DOCSLIB.ORG

Geology, Age, and Tectonic Setting of the Cretaceous Sliderock Mountain Volcano, Montana

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geology, Age, and Tectonic Setting of the Cretaceous Sliderock Mountain Volcano, Montana U.S. Department of the Interior U.S. Geological Survey Geology, Age, and Tectonic Setting of the Cretaceous Sliderock Mountain Volcano, Montana U.S. Geological Survey Professional Paper 1602 science for a changing world Availability of Publications of the U.S. Geological Survey Order U.S. Geological Survey (USGS) publications from the Documents. Check or money order must be payable to the offices listed below. Detailed ordering instructions, along with Superintendent of Documents. Order by mail from— prices of the last offerings, are given in the current-year issues of the catalog "New Publications of the U.S. Geological Superintendent of Documents Survey." Government Printing Office Washington, DC 20402 Books, Maps, and Other Publications Information Periodicals By Mail Many Information Periodicals products are available through Books, maps, and other publications are available by mail the systems or formats listed below: from— Printed Products USGS Information Services Box 25286, Federal Center Printed copies of the Minerals Yearbook and the Mineral Com­ Denver, CO 80225 modity Summaries can be ordered from the Superintendent of Publications include Professional Papers, Bulletins, Water- Documents, Government Printing Office (address above). Supply Papers, Techniques of Water-Resources Investigations, Printed copies of Metal Industry Indicators and Mineral Indus­ Circulars, Fact Sheets, publications of general interest, single try Surveys can be ordered from the Center for Disease Control copies of permanent USGS catalogs, and topographic and and Prevention, National Institute for Occupational Safety and thematic maps. Health, Pittsburgh Research Center, P.O. Box 18070, Pitts­ burgh, PA 15236-0070. Over the Counter Mines FaxBack: Return fax service Books, maps, and other publications of the U.S. Geological Survey are available over the counter at the following USGS 1. Use the touch-tone handset attached to your fax machine's Earth Science Information Centers (ESIC's), all of which are telephone jack. (ISDN [digital] telephones cannot be used with authorized agents of the Superintendent of Documents: fax machines.) • Anchorage, Alaska—Rm. 101,4230 University Dr. 2. Dial (703) 648^1999. • Denver, Colorado-Bldg. 810, Federal Center 3. Listen to the menu options and punch in the number of your • Menlo Park, California-Rm. 3128, Bldg. 3, selection, using the touch-tone telephone. 345 Middlefield Rd. 4. After completing your selection, press the start button on • Reston, Virginia-4lm. 1C402, USGS National Center, your fax machine. 12201 Sunrise Valley Dr. • Salt Lake City, Utah-2222 West, 2300 South (books and CD-ROM maps available for inspection only) A disc containing chapters of the Minerals Yearbook (1993- • Spokane, Washington-Rm. 135, U.S. Post Office 95), the Mineral Commodity Summaries (1995-97), a statisti­ Building, 904 West Riverside Ave. cal compendium (1970-90), and other publications is updated • Washington, D.C.-Rm. 2650, Main Interior Bldg., three times a year and sold by the Superintendent of Docu­ 18th and C Sts., NW. ments, Government Printing Office (address above). Maps only may be purchased over the counter at the following World Wide Web USGS office: • Rolla, Missouri—1400 Independence Rd. Minerals information is available electronically at http://minerals.er.usgs.gov/minerals/ Electronically Subscription to the catalog "New Publications of the U.S. Some USGS publications, including the catalog "New Publica­ Geological Survey" tions of the U.S. Geological Survey" are also available elec­ tronically on the USGS's World Wide Web home page at Those wishing to be placed on a free subscription list for the http://www.usgs.gov catalog "New Publications of the U.S. Geological Survey" should write to— Preliminary Determination of Epicenters U.S. Geological Survey Subscriptions to the periodical "Preliminary Determination of 903 National Center Epicenters" can be obtained only from the Superintendent of Reston, VA 20192 Geology, Age, and Tectonic Setting of the Cretaceous Sliderock Mountain Volcano, Montana By Edward A. du Bray and Stephen S. Harlan U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1602 Physical and compositional development of an Upper Cretaceous stratovolcano in south-central Montana UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1998 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Thomas J. Casadevall, Acting Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center Denver, CO 80225 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 Library of Congress Cataloging-in-Publication Data Du Bray, E.A. Geology and tectonic setting of the Cretaceous Sliderock Mountain volcano, Montana / by Edward A. du Bray and Stephen S. Harlan. p. cm. — (U.S. Geological Survey professional paper ; 1602) Includes bibliographical references. 1. Sliderock Mountain (Sweet Grass County, Mont.). 2. Geology, Stratigraphic— Cretaceous. 3. Geology—Montana—Sliderock Mountain (Sweet Grass County). 4. Volcanoes—Montana—Sweet Grass County. I. Harlan, Stephen S. II. Title. III. Series. QE523.S63D8 1999 551.2'1'0978664—dc21 98-18106 CIP CONTENTS Abstract........................................................................................................................... 1 Introduction and Geologic Setting.................................................................................. 1 Physical Volcanology of the Sliderock Mountain Volcano............................................ 