DOCSLIB.ORG

Proquest Dissertations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

INFORMATION TO USERS This mmuscript has bean reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quaiity of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Photographs included in the original manuscript have been reproduced xerographically In this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Beil & Howell Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 UMT PETROGENESIS OF CHROMITE AND ASSOCIATED MINERALS IN THE UPPER MANTLE PERIDOTITE OF THE NORTHERN SEMAIL OPmOLITE (UAE) “Volume I” DISSERTATION l*resented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University by Solaiman Al-Aabed, MS. ********* The Ohio State University 2000 Dissertation Committee: Approved by Professer Michael Barton, adviser Professer Hallen Noltimeir Professer Douglas Pride Adviser Professer Terry Wilson Department of Geological Sciences UMI Number 9982513 Copyright 2000 by Al-Aabed, Solaiman Ali All rights reserved. UMI* UMI Microform9982513 Copyright 2000 by Bell & Howell Information and Leaming Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. Bell & Howell Information and Leaming Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT The northern part of the Semai I (Oman) ophiolite extends along the northeastern border of the UAE. The upper mantle peridotites of this ophiolitic section contain chromite deposits in three main localities: Al’Hel, Siji and Zikt. The study is focussed in the Al’Hel and Zikt areas. Siji is not considered in detail because it is chemically similar to Al’Hel. Field, pétrographie, and geochemical evidence is used to divide the chromite fields into three major zones: Al’Hel, E. Zikt, and S. Zikt. The Al’Hel zone is very close to the mantle-crust transition, and is characterized by less depleted peridotites than those in Zikt. Al’Hel chromitites contain minor modal pyroxene, along with low-grade, Al-rich chromites. In contrast, the Zikt zone is located deeper in the mantle sequence, with E. Zikt closest to the mantle-crust transition, and S. Zikt furthest from the transition. The S. Zikt fields contain the highest-grade, Cr-rich chromites, whereas, the chromite composition at E. Zikt is between that of Al’Hel and S. Zikt. Chromite is always associated with olivine (sometimes with trace amounts of pyroxene) in chromitite and dunite lensoid bodies. The chromite/olivine ratio varies from 1 to zero, from massive chromitite to dunite. Olivine and chromite show a variety of textures such as net and circular texture. Some textures are characteristic for a specific zone (e.g. nodular texture at Zikt). Pré-, syn-, and post-emplacement deformation obliterated most of the original textures and formed new deformation fabrics. However, some original magmatic textures such as rhythmic layering are preserved. A magmatic origin for the formation of chromite and associated minerals is indicated by whoie-rocks and mineral geochemistry. The geochemical characteristics of the Al’Hel bodies are different from those of Zikt. Disequilibrium interaction between rising melts and the wall rocks was the main driving mechanism for chromite precipitation, particularly the massive chromitites. This process leads to Mg and Si enrichment in the melts by dissolution of some peridotite materials (e.g pyroxene). Increasing silica content increases polymerization and decreases Cr (and probably other heavy metals) solubility in the melts, and thus triggers chromite precipitation. It is concluded that there were three genetic stages of formation of chromite bodies in the UAE Semai 1 ophiolite. First, partial melting at a MOR spreading occurred center during drifting of Afro-Arabia from Eurasia (~ 200Ma ago). No significant chromite accumulation is expected during this phase. Second, island arc magmatism occurred above an intra-oceanic subduction zone that formed due to northeastward movement of Arabia toward Asia (begining at ca. 110 Ma). At this stage, the Zikt chromite orefields originated by interaction of calc-alkaline melts with upper mantle harzburgites. Third, back-arc (marginal basin) spreading began, and the Al’Hel orefields formed through interaction of MORB-like melts with the relatively less depleted peridotites. In other words, Al’Hel chromite bodies formed from MORB-like tholeiite melts in a marginal basin environment, whereas, the Zikt chromite bodies originated fiom calc-alkaline to boninite melts in an island arc to fore arc environment. Ill DEDICATION To my motherfor her love and patience To my wife fo r ahvays being with me To my sisters and my brothers for their encouragement and support IV ACNOWLEDGMENTS I thank my advisor Michael Barton for his assistance and patience, and for beneficial discussion. I would like to recognize Hallen Noltimeir, Douglas Pride, and Terry Wilson for serving in my committee, and for valuable guidance. I am grateful to Dr. Henery Clemmey from Derwent Company for his assistance and discussion in the field work. I would like to thank my family for their continuous support and encouragement, while 1 am at home and abroad. I greatly thank the UAE University and all people in the Department of Geological Sciences at the Ohio State University for the comprehensive support to make this study possible. VITA December, 21, 1965 ................................................ Bom -Dibba, Ai Fujairah,UAE 1984 .........................................................................Graduate, Uqba Bin Nafi High School, Diba A1 Fjairah 1988 .........................................................................B.S., Geology Department, UAE University, AI Ain 1988-1990 ............................................................... General Science and Geology Teacher, A1 Khalidiah School, Dibba AlFfujairah 1995 .........................................................................M.S. in Geological Science. The Ohio State University FIELD OF STUDY Major Field: Geological Sciences VI TABLE OF CONTENTS Page Dedication ..........................................................................................................................iv Acknowledgments ...............................................................................................................v Vita...................................................................................................................................tdi List of Tables ....................................................................................................................vii List of Figures ....................................................................................................................ix List of Plates ................................................................................................................... xxi Chapters; 1. Introduction ...................................................................................................................1 1.1 Preface................................................................................................. I 1.2 Historical synopsis ..............................................................................2 1.3 Oman Chromites ............................................................................... 12 1.4 The present study .............................................................................. 14 1.5 Research organization ....................................................................... 15 2. Oman mountains, ophiolites & the Semail ophiolite ...................................................17 2.1 Regional geology ..............................................................................17 2 .1.1 The Arabian (Persian) Gulf and Zagros Fold Belt ........................... 20 2.1.2 The Gulf of Oman and the Makran platform ................................... 23 2.1.3 The Arabian platform ....................................................................... 24 2.2 Tectonostratigraphy of The Oman mountains ................................. 36 2.3 Ophiolites .........................................................................................42 2.4 Oman (Semail) ophiolite: .................................................................44 2.4.1 Tectonic setting of the Semail ophiolite ..........................................49 \T l 3. Chromite fields in the UAE ........................................................................................59 3.1 Introduction ...................................................................................
Recommended publications
  • The Terrane Concept and the Scandinavian Caledonides: a Synthesis

