DOCSLIB.ORG

The Origin of Granites and Related Rocks

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Origin of Granites and Related Rocks The Origin of Granites and Related Rocks U.S. GEOLOGICAL SURVEY CIRCULAR 11 29 Cover. Boudins on several scales within layered amphibolite, Tolstik Peninsula, Karelia, Russia. Anatectic melt represented by leucosome has migrated preferentially parallel to the tectonic foliation to the boudin necks, at each of the scales, in response to applied differential stress. Width of field of view about 1 m. Photograph taken by Michael Brown. Cover design by Jane B. Russell. TH'EOB.Y OJ THE E A R T H, WIT1\ PR.OOFS AND ILLUSTRATIONS. IN FOUR. PAR. TS. Br J.AMMJ HUTTON, M.D. ~F. R. 8. E. VOL. 1. EDINBURGH: PRINTED FOR MESSRS CADEl-L, JUNIOR, AND DA\"1[_;, J,.ONJ.)Olf; A·ftD WILLIAM CREECH, EDINBURGH. J 7 9 S• Frontispiece. Facsimile of the title page of James Hutton's seminal work, Theory of the Earth, two volumes, Edinburgh, 1795. The geological writings of James Hutton (1726- 1797) provide the foundation of modem geology. Hutton recognized the length of geological time, the uniformity of geological processes through time, and the role of igneous activity, sedimentation, and erosion in forming the Earth as we know it. It is fitting that this Third Hutton Symposium on the Origin of Granites and Related Rocks should occur during the bicentenary of the publication of this great work, which records among its content an important stage in the development of ideas about igneous rocks. THE ORIGIN OF GRANITES AND RELATED ROCKS The Origin of Granites and Related Rocks THIRD HUTTON SYMPOSIUM A B S T R A C T S College Park, Maryland August 26-September 2, 1995 Edited by Michael Brown and Philip M. Piccoli U.S. GEOLOGICAL SURVEY CIRCULAR 1129 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY GORDON P. EATON, Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center, Denver, CO 80225 This report has been prepared by the University of Maryland in cooperation with the U.S. Geological Survey; the report has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Published in the Eastern Region, Reston, Va Manuscript approved for publication May 25, 1995. CONTENTS Introduction . 1 Program of Oral Presentations . 4 Abstracts . 7 Author Index . 169 v THE ORIGIN OF GRANITES AND RELATED ROCKS Michael Brown and Philip M. Piccoli, Editors INTRODUCTION country rocks. This represents the first demonstration of the class of rocks that we now refer to as intrusive igneous Towards the end of his life, James Hutton (1726-1797) rocks. The conclusions of his short paper "Observations on set forth his "Theory of the Earth" in which he recognized Granite" are important to all of us, and were: the length of geological time, the uniformity of geological "We are now fully assured that granite has been processes through time, and the role of igneous activity, made to break, displace and invade the Alpine sedimentation, and erosion in forming the Earth as we schistus or primary strata having been previously know it. These ideas had been formulated as a result of forced to flow in the bowels of the earth, and re­ much thought and discussion, and were based on a long duced into a state offusion. From this too we are to and critical study of rocks in the field. Hutton's four part draw the following conclusion: Granite, which has two-volume book was preceded by a public presentation of been hitherto considered by naturalists as being the these ideas in 1785, in a paper on "Examination of the original or primitive part of the earth, is now found System of the Habitable Earth with Regard to its Duration to be posterior to the Alpine schistus; which schistus, and Stability" read to members of the Royal Society of being stratified, is not itself original; though it may Edinburgh on March 7 and April 4. Subsequently, the be considered, perhaps, as primary, in relation to paper was published in Volume I of the Transactions of other strata, which are evidently of a later date." the Royal Society of Edinburgh in 1788. In the ten years The subject of the origin of granite and related rocks has between presentation of the paper to the Royal Society of remained of intense topical interest since the time of Edinburgh and publication of his book, Hutton occupied Hutton, and the Hutton Symposium Series began as a himself in accumulating the "proofs and illustrations" of result of the success of a symposium on "The Origin of his Theory of the Earth which enhance the fuller exposition Granites" organized jointly by the Royal Society of of the Theory as presented in the book. Indeed, for the Edinburgh and the Royal Society of London in 1987 to three summers that followed his 1785 presentations to the celebrate the bicentenary of the work of James Hutton. Royal Society of Edinburgh, Hutton examined key field Implicit in Hutton's conclusions concerning granite are the relationships along Glentilt in the Grampians (1785), ideas of crustal