DOCSLIB.ORG

Late Cretaceous Forearc Ophiolites of Iraniar 745 1..4

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Late Cretaceous Forearc Ophiolites of Iraniar 745 1..4 Island Arc (2011) 20, 1–4 Pictorial Article Late Cretaceous forearc ophiolites of Iraniar_745 1..4 HADI SHAFAII MOGHADAM1,* AND ROBERT J. STERN2 1School of Earth Sciences, Damghan University, Damghan, Iran (email: [email protected]), and 2Geosciences Department, University of Texas at Dallas, Richardson, TX75083-0688, USA Ophiolites are on-land tracts of oceanic lithosphere impregnations, chromite pods, ultramafic cumulate and the tectonic setting that they form in is often sills (Fig. 3d), pegmatite gabbroic pockets/sills controversial. Reconstruction of the Neotethyan (Fig. 3b) and isotropic gabbro lenses. The crustal Ocean from Permian rifting to final closure in sequences of these ophiolites vary in thickness and Cenozoic time is largely based on the ophiolitic lithology but are mostly similar (Fig. 2). Outer belt sutures, such as the Late Cretaceous Ophiolite ophiolites are characterized by slices of sheeted Belt of Southwest Asia (LCOBSWA). The dikes (Fig. 3e) associated with pillowed and LCOBSWA stretches for 3000 km from Cyprus to massive lavas (Fig. 3f). Cenomanian to Campanian Oman through Iran and is remarkably coherent, pelagic limestones are found as thin layers between continuous, and contemporary but is only well the lavas or lie on top of ophiolite. Sheeted dikes and known at its terminations: Cyprus (94–90 Ma) and pillow lavas are common in IB (Fig. 3a,c). The Oman (95 Ma). The rest of the LCOBSWA, espe- typical IB (Fig. 2a) is overlain by pyroclastic rocks cially in the Zagros region of Iran, is more poorly of Turonian to Maastrichtian age with basaltic to known. The Zagros Fold-and-Thrust Belt formed dacitic sills and rhyolitic dikes, demonstrating that as an accretionary prism and has grown in concert the nascent Urumieh–Dokhtar Arc to the northeast with the continuing subduction of Arabia beneath developed slightly after ophiolite formation. Iran, which began about 20 Ma. The Zagros Ophio- To reconstruct the tectonic setting of the lite Belt lies along the northeast flank of the Zagros ophiolites we use whole-rock and mineral Zagros Fold-and-Thrust Belt (Fig. 1a). Zagros geochemical indicators for peridotite and lavas. ophiolites represent forearc lithosphere that Most Zagros ophiolite peridotites are very formed during a Late Cretaceous episode of sub- depleted and have abundances of CaO and Al2O3 duction initiation on the north side of the Neot- that plot in the forearc field (Fig. 4a) and have high ethys (Shafaii Moghadam et al. 2010). Cr# (= Cr/Cr + Al) spinel compositions that also Zagros ophiolites can be subdivided into the mostly plot in the forearc field (Fig. 4b). ‘Inner Zagros’ and ‘Outer Zagros’ Ophiolitic Belts, Zagros ophiolitic lavas mostly have nearly flat to separated by the Sanandaj–Sirjan metamorphic slightly light rare earth element (LREE)-depleted terrane, which we interpret as exhumed subducted patterns. Extended trace element (spider) dia- materials (Fig. 1b). The Outer Zagros Ophiolitic grams show typical supra-subduction geochemical Belt (OB) includes the Kermanshah, Neyriz and signatures: enrichments in large ion lithophile and Esfandagheh ophiolites, from northwest to south- fluid