DOCSLIB.ORG

Late Miocene Exhumation and Uplift of the Washington Cascade Range

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Late Miocene Exhumation and Uplift of the Washington Cascade Range Late Miocene exhumation and uplift of the Washington Cascade Range Peter W. Reiners Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511, USA Todd A. Ehlers Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA John I. Garver Department of Geology, Union College, Schenectady, New York 12308, USA Sara Gran Mitchell Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, David R. Montgomery USA Joseph A. Vance Stefan Nicolescu Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511, USA ABSTRACT olith (Erikson, 1969; Tabor et al., 2000). Da- The Washington Cascade Range is a complex, polygenetic mountain range that domi- citic intrusions with 4±8 Ma ages are also pre- nates the topographic, climatic, and cultural con®gurations of Washington State. Although sent northeast of Mount Rainier (Armstrong et it has been the locus of ongoing arc magmatism since the Eocene, most of the range is al., 1976; Smith et al., 1989; P.E. Hammond, distinct from the southern part of the arc in Oregon and California in that bedrock uplift 2002, personal commun.), although our sam- has produced high surface elevations and topographic relief, rather than volcanic burial ples were collected tens of kilometers away or edi®ce construction. (U-Th)/He and ®ssion-track ages of bedrock samples on the east from these intrusions. In the north Cascades ¯ank of the range record relatively rapid cooling in the early Tertiary, but slow exhu- region, apatite ®ssion-track ages of samples mation rates (;0.2 km/m.y.) through most of the Oligocene. Samples on the west ¯ank may have been affected by the 16±18 Ma suggest rapid cooling in the late Miocene (8±12 Ma), and age variations in vertical tran- Mount Barr pluton (Holunga, 1996) or Chil- sects are consistent with a pulse of rapid exhumation (0.5±1.0 km/m.y.) at that time. Ap- liwack batholith or younger intrusions near atite He ages as young as 1±5 Ma in several areas suggest that high cooling and possibly Mount Baker. In most of our samples, how- exhumation rates persist locally. Accelerated exhumation rates ca. 10 Ma are also observed ever, apatite He ages are signi®cantly younger in the Coast Mountains of British Columbia and southeast Alaska, ;1500 km to the north, (by at least 5±10 m.y.) than higher tempera- suggesting a large-scale mechanism for the exhumation pulse at that time. ture ages of intrusions, suggesting that in most cases apatite He ages re¯ect cooling primarily Keywords: (U-Th)/He, thermochronology, apatite, Cascades, Washington. by surface erosion. INTRODUCTION for sample locations, data, and analytical de- RESULTS AND DISCUSSION The Cascade Range in Washington State tails1) from plutonic and metamorphic rocks West Flank and North Cascades Regions (Fig. 1) forms an important regional geologic, in three regions in the Washington (and south- Apatite and zircon (U-Th)/He and ®ssion- climatic, and cultural boundary. Numerous ern British Columbia) Cascade Range, here track ages are plotted against elevation in Fig- studies focusing on the high-temperature geo- termed the west ¯ank, east ¯ank, and north ure 2 (see footnote 1). In the west ¯ank and logic history (especially of the northern part of Cascades regions (Fig. 1). Samples along ver- north Cascades sample groups, apatite He ages the range) have documented a series of terrane- tical transects of ;1.1 and 1.7 km of relief do not vary systematically with elevation, and accretion episodes in the Cretaceous and Eo- over distances of ,;5 km were collected in nearly all are between 6 and 12 Ma. Excep- tions are a sample from near the town of Index cene, accompanied by crustal thickening, plu- the east and west ¯ank groups; a shorter ;0.8 at 13.5 Ma, two samples from northeast of tonism, and large-scale strike-slip faulting km transect was collected across an ;25 km Mount Rainier at 5 Ma, and samples from the (e.g., Haugerud et al., 1994; Cowan et al., distance in the north Cascades region. 