Subduction and Continental Collision in the Lufilian Arc
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CORDIERITE-GARNET GNEISS and ASSOCIATED MICRO- CLINE-RICH PEGMATITE at STURBRIDGE, I,{ASSA- CHUSETTS and UNION, CONNECTICUTI Fnor B.Cnrbn, [
THE AMERICAN MINERALOGIST, VOL 47, IVLY AUGUST, 1962 CORDIERITE-GARNET GNEISS AND ASSOCIATED MICRO- CLINE-RICH PEGMATITE AT STURBRIDGE, I,{ASSA- CHUSETTS AND UNION, CONNECTICUTI Fnor B.cnrBn, [/. S. GeologicalSurttey, Washington,D. C. Aesrnacr Gneiss of argillaceous composition at Sturbridge, Massachusetts, and at Union, Connecticut, 10 miles to the south, consists of the assemblagebiotite-cordierite-garnet- magnetite-microcline-quartz-plagioclase-sillimanite. The conclusion is made that this assemblagedoes not violate the phase rule. The cordierite contains 32 mole per cent of Fe- end member, the biotite is aluminous and its ratio MgO: (MgOf I'eO) is 0.54, and the gar- net is alm6e5 pyr26.agro2.espe1.2.Lenses of microcline-quartz pegmatite are intimately as- sociated with the gneissl some are concordant, others cut acrossthe foliation and banding of the gneiss. The pegmatites also contain small amounts of biotite, cordierite, garnet, graphite, plagioclase, and sillimanite; each mineral is similar in optical properties to the corresponding one in the gneiss. It is suggestedthat muscovite was a former constituent of the gneiss at a lower grade of metamorphism, and that it decomposedwith increasing metamorphism, and reacted with quartz to form siliimanite in situ and at lerst part of the microcline of the gneiss and pegmatites These rocks are compared with similar rocks of Fennoscandia and Canada. INtnouucrroN Cordierite-garnet-sillimanitegneisses that contain microcline-quartz pegmatiteare found in Sturbridge,Massachusetts, and Union, Connecti- cut. The locality (Fig. 1) at Sturbridgeis on the south sideof the \{assa- chusettsTurnpike at the overpassof the New Boston Road; this is about 1 mile west of the interchangeof Route 15 with the Turnpike. -
Two Contrasting Phanerozoic Orogenic Systems Revealed by Hafnium Isotope Data William J
ARTICLES PUBLISHED ONLINE: 17 APRIL 2011 | DOI: 10.1038/NGEO1127 Two contrasting Phanerozoic orogenic systems revealed by hafnium isotope data William J. Collins1*(, Elena A. Belousova2, Anthony I. S. Kemp1 and J. Brendan Murphy3 Two fundamentally different orogenic systems have existed on Earth throughout the Phanerozoic. Circum-Pacific accretionary orogens are the external orogenic system formed around the Pacific rim, where oceanic lithosphere semicontinuously subducts beneath continental lithosphere. In contrast, the internal orogenic system is found in Europe and Asia as the collage of collisional mountain belts, formed during the collision between continental crustal fragments. External orogenic systems form at the boundary of large underlying mantle convection cells, whereas internal orogens form within one supercell. Here we present a compilation of hafnium isotope data from zircon minerals collected from orogens worldwide. We find that the range of hafnium isotope signatures for the external orogenic system narrows and trends towards more radiogenic compositions since 550 Myr ago. By contrast, the range of signatures from the internal orogenic system broadens since 550 Myr ago. We suggest that for the external system, the lower crust and lithospheric mantle beneath the overriding continent is removed during subduction and replaced by newly formed crust, which generates the radiogenic hafnium signature when remelted. For the internal orogenic system, the lower crust and lithospheric mantle is instead eventually replaced by more continental lithosphere from a collided continental fragment. Our suggested model provides a simple basis for unravelling the global geodynamic evolution of the ancient Earth. resent-day orogens of contrasting character can be reduced to which probably began by the Early Ordovician12, and the Early two types on Earth, dominantly accretionary or dominantly Paleozoic accretionary orogens in the easternmost Altaids of Pcollisional, because only the latter are associated with Wilson Asia13. -
Phase Equilibria and Thermodynamic Properties of Minerals in the Beo