    The Terrane Concept and the Scandinavian Caledonides: a Synthesis

    The terrane concept and the Scandinavian Caledonides: a synthesis DAVID ROBERTS Roberts , D. 1988: The terrane concept and the Scandinavian Caledonides: a synthesis. Nor. geol . unders . Bull. 413. 93-99. A revised terrane map is presented for the Scandinavian Caledcnldes. and an outline is given of the principal suspect and exot ic terranes and terrane-complexe s identified outboa rd from the Baltoscand ian miogeocline. The outermost part of the Baltoscandian continental margin is itself suspect , in the terrane sense. since the true palaeogeographical location s of rocks now represented in the Seve and serey-seuano Nappes, while inferred, are not known. The orogen -internal exotic terranes embrace the oceanic/eugeoclinal elements of the Caledonides, represented by the mag­ matosed imentary assemblages of the Koli Nappes, including ophiolite fragments and island arc products. Even more exot ic terranes occur in the highest parts of the tectonostratigraphy, inclu­ ding units which are thought possibly to derive from the Laurentian side of lapetus . D. Roberts. Norges geologiske uruierseketse, Postboks 3006. Lade, N-7002 Trondbeim , Norway . Introduction Project 233 has been to prepare a preliminary Earlier in this decade much of the research terrane map' at 1:5 M scale (Roberts et al. effort in the Caledonides of Scandinavia was 1986) for a larger, circum-Atlantic compilation. channelled through the highly successfu l IGCP This map, much simplified, is really one of Project 27 The Caledonide Orogen ' (Gee & palaeo-environments (marginal basins, vol­ Sturt 1985). An important aspect of the collabo­ canic arc comp lexes, overstep sequences , rative work in this project was that of map etc.), and not of terranes in the true sense.
  • Late-Stage Tectonic Evolution of the Al-Hajar Mountains