anatexis, melt segregation, magma transfer around Loch Ken in Galloway (1786) and on Goatfell in and granite emplacement into lower-grade upper-crustal the north of Arran (1787), because he concluded, that if rocks. How far have we progressed in our understanding his account in 1785 was correct, some confirmation of it of these processes during the following 200 years? must appear at those places where granite and stratified Detailed field studies, such as those completed by rock are in contact. The development of Hutton's views on Hutton 200 years ago, remain the foundation of our the origin of igneous rocks was presented to members of understanding of granites and related rocks. Since Hutton's the Royal Society of Edinburgh on January 4, 1790, and time, field work has provided a necessary framework for subsequently published in Volume III of the Transactions the interpretation of studies of, for example: granite in 1794. The questions in Hutton's mind in 1785 con­ crystallization; coeval and cogenetic felsic volcanic cerned whether granites represented material "transfused systems; pegmatite genesis; and granite-related hydrother­ from the subterraneous regions, and made to break and mal systems (which may represent the culmination of the invade the strata". During his field work, Hutton was able granite crystallization process). After several decades of to find unequivocal evidence to show that molten granite experimental investigation, we have a firm understanding had invaded the surrounding stratified rock, that is to say of the melt production of common crustal protoliths as a it was an intrusive igneous rock of younger age than the function of pressure, temperature and activity of water. 1 2 The Origin of Granites and Related Rocks The thermal budget of continental collision belts that of the melting reaction remains in situ, provide informa­ involve thickening, thermal relaxation and exhumation has tion about plumbing in the crust and melt transfer path­ been modeled, and in many cases extension and/or ways. The relationship between lower crust that exhibits delamination of part of the lithosphere to increase the heat depleted geochemistry and fragments of apparently flux across the Moho is necessary to explain observed undepleted lower crustal material entrained as xenoliths in features of granite magmatism in orogenic belts. Nonethe­ basalts, remains unresolved. less, it remains unclear exactly how the thermal require­ There has been considerable debate concerning the ments for melting crustal protoliths are met in individual mechanisms of ascent of granitic magma through the cases. Additionally, the role of mantle-derived magma in continental crust. During the past decade support for the crustal anatexis remains a matter of debate, although traditionally assumed mechanism of diapirism has been hybridization and assimilation-fractional crystallization are waning as emphasis has been increasingly placed on the well-established processes and in many cases the isotopic relationship between plutons and shear zones. More evidence seems unambiguous. Our understanding of recently, magma transfer through the crust in dikes has controls on the geochemistry of crustal melts has improved become popular. Rates of melt segregation in response to significantly with increases in experimental data and better applied differential stress and melt ascent in dikes or major understanding of rates of, for example, diffusion and shear zones have been modeled, and in some circum­ mineral dissolution. In contrast, our knowledge of pres­ stances are thought to be fast. Both the processes them­ sure, temperature, fugacity of oxygen and fugacity of selves and the rates at which they proceed have important water in magmas during ascent and emplacement remains implications for the geochemistry of granites and for the sketchy at best. Since 1980 our understanding of and our potential to advect heat into higher levels of the crust. ability to model the processes that cause change in magma Additionally, the rheological consequences of partially composition during ascent, emplacement and final solidifi­ molten crust are significant. For example, if major crustal cation has advanced considerably, but the relative impor­ shear zones initiate in partially molten regions subjected to tance of these processes, such as fractional crystallization, applied differential stress, then melt will migrate to the assimilation-fractional crystallization, restite entrainment lower-pressure shear zone. In this way the shear zone may and unmixing, and hybridization remains uncertain. The localize the ascent path and emplacement site, but the past decade has seen a return to experimental work which driving forces both for ascent and emplacement will be is producing data to advance our understanding of the some combination of the regional applied differential stress physics of magma, a renewed interest in textural interpre­ and buoyancy forces of gravity.