3 Geochronology................................................................................................................ 5 Petrography..................................................................................................................... 11 Geochemistry.................................................................................................................. 11 Regional Tectono-magmatic Speculation....................................................................... 16 Acknowledgments........................................................................................................... 17 References....................................................................................................................... 18 FIGURES 1. Tectonic map of the Crazy Mountains Basin.............................................................................................................. 2 2. Simplified geologic map of Sliderock Mountain stratovolcano.................................................................................. 4 3. Photographs of Sliderock Mountain stratovolcano lahars........................................................................................... 6 4. 40Ar/39Ar age spectra and 39Ar/37Ar ratios................................................................................................................. 7 5. 39Ar/40Ar versus 36Ar/40Ar correlation diagrams....................................................................................................... 10 6. Total alkali-silica variation diagram............................................................................................................................ 11 7. Variation diagrams showing abundances of major oxides.......................................................................................... 13 8. Ternary variation diagram showing the relative proportions of Rb, K, and Sr........................................................... 14 9. Trace-element tectonic-setting-discrimination variation diagrams............................................................................. 15 10. Ternary AFM variation diagram ................................................................................................................................. 15 11. Variation diagram showing rubidium and strontium abundances............................................................................... 16 12. Variation diagram showing rubidium and potassium abundances.............................................................................. 17 TABLES 1. 40Ar/39Ar data for samples of the Sliderock Mountain stratovolcano........................................................................ 8 2. Chemical compositions of samples from the Sliderock Mountain stratovolcano, Montana....................................... 12 III Geology, Age, and Tectonic Setting of the Cretaceous Sliderock Mountain Volcano, Montana By Edward A. du Bray and Stephen S. Harlan ABSTRACT considered part of the Upper Cretaceous Livingston Group, exposed elsewhere in the Crazy Mountains, but clearly rep­ Sliderock Mountain volcano is an Upper Cretaceous resent a proximal, physically distinct volcanic source area. stratovolcano located along the southern margin of the Crazy These rocks are important in understanding the geologic and Mountains Basin in south-central Montana. The volcano is tectonic setting of the northern Rocky Mountains because part of an extensive northwest-trending volcanic field that they constitute one of the easternmost Late Cretaceous volca­ lies astride the folds and faults of the Nye-Bowler lineament. nic fields in the North American Cordillera. The volcanic, The volcano consists mostly of volcaniclastic strata, although volcaniclastic, and intrusive rocks that comprise this field basaltic andesite lava flows are also present. An extensively have been described by a
Load more

Recommended publications
  • Mineral Mania
    The Rock Factory A Pre-Visit Information Guide for Teachers Meets Next Generation Science Standards: 5-PS1-3; MS LS4-1,2; MS ESS1-4; MS-ESS2-1 How does our Earth create so many different types of rocks? Learn about the different processes that form and reform rocks as you identify many types of rocks, minerals and fossils. Students will learn to think like geologists as they move through interactive investigation stations packed with specimens from the Museum’s collections. OBJECTIVES The Rock Cycle: Students will examine the three types of rocks - igneous, metamorphic and sedimentary – and discover the processes that create them. Tracing the connections between shale and slate, limestone and marble, students will discover how the rock cycle changes the very ground beneath our feet! Characteristics of Rocks Students will learn how to observe and identify rocks through their unique characteristics, looking for telling clues such as layering, crystal size, fossils, magnetism, and more. Students will practice their observational skills as they describe the Museum’s unique rock and mineral specimens. Investigation Stations: Students will explore Museum geology specimens up close at investigation stations to answer such questions as: “Why do fossils form only in certain rocks?” “How do rocks form from volcanic eruptions?” “How can I recognize different types of rocks?”. ACTIVITIES Teachers are encouraged to conduct pre-visit and post-visit classroom discussions and activities with their classes to make the most of their experience. Encourage your students to start a classroom rock collection, and create an exhibit with the rocks organized by type – igneous, sedimentary and metamorphic.
