Ophiolite in Southeast Asia

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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.
Depleted Spinel Harzburgite Xenoliths in Tertiary Dykes from East Greenland: Restites from High Degree Melting

Earth and Planetary Science Letters 154Ž. 1998 221±235 Depleted spinel harzburgite xenoliths in Tertiary dykes from East Greenland: Restites from high degree melting Stefan Bernstein a,), Peter B. Kelemen b,1, C. Kent Brooks a,c,2 a Danish Lithosphere Centre, éster Voldgade 10, DK-1350 Copenhagen K, Denmark b Woods Hole Oceanographic Institution, Woods Hole, City, MA 02543, USA c Geological Institute, UniÕersity of Copenhagen, éster Voldgade 10, DK-1350 Copenhagen K, Denmark Received 28 April 1997; revised 19 September 1997; accepted 4 October 1997 Abstract A new collection of mantle xenoliths in Tertiary dykes from the Wiedemann Fjord area in Southeast Greenland shows that this part of the central Greenland craton is underlain by highly depleted peridotites. The samples are mostly spinel harzburgites with highly forsteritic olivinesŽ. Fo87± 94 , average Fo 92.7 . This, together with unusually high modal olivine contentsŽ. 70±)95% , places the Wiedemann harzburgites in a unique compositional field. Relative to depleted Kaapvaal harzburgites with comparable Fo in olivine, the Wiedemann samples have considerably lower bulk SiO2 Ž average 42.6 wt% versus 44±49 wt%. Spinel compositions are similar to those in other sub-cratonic harzburgites. Pyroxene equilibrium temperatures average 8508C, which is above an Archaean cratonic geotherm at an inferred pressure of 1±2 GPa, but low enough so that it is unlikely that the xenoliths represent residual peridotites created during Tertiary magmatism. Among mantle samples, the Wiedemann harzburgites are, in terms of their bulk composition, most similar to harzburgites from the ophiolites of Papua New GuineaŽ. PNG and New Caledonia Ž.
New Perspectives on Tasmanian Geology

TASMANIA - ANISLANDOFPOmNIIAL New perspectives on Tasmanian geology C. MeA. POWELL Geology Departrrumt, The University ofWe stem Australia. ABSTRACT New infonnation about the structure and sedimentary basin cotljiguration in the southern TastnIJII Fold Bell cotljirms thiltthe eastern TasmLlllia terrane is the on-strike COlllinuation o/the Melbourne Zone o/VictoriIL It represents a passive-margin to back-arc basin which was deformed and amalgamated with the western TasmLlllia terrane in the late Middle Devonian. The western TastnlJlliaterrane hils chilracteristics 0/ both the western lAchlan Fold Bell and the Kanmantao Fold Bell, and could be a largely exotic block lying across the jutlCtion between the tw%ld bells. The Precambrian "basemelll" o/TQStnIJ1Iia, regarded/or so long asfirmly rooted to its mafIlle lithosphere, could be composed o/thrust-bounded slices accreted to the TQStnIJ1I Fold Bell initially in the Middle Cambrian during westward thrusting o/the KanmafIloo Fold Belt over the platform margin in the Adelaide region. Renewed contraction in the Middle Devonian/ormed tnIJIIy o/the preselllthrust contacts. These new ideas make it imperative that existing esploration philosophies and nwdels are re-exmnined 10 take ill/o accoulllthe thrust-/aull geometry and the possible allochthonous nature o/much o/TasmLlllia. INTRODUCTION local areas of contractional deformation (powell, 1983, 1984a). The whole eastern Lachlan Fold Belt appears to have been a zone of transcurrence with local areas of transtension Tasmania occupies an imponant place in the geological and transpression. Theeasternand western] acblanFoldBelt framework of AuslIalia, lying at the southern extension of were reunited in the Middle Devonian when contractional the 1000-km wide Tasman Fold Belt, which occupies the deformation affected both parts, and the region rose above eastern third of the continent (fig.
Thermo-Mechanical Modeling of the Obduction Process Based on The