    Late-Stage Tectonic Evolution of the Al-Hajar Mountains

    Geological Magazine Late-stage tectonic evolution of the www.cambridge.org/geo Al-Hajar Mountains, Oman: new constraints from Palaeogene sedimentary units and low-temperature thermochronometry Original Article 1,2 3 4 3 4 5 Cite this article: Corradetti A, Spina V, A Corradetti , V Spina , S Tavani , JC Ringenbach , M Sabbatino , P Razin , Tavani S, Ringenbach JC, Sabbatino M, Razin P, O Laurent6, S Brichau7 and S Mazzoli1 Laurent O, Brichau S, and Mazzoli S (2020) Late-stage tectonic evolution of the Al-Hajar 1 Mountains, Oman: new constraints from School of Science and Technology, Geology Division, University of Camerino. Via Gentile III da Varano, 62032 2 Palaeogene sedimentary units and low- Camerino (MC), Italy; Department of Petroleum Engineering, Texas A&M University at Qatar, Doha, Qatar; temperature thermochronometry. Geological 3Total E&P, CSTJF, Avenue Larribau, 64000 Pau, France; 4DiSTAR, Università di Napoli Federico II, 21 Via vicinale Magazine 157: 1031–1044. https://doi.org/ cupa Cintia, 80126 Napoli, Italy; 5ENSEGID, Institut Polytechnique de Bordeaux, 1 allée Daguin, 33607 Pessac, 10.1017/S0016756819001250 France; 6Total E&P, Paris, France and 7Géosciences Environnement Toulouse (GET), Université de Toulouse, UPS, CNRS, IRD, CNES, 14 avenue E. Belin, 31400, Toulouse, France Received: 8 July 2019 Revised: 5 September 2019 Accepted: 15 September 2019 Abstract First published online: 12 December 2019 Mountain building in the Al-Hajar Mountains (NE Oman) occurred during two major short- – Keywords: ening stages, related to the convergence between Africa Arabia and Eurasia, separated by nearly Oman FTB; Cenozoic deformation; remote 30 Ma of tectonic quiescence. Most of the shortening was accommodated during the Late sensing; thermochronology Cretaceous, when northward subduction of the Neo-Tethys Ocean was followed by the ophio- lites obduction on top of the former Mesozoic margin.
  • Tectonostratigraphic Terrane Analysis on Neoproterozoic Times

    Tectonostratigraphic Terrane Analysis on Neoproterozoic Times

    Revista Brasileira de Geociências 30(1):078-081, março de 2000 TECTONOSTRATIGRAPHIC TERRANE ANALYSIS ON NEOPROTEROZOIC TIMES: THE CASE STUDY OF ARAXÁ SYNFORM, MINAS GERAIS STATE, BRAZIL: IMPLICATIONS TO THE FINAL COLLAGE OF THE GONDWANALAND. HILDOR JOSÉ SEER1 AND MARCEL AUGUSTE DARDENNE2 ABSTRACT The Araxá Synform is a regional fold with gently WNW plunging. The outcrops of the Araxá, Ibiá and Canastra Groups occur at their limbs. The region is the type locality of these units. These Groups belong to the Brasilia Fold Belt, a Neoproterozoic tectonic unit evolved at the western margin of the São Francisco-Congo Craton. Geological mapping, structural analysis, whole rock geochemistry, mineral chemistry, petrography and geochronology are the main tools to understand the tectonic evolution of these geological units. In this paper we apply tectonostratigraphic terrane analysis to the solution of stratigraphic problems in the Brasília Belt and Gondwanaland collage. Keywords: Brasília Belt, Neoproterozoic, Brasiliano orogeny, Tectonic Evolution, Structural Geology INTRODUCTION All geological information is necessary to The upper thrust sheet (Araxá Group) comprises a dominantly understand the history of an orogenic belt, basically it comprises the metamafic sequence (fine and coarse amphibolites, with rare ultramafic integration of stratigraphic data with structural geology. The rocks) which is transitional to pelitic metasedimentary rocks, both stratigraphic data provide information about paleogeography and ages metamorphosed under amphibolite facies conditions and intruded by of the geological units of an orogenic belt. The structural data describe granitoid rocks. The amphibolites represent gabbroic and basaltic the configuration of these units. To Howell (1993) an orogenic belt is protoliths. The basalts are high FeO tholeiites with REE signatures that essentially a puzzle, composed by a collection of crustal pieces.
  • Tectonostratigraphic Terrane Analysis of New Brunswick L