    [Show full text]
  • Geologic Boulder Map of Campus Has Been Created As an Educational Educational an As Created Been Has Campus of Map Boulder Geologic The
    Adam Larsen, Kevin Ansdell and Tim Prokopiuk Tim and Ansdell Kevin Larsen, Adam What is Geology? Igneous Geo-walk ing of marine creatures when the limestone was deposited. It also contains by edited and Written Geology is the study of the Earth, from the highest mountains to the core of The root of “igneous” is from the Latin word ignis meaning fire. Outlined in red, numerous fossils including gastropods, brachiopods, receptaculita and rugose the planet, and has traditionally been divided into physical geology and his- this path takes you across campus looking at these ancient “fire” rocks, some coral. The best example of these are in the Geology Building where the stone torical geology. Physical geology concentrates on the materials that compose of which may have been formed at great depths in the Earth’s crust. Created was hand-picked for its fossil display. Campus of the Earth and the natural processes that take place within the earth to shape by the cooling of magma or lava, they can widely vary in both grain size and Granite is another common building stone used on campus. When compa- its surface. Historical geology focuses on Earth history from its fiery begin- mineral composition. This walk stops at examples showing this variety to help nies sell granite, they do not use the same classification system as geologists. nings to the present. Geology also explores the interactions between the you understand what the change in circumstances will do to the appearance Granite is sold in many different colours and mineral compositions that a Map Boulder Geologic lithosphere (the solid Earth), the atmosphere, the biosphere (plants, animals of the rock.
    [Show full text]
  • SIMPSONS to SOUTH PARK-FILM 4165 (4 Credits) SPRING 2015 Tuesdays 6:00 P.M.-10:00 P.M
    CONTEMPORARY ANIMATION: THE SIMPSONS TO SOUTH PARK-FILM 4165 (4 Credits) SPRING 2015 Tuesdays 6:00 P.M.-10:00 P.M. Social Work 134 Instructor: Steven Pecchia-Bekkum Office Phone: 801-935-9143 E-Mail: [email protected] Office Hours: M-W 3:00 P.M.-5:00 P.M. (FMAB 107C) Course Description: Since it first appeared as a series of short animations on the Tracy Ullman Show (1987), The Simpsons has served as a running commentary on the lives and attitudes of the American people. Its subject matter has touched upon the fabric of American society regarding politics, religion, ethnic identity, disability, sexuality and gender-based issues. Also, this innovative program has delved into the realm of the personal; issues of family, employment, addiction, and death are familiar material found in the program’s narrative. Additionally, The Simpsons has spawned a series of animated programs (South Park, Futurama, Family Guy, Rick and Morty etc.) that have also been instrumental in this reflective look on the world in which we live. The abstraction of animation provides a safe emotional distance from these difficult topics and affords these programs a venue to reflect the true nature of modern American society. Course Objectives: The objective of this course is to provide the intellectual basis for a deeper understanding of The Simpsons, South Park, Futurama, Family Guy, and Rick and Morty within the context of the culture that nurtured these animations. The student will, upon successful completion of this course: (1) recognize cultural references within these animations. (2) correlate narratives to the issues about society that are raised.