2.5 6 0.1 Ma Lake Ann pluton (James, 1979) 1997; Whitney et al., 1999). As is the case Use of low-temperature thermochronome- at 1.3±2.0 Ma. Assuming geothermal gradi- farther south in Oregon and California, east- ters (closure temperatures ;70±180 8C) re- ents between 20 and 40 8C, the abundant 6± directed subduction has been ongoing off the quires consideration of potential spatial and 12 Ma apatite He ages in the north Cascades coast of Washington since ca. 40 Ma, resulting temporal variations in geothermal gradients. and west ¯ank regions require that at least in locally thick accumulations (3±5 km) of Modern gradients in most locations in the 1.5±3 km of crust have been eroded from the volcanic rocks with ages dominantly between Washington Cascade Range north of Mount Rainier are 20±40 8C/km with regionally surface since that time. The steep age- 15 and 36 Ma. Aside from ®ve Quaternary elevation correlations and scatter in both sam- stratovolcanoes however, little of the modern higher gradients largely restricted to a narrow zone between Mount St. Helens and Mount ple groups do not allow precise constraints on topographic expression of the Washington Adams (Blackwell et al., 1990). However, apparent exhumation rates in these regions, Cascade Range is due to volcanism. Instead, geothermal gradients at the time of cooling but if the Granite Mountain ages in the west the bedrock geology north of Snoqualmie Pass through apatite He and apatite ®ssion-track ¯ank group are due primarily to cooling by is dominated by crystalline rocks uplifted rel- closure temperatures may have been higher in exhumation (rather than magmatic cooling of ative to the surrounding Puget lowlands and some areas, especially in the west ¯ank region the Snoqualmie batholith), they indicate an Columbia basin. Indirect evidence, such as in and near the 17±25 Ma Snoqualmie bath- apparent exhumation rate of 0.5±1.0 km/m.y. warping of ca. 15±16 Ma Columbia River Ba- (Fig. 2). The much older apatite ®ssion-track salt Group lavas, suggests that at least some 1GSA Data Repository item 2002088, Apatite and age at a high elevation (43 Ma) in the west of this uplift is younger than middle Miocene. zircon (U-Th)/He and apatite ®ssion-track sample lo- ¯ank, however, limits total post-Eocene ero- We determined apatite and zircon (U-Th)/ cations, data, and analytical methods, is available from Documents Secretary, GSA, P.O. Box 9140, sion to ,;3±5 km. Differences between ap- He and apatite ®ssion-track ages (see GSA Boulder, CO 80301-9140, [email protected], or atite ®ssion-track and apatite He ages in the Data Repository supplementary information at www.geosociety.org/pubs/ft2002.htm. north Cascades group suggest that prior to the q 2002 Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or [email protected]. Geology; September 2002; v. 30; no. 9; p. 767±770; 3 ®gures; Data Repository item 2002088. 767 Figure 1. Map of Washington Cascade Range and surrounding region. Boxes en- Figure 2. (U-Th)/He and apatite ®ssion-track close three primary sample regions, and blue lines enclose speci®c regions, re- (AFT) ages of Washington (and southern ferred to in text, Figure 2, and GSA Data Repository item (see text footnote 1). British Columbia) Cascade Range samples, MSBÐMount Stuart batholith. Quaternary volcanoes of or near modern arc: MGÐ plotted against elevation. Error bars are 2s Mount Garibaldi, MBÐMount Baker, GPÐGlacier Peak, MRÐMount Rainier, MSHÐ for (U-Th)/He and 1s for AFT. See text foot- Mount St. Helens, IHÐIndian Heaven volcanic ®eld, MAÐMount Adams, SIMÐ note 1 for detailed data tabulation. MSBÐ Simcoe. Mount Stuart batholith, FOJÐFourth of July; a.s.l.Ðabove sea level. late Miocene, cooling and most likely exhu- These old cooling ages require that at least mation rates were relatively slow, ;0.05±0.2 locally on the east ¯ank, exhumation was gions with 2 km of local relief are generally km/m.y., depending on geothermal gradients. limited to ,;2±3 km since the early Tertia- subject to mean erosion rates of at least ;0.4 If the Granite Mountain transect re¯ects 0.5± ry. Most apatite ®ssion-track ages of east km/m.y. (e.g., Pazzaglia and Brandon, 1996). 1.0 km/m.y. exhumation at 10±12 Ma, exhu- ¯ank samples are relatively old, between 41 If this is the case on the east ¯ank of the Cas- mation rates must have since decreased by at and 83 Ma. With the exception of one sample, cades, these high exhumation rates could not least a factor of 2±4, because such rates would these ages are an average of 33 m.y., and a have begun earlier than ca. 8 Ma, because old produce ages of 2±4 Ma if ongoing today. minimum of 20 m.y., older than apatite He cooling ages at high elevations in this region ages on the same samples or on samples at limit total erosion to ,;3 km. Thus the in- East Flank Region similar elevations. These age differences re- ferred late Miocene uplift that affected the In the east ¯ank region, apatite He ages quire slow time-averaged cooling (1±2 8C/m.y.) west ¯ank may have also increased relief and range from 18 to 60 Ma and show a broad between apatite ®ssion-track and apatite He surface uplift on the east ¯ank. correlation with elevation, especially within closure in the early to mid-Tertiary (exhuma- the 1.7 km Fourth of July vertical transect tion rates of only ;0.02±0.10 km/m.y.)Ð Late Miocene Uplift (Fig.