    Tectonostratigraphic Terrane Analysis of New Brunswick L

    Document generated on 09/30/2021 12:46 p.m. Atlantic Geology Tectonostratigraphic terrane analysis of New Brunswick L. R. Fyffe and A. Fricker Volume 23, Number 3, December 1987 Article abstract the URI: https://id.erudit.org/iderudit/ageo23_3art01 The contents of a computerized lexicon database are displayed in the form of a range chart that demonstrate the spartial and temporal relationships of See table of contents lithtostratigraphic units to tectonostratigraphic terrans of New Brunsiwck. The chart provides a reference basis from which to derive the accretionary history of these terrance. Publisher(s) The tectonostratigraphlc zonation of Hew Brunswick ia based upon the Atlantic Geoscience Society uniqueness of the pre-Taconlan stratigraphy within each fault-bounded terrane. From northwest to southeast, the following terranes and cover sequences are recognized: Matapedia Cover. Blmtree Terrane, Mlramichi ISSN Terrane, Frederlcton Cover, St. Croix Terrane, Hascarene Terrane, and 0843-5561 (print) Avalonian Terrane. 1718-7885 (digital) Overstepping of the Matapedia Cover Sequence indicates that the Elmtree and Mlramichi terranes were docked with the North American craton by the Late Explore this journal Ordovician to Early Silurian. The presence of a similar early Paleozoic stratigraphy, tectonic style and major Silurian unconformity in the St. Croix Terrane suggests that it had become docked to the Mlramichi Terrane prior to this subduction-related Taconian event. Cite this article Detritus and a similar fauna in the cover rocks of the St. Croix Terrane provide Fyffe, L. R. & Fricker, A. (1987). Tectonostratigraphic terrane analysis of New evidence that it was docked to the Hascarene Terrane by the Late Silurian.
  • Thermo-Mechanical Modeling of the Obduction Process Based on The

    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.
  • Tectonic Development of the Samail Ophiolite

    Tectonic Development of the Samail Ophiolite

    JOURNAL OF GEOPHYSICAL RESEARCH: SOLID EARTH, VOL. 118, 2085–2101, doi:10.1002/jgrb.50139, 2013 Tectonic development of the Samail ophiolite: High-precision U-Pb zircon geochronology and Sm-Nd isotopic constraints on crustal growth and emplacement Matthew Rioux,1,2 Samuel Bowring,1 Peter Kelemen,3 Stacia Gordon,4 Robert Miller,5 and Frank Dudás1 Received 11 July 2012; revised 13 December 2012; accepted 18 February 2013; published 29 May 2013. [1] New high-precision single grain U-Pb zircon geochronology and whole rock Nd isotopic data provide insight into the magmatic and tectonic development of the Samail ophiolite. The analyzed rocks can be broadly divided into two groups based on their structural position, dates, and isotopic composition: an older group related to on-axis magmatism and a younger group of post-ridge dikes, sills, and stocks. On-axis gabbros, tonalites and trondhjemites yielded Th-corrected 206Pb/238U dates from 96.441 Æ 0.062 to 95.478 Æ 0.056 Ma. These dates, combined with dates from Rioux et al. (2012), suggest that most of the ophiolite crust formed at an oceanic spreading center in <1Ma. The post-ridge intrusions come from all depths in the crust, the upper mantle, and the metamorphic sole. Post-ridge gabbros, tonalites, and trondhjemites from the crust and mantle yielded Th-corrected 206Pb/238U dates of 95.405 Æ 0.062 to 95.077 Æ 0.062 Ma. A small trondhjemitic pod from the metamorphic sole yielded younger Th-corrected 206Pb/238U dates of 94.90 Æ 0.38 to 94.69 Æ 0.12 Ma.
  • Chapter 1 Introduction and Tectonic Framework