Load more

Recommended publications
  • An Evolutionary System of Mineralogy: Proposal for a Classification Of
    1 1 02 November 2018—American Mineralogist—Revision 1 2 3 4 An evolutionary system of mineralogy: Proposal for a classification 5 of planetary materials based on natural kind clustering 6 7 ROBERT M. HAZEN1,* 8 1Geophysical Laboratory, Carnegie Institution for Science, 9 5251 Broad Branch Road NW, Washington, DC 20015, U. S. A. 10 11 ABSTRACT 12 Minerals reveal the nature of the co-evolving geosphere and biosphere through billions of years 13 of Earth history. Mineral classification systems have the potential to elucidate this rich 14 evolutionary story; however, the present mineral taxonomy, based as it is on idealized major 15 element chemistry and crystal structure, lacks a temporal aspect and thus cannot reflect planetary 16 evolution. A complementary evolutionary system of mineralogy based on the quantitative 17 recognition of “natural kind clustering” for a wide range of condensed planetary materials with 18 different paragenetic origins has the potential to amplify, though not supersede, the present 19 classification system. 20 21 _________________________________ 22 *E-mail: [email protected] 23 Keywords: philosophy of mineralogy; classification; mineral evolution; mineral ecology; data- 24 driven discovery; cluster analysis; natural kinds 2 25 INTRODUCTION 26 For more than 2000 years, the classification of natural objects and phenomena into “kinds” has 27 been a central pursuit of natural philosophers (Aristotle/Thompson 1910; Locke 1690; Linnaeus 28 1758). The modern mineral classification system, rooted in the chemical framework of James 29 Dwight Dana (1850), is based on unique combinations of idealized major element composition 30 and crystal structure (Strunz 1941; Palache et al. 1944, 1951; Liebau 1985; Mills et al.
    [Show full text]
  • Chemical and Structural Evolution of “Metamorphic Vermiculite” in Metaclastic Rocks of the Betic Cordillera, Málaga, Spain: a Synthesis
    249 The Canadian Mineralogist Vol. 44, pp. 249-265 (2006) CHEMICAL AND STRUCTURAL EVOLUTION OF “METAMORPHIC VERMICULITE” IN METACLASTIC ROCKS OF THE BETIC CORDILLERA, MÁLAGA, SPAIN: A SYNTHESIS MARÍA DOLORES RUIZ CRUZ§ Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, Campus de Teatinos, E-29071 Málaga, Spain JOSÉ MIGUEL NIETO Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, E-21071 Huelva, Spain ABSTRACT Vermiculite-like minerals from a metamorphic sequence of the Betic Cordillera, near Málaga, southeastern Spain, were investigated in detail by X-ray diffraction, electron-microprobe analysis, and transmission-analytical electron microscopy. Our results reveal that the chlorite-to-biotite transformation is much more complex than previously assumed. In addition to mixed- layer minerals with a mica:chlorite ratio of 2:1 and 1:1, which had previously been identifi ed, mixed-layer phases with very high and very low chlorite:vermiculite ratios have been identifi ed, together with true vermiculite, as intermediate steps in the chlorite-to-biotite transformation. The observed sequence is: chlorite → random to ordered 1:2 mica–chlorite mixed-layer phases → regular 1:1 chlorite–vermiculite mixed-layer phases → Vrm-rich chlorite–vermiculite mixed-layer phases → vermiculite → biotite. This sequence includes a continuous increase of interlayer cation content, and is similar to that described in the smectite- to-illite transformation. The high Na content of most of these phases suggests that in the absence of K-feldspar, two parallel sites of reactants, chlorite + phengite and chlorite + albite, account for the formation of vermiculitic phases, and later, of biotite. Keywords: mixed-layer minerals, metamorphic vermiculite, X-ray diffraction, electron-microprobe analysis, transmission elec- tron microscopy, analytical electron microscopy, Betic Cordillera, Spain.
    [Show full text]
  • Bedrock Geology Glossary from the Roadside Geology of Minnesota, Richard W
    Minnesota Bedrock Geology Glossary From the Roadside Geology of Minnesota, Richard W. Ojakangas Sedimentary Rock Types in Minnesota Rocks that formed from the consolidation of loose sediment Conglomerate: A coarse-grained sedimentary rock composed of pebbles, cobbles, or boul- ders set in a fine-grained matrix of silt and sand. Dolostone: A sedimentary rock composed of the mineral dolomite, a calcium magnesium car- bonate. Graywacke: A sedimentary rock made primarily of mud and sand, often deposited by turbidi- ty currents. Iron-formation: A thinly bedded sedimentary rock containing more than 15 percent iron. Limestone: A sedimentary rock composed of calcium carbonate. Mudstone: A sedimentary rock composed of mud. Sandstone: A sedimentary rock made primarily of sand. Shale: A deposit of clay, silt, or mud solidified into more or less a solid rock. Siltstone: A sedimentary rock made primarily of sand. Igneous and Volcanic Rock Types in Minnesota Rocks that solidified from cooling of molten magma Basalt: A black or dark grey volcanic rock that consists mainly of microscopic crystals of pla- gioclase feldspar, pyroxene, and perhaps olivine. Diorite: A plutonic igneous rock intermediate in composition between granite and gabbro. Gabbro: A dark igneous rock consisting mainly of plagioclase and pyroxene in crystals large enough to see with a simple magnifier. Gabbro has the same composition as basalt but contains much larger mineral grains because it cooled at depth over a longer period of time. Granite: An igneous rock composed mostly of orthoclase feldspar and quartz in grains large enough to see without using a magnifier. Most granites also contain mica and amphibole Rhyolite: A felsic (light-colored) volcanic rock, the extrusive equivalent of granite.