    [Show full text]
  • Chapter 1 – Introduction – Review of Rocks and Plate Tectonics Practice Exam and Study Guide
    Chapter 1 – Introduction – Review of Rocks and Plate Tectonics Practice Exam and Study Guide To be able to understand the material covered during this course you need to have a basic background in the kinds of rocks making up our planet. This section of the study guide is aimed at helping you gain that background. 1. What are the three major groups of rocks found on planet Earth? Igneous Rocks 2. Which of the following processes is associated with igneous rocks? a. Solid‐state recrystallization b. Weathering and erosion c. Transportation and deposition d. Cooling a silicate liquid to a solid rock e. The accumulation of granitic debris in a moraine 3. If a silicate liquid flows out along the Earth’s surface or seabed, then it is called _______________. 4. If a silicate liquid exists beneath the Earth’s surface or seabed, then it is called _______________. 5. Which of the following terms refer to a body of magma or its solidified equivalent? a. Basalt b. Sandstone c. Gneiss d. Pluton e. Schist 6. If you can see the crystals making up an igneous rock with the naked eye, then the texture is described as a. Pyroclastic b. Phaneritic c. Aphanitic d. Porphyritic e. Aphyric from Perilous Earth: Understanding Processes Behind Natural Disasters, ver. 1.0, June, 2009 by G.H. Girty, Department of Geological Sciences, San Diego State University Page 1 7. In an aphanitic igneous rock can you make out the outlines of individual crystals with the naked eye? Yes or No 8. What type of igneous rock is the most volumetrically important on our planet? Intrusive Igneous Rocks 9.
    [Show full text]
  • Eg, Change Or Extinction of Particular Living Organisms; Field Evidence Or
    6.4. Construct explanations from geologic evidence (e.g., change or extinction of particular living organisms; field evidence or representations, including models of geologic cross-sections; sedimentary layering) to identify patterns of Earth’s major historical events (e.g., formation of mountain chains and ocean basins, significant volcanic eruptions, fossilization, folding, faulting, igneous intrusion, erosion). Use the diagram of a geologic cross section below to answer questions #1-2 1. Which rock layer most likely contains the most recently evolved organisms? a. 1 c. 3 b. 2 d. 4 2. Which rock layer represents the oldest rock? a. 1 c. 3 b. 2 d. 4 3. Use the diagram below to answer the question. The diagram shows the fossils in two different sections of rock found on opposite sides of a canyon. Which layer in rock section one is approximately the same age as layer X in rock section 2? a. Layer 1 b. Layer 2 c. Layer 3 d. Layer 4 4. Which statement is true about undisturbed layers of rocks on the side of a mountain? a. The rock layers closest to the ground level have more fossils in them. b. The layers of rock closest to the ground level are older than the layers on top. c. The layers of rocks that are the darkest in color are older than those that are lighter. d. The layers of rocks that are lighter in color are older than those that are darker. 5. The diagram below shows four different rock layers in a hillside. What is the best evidence that one of those rock layers was formed under an ocean.
