia are near universally accepted names for the late Paleozoic and Neoproterozoic su- Keywords: percontinent respectively; however, there is a recent push to change the Paleo-Mesoproterozoic superconti- Columbia nent moniker from “Columbia” to “Nuna”. A careful examination of the “Nuna” and “Columbia” proposals Supercontinent tectonics reveals that although the term “Nuna” was published prior to “Columbia”, the “Nuna” proposal is a bit nebu- Pangaea lous in terms of the constitution of the giant continent. -
Synoptic Taxonomy of Major Fossil Groups
APPENDIX Synoptic Taxonomy of Major Fossil Groups Important fossil taxa are listed down to the lowest practical taxonomic level; in most cases, this will be the ordinal or subordinallevel. Abbreviated stratigraphic units in parentheses (e.g., UCamb-Ree) indicate maximum range known for the group; units followed by question marks are isolated occurrences followed generally by an interval with no known representatives. Taxa with ranges to "Ree" are extant. Data are extracted principally from Harland et al. (1967), Moore et al. (1956 et seq.), Sepkoski (1982), Romer (1966), Colbert (1980), Moy-Thomas and Miles (1971), Taylor (1981), and Brasier (1980). KINGDOM MONERA Class Ciliata (cont.) Order Spirotrichia (Tintinnida) (UOrd-Rec) DIVISION CYANOPHYTA ?Class [mertae sedis Order Chitinozoa (Proterozoic?, LOrd-UDev) Class Cyanophyceae Class Actinopoda Order Chroococcales (Archean-Rec) Subclass Radiolaria Order Nostocales (Archean-Ree) Order Polycystina Order Spongiostromales (Archean-Ree) Suborder Spumellaria (MCamb-Rec) Order Stigonematales (LDev-Rec) Suborder Nasselaria (Dev-Ree) Three minor orders KINGDOM ANIMALIA KINGDOM PROTISTA PHYLUM PORIFERA PHYLUM PROTOZOA Class Hexactinellida Order Amphidiscophora (Miss-Ree) Class Rhizopodea Order Hexactinosida (MTrias-Rec) Order Foraminiferida* Order Lyssacinosida (LCamb-Rec) Suborder Allogromiina (UCamb-Ree) Order Lychniscosida (UTrias-Rec) Suborder Textulariina (LCamb-Ree) Class Demospongia Suborder Fusulinina (Ord-Perm) Order Monaxonida (MCamb-Ree) Suborder Miliolina (Sil-Ree) Order Lithistida -
The Pangea Conundrum
The Pangea conundrum J. Brendan Murphy1, R. Damian Nance 2 1Department of Earth Sciences, St. Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada 2Department of Geological Sciences, Ohio University, Athens, Ohio 45701, USA ABSTRACT Geodynamic models for supercontinent assembly, whereby the dispersing continen- tal fragments of a supercontinent break up and migrate from geoid highs to reassemble at geoid lows, fail to account for the amalgamation of Pangea. Such models would predict that the oceans created by continental breakup in the early Paleozoic (e.g., Iapetus, Rheic) would have continued to expand as the continents migrated toward sites of mantle downwelling in the paleo-Pacifi c, reassembling an extroverted supercontinent as this ocean closed. Instead, Pangea assembled as a result of the closure of the younger Iapetus and Rheic Oceans. Geo- dynamic linkages between these three oceans preserved in the rock record suggest that the reversal in continental motion may have coincided with the Ordovician emergence of a super- plume that produced a geoid high in the paleo-Pacifi c. If so, the top-down geodynamics used to account for the breakup and dispersal of a supercontinent at ca. 600–540 Ma may have been overpowered by bottom-up geodynamics during the amalgamation of Pangea. Keywords: Pangea, geodynamics, supercontinents, Appalachian orogen, Terra Australis orogen. INTRODUCTION subduction zones in the exterior paleo–Pacifi c Ocean, and it is this ocean Although the existence of Pangea is one of the cornerstones of geol- that should have closed. Instead, a wealth of geologic evidence indi- ogy, the mechanisms responsible for its amalgamation are poorly under- cates that subduction commenced in the relatively newly formed interior stood.