mobile incompatible trace elements and east, cropping out south of the Main Zagros Thrust depletions in high field strength elements (HFSE) Fault (Fig. 1a). The Inner Zagros Ophiolite Belt (Fig. 4c). Some lavas have low REE and very low (IB) lies along the southwest margin of the Central HFSE abundances, similar to boninites, generated Iranian Block, comprising the Nain, Dehshir, by melting of highly depleted (harzburgitic) Shahr-e-Babak, and Baft ophiolites. These ophio- mantle. Nearly all of the Zagros ophiolite lavas fall lites are disrupted by faulting but generalized litho- into island-arc tholeiitic and boninite fields on a spheric columns can be reconstructed based on field Ti–V diagram (Fig. 4d), similar to the depleted observations (Fig. 2). Mantle sequences of IB and Lasail lavas (V2 unit) of Oman. OB ophiolites are similar, comprising depleted In summary, all rock units of the Inner and harzburgites with diabasic–gabbroic dikes; melt Outer Zagros Ophiolitic Belts, from harzburgitic mantle to lavas, are characterized by strong supra- *Correspondence. subduction zone compositional features. The simi- Received 14 February 2010; accepted for publication 10 September 2010. larity of ages for igneous rocks and overlying © 2010 Blackwell Publishing Asia Pty Ltd doi:10.1111/j.1440-1738.2010.00745.x 2 H. S. Moghadam and R. J. Stern (a) Main Zagros Thrust Zagros Fold-Thrust + Belt + + + + Urumieh-Dokhtar arc + Caspian Sea Khoy + Other Mesozoic + ophiolites + + Late Cretaceous Forearc Ophiolites + Sabzevar + Mashhad Kermanshah Tehran + 34° + N + G o lp + ay + eg + S an Birjand Z an + a + g an Nain ro d s aj F -S + o ir ld ja B - n + T Z h o r n Dehshir u e 30° st B + e Shahr-e-Babak lt + Balvard + + P Neyriz + e Baft + r + s + Iranshahr ia + + n Esfandagheh + + G u Band-Zeyarat lf 25 mm/yr A Fanuj- Maskutan 26° Semail Gulf of Oman 200 km ophiolite 50°E 54° 58° (b) SW ONCE-CONTINUOUS FOREARC OPHIOLITIC NAPPE NE Inner Zagros Imbricated Zone Outer Zagros Ophiolitic Belt Ophiolitic Belt (Dehshir) Zagros Simply Urumieh-Dokhtar Arc Folded Belt MZT Persian Gulf < < < < < < < < < < < < < < < < < < < < < < < < < < Iranian Arabian Continental Crust Continental Crust Sanandaj-Sirjan Zone Continental Crust Metamorphic Rocks < < < < < < Magmatic Rocks Sedimentary Cover < < < Folding Fig. 1 (a) Map showing the distribution of late Cretaceous Inner Zagros (IB) and Outer Zagros (OB) Ophiolitic Belt the location of the Urumieh–Dokhtar magmatic arc (Eocene–Quaternary), Zagros Fold–Thrust Belt and main Zagros thrust (MZT). (b) Schematic cross-section showing the relationships between the Outer and the Inner Zagros Ophiolitic Belts, the Zagros Thrust-Fold Belt, the Sanandaj-Sirjan Zone, and the Urumieh-Dokhtar Magmatic Arc. © 2010 Blackwell Publishing Asia Pty Ltd Iranian Forearc Ophiolites 3 (a) (b) Typical Inner Belt Ophiolite Typical Outer Belt Ophiolite (BAFT) (NEYRIZ) UK pelagic limestone Massive lava Pillow lava Pyroclastic rocks Chert & UK p. limestone v v v v v v v P. limestone & chert v v Gabbroic-pyroxenitic v / / / v / / / / / Sheeted dike complex Hyaloclastites / dike & sill + + + / + + / + / / + v / / + v v - v v v Tuffaceous SS Impregnated + + + v v v v v v / - - = Coarse-grained gabbros + v v v v v v v v - - - - v v - v v v v v v - v = = - & tuff - - peridotite + - Massive lava - - Plagiogranite - = = Rhyolitic dike Marble - - Pillow lava v . Wehrlite, pyroxenite v . v ... .... ... = v v .... v . v . v v v v v v = Basaltic to dacitic Highly depleted = v v v v cumulates = Chromitite pod v v sill harzburgite v = v v . .. .. Isotropic gabbro v . .. .. Isotropic gabbro v . .. v . .. Pyroxenitic sill .. Chromitite pod Diabasic dike . + Harzburgite Gabbroic dike .... v Melt pathways ..... Pegmatite gabbro . v . .. .. .. ... .. v . ..... Residual dunite . Pegmatite gabbro v v Harzburgite Diabasic dike Pyroxenitic sill & dike Fig. 2 Simplified psuedostratigraphic Amphibolitic sole Amphibolitic sole Mylonitic harzburgite lithospheric columns displaying general- ized lithological successions in typical (a) inner (Baft), and (b) outer (Neyriz) Inner Belt Ophiolites Outer Belt Ophiolites Ophiolite Overlying pelagic sediments age Crust thickness (km) Ophiolite Overlying pelagic sediments age Crust thickness (km) belt ophiolites. The age of the overlying Nain Coniacian to Maastrichtian 1-2 pelagic sediments and crust thickness of Neyriz Cenomanian-Turonian to early Santonian 1-2 Dehshir Turonian to Maastrichtian 0.5-1 Kermanshah Turonian to Campanian 2-3 each ophiolite from IB and OB are pre- Shahr-e-Babak Turonian-Coniacian to Maastrichtian 1-2 Haji-Abad late Cretaceous, study in progres 2-3 sented for comparison. Baft Cenomanian?-Turonian to Maastrichtian 2-3 Fig. 3 Field photographs of inner and outer belt ophiolite components. (a) Sheeted dike complex in the Nain ophio- lite (inner belt, IB). (b) Pegmatite gabbro sill within depleted harzburgite from the Nain ophiolite (IB). (c) Pillow lava sequence from the Baft ophiolite (IB). (d) Ultramafic–mafic cumulate sills within the mantle sequence from the Neyriz ophiolite (outer belt, OB). (e) Contact between dikes in sheeted dike complex from the Kermanshah ophiolite (OB). (f) Outcrop of pillow lavas in the Haji–Abad ophiolite (OB). Author (Hadi Shafaii) for scale. © 2010 Blackwell Publishing Asia Pty Ltd 4 H. S. Moghadam and R. J. Stern (a) (c) Peridotite Whole Rock Composition PUM 100 Baft 4 Shahr-e-Babak FMM 10 Inner Belt ) k c Abyssal peridotite o 3 r Nain k l u 1 b s u o r d y 2 h d n en a r Sample/N-MORB 0.1 ( T n Dehshir io % t t e pl w e D 3 le nt O 1 a 2 M l A 0.01 Mariana Forearc peridotite 0 0 1 2 3 4 100 CaO wt% (anhydrous bulk rock) Outer Belt Inner Ophiolite Belt (11 WRS ; 77 Sp) Nain ophiolite (4 ; 40) 10 Haji-Abad Dehshir ophiolite (3 ; 20) Baft ophiolite (3 ; 12) 1 Neyriz Shahr-e-Babak (1 ; 5) Outer Ophiolite Belt (15 WRS ; 110 Sp) Kermanshah Fig. 4 (a) Al2O3 vs CaO diagram Neyriz ophiolite (2 ; 96) Sample/N-MORB 0.1 Haji-Abad (12) (volatile free, normalized to 100% total) Kermanshah (1 ; 14) for Zagros forearc ophiolitic peridotites. 0.01 Semail ophiolite (Oman) The composition of primary upper Rb Th Nb K Ce Pr P Zr Ti Yb mantle (PUM) and fertile mid-oceanic (b) Ba U Ta La Pb Sr Nd Hf Y ridge basalt (MORB) mantle (FMM) are 1.0 Oman boninite (d) Increasing Compatibility also shown for comparison. WRS, whole rocks; Sp, spinel. (b) Cr# (=Cr/Cr + Al) Boninite Arc tholeiites 600 Ophiolitic lavas vs Mg# (=Mg/Mg + Fe) diagram (modi- fied after Dick & Bullen 1984) for spinels 500 Oman V2 in Zagros forearc harzburgites. (c) MORB & BABB ) 400 N-MORB normalized multi-elements m p p patterns for inner belt and outer belt ( 300 V Zagros ophiolitic lavas.