Load more

Recommended publications
  • Mount Rainier National Park
    MOUNT RAINIER NATIONAL PARK • WASHINGTON • UNITED STATES DEPARTMENT OF THE INTERIOR NATIONAL PARK SERVICE Mount Rainier [WASHINGTON] National Park United States Department of the Interior Harold L. Ickes, Secretary NATIONAL PARK SERVICE Arno B. Cammerer, Director UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1936 Rules and Regulations [BRIEFED] Events kjERVING a dual purpose, park regulations are designed for the comfort and convenience of visitors as well as for the protection of natural beauties OF HISTORICAL IMPORTANCE and scenery. The following synopsis is for the guidance of visitors, who are requested to assist the park administration by observing the rules. Complete rules and regulations may be seen at the superintendent's office 1792 May 8. The first white man to sec "The Mountain" (Capt. and at ranger stations. George Vancouver, of the Royal English Navy) sighted Fires. the great peak and named it Mount Rainier. Light carefully and in designated places. Extinguish COMPLETELY before leaving 1833 September 2. Dr. William Eraser Tolmie of Nisqually camp, even for temporary absence. Do not guess your fire is out—KNOW it. Do not House, a Hudson's Bay post, entered the northwest corner throw burning tobacco or matches on road or trail sides. of what is now the park. He was the first white man to penetrate this region. Camps. Keep your camp clean. As far as possible burn garbage in camp fire, and empty 1857 July. Lieut. A. V. Kautz, of the United States Army garri­ son at Fort Steilacoom, and four companions made the cans and residue into garbage cans provided. If no can is provided, bury the refuse.
    [Show full text]
  • North Cascades Contested Terrain
    North Cascades NP: Contested Terrain: North Cascades National Park Service Complex: An Administrative History NORTH CASCADES Contested Terrain North Cascades National Park Service Complex: An Administrative History CONTESTED TERRAIN: North Cascades National Park Service Complex, Washington An Administrative History By David Louter 1998 National Park Service Seattle, Washington TABLE OF CONTENTS adhi/index.htm Last Updated: 14-Apr-1999 http://www.nps.gov/history/history/online_books/noca/adhi/[11/22/2013 1:57:33 PM] North Cascades NP: Contested Terrain: North Cascades National Park Service Complex: An Administrative History (Table of Contents) NORTH CASCADES Contested Terrain North Cascades National Park Service Complex: An Administrative History TABLE OF CONTENTS Cover Cover: The Southern Pickett Range, 1963. (Courtesy of North Cascades National Park) Introduction Part I A Wilderness Park (1890s to 1968) Chapter 1 Contested Terrain: The Establishment of North Cascades National Park Part II The Making of a New Park (1968 to 1978) Chapter 2 Administration Chapter 3 Visitor Use and Development Chapter 4 Concessions Chapter 5 Wilderness Proposals and Backcountry Management Chapter 6 Research and Resource Management Chapter 7 Dam Dilemma: North Cascades National Park and the High Ross Dam Controversy Chapter 8 Stehekin: Land of Freedom and Want Part III The Wilderness Park Ideal and the Challenge of Traditional Park Management (1978 to 1998) Chapter 9 Administration Chapter 10 http://www.nps.gov/history/history/online_books/noca/adhi/contents.htm[11/22/2013
    [Show full text]
  • Cascades Butterfly Project North Cascades National Park Resource Brief - 2011
    CASCADES BUTTERFLY PROJECT NORTH CASCADES NATIONAL PARK RESOURCE BRIEF - 2011 Cascades Butterfly Project Climate change is expected to affect mountain ecosystems in many ways. Scientists predict that warmer summers may result in earlier snowmelt, more frequent forest fires, and changes in distributions of plants and animals. Although some ecosystem changes have already been observed, (e.g. melting glaciers), many future impacts remain uncertain. Monitoring provides a way to document ecosystem changes, anticipate future changes, and improve management of protected lands. Butterflies are sensitive indicators of butterflies are able to fly to higher eleva- climate change because temperature tions in response to warming tempera- influences the timing of an individual’s tures, will they be able to establish as life cycle and the geographic distribu- breeding residents? Will host plants be tion of species. As individuals