    Chapter 1 Introduction and Tectonic Framework

    Chapter 1 Introduction and tectonic framework Andreas Scharf1*, Frank Mattern1, Mohammed Al-Wardi1, Gianluca Frijia2, Daniel Moraetis3, Bernhard Pracejus1, Wilfried Bauer4 and Ivan Callegari4 1Department of Earth Sciences, College of Science, Sultan Qaboos University, PO Box 36, PC 123, Al-Khod, Muscat, Sultanate of Oman 2Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44122, Ferrara, Italy 3Department of Applied Physics and Astronomy, College of Sciences, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates 4Department of Applied Geosciences, German University of Technology GUtech, PO Box 1816, PC 130, Halban, Sultanate of Oman *Correspondence: [email protected] Abstract: The extraordinary outcrop conditions provide a unique opportunity to study the geology and tectonics of the Oman Mountains, which record a geological history of more than 800 million years. We provide a summary of the geological evolution of the Oman Mountains with the emphasis on the Jabal Akhdar and Saih Hatat domes. This Memoir comprises seven chapters. This first chapter summarizes the former studies and the tectonic framework. This is followed by a comprehensive description of all geological formations/rock units (Scharf et al. 2021a, Chapter 2, this Memoir) including the famous Semail Ophiolite, the fault and fold pattern (Scharf et al. 2021b, Chapter 3, this Memoir) and the overall structure (Scharf et al. 2021c, Chapter 4, this Memoir). Chapter 5 (Scharf et al. 2021d) explains the varied tectonic evolution of the study area, ranging from the Neoproterozoic until present, while Chapter 6 (Scharf et al. 2021e) contains the conclusions and a catalogue of open questions. Finally, Chapter 7 (Scharf et al.
  • Lithostratigraphy and Structure of the Dharan–Mulghat Area, Lesser Himalayan Sequence, Eastern Nepal Himalaya

    Lithostratigraphy and Structure of the Dharan–Mulghat Area, Lesser Himalayan Sequence, Eastern Nepal Himalaya

    Journal of Nepal Geological Society,Lithostratigraphy 2016, Vol. 51, pp. and 77-88 structure of the Dharan–Mulghat area, Lesser Himalayan Sequence Lithostratigraphy and structure of the Dharan–Mulghat area, Lesser Himalayan sequence, eastern Nepal Himalaya *L. K. Rai1, K. K. Acharya2 and M. R. Dhital2 1Central Campus of Technology, Tribhuvan University, Dharan, Sunsari, Nepal 2Central Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal (*E-mail: [email protected]) ABSTRACT The Dharan–Mulghat area of the eastern Nepal can be divided into three tectonic units: the Higher Himalayan Crystallines, the Lesser Himalayan Sequence and the Siwaliks from north to south separated by the Main Central Thrust (MCT) and Main Boundary Thrust (MBT), respectively. The Lesser Himalayan Sequence is divided into two groups separated by Chimra Thrust: the Bhedetar Group and the Dada Bajar Group. The Bhedetar Group includes the Raguwa Formation, the Phalametar Quartzite, the Churibas Formation, the Sangure Quartzite, and the Karkichhap Formation from the bottom to top, respectively; over- thrusted by the Dada Bajar Group consisting: the Ukhudanda Formation, the Mulghat Formation, the Okhre Formation, and the Patigau Formation, from lower to upper sections, respectively along the Chimra Thrust and the Bhorleni Formation as an individual formation overthrusted by Bhedetar Group along the Chhotimorang Thrust. The Main Central Thrust, the Main Boundary Thrust, the Chimra Thrust and the Chhotimorang Thrust are the major faults in Dharan–Mulghat area. The Leutiphedi Anticline and the Malbase Syncline are the major folds in the study area plunging towards east. The trend/plunge of anticline and syncline are 131o/24o and 096o/09o respectively.
  • Synchronous Formation of the Metamorphic

    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.
  • The Formation of Dunite Channels Within Harzburgite in the Wadi

    The Formation of Dunite Channels Within Harzburgite in the Wadi

    minerals Article The Formation of Dunite Channels within Harzburgite in the Wadi Tayin Massif, Oman Ophiolite: Insights from Compositional Variability of Cr-Spinel and Olivine in Holes BA1B and BA3A, Oman Drilling Project Giuseppe Cocomazzi 1, Giovanni Grieco 1,* , Paola Tartarotti 1 , Micol Bussolesi 1 , 2 3 Federica Zaccarini , Laura Crispini and Oman Drilling Project Science Team y 1 Department of Earth Sciences, Università degli Studi di Milano, via Mangiagalli 34, 20133 Milan, Italy; [email protected] (G.C.); [email protected] (P.T.); [email protected] (M.B.) 2 Department of Applied Geological Sciences and Geophysics, University of Leoben, A-8700 Leoben, Austria; [email protected] 3 Dipartimento di Scienze della Terra dell’Ambiente e della Vita (DISTAV), University of Genova, Corso Europa, 26, I-16132 Genova, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-02-5031-5629 Oman Drilling Project Science Team: https://www.omandrilling.ac.uk. y Received: 23 December 2019; Accepted: 5 February 2020; Published: 13 February 2020 Abstract: Holes BA1B and BA3A were drilled into the Wadi Tayin Massif, southern ophiolite complex of Oman, a fragment of the Tethyan oceanic lithosphere obducted onto the Arabian continent. Within the sequence, we have studied a portion of the shallow mantle, composed mainly of strongly serpentinised harzburgite that embeds dunitic levels, the biggest being over 150 m thick. The formation of thick dunitic channels, already approached via published structural and mathematical models, is here investigated with a mineral chemistry approach. We focused on Cr-spinel, the only widespread phase preserved during serpentinization, whose TiO2 content displays a wide variability from low in harzburgite, (TiO2 < 0.25 wt.
  • ASTER-Based Remote Sensing Image Analysis for Prospection Criteria of Podiform Chromite at the Khoy Ophiolite (NW Iran)

