DOCSLIB.ORG

The Boulder Creek Batholith, Front Range, Colorado

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Boulder Creek Batholith, Front Range, Colorado I u The Boulder Creek Batholith, Front Range, Colorado By DOLORES J. GABLE GEOLOGICAL SURVEY PROFESSIONAL PAPER 1101 A study of differentiation, assimilation, and origin of a granodiorite batholith showing interrelated differences in chemistry and mineralogy in the batholith and cogenetic rock types UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1980 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director Library of Congress Cataloging in Publication Data Gable, Dolores J. 1922- The Boulder Creek batholith, Front Range, Colorado (Geological Survey Professional Paper 1101) Bibliography: p. 85 Supt. of Docs. No.: I 19.16:1101 1. Batholiths Colorado Boulder region. I. Title. II. Series: United States Geological Survey Professional Paper 1101. QE611.5.U6G3 551.8; 8 78-24482 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Page Abstract................................................ 1 Origin of the Boulder Creek Granodiorite and the Twin Introduction ............................................ 1 Spruce Quartz Monzonite .......................... 62 Previous work........................................... 2 Mineralogy, petrology, and chemistry of minerals in the Techniques used in this study ............................ 2 batholith.......................................... 64 Geologic setting ......................................... 3 Biotite ...'........................................... 64 The batholith ........................................... 3 Boulder Creek Granodiorite ....................... 64 Constitution of the batholith.......................... 4 Twin Spruce Quartz Monzonite ................... 69 Contact relations and mode of emplacement............ 6 Mafic inclusions and lamprophyre dikes in the Constituent rocks of the batholith ..................... 7 Boulder Creek Granodiorite ..................... 69 Boulder Creek Granodiorite ....................... 7 Petrogenesis .................................... 69 Inclusions in Boulder Creek Granodiorite .......... 17 Hornblende ......................................... 71 Mafic plutonic rocks ............................. 20 Boulder Creek Granodiorite ....................... 71 Gabbro and pyroxenite ....................... 23 Mafic inclusions and lamprophyre dikes in the Hornblendite, hornblende diorite, quartz Boulder Creek Granodiorite ..................... 73 diorite ..................................... 25 Hornblende diorite and hornblendite............... 73 Twin Spruce Quartz Monzonite ................... 26 Petrogenesis .................................... 73 Granite gneiss, gneissic aplite, and pegmatite ...... 34 Plagioclase .......................................... 73 Ages of batholithic rocks ......................... 35 Boulder Creek Granodiorite ....................... 73 Structure ............................................... 35 Twin Spruce Quartz Monzonite ................... 77 Geochemistry ........................................... 38 Mafic inclusions in the Boulder Creek Granodiorite . 77 Boulder Creek Granodiorite........................... 38 Potassium feldspar .................................. 77 Chemical trends within the batholith .............. 38 Boulder Creek Granodiorite ....................... 77 Mineralogy in relation to chemical trends .......... 45 Mafic inclusions and lamprophyre dikes in the Chemical trends in mafic inclusions ................ 48 Boulder Creek Granodiorite ..................... 79 Chemical trends in gabbro, pyroxenite, and horn­ Twin Spruce Quartz Monzonite ................... 79 blende diorite ................................. 50 Quartz .............................................. 79 Chemical and mineralogical trends in the Twin Accessory minerals .................................. 80 Spruce Quartz Monzonite ...................... 50 Alteration minerals .................................. 83 Chemical equilibrium in the Boulder Creek Granodiorite .... 51 Assimilation and differentiation in the Boulder Creek Grano­ References cited ......................................... 85 diorite ............................................ 52 Index................................................... 87 ILLUSTRATIONS Page PLATE 1. Generalized geologic map of the Boulder Creek batholith with emphasis on cogenetic mafic rocks in the vicinity of the Boulder Creek batholith, central Colorado ................................................................ In pocket 2. Geologic map of the Boulder Creek batholith .................................................................. In pocket FIGURE 1. Index map of the Boulder Creek batholith ....................................................................... 2 2. Photographs of typical weathered bouldery outcrops of Boulder Creek Granodiorite ................................. 