develop able to migrate up quickly enough to from egg to larvae to pupae and finally support butterfly populations, or will to mature butterfly, temperature thresh- some species become extinct? olds may trigger these changes. Annual temperature patterns are often the What are we doing? primary determinant of the distribution Six protected areas in the Cascade of “generalist” butterflies. Generalist Mountains are establishing a program butterflies are species that can utilize to monitor butterflies to learn how cli- many different plant species for nectar, mate is affecting their populations. The larval development, and egg deposition. six areas include four sites in Washing- Specialist butterflies depend on a few ton: North Cascades National Park, plant species for food and development Mount Baker-Snoqualmie National and they can be directly and indirectly Forest, Okanagan-Wenatchee National influenced by climate (temperature and Forest, and Mount Rainier National precipitation).
    [Show full text]
  • Most Impaired" Coral Reef Areas in the State of Hawai'i
    Final Report: EPA Grant CD97918401-0 P. L. Jokiel, K S. Rodgers and Eric K. Brown Page 1 Assessment, Mapping and Monitoring of Selected "Most Impaired" Coral Reef Areas in the State of Hawai'i. Paul L. Jokiel Ku'ulei Rodgers and Eric K. Brown Hawaii Coral Reef Assessment and Monitoring Program (CRAMP) Hawai‘i Institute of Marine Biology P.O.Box 1346 Kāne'ohe, HI 96744 Phone: 808 236 7440 e-mail: [email protected] Final Report: EPA Grant CD97918401-0 April 1, 2004. Final Report: EPA Grant CD97918401-0 P. L. Jokiel, K S. Rodgers and Eric K. Brown Page 2 Table of Contents 0.0 Overview of project in relation to main Hawaiian Islands ................................................3 0.1 Introduction...................................................................................................................3 0.2 Overview of coral reefs – Main Hawaiian Islands........................................................4 1.0 Ka¯ne‘ohe Bay .................................................................................................................12 1.1 South Ka¯ne‘ohe Bay Segment ...................................................................................62 1.2 Central Ka¯ne‘ohe Bay Segment..................................................................................86 1.3 North Ka¯ne‘ohe Bay Segment ....................................................................................94 2.0 South Moloka‘i ................................................................................................................96 2.1 Kamalō
    [Show full text]
  • National Endowment for the Arts Annual Report 1982
    Nat]onal Endowment for the Arts National Endowment for the Arts Washington, D.C. Dear Mr. President: I have the honor to submit to you the Annual Report of the National Endowment for the Arts and the National Council on the Arts for the Fiscal Year ended September 30, 1982. Respectfully, F. S. M. Hodsoll Chairman The President The White House Washington, D.C. March 1983 Contents Chairman’s Statement 3 The Agency and Its Functions 6 The National Council on the Arts 7 Programs 8 Dance 10 Design Arts 30 Expansion Arts 46 Folk Arts 70 Inter-Arts 82 International 96 Literature 98 Media Arts: Film/Radio/Television 114 Museum 132 Music 160 Opera-Musical Theater 200 Theater 210 Visual Arts 230 Policy, Planning and Research 252 Challenge Grants 254 Endowment Fellows 259 Research 261 Special Constituencies 262 Office for Partnership 264 Artists in Education 266 State Programs 272 Financial Summary 277 History of Authorizations and Appropriations 278 The descriptions of the 5,090 grants listed in this matching grants, advocacy, and information. In 1982 Annual Report represent a rich variety of terms of public funding, we are complemented at artistic creativity taking place throughout the the state and local levels by state and local arts country. These grants testify to the central impor­ agencies. tance of the arts in American life and to the TheEndowment’s1982budgetwas$143million. fundamental fact that the arts ate alive and, in State appropriations from 50 states and six special many cases, flourishing, jurisdictions aggregated $120 million--an 8.9 per­ The diversity of artistic activity in America is cent gain over state appropriations for FY 81.
