TEXTURES of IGNEOUS ROCKS Today, Geologist Working With
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Structural Geology of the Upper Rock Creek Area, Inyo County, California, and Its Relation to the Regional Structure of the Sierra Nevada
Structural geology of the upper Rock Creek area, Inyo County, California, and its relation to the regional structure of the Sierra Nevada Item Type text; Dissertation-Reproduction (electronic); maps Authors Trent, D. D. Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 27/09/2021 06:38:23 Link to Item http://hdl.handle.net/10150/565293 STRUCTURAL GEOLOGY OF THE UPPER ROCK CREEK AREA, INYO COUNTY, CALIFORNIA, AND ITS RELATION TO THE REGIONAL STRUCTURE OF THE SIERRA NEVADA by Dee Dexter Trent A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 3 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by __________ Dee Dexter Trent______________________ entitled Structural Geology of the Upper Rock Creek Area . Tnvo County, California, and Its Relation to the Regional Structure of the Sierra Nevada ________________ be accepted as fulfilling the dissertation requirement of the degree of ____________Doctor of Philosophy_________ ___________ P). /in /'-/7. 3 Dissertation Director fJ Date After inspection of the final copy of the dissertation, the following members of the Final Examination Committee concur in its approval and recommend its acceptance:* f t M m /q 2 g ££2 3 This approval and acceptance is contingent on the candidate's adequate performance and defense of this dissertation at the final oral examination. -
Ocean Drilling Program Scientific Results Volume
Von Herzen, R. P., Robinson, P. T., et al., 1991 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 118 22. PLASTIC DEFORMATION AT AN OCEANIC SPREADING RIDGE: A MICROSTRUCTURAL STUDY OF THE SITE 735 GABBROS (SOUTHWEST INDIAN OCEAN)1 Mathilde Cannat2 ABSTRACT Microstructural analysis suggests that some Site 735 gabbros were deformed in the crystal mush stage, before they had completely crystallized. Later, solid-state deformation began in granulite-facies metamorphic conditions. At this stage, temperature-dependent diffusion processes may have controlled the plastic deformation of these gabbros, and mylonites formed only in intervals containing more than 10% Fe-Ti oxides. Most oxides in these mylonites are interpreted as magmatic in origin. A sharp change of deformation processes occurred as temperature decreased to the stability conditions of amphibolite-facies metamorphic assemblages: dislocation slip in plagioclase may have become the leading plastic flow mechanism. This change of deformation processes coincides with increased availability of hydrothermal water and with a marked decrease of the plagioclase recrystallized grain size. This reduction in recrystallized grain size is thought to result from an increase of the deviatoric stress, and thus from an increase of the yield strength of the gabbros. In amphibolite-facies metamorphic conditions, dynamic recrystallization of plagioclase locally caused strain-softening, leading to the formation of mylonites. Relict porphyroclasts (plagioclase, olivine, and pyroxenes) in these mylonites are fractured and boudinaged. The cracks produced by this brittle failure are filled with green to brown hydrothermal hornblende. INTRODUCTION the Site 735 deformed gabbros. These results are used to interpret the tectonic evolution of these gabbros (Cannat et A total of 500 m of gabbro was drilled at Site 735 during al., this volume). -
Actually Consists of 2 Cleavages