    ASTER-Based Remote Sensing Image Analysis for Prospection Criteria of Podiform Chromite at the Khoy Ophiolite (NW Iran)

    minerals Article ASTER-Based Remote Sensing Image Analysis for Prospection Criteria of Podiform Chromite at the Khoy Ophiolite (NW Iran) Behnam Mehdikhani and Ali Imamalipour * Department of Mining Engineering, Urmia University, Urmia 57561-51818, Iran; [email protected] * Correspondence: [email protected] Abstract: A single chromite deposit occurrence is found in the serpentinized harzburgite unit of the Khoy ophiolite complex in northwest Iran, which is surrounded by dunite envelopes. This area has mountainous features and extremely rugged topography with difficult access, so prospecting for chromite deposits by conventional geological mapping is challenging. Therefore, using remote sensing techniques is very useful and effective, in terms of saving costs and time, to determine the chromite-bearing zones. This study evaluated the discrimination of chromite-bearing mineralized zones within the Khoy ophiolite complex by analyzing the capabilities of ASTER satellite data. Spectral transformation methods such as optimum index factor (OIF), band ratio (BR), spectral angle mapper (SAM), and principal component analysis (PCA) were applied on the ASTER bands for lithological mapping. Many chromitite lenses are scattered in this ophiolite, but only a few have been explored. ASTER bands contain improved spectral characteristics and higher spatial resolution for detecting serpentinized dunite in ophiolitic complexes. In this study, after the correction of ASTER data, many conventional techniques were used. A specialized optimum index factor RGB (8, 6, 3) Citation: Mehdikhani, B.; was developed using ASTER bands to differentiate lithological units. The color composition of band Imamalipour, A. ASTER-Based ratios such as RGB ((4 + 2)/3, (7 + 5)/6, (9 + 7)/8), (4/1, 4/7, 4/5), and (4/3 × 2/3, 3/4, 4/7) produced Remote Sensing Image Analysis for the best results.
  • Crustal Structure of the Bhutanese Himalaya: New Insights from a Gravity Analysis in Western and Central Bhutan

    Crustal Structure of the Bhutanese Himalaya: New Insights from a Gravity Analysis in Western and Central Bhutan

    BearWorks MSU Graduate Theses Spring 2018 Crustal Structure of the Bhutanese Himalaya: New Insights from a Gravity Analysis in Western and Central Bhutan Kinzang Duba Missouri State University, [email protected] As with any intellectual project, the content and views expressed in this thesis may be considered objectionable by some readers. However, this student-scholar’s work has been judged to have academic value by the student’s thesis committee members trained in the discipline. The content and views expressed in this thesis are those of the student-scholar and are not endorsed by Missouri State University, its Graduate College, or its employees. Follow this and additional works at: https://bearworks.missouristate.edu/theses Part of the Geophysics and Seismology Commons Recommended Citation Duba, Kinzang, "Crustal Structure of the Bhutanese Himalaya: New Insights from a Gravity Analysis in Western and Central Bhutan" (2018). MSU Graduate Theses. 3240. https://bearworks.missouristate.edu/theses/3240 This article or document was made available through BearWorks, the institutional repository of Missouri State University. The work contained in it may be protected by copyright and require permission of the copyright holder for reuse or redistribution. For more information, please contact [email protected]. CRUSTAL STRUCTURE OF THE BHUTANESE HIMALAYA: NEW INSIGHTS FROM A GRAVTITY ANALYSIS IN WESTERN AND CENTRAL BHUTAN A Master’s Thesis Presented to The Graduate College of Missouri State University TEMPLATE In Partial