Load more

Recommended publications
  • Hydrothermal Alteration of a Supra-Subduction Zone Ophiolite Analog, Tonga
    AN ABSTRACT OF THE THESIS OF Melanie C. Kelman for the degree of Master of Science in Geology presented on May 29, 1998. Title: Hydrothermal Alteration of a Supra-Subduction Zone Ophiolite Analog, Tonga. Southwest Pacific. Abstract approved: Redacted for Privacy Sherman Bloomer The basement of the Tonga intraoceanic forearc comprises Eocene arc volcanic crust formed during the earliest phases of subduction. Volcanic rocks recovered from the forearc include boninites and arc tholeiites, apparently erupted into and upon older mid- oceanic ridge tholeiites. Rock assemblages suggest that the forearc basement is a likely analog for large supra-subduction zone (SSZ) ophiolites not only in structure and Ethology, but also in the style of hydrothermal alteration. Dredged volcanic samples from the central Tonga forearc (20-24° S) exhibit the effects of seafloor weathering, low (<200°C, principally <100°C) alteration, and high temperature (>200°C) alteration. Tholeiites and arc tholeiites are significantly more altered than boninites. Seafloor weathering is due to extensive interaction with cold oxidizing seawater, and is characterized by red-brown staining and the presence of Fe- oxyhydroxides. Low temperature alteration is due to circulation of evolving seawater- derived fluids through the volcanic section until fluid pathways were closed by secondary mineral precipitation. Low temperature alteration is characterized by smectites, celadonite, phillipsite, mixed-layer smectite/chlorite, carbonates, and silica. All phases fill veins and cavities; clay minerals and silica also replace the mesostasis and groundmass phases. Low temperature alteration enriches the bulk rock in K, Ba, and Na, and mobilizes other elements to varying extents. The few high temperature samples are characterized by mobilizes other elements to varying extents.
    [Show full text]
  • Characterizing the Evolution of Slab Inputs
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School 3-23-2017 Characterizing the Evolution of Slab Inputs in the Earliest Stages of Subduction: Preliminary Evidence from the Fluid-Mobile Element (B, Cs, As, Li) Systematics of Izu-Bonin Boninitic Glasses Recovered During IODP Expedition 352 Keir Aavon Sanatan University of South Florida, [email protected] Follow this and additional works at: http://scholarcommons.usf.edu/etd Part of the Geochemistry Commons, and the Geology Commons Scholar Commons Citation Sanatan, Keir Aavon, "Characterizing the Evolution of Slab Inputs in the Earliest Stages of Subduction: Preliminary Evidence from the Fluid-Mobile Element (B, Cs, As, Li) Systematics of Izu-Bonin Boninitic Glasses Recovered During IODP Expedition 352" (2017). Graduate Theses and Dissertations. http://scholarcommons.usf.edu/etd/6755 This Thesis is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Characterizing the Evolution of Slab Inputs in the Earliest Stages of Subduction: Preliminary Evidence from the Fluid-Mobile Element (B, Cs, As, Li) Systematics of Izu-Bonin Boninitic Glasses Recovered During IODP Expedition 352 by Keir Aavon Sanatan A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geology School of Geosciences College of Arts and Sciences University of South Florida Major Professor: Jeffrey G. Ryan, Ph.D. Zachary D. Atlas, Ph.D. Aurelie Germa, Ph.D. Date of Approval: March 24, 2017 Keywords: Boninites, Fluid-mobile elements, Izu-Bonin-Mariana, Laser ablation, Subduction initiation, Volcanic glass Copyright © 2017, Keir Aavon Sanatan TABLE OF CONTENTS List of Tables .................................................................................................................................