American Mineralogist, Volwne 71, pages 277-300, 1986 Phaseequilibria and thermodynamic properties of mineralsin the BeO-AlrO3-SiO2-H2O(BASH) system,with petrologicapplications Mlnx D. B.qnroN Department of Earth and SpaceSciences, University of California, Los Angeles,Los Angeles,California 90024 Ansrru,cr The phase relations and thermodynamic properties of behoite (Be(OH)r), bertrandite (BeoSirOr(OH)J, beryl (BerAlrSiuO,r),bromellite (BeO), chrysoberyl (BeAl,Oo), euclase (BeAlSiOo(OH)),and phenakite (BerSiOo)have been quantitatively evaluatedfrom a com- bination of new phase-equilibrium, solubility, calorimetric, and volumetric measurements and with data from the literature. The resulting thermodynamic model is consistentwith natural low-variance assemblagesand can be used to interpret many beryllium-mineral occurTences. Reversedhigh-pressure solid-media experimentslocated the positions of four reactions: BerAlrSiuO,,: BeAlrOo * BerSiOo+ 5SiO, (dry) 20BeAlSiOo(OH): 3BerAlrsi6or8+ TBeAlrOo+ 2BerSiOn+ l0HrO 4BeAlSiOo(OH)+ 2SiOr: BerAlrSiuO,,+ BeAlrOo+ 2H2O BerAlrSiuO,,+ 2AlrSiOs : 3BeAlrOa + 8SiO, (water saturated). Aqueous silica concentrationswere determined by reversedexperiments at I kbar for the following sevenreactions: 2BeO + H4SiO4: BerSiOo+ 2H2O 4BeO + 2HoSiOo: BeoSirO'(OH),+ 3HrO BeAlrOo* BerSiOo+ 5H4Sio4: Be3AlrSiuOr8+ loHro 3BeAlrOo+ 8H4SiO4: BerAlrSiuOrs+ 2AlrSiO5+ l6HrO 3BerSiOo+ 2AlrSiO5+ 7H4SiO4: 2BerAlrSiuOr8+ l4H2o aBeAlsioloH) + Bersio4 + 7H4sio4:2BerAlrsiuors + 14Hro 2BeAlrOo+ BerSiOo+ 3H4SiOo: 4BeAlSiOr(OH)+ 4HrO. -
Cordierite-Bearing Gneisses in the West-Central Adirondack Highlands
Trip A-6 CORDIERITE-BEARING GNEISSES IN THE WEST -CENTRAL ADIRONDACK HIGHLANDS Frank P. Florence Science Division, Jefferson Community College, Watertown, NY, USA 13601 [email protected] Robert S. Darling Department of Geology, SUNY College at Cortland, Cortland, NY, USA 13045 Phillip R. Whitney New York State Geological Survey (ret.), New York State Museum, Albany, NY, USA 12230 Gregory W. Lester Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, Ontario, CANADA K7L 3N6 INTRODUCTION Cordierite-bearing gneiss is uncommon in the Adirondack Highlands. To date, it is has been described from three locations, one near the village ofInlet (Seal, 1986; Whitney et aI, 2002) and two along the Moose River further to the west (Darling et aI, 2004). All of these cordierite occurrences are located in the west-central Adirondacks, a region characterized by somewhat lower metamorphic pressures as compared to the rest of the Adirondack Highlands (Florence et aI, 1995; Darling et aI, 2004). In the Fulton Chain of Lakes area of the west-central Adirondack Highlands, a heterogeneous unit of metasedimentary rocks, including cordierite-bearing gneisses, forms the core of a major NE to ENE trending synform. Cordierite appears in an assortment of mineral assemblages, including one containing the uncommon borosilicate, prismatine, the boron-rich end-member ofkornerupine (Grew et ai., 1996). The assemblage cordierite + orthopyroxene is also present, the first recognized occurrence of this mineral pair in the Adirondack Highlands (Darling et aI, 2004). This field trip includes stops at four outcrops containing cordierite in mineral assemblages that are characteristic of granulite facies metamorphism in aluminous rocks. -
Washington State Minerals Checklist
Division of Geology and Earth Resources MS 47007; Olympia, WA 98504-7007 Washington State 360-902-1450; 360-902-1785 fax E-mail: [email protected] Website: http://www.dnr.wa.gov/geology Minerals Checklist Note: Mineral names in parentheses are the preferred species names. Compiled by Raymond Lasmanis o Acanthite o Arsenopalladinite o Bustamite o Clinohumite o Enstatite o Harmotome o Actinolite o Arsenopyrite o Bytownite o Clinoptilolite o Epidesmine (Stilbite) o Hastingsite o Adularia o Arsenosulvanite (Plagioclase) o Clinozoisite o Epidote o Hausmannite (Orthoclase) o Arsenpolybasite o Cairngorm (Quartz) o Cobaltite o Epistilbite o Hedenbergite o Aegirine o Astrophyllite o Calamine o Cochromite o Epsomite o Hedleyite o Aenigmatite o Atacamite (Hemimorphite) o Coffinite o Erionite o Hematite o