Thermo-mechanical modeling of the obduction process based on the Oman ophiolite case Thibault Duretz, Philippe Agard, Philippe Yamato, Céline Ducassou, Evgenii Burov, T. V. Gerya To cite this version: Thibault Duretz, Philippe Agard, Philippe Yamato, Céline Ducassou, Evgenii Burov, et al.. Thermo- mechanical modeling of the obduction process based on the Oman ophiolite case. Gondwana Research, Elsevier, 2016, 32, pp.1-10. 10.1016/j.gr.2015.02.002. insu-01120232 HAL Id: insu-01120232 https://hal-insu.archives-ouvertes.fr/insu-01120232 Submitted on 9 Mar 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. ACCEPTED MANUSCRIPT Thermo-mechanical modeling of the obduction process based on the Oman ophiolite case Thibault Duretz1,2, Philippe Agard2, Philippe Yamato3, Céline Ducassou4, Evguenii B. Burov2, Taras V. Gerya5 1Institut des sciences de la Terre, University of Lausanne, 1015 Lausanne, Switzerland 2ISTEP, UMR CNRS 7193, UPMC Sorbonne Universités, 75252 Cedex 05, Paris, France 3Geosciences Rennes, UMR CNRS 6118, Université de Rennes 1, 35042 Rennes Cedex, France 4Applied Geosciences, GUtech, PO Box 1816, Athaibah, PC 130, Sultanate of Oman 5Institute of Geophysics, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland submission to – Gondwana Research Keywords: Obduction; Oman; numerical modeling ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT Abstract Obduction emplaces regional-scale fragments of oceanic lithosphere (ophiolites) over continental lithosphere margins of much lower density.
Major Chemical Characteristics of Mesozoic Coast Range Ophiolite in California

JOURNAL OF OF THE U.S. GEOLOGICAL SURVEY NOVEMBER-DECEMBER 1974 VOLUME 2, NUMBER 6 Scientific notes and summaries of investigations in geology, hydrology, and related fields +r U«/ fc/ U.S. DEPARTMENT OF THE INTERIOR UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC The Journal of Research is pub Correspondence and inquiries concerning the Jour 20402. Order by SD Catalog No. lished every 2 months by the U.S. nal (other than subscription inquiries and address JRGS. Annual subscription rate Geological Survey. It contains changes) should be directed to the Journal of Re $15.50 (plus $3.75 for foreign mail papers by members of the Geologi search, Publications Division, U.S. Geological Survey, ing). Single copy $2.75. Make cal Survey and their professional National Center 321, Reston, VA 22092. checks or money orders payable to colleagues on geologic, hydrologic, the Superintendent of Documents. topographic, and other scientific Papers for the Journal should be submitted through Send all subscription inquiries and technical subjects. regular Division publication channels. and address changes to the Superin tendent of Documents at the above address. Purchase orders should not be sent to the U.S. Geological Survey The Secretary of the Interior has determined that the publication of this periodical is library. necessary in the transaction of the public business required by law of this Department. Library of Congress Catalog-card Use of funds for printing this periodical has been approved by the Director of the Office No.
Global Variations in Abyssal Peridotite Compositions

Lithos 248–251 (2016) 193–219 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos Invited review article Global variations in abyssal peridotite compositions Jessica M. Warren Dept. of Geological Sciences, University of Delaware, Penny Hall, Newark, DE 19716, USA article info abstract Article history: Abyssal peridotites are ultramafic rocks collected from mid-ocean ridges that are the residues of adiabatic decom- Received 28 March 2015 pression melting. Their compositions provide information on the degree of melting and melt–rock interaction Accepted 24 December 2015 involved in the formation of oceanic lithosphere, as well as providing constraints on pre-existing mantle hetero- Available online 9 January 2016 geneities. This review presents a compilation of abyssal peridotite geochemical data (modes, mineral major elements, and clinopyroxene trace elements) for N1200 samples from 53 localities on 6 major ridge systems. Keywords: fi fi Abyssal peridotite On the basis of composition and petrography, peridotites are classi ed into one of ve lithological groups: (1) re- Mid-ocean ridge sidual peridotite, (2) dunite, (3) gabbro-veined and/or plagioclase-bearing peridotite, (4) pyroxenite-veined Partial melting peridotite, and (5) other types of melt-added peridotite. Almost a third of abyssal peridotites are veined, indicat- Melt–rock interaction ing that the oceanic lithospheric mantle is more fertile, on average, than estimates based on residual peridotites Mantle geochemistry alone imply. All veins appear to have formed recently during melt transport beneath the ridge, though some py- Pyroxenite roxenites may be derived from melting of recycled oceanic crust. A limited number of samples are available at intermediate and fast spreading rates, with samples from the East Pacific Rise indicating high degrees of melting.
The Callovian Unconformity and the Ophiolite Obduction Onto the Pelagonian Carbonate Platform of the Internal Hellenides