    [Show full text]
  • Fact Sheet 5 Principles of Stone Extraction
    QuarryScapes guide to ancient stone quarries Fact Sheet 5 Fact Sheet 5 Principles of stone extraction In all stone quarry situations the extraction phase rich) ones. Partly because they in general display is based on one or combinations of three the most brittle behaviour, but also because it is a fundamental principles: well documented fact (and experience among quarrymen) that siliceous rocks (granite in 1. Levering; expanding open fractures by particular) have well defined preferred splitting inserting levers, crowbars or stones 2. Splitting; creating fractures, preferable directions defined by microfractures in quartz. planar, by strokes (i.e. sledge hammer), Splitting by heating is caused by a combination of wedging; heating or blasting with thermal expansion properties and brittle explosives behaviour. It works best on quartz-rich rocks due 3. Channelling (carving); making channels in to the well known but poorly understood change the rock by carving with hammer and of mechanical properties of quartz when heated. chisel, pickaxe or stone tools, heating with fire, sawing or drilling Channelling is the third fundamental principle. Channels in the rock are made by removing the Levering may be described as the “simplest” way rock mass by chiselling, picking, sawing or of extraction, involving the expansion of natural heating. In most soft stone quarries from the cracks or other planes of weakness (such as Bronze Age onwards, channelling is the most bedding planes) using various tools. important extraction method. In most cases, channelling is combined with other methods. For Splitting may be defined as the act of generating instance, channels are made perpendicular to the new fractures for extracting rock.
    [Show full text]
  • Network Analysis of Mineralogical Systems
    American Mineralogist, Volume 102, pages 1588–1596, 2017 OUTLooKS IN EARTH AND PLANETARY MATERIALS k Network analysis of mineralogical systems SHAUNNA M. MORRISON1, CHAO LIU1, AHmeD ELEISH1,2, ANIRUDH PRABHU2, CONGRUI LI2, JOLYON RALPH3, ROBERT T. DOWNS4, JOSHUA J. GOLDEN4, PETER FOX2, DANIEL R. HUmmeR1,5, MICHAEL B. MEYER1, AND ROBERT M. HAZEN1,* 1Geophysical Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, D.C. 20015, U.S.A. 2Tetherless World Constellation, Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, U.S.A. 3Mindat.org, 128 Mullards Close, Mitcham, Surrey, CR4 4FD, U.K. 4Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721-0077, U.S.A. 5Department of Geology, Southern Illinois University, Carbondale, Illinois 62901, U.S.A. ABSTRACT A fundamental goal of mineralogy and petrology is the deep understanding of mineral phase relation- ships and the consequent spatial and temporal patterns of mineral coexistence in rocks, ore bodies, sediments, meteorites, and other natural polycrystalline materials. The multi-dimensional chemical com- plexity of such mineral assemblages has traditionally led to experimental and theoretical consideration of 2-, 3-, or n-component systems that represent simplified approximations of natural systems. Network analysis provides a dynamic, quantitative, and predictive visualization framework for employing “big data” to explore complex and otherwise hidden higher-dimensional patterns of diversity and distribution in such mineral systems. We introduce and explore applications of mineral network analysis, in which mineral species are represented by nodes, while coexistence of minerals is indicated by lines between nodes. This approach provides a dynamic visualization platform for higher-dimensional analysis of phase relationships, because topologies of equilibrium phase assemblages and pathways of mineral reaction series are embedded within the networks.