    [Show full text]
  • Schofield Barracks
    ARMY ✭✭ AIR FORCE ✭✭ NAVY ✭✭ MARINES ONLINE PORTAL Want an overview of everything military life has to offer in Hawaii? This site consolidates all your benefits and priveleges and serves all branches of the military. ON BASE OFF BASE DISCOUNTS • Events Calendar • Attractions • Coupons & Special Offers • Beaches • Recreation • Contests & Giveaways • Attractions • Lodging WANT MORE? • Commissaries • Adult & Youth Go online to Hawaii • Exchanges Education Military Guide’s • Golf • Trustworthy digital edition. • Lodging Businesses Full of tips on arrival, • Recreation base maps, phone • MWR numbers, and websites. HawaiiMilitaryGuide.com 4 Map of Oahu . 10 Honolulu International Airport . 14 Arrival . 22 Military Websites . 46 Pets in Paradise . 50 Transportation . 56 Youth Education . 64 Adult Education . 92 Health Care . 106 Recreation & Activities . 122 Beauty & Spa . 134 Weddings. 138 Dining . 140 Waikiki . 148 Downtown & Chinatown . 154 Ala Moana & Kakaako . 158 Aiea/West Honolulu . 162 Pearl City & Waipahu . 166 Kapolei & Ko Olina Resort . 176 Mililani & Wahiawa . 182 North Shore . 186 Windward – Kaneohe . 202 Windward – Kailua Town . 206 Neighbor Islands . 214 6 PMFR Barking Sands,Kauai . 214 Aliamanu Military Reservation . 218 Bellows Air Force Station . 220 Coast Guard Base Honolulu . 222 Fort DeRussy/Hale Koa . 224 Fort Shafter . 226 Joint Base Pearl Harbor-Hickam . 234 MCBH Camp Smith . 254 MCBH Kaneohe Bay . 258 NCTAMS PAC (JBPHH Wahiawa Annex) . 266 Schofield Barracks . 268 Tripler Army Medical Center . 278 Wheeler Army Airfield . 282 COVID-19 DISCLAIMER Some information in the Guide may be compromised due to changing circumstances. It is advisable to confirm any details by checking websites or calling Military Information at 449-7110. HAWAII MILITARY GUIDE Publisher ............................Charles H.
    [Show full text]
  • Igneous Rocks and Their Origin
    IIggnneeoouuss RRocockkss aanndd ThTheeiirr OOrigrigiinn Chapter 5 Three Types of Rocks • Igneous rocks - Formed from volcanic eruptions - either external or internal • Sedimentary rocks - Formed from erosional processes • Metamorphic rocks - Deforming of rocks above from exposure to high pressure and temperature The Rock Cycle • A rock is composed of grains of one or more minerals • The rock cycle shows how one type of rocky material is transformed into ano ther Igneous Rocks Extrusive igneous rocks form when lava erupts at the surface. Igneous extrusion (lava) The resulting rock is fine-grained or has a glassy texture. Basalt Igneous Rocks Igneous intrusion Intrusive igneous rocks form when magma intrudes into unmelted rock masses. Granite The slow cooling process produces coarsely grained rocks. How do we Know Igneous Rocks Formed at Depth? Torres del Paine, Chile • Mineralogy / Chemistry ? • Grain size (coarse vs fine grained) • Lab expmts require high P & T to form large grains • Outcrops: See intrusions into country rock -Contact/chill zones, baked and metamorphosed • Xenoliths of country rock found in igneous intrusions Igneous Rock Identification • Igneous rock names are based on texture (grain size) and composition • Textural classification – Coarse-grained: Plutonic rocks (gabbro-diorite-granite) cooled slowly at depth – Fine-Grained: Volcanic rocks (basalt-andesite-rhyolite) cooled rapidly at the Earth’s surface • Compositional classification – Mafic rocks (gabbro-basalt) contain dark-colored ferromagnesian minerals, iron rich
    [Show full text]
  • Landslides and the Weathering of Granitic Rocks
    Geological Society of America Reviews in Engineering Geology, Volume III © 1977 7 Landslides and the weathering of granitic rocks PHILIP B. DURGIN Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Berkeley, California 94701 (stationed at Arcata, California 95521) ABSTRACT decomposition, so they commonly occur as mountainous ero- sional remnants. Nevertheless, granitoids undergo progressive Granitic batholiths around the Pacific Ocean basin provide physical, chemical, and biological weathering that weakens examples of landslide types that characterize progressive stages the rock and prepares it for mass movement. Rainstorms and of weathering. The stages include (1) fresh rock, (2) core- earthquakes then trigger slides at susceptible sites. stones, (3) decomposed granitoid, and (4) saprolite. Fresh The minerals of granitic rock weather according to this granitoid is subject to rockfalls, rockslides, and block glides. sequence: plagioclase feldspar, biotite, potassium feldspar, They are all controlled by factors related to jointing. Smooth muscovite, and quartz. Biotite is a particularly active agent in surfaces of sheeted fresh granite encourage debris avalanches the weathering process of granite. It expands to form hydro- or debris slides in the overlying material. The corestone phase biotite that helps disintegrate the rock into grus (Wahrhaftig, is characterized by unweathered granitic blocks or boulders 1965; Isherwood and Street, 1976). The feldspars break down within decomposed rock. Hazards at this stage are rockfall by hyrolysis and hydration into clays and colloids, which may avalanches and rolling rocks. Decomposed granitoid is rock migrate from the rock. Muscovite and quartz grains weather that has undergone granular disintegration. Its characteristic slowly and usually form the skeleton of saprolite.