Types of foliations • Crenulation Cleavage- – Actually consists of 2 cleavages – The first may be a slaty cleavage or schistosity that becomes microfolded – Fold axial planes typically form at high angle to the σ1 of the second compressional phase 1 Progressive development (a → c) of a crenulation cleavage for both asymmetric (top) and symmetric (bottom) situations. From Spry (1969) Metamorphic Textures. Pergamon. Oxford. 2 Figure 23.24a. Symmetrical crenulation cleavages in amphibole-quartz-rich schist. Note concentration of quartz in hinge areas. From Borradaile et al. (1982) Atlas of Deformational and Metamorphic Rock Fabrics. Springer-Verlag. 3 Figure 23.24b. Asymmetric crenulation cleavages in mica-quartz-rich schist. Note horizontal compositional layering (relict bedding) and preferential dissolution of quartz from one limb of the folds. From Borradaile et al. (1982) Atlas of Deformational and Metamorphic Rock Fabrics. Springer-Verlag. 4 Figure 23.25. Stages in the development of crenulation cleavage as a function of temperature and intensity of the second deformation. From Passchier and Trouw (1996) Microtectonics. Springer-Verlag. Development of S2 micas depends upon T and the intensity of the second deformation 5 Types of lineations a. Preferred orientation of elongated mineral aggregates b. Preferred orientation of elongate minerals c. Lineation defined by platy minerals d. Fold axes (especially of crenulations) e. Intersecting planar elements. Figure 23.26. Types of fabric elements that define a lineation. From Turner and Weiss (1963) Structural 6 Analysis of Metamorphic Tectonites. McGraw Hill. Analysis of Deformed Rocks • If two or more geometric elements are present, we can add a numeric subscript to denote the chronological sequence in which they were developed and superimposed- • Deformational events: D1 D2 D3 … • Metamorphic events: M1 M2 M3 … • Foliations: So S1 S2 S3 … • Lineations: Lo L1 L2 L3 … • Plot on a metamorphism-deformation-time plot showing the crystallization of each mineral 7 Deformation vs. -
Megaliths and Geology: a Journey Through Monuments, Landscapes and Peoples
Megaliths and Geology Megálitos e Geologia MEGA-TALKS 2 19-20 November 2015 (Redondo, Portugal) Edited by Rui Boaventura, Rui Mataloto and André Pereira Access Archaeology aeopr ch es r s A A y c g c e o l s o s e A a r c Ah Archaeopress Publishing Ltd Summertown Pavilion 18-24 Middle Way Summertown Oxford OX2 7LG www.archaeopress.com ISBN 978-1-78969-641-7 ISBN 978-1-78969-642-4 (e-Pdf) © the individual authors and Archaeopress 2020 Financial support for the meeting Mega-Talks 2 has been provided by the project Moving megaliths in the Neolithic (PTDC/EPH-ARQ/3971/2012), funded by FCT (Fundação para a Ciência e a Tecnologia, Portugal) and the Municipality of Redondo (Portugal). All rights reserved. No part of this book may be reproduced, stored in retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior written permission of the copyright owners. This book is available direct from Archaeopress or from our website www.archaeopress.com Contents Introduction: Megaliths and Geology: a journey through monuments, landscapes and peoples ........................... iii Moving megaliths in the Neolithic - a multi analytical case study of dolmens in Freixo-Redondo (Alentejo, Portugal). Rui Boaventura, Patrícia Moita, Jorge Pedro, Rui Mataloto, Luis Almeida, Pedro Nogueira, Jaime Máximo, André Pereira, José Francisco Santos & Sara Ribeiro ............................................................... 1 Funerary megalithism in the south of Beira Interior: architectures, spoils and cultural sequences. João Luís Cardoso .................................................................................................................................................................. 25 A look at Proença-a-Nova’s Megalithism (Beira Baixa Intermunicipal Community, UNESCO Global Geopark Naturtejo, Portugal). -
The Sierra Nevada Batholith a Synthesis. of Recent Work Across the Central Part
I _; The Sierra Nevada Batholith A Synthesis. of Recent Work Across the Central Part By PAUL C. BATEMAN, LORIN ~- CLARK, N. KING HUBER, JAMES G. MOORE, and C. DEAN RINEHART SHORTER CONTRIBU.TIONS TO GENERAL GEOLOGY· G E 0 L 0 G I CAL SURVEY P R 0 FE S S I 0 N A L PAPER 414-D Prepared in cooperation with the State of Caltfornia, Division of Mines and Geology · ti II R fA u 0 F u' N f I ._rBRARV SPUI\ANf:.. !NASH. JUN 31971 . ·~-~ - ~ ... -- --s PtfASf RfT,fJR~ fO liBRARY UNITED S.TATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 CONTENTS Page Abstract------------------------------------------- D1 Constitution' of the batho1ith-Continued Introduction ______________________________________ _ 2 Contact relations _______________ ~ ______ - -- _----- D22 Genernl geologic relations _______________________ _ 2 Contacts between different granitic rocks _____ - 22 Previous geologic work _________________________ _ 4 Contacts between granitic rocks and meta- Acknowledgments _____________________________ _ 5 morphic rocks or diorite ___________ -- __ ---- 22 Wu.llrocks u.nd roof rocks ___________________________ _ 5 Felsic dike swarms __________________ - ___ -------- 24 Pu.leozoic rocks ________________________________ _ 5 Mafic dike swarms _________________________ ----- 25 Mesozoic rocks ________________________________ _ 6 Structure -