    [Show full text]
  • New Titles for Spring 2021 Green Trails Maps Spring
    GREEN TRAILS MAPS SPRING 2021 ORDER FORM recreation • lifestyle • conservation MOUNTAINEERS BOOKS [email protected] 800.553.4453 ext. 2 or fax 800.568.7604 Outside U.S. call 206.223.6303 ext. 2 or fax 206.223.6306 Date: Representative: BILL TO: SHIP TO: Name Name Address Address City State Zip City State Zip Phone Email Ship Via Account # Special Instructions Order # U.S. DISCOUNT SCHEDULE (TRADE ONLY) ■ Terms: Net 30 days. 1 - 4 copies ........................................................................................ 20% ■ Shipping: All others FOB Seattle, except for orders of 25 books or more. FREE 5 - 9 copies ........................................................................................ 40% SHIPPING ON BACKORDERS. ■ Prices subject to change without notice. 10 - 24 copies .................................................................................... 45% ■ New Customers: Credit applications are available for download online at 25 + copies ................................................................45% + Free Freight mountaineersbooks.org/mtn_newstore.cfm. New customers are encouraged to This schedule also applies to single or assorted titles and library orders. prepay initial orders to speed delivery while their account is being set up. NEW TITLES FOR SPRING 2021 Pub Month Title ISBN Price Order February Green Trails Mt. Jefferson, OR No. 557SX 9781680515190 18.00 _____ February Green Trails Snoqualmie Pass, WA No. 207SX 9781680515343 18.00 _____ February Green Trails Wasatch Front Range, UT No. 4091SX 9781680515152 18.00 _____ TOTAL UNITS ORDERED TOTAL RETAIL VALUE OF ORDERED An asterisk (*) signifies limited sales rights outside North America. QTY. CODE TITLE PRICE CASE QTY. CODE TITLE PRICE CASE WASHINGTON ____ 9781680513448 Alpine Lakes East Stuart Range, WA No. 208SX $18.00 ____ 9781680514537 Old Scab Mountain, WA No. 272 $8.00 ____ ____ 9781680513455 Alpine Lakes West Stevens Pass, WA No.
    [Show full text]
  • Information Circular 41: Origin of Cascade Landscapes
    111ackin I CdrlJ .rc-1J ORIGIN OF CASCADE LANDSCAPES ---=-~--=---------=---- FRONTISPIECE Picket Range in upper Skagit area, Northern Cascade Mountains. Snowfields occupy a former ice-filled cirque. Grass is enroaching on ice-polished rock surfaces. State of Washington DANIEL J. EVANS, Governor Department of Conservation ROY MUNDY, Director DIVISION OF MINES AND GEOLOGY MARSHALL T. HUNTTING, SupervisoT Information Circular No. 41 ORIGIN OF CASCADE LANDSCAPES By J. HOOVER MACKIN and ALLENS. CARY STATE PRINTING PLANT, OLYMPIA, WASHINGTON 1965 For sale by Department of Conservation, Olympia, Washington. Price, 50 cents. FOREWORD The Cascade Range has had an important influence on the lives of a great many people ever since man has inhabited the Northwest. The mountains were a barrier to Indian travel; they were a challenge to the westward migration of the early settlers in the area; they posed serious problems for the early railroad builders; and they still constitute an obstruction to east-west travel. A large part of the timber, mineral, and surface water resources of the State come from the Cascades. About 80 percent of the area covered by glaciers in the United States, exclusive of Alaska, is in the Cascades of Washington. This region includes some of the finest mountain scenery in the country and is a popular outdoor recreation area. The Cascade Range is a source of economic value to many, a source of pleasure to many others, and a problem or source of irritation to some. Regardless of their reactions, many people have wondered about the origin of the mountains­ How and when did the Cascades come into being, and what forces were responsible for the construction job? -This report, "Origin of Cascade Landscapes," gives the answers to these questions.