Aeschynite o Atokite o Calaverite o Columbite o Erythrite o Hemimorphite o Agardite-Y o Augite o Calciohilairite (Ferrocolumbite) o Euchroite o Hercynite o Agate (Quartz) o Aurostibite o Calcite, see also o Conichalcite o Euxenite o Hessite o Aguilarite o Austinite Manganocalcite o Connellite o Euxenite-Y o Heulandite o Aktashite o Onyx o Copiapite o o Autunite o Fairchildite Hexahydrite o Alabandite o Caledonite o Copper o o Awaruite o Famatinite Hibschite o Albite o Cancrinite o Copper-zinc o o Axinite group o Fayalite Hillebrandite o Algodonite o Carnelian (Quartz) o Coquandite o o Azurite o Feldspar group Hisingerite o Allanite o Cassiterite o Cordierite o o Barite o Ferberite Hongshiite o Allanite-Ce o Catapleiite o Corrensite o o Bastnäsite -
52. Iron-Rich Cordierite Structurally Close to Indialite by Miyoji SAMBONSUGI Geological Institute, Faculty of Arts And. Science
190 [Vol. 33, 52. Iron-rich Cordierite Structurally Close to Indialite By Miyoji SAMBONSUGI GeologicalInstitute, Faculty of Arts and. Sciences,Fukushima University (Comm.by S. TsuBOI,M.J.A., April 1.2, 1957) Introduction In the course of his geological investigation of the Abukuma plateau, northeast Japan, the writer's attention was drawn to numerous pegmatites intruding the granitic and gneissic rocks which form the foundation of this district. In 1950 the writer found a peculiar mineral from one of the above-mentioned pegmatites, at Sugama. From its appearance the mineral was first identified as scapolite by the writer (Sambonsugi, 1953), but after further observations it has become clear that the mineral belongs to an iron-rich variety of cordierite, and that it is structurally close to indialite, hexagonal polymorph of cordierite, first found by Miyashiro and Iiyama (1954) from the fused sediment in the Bakaro coalfield, India. Miyashir0 et al. (1955) suspected that a structural gradation may exist between the hexagonal lattice of in- dialite and the orthorhombic lattice of cordierite, viz, that there may be some varieties of cordierite structurally close to indialite, though all then known show marked structural difference from indialite. The mineral found by the writer from the Sugama pegmatite is the first example of cordierite structurally close to indialite. It is the purpose of this paper to describe the mode of occurrence, the optical properties, and the chemical composition of the mineral. Recent- ly, the optical properties and the unit cell dimensions of the mineral were studied by T. Iiyama (1956). X-ray and thermal studies of the mineral were carried out by Miyashiro (1957). -
Back Matter (PDF)
Index Page numbers in italic refer to tables, and those in bold to figures. accretionary orogens, defined 23 Namaqua-Natal Orogen 435-8 Africa, East SW Angola and NW Botswana 442 Congo-Sat Francisco Craton 4, 5, 35, 45-6, 49, 64 Umkondo Igneous Province 438-9 palaeomagnetic poles at 1100-700 Ma 37 Pan-African orogenic belts (650-450 Ma) 442-50 East African(-Antarctic) Orogen Damara-Lufilian Arc-Zambezi Belt 3, 435, accretion and deformation, Arabian-Nubian Shield 442-50 (ANS) 327-61 Katangan basaltic rocks 443,446 continuation of East Antarctic Orogen 263 Mwembeshi Shear Zone 442 E/W Gondwana suture 263-5 Neoproterozoic basin evolution and seafloor evolution 357-8 spreading 445-6 extensional collapse in DML 271-87 orogenesis 446-51 deformations 283-5 Ubendian and Kibaran Belts 445 Heimefront Shear Zone, DML 208,251, 252-3, within-plate magmatism and basin initiation 443-5 284, 415,417 Zambezi Belt 27,415 structural section, Neoproterozoic deformation, Zambezi Orogen 3, 5 Madagascar 365-72 Zambezi-Damara Belt 65, 67, 442-50 see also Arabian-Nubian Shield (ANS); Zimbabwe Belt, ophiolites 27 Mozambique Belt Zimbabwe Craton 427,433 Mozambique Belt evolution 60-1,291, 401-25 Zimbabwe-Kapvaal-Grunehogna Craton 42, 208, 250, carbonates 405.6 272-3 Dronning Mand Land 62-3 see also Pan-African eclogites and ophiolites 406-7 Africa, West 40-1 isotopic data Amazonia-Rio de la Plata megacraton 2-3, 40-1 crystallization and metamorphic ages 407-11 Birimian Orogen 24 Sm-Nd (T DM) 411-14 A1-Jifn Basin see Najd Fault System lithologies 402-7 Albany-Fraser-Wilkes -