    [Show full text]
  • Article Is Available Online Initiation, Earth Planet
    Solid Earth, 9, 713–733, 2018 https://doi.org/10.5194/se-9-713-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Boninite and boninite-series volcanics in northern Zambales ophiolite: doubly vergent subduction initiation along Philippine Sea plate margins Americus Perez1, Susumu Umino1, Graciano P. Yumul Jr.2, and Osamu Ishizuka3,4 1Division of Natural System, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan 2Apex Mining Company Inc., Ortigas Center, Pasig City, 1605, Philippines 3Research Institute of Earthquake and Volcano Geology, Geological Survey of Japan, AIST, Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan 4Research and Development Center for Ocean Drilling Science, JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa 237-0061, Japan Correspondence: Americus Perez ([email protected], [email protected]) Received: 25 December 2017 – Discussion started: 31 January 2018 Revised: 7 May 2018 – Accepted: 12 May 2018 – Published: 5 June 2018 Abstract. A key component of subduction initiation rock itudes derived from tilt-corrected sites in the Acoje Block suites is boninite, a high-magnesium andesite that is uniquely place the juvenile arc of northern Zambales ophiolite in the predominant in western Pacific forearc terranes and in select western margin of the Philippine Sea plate. In this scenario, Tethyan ophiolites such as Oman and Troodos. We report, for the origin of Philippine Sea plate boninites (IBM and Zam- the first time, the discovery of low-calcium, high-silica boni- bales) would be in a doubly vergent subduction initiation set- nite in the middle Eocene Zambales ophiolite (Luzon Island, ting.
    [Show full text]
  • Foreland-Forearc Collisional Granitoid and Mafic Magmatism Caused By
    Foreland-forearc collisional granitoid and ma®c magmatism caused by lower-plate lithospheric slab breakoff: The Acadian of Maine, and other orogens A. Schoonmaker Department of Geology, University of Vermont, Burlington, Vermont 05405, USA W.S.F. Kidd Earth and Atmospheric Sciences, University at Albany, Albany, New York 12222, USA D.C. Bradley U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508, USA ABSTRACT canic belt. This model (Fig. 1) was elaborated on in Bradley et al. During collisional convergence, failure in extension of the lith- (1996), Robinson et al. (1998), Bradley and Tucker (2002), and Begeal osphere of the lower plate due to slab pull will reduce the thickness et al. (2004). Similarly, Sacks and Secor (1990) suggested lithospheric or completely remove lower-plate lithosphere and cause decom- necking to explain early granitic magmatism in the lower plate of the pression melting of the asthenospheric mantle; magmas from this southern Appalachian system during the Alleghenian orogeny. These source may subsequently provide enough heat for substantial par- models propose detachment of sections of the underthrust lower plate tial melting of crustal rocks under or beyond the toe of the colli- during the early orogenic stages of the subduction of a passive margin, sional accretionary system. In central Maine, United States, this rather than later, as proposed by Bird (1978) for the Himalaya, when type of magmatism is ®rst apparent in the Early Devonian West signi®cant lithospheric thickening and overthrusting has occurred. Branch Volcanics and equivalent ma®c volcanics, in the slightly younger voluminous ma®c/silicic magmatic event of the Moxie ACADIAN OF CENTRAL MAINEÐGEOLOGY OF THE Gabbro±Katahdin batholith and related ignimbrite volcanism, and CHESUNCOOK DOME in other Early Devonian granitic plutons.
    [Show full text]
  • Geology of the Eoarchean, >3.95 Ga, Nulliak Supracrustal
    ÔØ ÅÒÙ×Ö ÔØ Geology of the Eoarchean, > 3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics Tsuyoshi Komiya, Shinji Yamamoto, Shogo Aoki, Yusuke Sawaki, Akira Ishikawa, Takayuki Tashiro, Keiko Koshida, Masanori Shimojo, Kazumasa Aoki, Kenneth D. Collerson PII: S0040-1951(15)00269-3 DOI: doi: 10.1016/j.tecto.2015.05.003 Reference: TECTO 126618 To appear in: Tectonophysics Received date: 30 December 2014 Revised date: 30 April 2015 Accepted date: 17 May 2015 Please cite this article as: Komiya, Tsuyoshi, Yamamoto, Shinji, Aoki, Shogo, Sawaki, Yusuke, Ishikawa, Akira, Tashiro, Takayuki, Koshida, Keiko, Shimojo, Masanori, Aoki, Kazumasa, Collerson, Kenneth D., Geology of the Eoarchean, > 3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics, Tectonophysics (2015), doi: 10.1016/j.tecto.2015.05.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT Geology of the Eoarchean, >3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics Tsuyoshi Komiya1*, Shinji Yamamoto1, Shogo Aoki1, Yusuke Sawaki2, Akira Ishikawa1, Takayuki Tashiro1, Keiko Koshida1, Masanori Shimojo1, Kazumasa Aoki1 and Kenneth D.