Δελτίο της Ελληνικής Γεωλογικής Εταιρίας, τόμος L, σελ. 144-152 Bulletin of the Geological Society of Greece, vol. L, p. 144-152 Πρακτικά 14ου Διεθνούς Συνεδρίου, Θεσσαλονίκη, Μάιος 2016 Proceedings of the 14th International Congress, Thessaloniki, May 2016 THE CALLOVIAN UNCONFORMITY AND THE OPHIOLITE OBDUCTION ONTO THE PELAGONIAN CARBONATE PLATFORM OF THE INTERNAL HELLENIDES Scherreiks R.1, Meléndez G.2, Bouldagher-Fadel M.3, Fermeli G.4 and Bosence D.5 1Bayerische Staaatssammlung, Department of Geology, University of Munich, Luisenstr. 33, 80333 Munich, Germany, [email protected] 2Departamento de Geologia (Paleontologia), Universidad de Zaragoza, 50009 Saragossa, Spain, [email protected] 3Earth Sciences, University College London, Gower Street, London WC1E6BT, UK, [email protected] 4Department of Historical Geology and Paleontology, University of Athens, Panepistimioupolis, Zographou, 15784 Athens, Greece, [email protected] 5Department of Earth Sciences, Royal Holloway University of London, Egham TW20 0EX, UK, [email protected] Abstract The carbonate-platform-complex and the oceanic formations of the central Pelagonian zone of the Hellenides evolved in response to a sequence of plate-tectonic episodes of ocean spreading, plate convergence and ophiolite obduction. The bio- stratigraphies of the carbonate platform and the oceanic successions, show that the Triassic-Early Jurassic platform was coeval with an ocean where pillow basalts and radiolarian cherts were being deposited. After convergence began during late Early- Jurassic - Middle Jurassic time, the oceanic leading edge of the Pelagonian plate was subducted beneath the leading edge of the oceanic, overriding plate. The platform subsided while a supra-subduction, volcanic-island-arc evolved.
Zeolites in Tasmania

Mineral Resources Tasmania Tasmanian Geological Survey Record 1997/07 Tasmania Zeolites in Tasmania by R. S. Bottrill and J. L. Everard CONTENTS INTRODUCTION ……………………………………………………………………… 2 USES …………………………………………………………………………………… 2 ECONOMIC SIGNIFICANCE …………………………………………………………… 2 GEOLOGICAL OCCURRENCES ………………………………………………………… 2 TASMANIAN OCCURRENCES ………………………………………………………… 4 Devonian ………………………………………………………………………… 4 Permo-Triassic …………………………………………………………………… 4 Jurassic …………………………………………………………………………… 4 Cretaceous ………………………………………………………………………… 5 Tertiary …………………………………………………………………………… 5 EXPLORATION FOR ZEOLITES IN TASMANIA ………………………………………… 6 RESOURCE POTENTIAL ……………………………………………………………… 6 MINERAL OCCURRENCES …………………………………………………………… 7 Analcime (Analcite) NaAlSi2O6.H2O ……………………………………………… 7 Chabazite (Ca,Na2,K2)Al2Si4O12.6H2O …………………………………………… 7 Clinoptilolite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 7 Gismondine Ca2Al4Si4O16.9H2O …………………………………………………… 7 Gmelinite (Na2Ca)Al2Si4O12.6H2O7 ……………………………………………… 7 Gonnardite Na2CaAl5Si5O20.6H2O ………………………………………………… 10 Herschelite (Na,Ca,K)Al2Si4O12.6H2O……………………………………………… 10 Heulandite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 10 Laumontite CaAl2Si4O12.4H2O …………………………………………………… 10 Levyne (Ca2.5,Na)Al6Si12O36.6H2O ………………………………………………… 10 Mesolite Na2Ca2(Al6Si9O30).8H2O ………………………………………………… 10 Mordenite K2.8Na1.5Ca2(Al9Si39O96).29H2O ………………………………………… 10 Natrolite Na2(Al2Si3O10).2H2O …………………………………………………… 10 Phillipsite (Ca,Na,K)3Al3Si5O16.6H2O ……………………………………………… 11 Scolecite CaAl2Si3O10.3H20 ………………………………………………………
Mineralogical Evidence for Partial Melting and Melt-Rock Interaction Processes in the Mantle Peridotites of Edessa Ophiolite (North Greece)