    [Show full text]
  • Geologic Guide to Stone Mountain Park
    GEOLOGIC GUIDE TO STONE MOUNTAIN PARK by Robert L. Atkins and Lisa G. Joyce Georgia Department of Natural Resources Georgia Geologic Survey GEOLOGIC GUIDE 4 Common Misconceptions About Stone Mountain An average of four million people visit Stone Mountain Park each year. Very little geologic information is available to these visitors. With this lack of information, some misconceptions have developed concerning Stone Moun­ tain and the granite named after the mountain. Several of these misconcep­ tions are discussed below. MYTH 1: Stone Mountai n granite underlies half of Georgia, all of Geor­ gia, three states, seven states, etc. FACT: The Stone Mountain Granite is a relatively small unit. It extends northward to U.S. 78, southward to the park boundary, and its western contact lies within the park limits. It extends eastward towards C enterville (see Geologic Map of the Stone Mountain Area, p. 12-13). MYTH 2: Stone Mountain is the largest exposed granite outcrop in the world. FACT: Stone Mountain's size is quite inspiring. It probably is the largest granite dome east of the Mississippi River, as it rises approxi­ mately 750 feet (ft) above the surrounding topography; how­ ever, it is not the largest dome in the world. Many granite domes in the Sierras in the western United States are larger. MYTH 3: Stone Mountain is 300 million years old. FACT: The granite that forms Stone Mountain is approximately 300 million years old, but the mountain itself has only been exposed for approximately 15 million years. MYTH 4: Stone Mountain used to be a volcano. FACT: Although Stone Mountain Granite, like all other granites, is igneous in origin, it was formed quite differently from a volcano.
    [Show full text]
  • Geologic Interpretation of Floodplain Deposits of the Southwestern
    Geologic Interpretation of Floodplain Deposits of the Southwestern Willamette Valley, T17SR4W With Some Implications for Restoration Management Practices Eugene, Oregon Michael James, James Geoenvironmental Services Karin Baitis, Eugene District BLM JULY 2003 TABLE OF CONTENTS Page EXECUTIVE SUMMARY i ACKNOWLEDGEMENTS 1 CHAPTER 1 INTRODUCTION 1 Location 2 CHAPTER 2 WEST EUGENE GEOLOGIC BACKGROUND 9 CHAPTER 3 RESULTS 15 3.1 MAPPING 15 3.1.1Stratigraphic and Soil Investigation 15 3.1.2 Chronology of Lithologic Units: Radiocarbon Dating and Paleopedology 17 3.1.3 Summary 23 3.2 CHARACTERIZATION OF SEDIMENTS 24 3.2.1 Textural and Sedimentological Analysis 24 3.3 MINERALOGY 26 3.3.1 Soil 26 3.3.2 Tephra Analysis 32 3.3.3 Clay XRD 33 3.3.4 Summary 38 3.4 MINERAL CHEMISTRY 40 3.4.1 Microprobe and Neutron Activation Analysis 40 3.4.2 Trace Elements 48 3.4.3 Summary 52 3.5 SURFACE AND SOIL WATER CONDUCTIVITY 53 3.5.1 General Experiment Design 53 3.5.2 Amazon Creek and Area Stream Conductivities 58 3.5.3 Soil/Water Conductivity 60 3.5.4 Ion Chromatography of Soil Profiles--Paul Engelking 60 3.5.5 Summary 61 3.6 RESTORATION TREATMENT SOIL CONDUCTIVITY ANALYSES 62 3.6.1 Conductivity and Ion Chromatography 62 3.6.2 Nutrient Tests 65 3.6.3 Summary 66 CHAPTER 4 CONCLUSIONS AND RECOMMENDATIONS 68 4.1 Conclusions 68 4.2 Recommendations 71 REFERENCES 73 Appendix A Soil Descriptions Appendix B Soil Photographs with Descriptions Appendix C Stratigraphic Columns Appendix D Textural and Mineralogic Table Appendix E XRD Appendix F Neutron Activation Appendix G Soil and Water Conductivity Appendix H Soil Treatment Conductivity EXECUTIVE SUMMARY A three-and-one-half mile, NW-SE transect of soil auger borings was done in West Eugene from Bailey Hill Rd to Oak Knoll across parcels that make up part of the West Eugene Wetlands.