    [Show full text]
  • Geochemistry and Isotopic Signatures of Metavolcanic and Metaplutonic
    Precambrian Research 292 (2017) 350–377 Contents lists available at ScienceDirect Precambrian Research journal homepage: www.elsevier.com/locate/precamres Geochemistry and isotopic signatures of metavolcanic and metaplutonic rocks of the Faina and Serra de Santa Rita greenstone belts, Central Brazil: Evidences for a Mesoarchean intraoceanic arc ⇑ Caio César Aguiar Borges a, , Catarina Labouré Bemfica Toledo a, Adalene Moreira Silva a, Farid Chemale Junior b, Hardy Jost a, Cristiano de Carvalho Lana c a Universidade de Brasília, Instituto de Geociências, 70910-900 Brasília, DF, Brazil b Universidade do Vale do Rio dos Sinos, Departamento de Geologia, 93022-000 São Leopoldo, RS, Brazil c Escola de Minas de Ouro Preto, Departamento de Geologia, 35400-000 Ouro Preto, MG, Brazil article info abstract Article history: The Archean-Paleoproterozoic Terrane of Goiás, Central Brazil, is an allochthonous block within the Received 23 May 2016 Neoproterozoic Tocatins Province and consists of an association of Archean TTG complexes and gold- Revised 20 February 2017 bearing Archean-Paleoproterozoic greenstone belts. The Faina and Serra Santa Rita greenstone belts, Accepted 22 February 2017 located in the southern portion of the terrane, are investigated using geochemistry and isotope geology Available online 24 February 2017 to establish the time of magmatism and tectonic environment. Our data show that the ultramafic rocks have some chemical characteristics similar to modern boninites, whereas the amphibolites are subdi- Keywords: vided into two groups: the type 1 basalts group are tholeiites with flat REE patterns and are similar to Tocantins Province back-arc basin basalts; the type 2 basalts group have high Nb contents and are comparable to Nb- Archean-Paleoproterozoic Terrane of Goiás Faina greenstone belt enriched basalts.
    [Show full text]
  • Magmatic Evolution of Early Subduction Zones: Geochemical Modeling and Chemical Stratigraphy of Boninite and Fore Arc Basalt from the Bonin Fore Arc
    Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2017 Magmatic Evolution of Early Subduction Zones: Geochemical Modeling and Chemical Stratigraphy of Boninite and Fore Arc Basalt from the Bonin Fore Arc Emily A. Haugen Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Geology Commons Recommended Citation Haugen, Emily A., "Magmatic Evolution of Early Subduction Zones: Geochemical Modeling and Chemical Stratigraphy of Boninite and Fore Arc Basalt from the Bonin Fore Arc" (2017). All Graduate Theses and Dissertations. 5934. https://digitalcommons.usu.edu/etd/5934 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. MAGMATIC EVOLUTION OF EARLY SUBDUCTION ZONES: GEOCHEMICAL MODELING AND CHEMICAL STRATIGRAPHY OF BONINITE AND FORE ARC BASALT FROM THE BONIN FORE ARC by Emily A. Haugen A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Geology Approved: ________________________ ________________________ John Shervais, Ph.D. Alexis Ault, Ph.D. Major Professor Committee Member ________________________ ________________________ Anthony Lowry, Ph.D. Mark R. McLellan, Ph.D. Committee Member Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2017 ii Copyright Emily A. Haugen 2017 All Rights Reserved iii ABSTRACT Magmatic Evolution of Early Subduction Zones: Geochemical Modeling and Chemical Stratigraphy of Boninite and Fore Arc Basalt from the Bonin Fore Arc by Emily A.