minerals Article Mineralogical Evidence for Partial Melting and Melt-Rock Interaction Processes in the Mantle Peridotites of Edessa Ophiolite (North Greece) Aikaterini Rogkala 1,* , Petros Petrounias 1 , Basilios Tsikouras 2 , Panagiota P. Giannakopoulou 1 and Konstantin Hatzipanagiotou 1 1 Section of Earth Materials, Department of Geology, University of Patras, 265 04 Patras, Greece; [email protected] (P.P.); [email protected] (P.P.G.); [email protected] (K.H.) 2 Physical and Geological Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Bandar Seri Begawan, Brunei Darussalam; [email protected] * Correspondence: [email protected]; Tel.: +30-2610996288 Received: 10 December 2018; Accepted: 14 February 2019; Published: 17 February 2019 Abstract: The Edessa ophiolite complex of northern Greece consists of remnants of oceanic lithosphere emplaced during the Upper Jurassic-Lower Cretaceous onto the Palaeozoic-Mesozoic continental margin of Eurasia. This study presents new data on mineral compositions of mantle peridotites from this ophiolite, especially serpentinised harzburgite and minor lherzolite. Lherzolite formed by low to moderate degrees of partial melting and subsequent melt-rock reaction in an oceanic spreading setting. On the other hand, refractory harzburgite formed by high degrees of partial melting in a supra-subduction zone (SSZ) setting. These SSZ mantle peridotites contain Cr-rich spinel residual after partial melting of more fertile (abyssal) lherzolite with Al-rich spinel. Chromite with Cr# > 60 in harzburgite resulted from chemical modiﬁcation of residual Cr-spinel and, along with the presence of euhedral chromite, is indicative of late melt-peridotite interaction in the mantle wedge. Mineral compositions suggest that the Edessa oceanic mantle evolved from a typical mid-ocean ridge (MOR) oceanic basin to the mantle wedge of a SSZ.
Synchronous Formation of the Metamorphic

Earth and Planetary Science Letters 451 (2016) 185–195 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Synchronous formation of the metamorphic sole and igneous crust of the Semail ophiolite: New constraints on the tectonic evolution during ophiolite formation from high-precision U–Pb zircon geochronology ∗ Matthew Rioux a, , Joshua Garber a,b, Ann Bauer c, Samuel Bowring c, Michael Searle d, Peter Kelemen e, Bradley Hacker a,b a Earth Research Institute, University of California, Santa Barbara, CA 93106, USA b Department of Earth Science, University of California, Santa Barbara, CA 93106, USA c Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA d Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK e Department of Earth and Environmental Studies, Columbia University, Lamont Doherty Earth Observatory, Palisades, NY 10964, USA a r t i c l e i n f o a b s t r a c t Article history: The Semail (Oman–United Arab Emirates) and other Tethyan-type ophiolites are underlain by a Received 11 April 2016 sole consisting of greenschist- to granulite-facies metamorphic rocks. As preserved remnants of the Received in revised form 2 June 2016 underthrust plate, sole exposures can be used to better understand the formation and obduction Accepted 25 June 2016 of ophiolites. Early models envisioned that the metamorphic sole of the Semail ophiolite formed Available online 29 July 2016 as a result of thrusting of the hot ophiolite lithosphere over adjacent oceanic crust during initial Editor: M.
RESEARCH a Non–Plate Tectonic