    [Show full text]
  • The Geology, Paleontology and Paleoecology of the Cerro Fortaleza Formation
    The Geology, Paleontology and Paleoecology of the Cerro Fortaleza Formation, Patagonia (Argentina) A Thesis Submitted to the Faculty of Drexel University by Victoria Margaret Egerton in partial fulfillment of the requirements for the degree of Doctor of Philosophy November 2011 © Copyright 2011 Victoria M. Egerton. All Rights Reserved. ii Dedications To my mother and father iii Acknowledgments The knowledge, guidance and commitment of a great number of people have led to my success while at Drexel University. I would first like to thank Drexel University and the College of Arts and Sciences for providing world-class facilities while I pursued my PhD. I would also like to thank the Department of Biology for its support and dedication. I would like to thank my advisor, Dr. Kenneth Lacovara, for his guidance and patience. Additionally, I would like to thank him for including me in his pursuit of knowledge of Argentine dinosaurs and their environments. I am also indebted to my committee members, Dr. Gail Hearn, Dr. Jake Russell, Dr. Mike O‘Connor, Dr. Matthew Lamanna, Dr. Christopher Williams and Professor Hermann Pfefferkorn for their valuable comments and time. The support of Argentine scientists has been essential for allowing me to pursue my research. I am thankful that I had the opportunity to work with such kind and knowledgeable people. I would like to thank Dr. Fernando Novas (Museo Argentino de Ciencias Naturales) for helping me obtain specimens that allowed this research to happen. I would also like to thank Dr. Viviana Barreda (Museo Argentino de Ciencias Naturales) for her allowing me use of her lab space while I was visiting Museo Argentino de Ciencias Naturales.
    [Show full text]
  • Mapping a Hidden Terrane Boundary in the Mantle Lithosphere with Lamprophyres
    ARTICLE DOI: 10.1038/s41467-018-06253-7 OPEN Mapping a hidden terrane boundary in the mantle lithosphere with lamprophyres Arjan H. Dijkstra 1 & Callum Hatch1,2 Lamprophyres represent hydrous alkaline mantle melts that are a unique source of information about the composition of continental lithosphere. Throughout southwest Britain, post-Variscan lamprophyres are (ultra)potassic with strong incompatible element enrich- 1234567890():,; ments. Here we show that they form two distinct groups in terms of their Sr and Nd isotopic compositions, occurring on either side of a postulated, hitherto unrecognized terrane boundary. Lamprophyres emplaced north of the boundary fall on the mantle array with εNd −1 to +1.6. Those south of the boundary are enriched in radiogenic Sr, have initial εNd values of −0.3 to −3.5, and are isotopically indistinguishable from similar-aged lamprophyres in Armorican massifs in Europe. We conclude that an Armorican terrane was juxtaposed against Avalonia well before the closure of the Variscan oceans and the formation of Pangea. The giant Cornubian Tin-Tungsten Ore Province and associated batholith can be accounted for by the fertility of Armorican lower crust and mantle lithosphere. 1 School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL4 8AA, UK. 2 Department of Core Research Laboratories, Natural History Museum, Cromwell Road, London, SW7 5BD UK. Correspondence and requests for materials should be addressed to A.H.D. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3770 | DOI: 10.1038/s41467-018-06253-7 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-06253-7 ilson’s cycle1 of the opening and closing of ocean typically form 10 cm to m-wide dykes and other types of minor Wbasins throughout Earth history was based on the intrusions cutting across Variscan foliations in Carboniferous and similarity of Early Palaeozoic faunal assemblages in Devonian rocks.
    [Show full text]
  • 169060: Porphyritic Syenogranite, Yangibana Bore
    169060.1.pdfCompilation - ofGeochronology geochronology datasetdata, 2001 134 169060: porphyritic syenogranite, Yangibana Bore Location and sampling EDMUND (SF 50-14), EDMUND (2158) MGA Zone 50, 419130E 7355190N Sampled on 15 October 2000. The sample was taken from the edge of an undulating pavement located 5 km southeast of Yangibana Bore. Tectonic unit/relations This sample is a light to medium grey, undeformed seriate porphyritic syenogranite of the Pimbyana Granite (Pearson et al., 1996; Martin et al., 2002), Gascoyne Complex. The syenogranite contains scattered tabular, feldspar phenocrysts up to 5 cm long, within a dark, fine-grained groundmass. Feldspar phenocrysts are aligned and range from very abundant to sparse over distances of several metres. Petrographic description This sample consists principally of microcline and orthoclase (60–65 vol.%), quartz (20 vol.%), plagioclase (10 vol.%), biotite (4 vol.%), and muscovite (3 vol.%), with accessory apatite (trace) opaque oxide (trace), possible monazite (trace), and zircon (trace). This is a porphyritic syenogranite with partly altered biotite and muscovite, very minor opaque oxide and zircon, and possible monazite. Feldspar phenocrysts to 30 mm long are visible in hand specimen. In thin section these are perthitic K-feldspar, varying from orthoclase to microcline, with inclusions of quartz, altered plagioclase, fresh to altered biotite, and muscovite. The largest grain within the area of the thin section is only about 10 mm long, but larger crystals are more widely dispersed. Separate plagioclase grains are up to 4 mm long, with irregular flooding by sericite. Quartz occurs as lensoidal to rounded grains to 7 mm long, deformed with undulose extinction and subgrains.