Post-Collisional Formation of the Alpine Foreland Rifts
Annales Societatis Geologorum Poloniae (1991) vol. 61:37 - 59 PL ISSN 0208-9068 POST-COLLISIONAL FORMATION OF THE ALPINE FORELAND RIFTS E. Craig Jowett Department of Earth Sciences, University of Waterloo, Waterloo, Ontario Canada N2L 3G1 Jowett, E. C., 1991. Post-collisional formation of the Alpine foreland rifts. Ann. Soc. Geol. Polon., 6 1 :37-59. Abstract: A series of Cenozoic rift zones with bimodal volcanic rocks form a discontinuous arc parallel to the Alpine mountain chain in the foreland region of Europe from France to Czechos lovakia. The characteristics of these continental rifts include: crustal thinning to 70-90% of the regional thickness, in cases with corresponding lithospheric thinning; alkali basalt or bimodal igneous suites; normal block faulting; high heat flow and hydrothermal activity; regional uplift; and immature continental to marine sedimentary rocks in hydrologically closed basins. Preceding the rifting was the complex Alpine continental collision orogeny which is characterized by: crustal shortening; thrusting and folding; limited calc-alkaline igneous activity; high pressure metamorphism; and marine flysch and continental molasse deposits in the foreland region. Evidence for the direction of subduction in the central area is inconclusive, although northerly subduction likely occurred in the eastern and western Tethys. The rift events distinctly post-date the thrusthing and shortening periods of the orogeny, making “impactogen” models of formation untenable. However, the succession of tectonic and igneous events, the geophysical characteristics, and the timing and location of these rifts are very similar to those of the Late Cenozoic Basin and Range province in the western USA and the Early Permian Rotliegendes troughs in Central Europe. -
World Map Showing Surface and Subsurface Distribution, and Lithologic Character of Middle and Late Neoproterozoic Rocks
World Map Showing Surface and Subsurface Distribution, and Lithologic Character of Middle and Late Neoproterozoic Rocks By John H. Stewart1 Open-File Report 2007-1087 2007 U.S. Department of the Interior U.S. Geological Survey 1 Menlo Park, Calif. U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Reston, Virginia 2007 Revised and reprinted: 2007 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Suggested citation: Stewart, John H., 2007, World map showing surface and subsurface distribution, and lithologic character of Middle and Late Neoproterozoic rocks: U.S. Geological Survey Open-File Report 2007-1087. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. ii Contents Introduction......................................................................................................................... 3 Sources of information ........................................................................................................ 2 Africa [AF] -
Pan-African Orogeny 1
Encyclopedia 0f Geology (2004), vol. 1, Elsevier, Amsterdam AFRICA/Pan-African Orogeny 1 Contents Pan-African Orogeny North African Phanerozoic Rift Valley Within the Pan-African domains, two broad types of Pan-African Orogeny orogenic or mobile belts can be distinguished. One type consists predominantly of Neoproterozoic supracrustal and magmatic assemblages, many of juvenile (mantle- A Kröner, Universität Mainz, Mainz, Germany R J Stern, University of Texas-Dallas, Richardson derived) origin, with structural and metamorphic his- TX, USA tories that are similar to those in Phanerozoic collision and accretion belts. These belts expose upper to middle O 2005, Elsevier Ltd. All Rights Reserved. crustal levels and contain diagnostic features such as ophiolites, subduction- or collision-related granitoids, lntroduction island-arc or passive continental margin assemblages as well as exotic terranes that permit reconstruction of The term 'Pan-African' was coined by WQ Kennedy in their evolution in Phanerozoic-style plate tectonic scen- 1964 on the basis of an assessment of available Rb-Sr arios. Such belts include the Arabian-Nubian shield of and K-Ar ages in Africa. The Pan-African was inter- Arabia and north-east Africa (Figure 2), the Damara- preted as a tectono-thermal event, some 500 Ma ago, Kaoko-Gariep Belt and Lufilian Arc of south-central during which a number of mobile belts formed, sur- and south-western Africa, the West Congo Belt of rounding older cratons. The concept was then extended Angola and Congo Republic, the Trans-Sahara Belt of to the Gondwana continents (Figure 1) although West Africa, and the Rokelide and Mauretanian belts regional names were proposed such as Brasiliano along the western Part of the West African Craton for South America, Adelaidean for Australia, and (Figure 1). -