    [Show full text]
  • Geodynamic Evolution of a Forearc Rift in the Southernmost Mariana Arc Julia M
    University of Rhode Island DigitalCommons@URI Graduate School of Oceanography Faculty Graduate School of Oceanography Publications 2013 Geodynamic Evolution of a Forearc Rift in the Southernmost Mariana Arc Julia M. Ribeiro Robert J. Stern See next page for additional authors Follow this and additional works at: https://digitalcommons.uri.edu/gsofacpubs The University of Rhode Island Faculty have made this article openly available. Please let us know how Open Access to this research benefits oy u. This is a pre-publication author manuscript of the final, published article. Terms of Use This article is made available under the terms and conditions applicable towards Open Access Policy Articles, as set forth in our Terms of Use. Citation/Publisher Attribution Ribeiro, Julia M., et al. "Geodynamic Evolution of a Forearc Rift in the outheS rnmost Mariana Arc." Island Arc 22.4 (2013): 453-476. Available at: http://dx.doi.org/10.1111/iar.12039 This Article is brought to you for free and open access by the Graduate School of Oceanography at DigitalCommons@URI. It has been accepted for inclusion in Graduate School of Oceanography Faculty Publications by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. Authors Julia M. Ribeiro, Robert J. Stern, Fernando Martinez, Osamu Ishizuka, Susan G. Merle, Katherine Kelley, Elizabeth Y. Anthony, Minghua Ren, Yasuhiko Ohara, Mark Reagan, Guillaume Girard, and Sherman Bloomer This article is available at DigitalCommons@URI: https://digitalcommons.uri.edu/gsofacpubs/37 1 Geodynamic evolution of a forearc rift in the southernmost Mariana Arc 2 3 Julia M.
    [Show full text]
  • Precambrian Greenstone Sequences Represent Different Ophiolite Types
    GR-01066; No of Pages 37 Gondwana Research xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR Focus Review Precambrian greenstone sequences represent different ophiolite types H. Furnes a,⁎, Y. Dilek b,c, M. de Wit d a Department of Earth Science and Centre for Geobiology, University of Bergen, Allégaten 41, 5007 Bergen, Norway b Department of Geology & Environmental Earth Science, Miami University, Oxford, OH 45056, USA c State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China d AEON – Africa Earth Observatory Network, and Faculty of Science, Nelson Mandela Metropolitian University 7701, Port Elizabeth, 6031, South Africa article info abstract Article history: We present here a global geochemical dataset from one hundred-and-five greenstone sequences, ranging in Received 14 March 2013 age from the Eoarchean through the Archean and Proterozoic Eons that we have examined to identify differ- Received in revised form 14 June 2013 ent ophiolite types (c.f. Dilek and Furnes, 2011) with distinct tectonic origins in the Precambrian rock record. Accepted 14 June 2013 We apply well-established discrimination systematics (built on immobile elements) of basaltic components Available online xxxx of the greenstone sequences as our geochemical proxies. The basaltic rocks are classified under two major groups, subduction-related and subduction-unrelated. This analysis suggests that ca. 85% of the greenstone Keywords: fi Precambrian greenstone belts sequences can be classi ed as subduction-related ophiolites, generated in backarc to forearc tectonic envi- Ophiolite classification ronments.
    [Show full text]
  • Ocean Trenches Trolled Depression in the Rocky Mountains
    Article Number: GEOL: 00141 a0005 EARTH PROCESSES after the war ended to describe a structurally con- AU:1 Ocean Trenches trolled depression in the Rocky Mountains. Johnstone, AU:6 in his 1923 textbook An Introduction to Ocean- ography, first used the term in its modern sense R J Stern, The University of Texas at Dallas, to describe a marked elongate depression of the Richardson, TX, USA seafloor. ß 2004, Elsevier Ltd. All Rights Reserved. During the 1920s and 1930s, Vening Meinesz p0015 developed a unique gravimeter that could measure gravity in the stable environment of a submarine s0005 Introduction AU:3 and used it to measure gravity over ocean trenches. p0005 An oceanic trench is a long, narrow, and generally His gravity measurements revealed that trenches are very deep depression of the seafloor. Oceanic trenches sites of downwelling in the solid Earth. The concept are the deepest places on the Earth’s solid surface and of downwelling at trenches was characterized by range down to 11 km below sea-level. These tremen- Griggs in 1939 as the tectogene hypothesis, for AU:7 dous depths mark fundamental breaks in the Earth’s which he developed an analogous model using a lithosphere, the great plates that we all ride on. If pair of rotating drums. The war in the Pacific led to AU:8 mid-ocean ridges are where the Earth turns itself great improvements in bathymetry, especially in the inside out, trenches are where the Earth swallows its western and northern Pacific, and the linear nature of skin. The asymmetry of trenches reflects a deeper the trenches became clear.