    [Show full text]
  • Table of Contents. Letter of Transmittal. Officers 1910
    TWELFTH REPORT OFFICERS 1910-1911. OF President, F. G. NOVY, Ann Arbor. THE MICHIGAN ACADEMY OF SCIENCE Secretary-Treasurer, GEO. D. SHAFER, East Lansing. Librarian, A. G. RUTHVEN, Ann Arbor. CONTAINING AN ACCOUNT OF THE ANNUAL MEETING VICE-PRESIDENTS. HELD AT Agriculture, CHARLES E. MARSHALL, East Lansing. Geography and Geology, W. H. SHERZER, Ypsilanti. ANN ARBOR, MARCH 31, APRIL 1 AND 2, 1910. Zoology, A. S. PEARSE, Ann Arbor. Botany, C. H. KAUFFMAN, Ann Arbor. PREPARED UNDER THE DIRECTION OF THE Sanitary and Medical Science, GUY KIEFER, Detroit. COUNCIL Economics, H. S. SMALLEY, Ann Arbor. BY PAST-PRESIDENTS. GEO. D. SHAFER DR. W. J. BEAL, East Lansing. Professor W. H. SHERZER, Ypsilanti. BRYANT WALKER, ESQ. Detroit. BY AUTHORITY Professor V. M. SPALDING, Tucson, Arizona. LANSING, MICHIGAN DR. HENRY B. BAKER, Holland. WYNKOOP HALLENBECK CRAWFORD CO., STATE PRINTERS Professor JACOB REIGHARD, Ann Arbor. 1910 Professor CHARLES E. BARR, Albion. Professor V. C. VAUGHAN, Ann Arbor. Professor F. C. NEWCOMBE, Ann Arbor. TABLE OF CONTENTS. DR. A. C. LANE, Tuft's College, Mass. Professor W. B. BARROWS, East Lansing. DR. J. B. POLLOCK, Ann Arbor. Letter of Transmittal .......................................................... 1 Professor M. H. W. JEFFERSON, Ypsilanti. DR. CHARLES E. MARSHALL, East Lansing. Officers for 1910-1911. ..................................................... 1 Professor FRANK LEVERETT, Ann Arbor. Life of William Smith Sayer. .............................................. 1 COUNCIL. Life of Charles Fay Wheeler.............................................. 2 The Council is composed of the above named officers Papers published in this report: and all Resident Past-Presidents. President's Address—Outline of the History of the Great Lakes, Frank Leverett.......................................... 3 On the Glacial Origin of the Huronian Rocks of WILLIAM SMITH SAYER.
    [Show full text]
  • Programa Del Curso Posgrado: Geología Del Basamento. La Aportación De La Geocronología
    Programa del Curso Posgrado: Geología del Basamento. La aportación de la Geocronología. Docente: Dr. Cesar Casquet Objetivos El curso va dirigido a estudiantes de posgrado que incluyen en sus temas de tesis la investigación de las unidades del basamento cristalino. El principal objetivo del curso es mostrar diferentes modalidades de abordaje en el estudio geocronológico de rocas ígneas y metamórficas en función del problema que se pretende resolver. No se trata de un curso de geología de basamento en general, ni de aspectos teóricos de la geocronología, sino de geocronología aplicada a la resolución de problemas inherentes a la geología de basamento. Para el cursado del mismo se requieren conocimientos básicos de los diferentes métodos geocronológicos aplicados a rocas antiguas y de geología general de rocas ígneas y metamórficas. Durante el dictado del curso se expondrán y discutirán diferentes ejemplos de aplicaciones geocronológicas a la resolución de problemas del basamento cristalino de las Sierras Pampeanas de Argentina. Se expondrá principalmente la experiencia acumulada como resultado de las investigaciones realizada desde el año 1993 por el grupo de investigación PAMPRE. El curso concluirá con una clase/conferencia dedicada a resumir precisamente la interpretación sobre la evolución de las Sierras Pampeanas desde el Proterozoico medio hasta el Paleozoico inferior y una excursión de campo. Programa del Curso 1era Parte (incluye las actividades de la mitad del primer día) Introducción al Problema de la datación en el basamento: 1-Definición del término basamento cristalino. 2-Principales problemas que plantea el estudio de las unidades de basamento. 3-El principal problema de la geología de basamento: Las edades de los eventos magmáticos, metamórficos y deformacionales.