    [Show full text]
  • Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska
    no O lca bs o er V v a a k t o s r a y l A U S S G G S G - AD UAF/GI - Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska Scientific Investigations Report 2008-5159 U.S. Department of the Interior U.S. Geological Survey The Alaska Volcano Observatory (AVO) was established in 1988 to monitor dangerous volcanoes, issue eruption alerts, assess volcano hazards, and conduct volcano research in Alaska. The cooperating agencies of AVO are the U.S. Geological Survey (USGS), the University of Alaska Fairbanks Geophysical Institute (UAFGI) , and the Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO also plays a key role in notification and tracking eruptions on the Kamchatka Peninsula of the Russian Far East as part of a formal working relationship with the Kamchatkan Volcanic eruptions Response Team. Cover: Lava flows from a 20th-century eruption drape the south flank of Gareloi’s South Peak crater. The white zone on the crater headwall is an extensive fumarole field. Photograph by R.G. McGimsey, August 2003. Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska By Michelle L. Coombs, Robert G. McGimsey, and Brandon L. Browne Scientific Investigations Report 2008–5159 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Reston, Virginia: 2008 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS--the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S.
    [Show full text]
  • Chapter 3 Intrusive Igneous Rocks
    Chapter 3 Intrusive Igneous Rocks Learning Objectives After carefully reading this chapter, completing the exercises within it, and answering the questions at the end, you should be able to: • Describe the rock cycle and the types of processes that lead to the formation of igneous, sedimentary, and metamorphic rocks, and explain why there is an active rock cycle on Earth. • Explain the concept of partial melting and describe the geological processes that lead to melting. • Describe, in general terms, the range of chemical compositions of magmas. • Discuss the processes that take place during the cooling and crystallization of magma, and the typical order of crystallization according to the Bowen reaction series. • Explain how magma composition can be changed by fractional crystallization and partial melting of the surrounding rocks. • Apply the criteria for igneous rock classification based on mineral proportions. • Describe the origins of phaneritic, porphyritic, and pegmatitic rock textures. • Identify plutons on the basis of their morphology and their relationships to the surrounding rocks. • Explain the origin of a chilled margin. 65 Physical Geology - 2nd Edition 66 Figure 3.0.1 A fine-grained mafic dyke (dark green) intruded into a felsic dyke (pink) and into coarse diorite (grey), Quadra Island, B.C. All of these rocks are composed of more than one type of mineral. The mineral components are clearly visible in the diorite, but not in the other two rock types. A rock is a consolidated mixture of minerals. By consolidated, we mean hard and strong; real rocks don’t fall apart in your hands! A mixture of minerals implies the presence of more than one mineral grain, but not necessarily more than one type of mineral (Figure 3.0.1).
    [Show full text]