    [Show full text]
  • Curved Orogenic Belts, Back-Arc Basins, And
    https://doi.org/10.1130/G48919.1 Manuscript received 6 February 2021 Revised manuscript received 10 May 2021 Manuscript accepted 21 June 2021 © 2021 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Curved orogenic belts, back-arc basins, and obduction as consequences of collision at irregular continental margins Nicholas Schliffke1, Jeroen van Hunen1, Frédéric Gueydan2, Valentina Magni3 and Mark B. Allen1 1 Department of Earth Sciences, Durham University, DH1 3LE Durham, UK 2 Géosciences Montpellier, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier cedex 5, France 3 The Centre for Earth Evolution and Dynamics (CEED), University of Oslo, SemSaelandsvei 24, P.O. Box 1048, Blindern, NO-0316 Oslo, Norway ABSTRACT by thrusting of an older Jurassic rifted margin Continental collisions commonly involve highly curved passive plate margins, leading to (Tubia et al., 2009), or by hyperextension of diachronous continental subduction during trench rollback. Such systems may feature back- the overriding plate before, and thrusting dur- arc extension and ophiolite obduction postdating initial collision. Modern examples include ing, continental collision (Frasca et al., 2017; the Alboran and Banda arcs. Ancient systems include the Newfoundland and Norwegian Cale- Gueydan et al., 2019; see Fig. 1C). It is unclear donides. While external forces or preexisting weaknesses are often invoked, we suggest that in these examples how the geologic evolution ophiolite obduction can equally be caused by internal stress buildup during collision. Here, is linked to the highly arcuate geometry and we modeled collision with an irregular subducting continental margin in three-dimensional irregular shape of the subducting continental (3-D) thermo-mechanical models and used the generated stress field evolution to understand margin, if at all.
    [Show full text]
  • Subduction Erosion: Rates, Mechanisms, and Its Role in Arc Magmatism and the Evolution of the Continental Crust and Mantle
    GR-00621; No of Pages 25 Gondwana Research xxx (2011) xxx–xxx Contents lists available at ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR focus review Subduction erosion: Rates, mechanisms, and its role in arc magmatism and the evolution of the continental crust and mantle Charles R. Stern ⁎ Department of Geological Sciences, University of Colorado, Boulder, CO, 80309-0399, USA article info abstract Article history: Subduction erosion occurs at all convergent plate boundaries, even if they are also accretionary margins. Received 30 November 2010 Frontal subduction erosion results from a combination of erosion and structural collapse of the forearc wedge Received in revised form 23 March 2011 into the trench, and basal subduction erosion by abrasion and hydrofracturing above the subduction channel. Accepted 27 March 2011 High rates of subduction erosion are associated with relatively high convergence rates (N60 mm/yr) and low Available online xxxx rates of sediment supply to the trench (b40 km2/yr), implying a narrow and topographically rough fi Handling Editor: M. Santosh subduction channel which is neither smoothed out nor lubricated by ne-grained water-rich turbidites such as are transported into the mantle below accreting plate boundaries. Rates of subduction erosion, which range 3 Keywords: up to N440 km /km/my, vary temporally as a function of these same factors, as well as the subduction of Subduction erosion buoyant features such as seamount chains, submarine volcanic plateaus, island arcs and oceanic spreading Arc magmatism ridge, due to weakening of the forearc wedge. Revised estimates of long-term rates of subduction erosion Crustal recycling appropriate for selected margins, including SW Japan (≥30 km3/km/my since 400 Ma), SW USA (≥30 km3/ Mantle evolution km/my since 150 Ma), Peru and northern Chile (50–70 km3/km/my since N150 Ma), and central (115 km3/ Supercontinent cycle km/my since 30 Ma) and southernmost Chile (30–35 km3/km/my since 15 Ma), are higher than in previous compilations.
    [Show full text]