    [Show full text]
  • Briefguiderocks Copy
    BRIEF GUIDE TO ROCKS What is a rock? • A mixture of minerals. • A naturally occurring solid. • A “time machine” with a story to tell. All rocks tell a story; a rock represents a period of time (during which it was formed), an environment (in which it was formed) and a geologic process (how it was formed). By “reading the record of a rock” you can understand its history. Sandia Granite How are rocks classified? • Igneous: solidified from magma (molten, or liquid, rock within the Earth) Note: Igneous rocks are further divided into Plutonic (the magma solidified beneath Earth’s surface) and Volcanic (the magma erupted onto Earth’s surface to become lava and the lava solidified at the surface). Examples: Plutonic = granite, gabbro, granodiorite, monzonite Volcanic = basalt, rhyolite, pumice, obsidian • Sedimentary: rocks produced by the movement and deposition of eroded minerals, sand, silt, pebbles, or cobbles or by the deposition of precipitates. Note: Sedimentary rocks are divided into Clastic (a rock with layers of sediment of various grain sizes) or Chemical (a rock formed by precipitation of chemicals layer by layer out of water). Examples: Clastic = sandstone, shale Chemical = limestone, travertine • Metamorphic: a pre-existing rock (igneous or sedimentary or even metamorphic) that has been altered by changes in temperature, pressure, or stress into a different type of rock by mineralogical, chemical, and/or structural changes, while in the solid state. Note: Metamorphic rocks are sometimes classified by geologists into levels of metamorphism (how much it has changed) from low to high intensity. Metamorphic rocks that have been under pressure show an alignment of minerals that is called foliation.
    [Show full text]
  • Muscovite Solid Solutions in the System K20-Mgo-Feo-A1203-Sio2-H20: an Experimental Study at 2 Kbar Ph2o and Comparison with Natural Li-Free White Micas
    MINERALOGICAL MAGAZINE, JUNE 1986, VOL. 50, PP. 257-66 Muscovite solid solutions in the system K20-MgO-FeO-A1203-SiO2-H20: an experimental study at 2 kbar PH2o and comparison with natural Li-free white micas GILLES MoNIER Laboratoire de P&rologie, Universit6 d'Or16ans, 45046 Orlrans Cedex, France AND JI~AN-LouIs ROBERT Centre de Recherche sur la Synthrse et Chimie des MinSraux, G.I.S.C.N.R.S.-B.R.G.M., 1A rue de la Frrollerie, 45071 Odrans Cedex 2, France ABSTRACT. This paper presents the results of an experi- K EY W OR O S : muscovite, phengite, solid solution, crystal- mental study of muscovite solid solutions in the system chemistry, experimental mineralogy, granites, hydro- K20-M~+O-A1203 SiO2-H20 (HF), with M2+= thermal alteration. Mg 2+ or Fe 2§ in the temperature range 300 700~ under 2 kbar P.~o, Muscovite solid solutions can be described, in this system, as the result of two substitutions. NATURAL lithium-free white micas are generally One is the phengitic substitution (x), which preserves the described as solid solutions between the muscovite pure dioctahedral character of the mica; the second is the end member K(A12R)(Si3AI)Olo(OH)2, where [] biotitic substitution (y), which leads to trioctahedral stands for an octahedral vacant site, and the micas and does not change the composition of the celadonite end member K(AIM z+ [3)Si4010(OH)2, tetrahedral layer Si3AI. The general formula of muscovite with M 2 + = Mg 2., Fe E+, thus, they are considered in this system is K(A12_~_2y/aM2+yOl_y/a)(Sia+~All_x) to belong to the so-called phengitic series.
    [Show full text]