    [Show full text]
  • Mt. Baker Ski Area
    Winter Activity Guide Mount Baker Ranger District North Cascades National Park Contacts Get ready for winter adventure! Head east along the Mt. Baker Mt. Baker-Snoqualmie National Forest State Road Conditions: /Mt. Baker Ranger District Washington State Dept. of Transportation Highway to access National Forest 810 State Route 20 Dial 511 from within Washington State lands and the popular Mt. Baker Ski Sedro-Woolley, WA 98284 www.wsdot.wa.gov Area. Travel the picturesque North (360) 856-5700 ext. 515 Glacier Public Service Center Washington State Winter Recreation and Cascades Highway along the Skagit 10091 Mt. Baker Highway State Sno-Park Information: Wild & Scenic River System into the Glacier, WA 98244 www.parks.wa.gov/winter heart of the North Cascades. (360) 599-2714 http://www.fs.usda.gov/mbs Mt. Baker Ski Area Take some time for winter discovery but North Cascades National Park Service Ski Area Snow Report: be aware that terrain may be challenging Complex (360) 671-0211 to navigate at times. Mountain weather (360) 854-7200 www.mtbaker.us conditions can change dramatically and www.nps.gov/noca with little warning. Be prepared and check Cross-country ski & snowshoe trails along the Mt. Baker Highway: forecasts before heading out. National Weather Service www.weather.gov www.nooksacknordicskiclub.org Northwest Weather & Avalanche For eagle watching information visit: Travel Tips Center: Skagit River Bald Eagle Interpretive Center Mountain Weather Conditions www.skagiteagle.org • Prepare your vehicle for winter travel. www.nwac.us • Always carry tire chains and a shovel - practice putting tire chains on before you head out.
    [Show full text]
  • Chapter 15 Comparative Phylogeography of North- Western North America: a Synthesis
    Chapter 15 Comparative phylogeography of north- western North America: a synthesis S. J. Brunsfeld,* J. Sullivan,†D. E. Soltis‡and P. S. Soltis§ Introduction Phylogeography is concerned with the principles and processes that determine the geographic distributions of genealogical lineages, within and among closely related species (Avise et al. 1987;Avise 2000).Although this field of study is very new (only a little more than a decade has passed since the term ‘phylogeography’was first coined; see Avise et al. 1987),the scientific literature in this research area is now voluminous. To date, most phylogeographic investigations of natural populations have focused on muticellular animals (Hewitt 1993; Patton et al. 1994; daSilva & Patton 1998; Eizirik et al. 1998;Avise 2000; Hewitt 2000; Schaal & Olsen 2000; Sullivan et al. 2000). This bias is due in large part to the ready availability of population-level genetic markers afforded by the animal mitochondrial genome. The more slowly evolving chloroplast genome,in contrast,often does not provide sufficient variation to reconstruct phylogeny at the populational level (Soltis et al. 1997; Schaal et al. 1998; Schaal & Olsen 2000). Phylogeographic data have accumulated so rapidly for animal taxa that it has been possible to compare phylogeographic structure among codistributed species. In fact, one of the most profound recent contributions of molecular phylogeography is the construction of regional phylogeographic perspec- tives that permit comparisons of phylogeographic structure among codistributed species, and subsequent integration of genealogical data with independent biogeo- graphic and systematic data. Probably the best-known regional phylogeographic analysis for North America involves animals from the southeastern USA (reviewed in Avise 2000).
    [Show full text]
  • Part 629 – Glossary of Landform and Geologic Terms
    Title 430 – National Soil Survey Handbook Part 629 – Glossary of Landform and Geologic Terms Subpart A – General Information 629.0 Definition and Purpose This glossary provides the NCSS soil survey program, soil scientists, and natural resource specialists with landform, geologic, and related terms and their definitions to— (1) Improve soil landscape description with a standard, single source landform and geologic glossary. (2) Enhance geomorphic content and clarity of soil map unit descriptions by use of accurate, defined terms. (3) Establish consistent geomorphic term usage in soil science and the National Cooperative Soil Survey (NCSS). (4) Provide standard geomorphic definitions for databases and soil survey technical publications. (5) Train soil scientists and related professionals in soils as landscape and geomorphic entities. 629.1 Responsibilities This glossary serves as the official NCSS reference for landform, geologic, and related terms. The staff of the National Soil Survey Center, located in Lincoln, NE, is responsible for maintaining and updating this glossary. Soil Science Division staff and NCSS participants are encouraged to propose additions and changes to the glossary for use in pedon descriptions, soil map unit descriptions, and soil survey publications. The Glossary of Geology (GG, 2005) serves as a major source for many glossary terms. The American Geologic Institute (AGI) granted the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) permission (in letters dated September 11, 1985, and September 22, 1993) to use existing definitions. Sources of, and modifications to, original definitions are explained immediately below. 629.2 Definitions A. Reference Codes Sources from which definitions were taken, whole or in part, are identified by a code (e.g., GG) following each definition.