Metamorphism and the Origin of Granitic Rocks Northgate District Colorado
Metamorphism and the Origin of Granitic Rocks Northgate District Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-M Metamorphism and the Origin of Granitic Rocks Northgate District Colorado By T. A. STEVEN SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-M A discussion of the progressive metamorphism, granitixation, and local rheomorphism of a layered sequence of rocks, and of the later emplacement and deuteric alteration of an unrelated granitic stock UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. CONTENTS Page Page Abstract_________________________________ 335 Pre-Cambrian geology—Continued Introduction-_______________________________________ 335 Dacite porphyry—____ ——— __ —— _____________ 364 Acknowledgments__ ___--_____-____-_____-______-_ 336 Intrusive quartz monzonite_-____--_-__-_--_-_-_. 365 Geologic setting._______ — _________________________ 336 Petrography ________—— —— _______________ 365 Pre-Cambrian geology—___________________________ 337 Main body of the stock____________— 366 Hornblende gneiss___-_________-_-_____-________ 338 Marginal dikes_________-____-__-__——— 366 Quartz monzonite gneiss_________________________ 342 Satellitic dikes___-___.__________ 367 Biotite-garnet gneiss___________________________ 345 Wall-rock alteration_________ _ __——_ 368 Pegmatite_________________________________ -
Petrology of Apollo 16 Poikilitic Rocks
Proceedings of the Fourth Lunar Science Conference (Supplement 4, Geochimica et Cosmochimica Acta) Vol. 1, pp. 613-632 1973LPSC....4..613S Petrology of Apollo 16 poikilitic rocks CHARLES H. SIMONDS The Lunar Science Institute, 3303 NASA Road 1, Houston, Texas 77058 JEFFREY L. WARNER and WILLIAM C. PHINNEY Geology Branch, TN6 NASA Johnson Space Center, Houston, Texas 77058 Abstract-Poikilitic rocks, virtually all with low K-KREEP composition are found in all non-mare suites of lunar samples. Most of these rocks have low calcium pyroxene oikocrysts enclosing many chadacrysts of feldspar. The poikilitic rocks are proposed to form by crystallization of an impact generated partial melt with over 70% liquid. The protolith is gas bearing polymict breccias and/or soil. The key to forming a poikilitic texture is to rapidly chill a low K-KREEP melt a few tens of degrees, so that abundant feldspar and olivine grains are nucleated. The melt then cools more slowly due to the presence of an insulating layer of material. Slow cooling through the plagioclase-olivine-pyroxene peritectic, allows few pyroxene nuclei to form. Continuous pyroxene growth is possible due to ease of silica transport through the abundant(> 50%) remaining melt. A number of observations support this hypothesis: (1) The euhedral shape of feldspar chadacrysts, not expected for subsolidus melt crystalli- zation or solid state recrystallization. (2) Flow alignment of feldspar chadacrysts. (3) Large spherical pores, which appear to have formed in a liquid. (4) Preservation of only refractory olivine and plagioclase relics and the lack of pyroxene which had a lower melting point than olivine or plagioclase. -
Download the Scanned