Non-Cylindrical Parasitic Folding and Strain Partitioning
Solid Earth Discuss., https://doi.org/10.5194/se-2018-6 Manuscript under review for journal Solid Earth Discussion started: 6 February 2018 c Author(s) 2018. CC BY 4.0 License. Non-cylindrical parasitic folding and strain partitioning during the Pan-African Lufilian orogeny in the Chambishi-Nkana Basin, Central African Copperbelt Koen Torremans1, Philippe Muchez1, Manuel Sintubin2 5 1KU Leuven, Department of Earth and Environmental Sciences, Geodynamics and Geofluids Research Group, Celestijnenlaan 200E, 3001 Leuven, Belgium. 2Present address: Irish Centre for Research in Applied Geosciences, University College Dublin, Dublin 4, Ireland. Correspondence to: Koen Torremans ([email protected]) 1 Solid Earth Discuss., https://doi.org/10.5194/se-2018-6 Manuscript under review for journal Solid Earth Discussion started: 6 February 2018 c Author(s) 2018. CC BY 4.0 License. Abstract. A structural analysis has been carried out along the southeast margin of the Chambishi-Nkana Basin in the Central African Copperbelt, hosting the world-class Cu-Co Nkana orebody. The geometrically complex structural architecture is interpreted to have been generated during a single NE-SW oriented compressional event, clearly linked to the Pan-African 5 Lufilian orogeny. This progressive deformation resulted primarily in asymmetric multiscale parasitic fold assemblages, characterized by non-cylindrical NW-SE elongated, periclinal folds that strongly interfere laterally, leading to fold linkage and bifurcation. The vergence and amplitude of these folds consistently reflect their position along an inclined limb of a NW plunging megascale first-order fold. A clear relation is observed between development of parasitic folds and certain lithofacies assemblages in the Copperbelt Orebody Member, which hosts most of the ore. -
Collision Orogeny
Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 PROCESSES OF COLLISION OROGENY Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 Shortening of continental lithosphere: the neotectonics of Eastern Anatolia a young collision zone J.F. Dewey, M.R. Hempton, W.S.F. Kidd, F. Saroglu & A.M.C. ~eng6r SUMMARY: We use the tectonics of Eastern Anatolia to exemplify many of the different aspects of collision tectonics, namely the formation of plateaux, thrust belts, foreland flexures, widespread foreland/hinterland deformation zones and orogenic collapse/distension zones. Eastern Anatolia is a 2 km high plateau bounded to the S by the southward-verging Bitlis Thrust Zone and to the N by the Pontide/Minor Caucasus Zone. It has developed as the surface expression of a zone of progressively thickening crust beginning about 12 Ma in the medial Miocene and has resulted from the squeezing and shortening of Eastern Anatolia between the Arabian and European Plates following the Serravallian demise of the last oceanic or quasi- oceanic tract between Arabia and Eurasia. Thickening of the crust to about 52 km has been accompanied by major strike-slip faulting on the rightqateral N Anatolian Transform Fault (NATF) and the left-lateral E Anatolian Transform Fault (EATF) which approximately bound an Anatolian Wedge that is being driven westwards to override the oceanic lithosphere of the Mediterranean along subduction zones from Cephalonia to Crete, and Rhodes to Cyprus. This neotectonic regime began about 12 Ma in Late Serravallian times with uplift from wide- spread littoral/neritic marine conditions to open seasonal wooded savanna with coiluvial, fluvial and limnic environments, and the deposition of the thick Tortonian Kythrean Flysch in the Eastern Mediterranean.