RESEARCH A non–plate tectonic model for the Eoarchean Isua supracrustal belt A. Alexander G. Webb1,*, Thomas Müller2, Jiawei Zuo1, Peter J. Haproff3, and Anthony Ramírez-Salazar2 1DEPARTMENT OF EARTH SCIENCES AND LABORATORY FOR SPACE RESEARCH, UNIVERSITY OF HONG KONG, POKFULAM ROAD, HONG KONG, CHINA 2SCHOOL OF EARTH AND ENVIRONMENT, UNIVERSITY OF LEEDS, MATHS/EARTH AND ENVIRONMENT BUILDING, LEEDS LS2 9JT, UK 3DEPARTMENT OF EARTH AND OCEAN SCIENCES, UNIVERSITY OF NORTH CAROLINA, WILMINGTON, NORTH CAROLINA 28403, USA ABSTRACT The ca. 3.8–3.6-b.y.-old Isua supracrustal belt of SW Greenland is Earth’s only site older than 3.2 Ga that is exclusively interpreted via plate- tectonic theory. The belt is divided into ca. 3.8 Ga and ca. 3.7 Ga halves, and these are interpreted as plate fragments that collided by ca. 3.6 Ga. However, such models are based on idiosyncratic interpretations of field observations and U-Pb zircon data, resulting in intricate, conflicting stratigraphic and structural interpretations. We reanalyzed published geochronological work and associated field constraints previously interpreted to show multiple plate-tectonic events and conducted field-based exploration of metamorphic and structural gra- dients previously interpreted to show heterogeneities recording plate-tectonic processes. Simpler interpretations are viable, i.e., the belt may have experienced nearly homogeneous metamorphic conditions and strain during a single deformation event prior to intrusion of ca. 3.5 Ga mafic dikes. Curtain and sheath folds occur at multiple scales throughout the belt, with the entire belt potentially representing Earth’s largest a-type fold. Integrating these findings, we present a new model in which two cycles of volcanic burial and resultant melt- ing and tonalite-trondhjemite-granodiorite (TTG) intrusion produced first the ca.
Mantle Melting and Origin of Basaltic Magma

Lecture 18 - Mantle Melting Monday, 28th, March, 2005 Mantle Melting and Origin of Basaltic Magma 1 Two principal types of basalt in the ocean basins Tholeiitic Basalt and Alkaline Basalt Table 10-1 Common petrographic differences between tholeiitic and alkaline basalts Tholeiitic Basalt Alkaline Basalt Usually fine-grained, intergranular Usually fairly coarse, intergranular to ophitic Groundmass No olivine Olivine common Clinopyroxene = augite (plus possibly pigeonite) Titaniferous augite (reddish) Orthopyroxene (hypersthene) common, may rim ol. Orthopyroxene absent No alkali feldspar Interstitial alkali feldspar or feldspathoid may occur Interstitial glass and/or quartz common Interstitial glass rare, and quartz absent Olivine rare, unzoned, and may be partially resorbed Olivine common and zoned Phenocrysts or show reaction rims of orthopyroxene Orthopyroxene uncommon Orthopyroxene absent Early plagioclase common Plagioclase less common, and later in sequence Clinopyroxene is pale brown augite Clinopyroxene is titaniferous augite, reddish rims after Hughes (1982) and McBirney (1993). Each is chemically distinct Evolve via FX as separate series along different paths ● Tholeiites are generated at mid-ocean ridges ✦ Also generated at oceanic islands, subduction zones ● Alkaline basalts generated at ocean islands ✦ Also at subduction zones 2 Sources of mantle material ● Ophiolites ✦ Slabs of oceanic crust and upper mantle ✦ Thrust at subduction zones onto edge of continent ● Dredge samples from oceanic fracture zones ● Nodules and xenoliths in some basalts ● Kimberlite xenoliths ✦ Diamond-bearing pipes blasted up from the mantle carrying numerous xenoliths from depth Lherzolite is probably fertile unaltered mantle Dunite and harzburgite are refractory residuum after basalt has been extracted by partial melting 15 Tholeiitic basalt 3 10 O 2 Partial Melting Wt.% Al Wt.% 5 Figure 10-1 Brown and Mussett, A.