THn AMERIceN M INERALoGIST JOURNAL OF THE MINERALOGICAL SOCIETY OF AMERICA Vol.22 DECEMBER, 1937 No. 12,Part 1 DEVELOPMENT OF PLAGIOCLASE PORPHYROBLASTSI G. E. Gootsrooo, U niver si.tyoJ W ashington, S eattle, W ashington. Assrnacr Porphyroblastic textures are common to hornfels in the Cornucopia area oJ the Wal- lowa Mountains of northeastern Oregon. Recent petrographic studies indicate that they are also common to some of the rocks of the Cascades of Washington. Plagioclase porphyro- blasts range from initial allotrioblastic forms to fully developed idioblastic crystals. They exhibit many characteristic features which may include poikioblastic structures, helizitic inclusions and complex aggregates. The arrangement within the crystal of inclusions of either identifiable minerals or turbid material, is apparently directly related to the stage of development of the porphyroblast. This included matter differs chiefly in its arrange- ment from the products of endogenetic or subsequent alteration. Recognition of these metamorphic textures and structures is one of the points essential to the interpretation of recrystallization-replacement as applied to igneous-appearing rocks which are believed to have been formed in situ by processesof additive hydrothermal metamorphism. In a previous paper the writer outlined the development of qaartz porphyroblasts in a siliceoushornfels.2 The quartz porphyroblasts in the siliceoushornfels were too small (0.5 mm.) to be conspicuousin the hand specimens,but were readily seenunder crossednicols, although in plane light they merged almost completely with the groundmass of the horn- fels, and contained the sameabundance of small inclusions as the ground- mass. The siliceoushornfels is not the most abundant; biotitic and horn- blendic varieties are far more common. -
Nucleation and Growth History in the Garnet Zone
Spear and Daniel Geological Materials Research v.1, n.1, p.1 Three-dimensional imaging of garnet porphyroblast sizes and chemical zoning: Nucleation and growth history in the garnet zone Frank S. Spear and Christopher G. Daniel Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 <[email protected]> (Received July 1, 1998; Published October 30, 1998) Abstract The three-dimensional (3-D) growth history of two garnet zone samples (Grt + Chl + Bt + Ms + Pl + Qtz + Ilm) from southwestern Maine was examined by serial sectioning and 3-D reconstructions of compositional zoning from backscatter images and X-ray maps. Mn, Fe, Mg, and Ca zoning is broadly concentric. The concentration of Mn in garnet cores generally correlates with size (d = 50 to 750 microns), indicating progressive nucleation. In detail, all elements show irregular, patchy zoning in the cores. Assuming constancy of Mn on the rims of all garnet crystals in a rock volume plus no subsequent diffusional modification, Mn concentration can be used as a Òtime lineÓ for garnet growth. Examination of the evolution of individual garnet crystals reveals that multiple nuclei formed simultaneously in the core regions and that nuclei expanded by growth in amoeba-shape forms along preexisting mineral grain boundaries (primarily quartz and plagioclase), dissolving the interior grains until the grains were either gone or encapsulated, at which time dissolution ceased. Amoeba-shaped garnet crystals coalesced as they grew and, simultaneously, new nuclei appeared in the nearby matrix. The net result was a single garnet porphyroblast that formed by the growth and coalescence of multiple nuclei. -
Petrologic Significance of Fe-Rich Staurolite in Pelitic Schists of the Silgará Formation, Santander Massif
EARTH SCIENCES RESEARCH JOURNAL Earth Sci. Res. J. Vol. 20, No. 1 (March, 2016): C1 - C7 PETROLOGY Petrologic significance of Fe-rich staurolite in pelitic schists of the Silgará Formation, Santander Massif Carlos Alberto Ríos R.1*, Oscar Mauricio Castellanos A.2 1*. Escuela de Geología, Universidad Industrial de Santander, Bucaramanga, Colombia, e-mail: [email protected] 2. Programa de Geología, Universidad de Pamplona, Colombia ABSTRACT Keywords: Staurolite, pelitic schists, Silgará Medium grade metapelites of the Silgará Formation at the Santander Massif (Colombian Andes) have been Formation, metamorphism, Santander Massif. affected by a medium-pressure/high-temperature Barrovian type of metamorphism, developing a sequence of metamorphic zones (biotite, garnet, staurolite and sillimanite). These rocks record a complex tectono- metamorphic evolution and reaction history. Metapelitic rocks from the staurolite zone are