    [Show full text]
  • Washington Division of Geology and Earth Resources Open File Report
    OF~ 76-~ PETR)3ENFSIS OF THE MXJNT STUART BATHOLITH PID:rrnIC EQJI\7ALENT OF THE HIGH-AIJ.JMINA BASALT ASSO:IATION by Erik H. Erikson Jr. Depart:rrent of Geology Eastern Washington State College Cheney ,Wc::.shington 99004 June 1, 1976 Abstract. The 1-bunt Stuart batholith is a Late Cretaceous calc-alkaline pluton · . canposed of intrusive phases ranging in canposition fran two-pyroxene gabbro to granite. This batholith appears to represent the plutonic counterpart of the high-alumina basalt association. Mineralogical, petrological and chrono­ logical characteristics are consistent with a m:::rlel in which the intrusive series evolved fran one batch of magnesian high-alumina basalt by successive crystal fractionation of ascending residual magrna. ' canputer m:::rleling of this intrusive sequence provides a quanti- tative evaluation of the sequential change of magrna CCIIlfX)sition. These calculations indicate that this intrusive suite is consanguineous, and that subtraction of early-fonned crystals £ran the oldest magrna is capable of reprcducing the entire magrna series with a remainder of 2-3% granitic liquid. Increasing f()tash discrepancies prcduced by the rrodeling may reflect the increasing effects of volatile transfer in progressively rrore hydrous and silicic melts. Mass-balances between the arrounts of curn-ulate and residual liquid ccnpare favorably with the observed arrounts of intenrediate rocks exposed in the batholith, but not with the mafic rocks. Ma.fie cum: ulates must lie at depth. Mafic magmas probably fractionated by crystal settling, while quartz diorite and rrore granitic magrnas underwent a process of inward crystallization producing exposed gradationally zoned plutons.Aat present erosional levels.
    [Show full text]
  • Tectonic Evolution of the Northern Sierra Nevada
    TECTONIC EVOLUTION OF THE NORTHERN SIERRA NEVADA BATHOLITH A DISSERTATION SUBMITTED TO THE DEPARTMENT OF GEOLOGICAL AND ENVIRONMENTAL SCIENCES AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Nicholas James Van Buer December 2011 © 2011 by Nicholas James Van Buer. All Rights Reserved. Re-distributed by Stanford University under license with the author. This work is licensed under a Creative Commons Attribution- Noncommercial 3.0 United States License. http://creativecommons.org/licenses/by-nc/3.0/us/ This dissertation is online at: http://purl.stanford.edu/xb187vq0064 Includes supplemental files: 1. Plate 1. Geologic Map of the Jayhawk Well 7.5' Quadrangle, Pershing County, Nevada (jayhawkwell.pdf) 2. Plate 2. Geologic Map of the Juniper Pass 7.5' Quadrangle, Pershing County, Nevada (Juniperpass.pdf) 3. Plate 3. Geologic Map of the Tohakum Peak NE 7.5' Quadrangle, Pershing County, Nevada (TohakumpkNE.pdf) 4. Plate 4. Geologic Map of the Tunnel Spring 7.5' Quadrangle, Pershing County, Nevada (tunnelspr.pdf) 5. Plate 5. Geologic Map of the Bob Spring 7.5' Quadrangle, Pershing County, Nevada (bobspring.pdf) 6. Plate 6. Geologic Map of the Tohakum Peak SE 7.5' Quadrangle, Pershing County, Nevada (TohakumpkSE.pdf) 7. Plate 7. Geologic Map of the Sage Hen Spring 7.5' Quadrangle, Pershing County, Nevada (SageHenSpr.pdf) 8. Plate 8. Geologic Map of the Bluewing Spring 7.5' Quadrangle, Pershing County, Nevada (BluewingSpr.pdf) ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy.
    [Show full text]