typically foliated, medium- to coarse-grained, pelitic to semipelitic schists that contain the mineral assemblage biotite + garnet + staurolite ± kyanite; all contain muscovite + quartz + plagioclase with minor K-feldspar, tourmaline, apatite, zircon, epidote, calcite, and Fe–Ti oxides. Field and microscopic evidences reveal that Fe-rich staurolite in pelitic schists is involved in several chemical reactions, which explains its formation and transformation to other minerals, which are very important to elucidate the reaction history of the Silgará Formation metapelites. Significado Petrológico de Estaurolita Rica en Fe en Esquistos Pelíticos de la Formación Silgará, Macizo de Santander RESUMEN Palabras clave: Estaurolita, esquistos pelíticos, Medium grade metapelites of the Silgará Formation en el Macizo de Santander (Andes Colombianos) han sido Formación Silgará, metamorfismo, Macizo de afectadas por un metamorfismo de tipo Barroviense, el cual se ha producido en condiciones de media presión y Santander. -
A Sillimanite Gneiss Dome in the Yukon Crystalline Terrane, East-Central Alaska: Petrography and Garnet- Biotite Geothermometry
PROPERTY OF DUG,r c LiiiRARYyw A Sillimanite Gneiss Dome in the Yukon Crystalline Terrane, East-Central Alaska: Petrography and Garnet- Biotite Geothermometry By CYNTHIA DUSEL-BACON and HELEN L. FOSTER SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 1170-E Petrographic, geothermometric, and structural data are used to support the hypothesis that a 600-km* area of pelitic metamorphic rocks is a gneiss dome -- -- UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1983 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Dusel-Bacon. Cynthia. A sillimanite gneiss dome in the Yukon crystalline terrane, eastcentral Alaska. (Shorter contributions to general geology) (Geological Survey Professional Paper 1170-E) Bibliography Supt. of Docs. no.: 1 19.412: 1170-E 1. Gneiss--Alaska. 2. Intrusions (Geology)-Alaska. I. Foster, Helen Laura. 1919- . 11. Title. Ill. Series. IV. Series: United States: Geological Survey. Professional Paper 1170-E. QE475.G55D87 1983 552'.4 83-60003 1 For sale by the Distribution Branch, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 42304 CONTENTS Page Abstract .............................................................................................................................................................. El Introduction ..................................................................................................................................................... -
Geology of the Crater of Diamonds State Park and Vicinity, Pike County, Arkansas
SPS-03 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director STATE PARK SERIES 03 GEOLOGY OF THE CRATER OF DIAMONDS STATE PARK AND VICINITY, PIKE COUNTY, ARKANSAS by J. M. Howard and W. D. Hanson Little Rock, Arkansas 2008 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director STATE PARK SERIES 03 GEOLOGY OF THE CRATER OF DIAMONDS STATE PARK AND VICINITY, PIKE COUNTY, ARKANSAS by J. M. Howard and W. D. Hanson Little Rock, Arkansas 2008 STATE OF ARKANSAS Mike Beebe, Governor ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director COMMISSIONERS Dr. Richard Cohoon, Chairman………………………………………....Russellville William Willis, Vice Chairman…………………………………...…….Hot Springs David J. Baumgardner………………………………………….………..Little Rock Brad DeVazier…………………………………………………………..Forrest City Keith DuPriest………………………………………………………….….Magnolia Becky Keogh……………………………………………………...……..Little Rock David Lumbert…………………………………………………...………Little Rock Little Rock, Arkansas 2008 i TABLE OF CONTENTS Introduction…………………………………………………………………………..................... 1 Geology…………………………………………………………………………………………... 1 Prairie Creek Diatreme Rock Types……………………………….…………...……...………… 3 Mineralogy of Diamonds…………………….……………………………………………..……. 6 Typical shapes of Arkansas diamonds…………………………………………………………… 6 Answers to Frequently Asked Questions……………..……………………………….....……… 7 Definition of Rock Types……………………………………………………………………… 7 Formation Processes.…...…………………………………………………………….....…….. 8 Search Efforts……………...……………………………...……………………...………..….