4 3. Map of Boulder Creek batholith showing rock types .............................................................. 5 4. Photographs of typical Boulder Creek Granodiorite in hand specimen .............................................. 8 5. Photomicrographs of Boulder Creek Granodiorite ................................................................ 9 6. Maps showing modal distribution of quartz, ores, sphene, allanite, hornblende, and potassium feldspar: plagioclase ratiosand An content of plagioclase in Boulder Creek Granodiorite............................................. 10 7. Map and diagrams showing modal variation of quartz, plagioclase, and potassium feldspar for Boulder Creek Granodiorite .............................................................................................. 21 8. Photographs of exposures of mafic inclusions in Boulder Creek Granodiorite........................................ 22 9. Photographs of hand specimens of mafic inclusions in Boulder Creek Granodiorite .................................. 23 10. Photograph of oval-shaped lenses of Boulder Creek Granodiorite in mafic inclusion .................................. 25 11. Photomicrographs of mafic inclusions in Boulder Creek Granodiorite............................................... 26 ill IV CONTENTS Page FIGURE 12. Photographs of outcrops of layered and foliated biotitic hornblende diorite and massive pyroxenite ................... 27 13. Photomicrographs of Twin Spruce Quartz Monzonite ............................................................. 29 14. Ternary diagrams of modal variation of quartz-plagioclase-potassium feldspar for Twin Spruce Quartz Monzonite ..... 35 15. Ternary diagram of modal variation in quartz-plagioclase-potassium feldspar for granite gneiss from the granite gneiss and pegmatite unit......................................................................................... 37 16. Diagram of more prominent joint sets, Tungsten and Gold Hill quadrangles ........................................ 37 17. Sample locality map for rock and mineral analyses shown in tables in this report.................................... 49 18. Graphs of minor elements for rock units included in text.......................................................... 50 19. Variation diagrams of common oxides in Boulder Creek Granodiorite plotted against SiO2 ........................... 52 20. Variation diagrams of CaO plotted against other oxides and fluorine for Boulder Creek Granodiorite .................. 54 21. Ternary diagrams of K2O-Na2O-CaO chemical variation of Boulder Creek Granodiorite............................... 56 22. Ternary diagram of chemical variation of Boulder Creek Granodiorite expressed in terms of normative Q-Ab+An-Or... 56 23. Mole percent variation in an AFM diagram for Boulder Creek Granodiorite and mafic rocks .......................... 57 24. Diagrams of CaO content plotted against weight percent of rock-forming minerals in the Boulder Creek Granodiorite .. 58 25. Ternary plot of K2O-Na2O-CaO showing chemical variation of Twin Spruce Quartz Monzonite ........................ 59 26. Ternary plot of normative Q-Ab-f An-Or showing chemical variation of Twin Spruce Quartz Monzonite ............... 59 27. AFM diagram showing molar variation of Twin Spruce Quartz Monzonite .......................................... 59 28. Diagram of sample variation of plagioclase in relation to CaO in Twin Spruce Quartz Monzonite ...................... 59 29. Diagram of distribution of manganese in biotite and hornblende in Boulder Creek Granodiorite and hornblende diorite . 60 30. Diagram of phase relations for Boulder Creek Granodiorite in system SiO2-NaAlSi3O8-KAlSi3O8-CaAl2Si2O8-H2O ....... 62 31. Graph of strontium, rubidium, and potassium feldspar plotted against Or/Ab in Boulder Creek Granodiorite .......... 63 32. Modal biotite plotted against potassium feldspar for the batholith ................................................. 65 33. Graph of percent biotite in Boulder Creek Granodiorite and Twin Spruce Quartz Monzonite in relation to percent SiO2 in rock .................................................................................................... 65 34. Plot of compositional variations of K2O, MgO, FeO, A12O3, and SiO2 in biotites ...................................... 72 35. Graph of fluorine in biotite plotted against d(005) spacing of biotite.................................................. 72 36. Ternary diagram of relation of Fe+3-Fe+2-Mg between biotites ...................................................... 72 37. Photomicrograph of allanite and monazite crystals
Load more

Recommended publications
  • Petrographic Study of a Quartz Diorite Stock Near Superior, Pinal County, Arizona
    Petrographic study of a quartz diorite stock near Superior, Pinal County, Arizona Item Type text; Thesis-Reproduction (electronic); maps Authors Puckett, James Carl, 1940- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 23/09/2021 23:40:37 Link to Item http://hdl.handle.net/10150/554062 PETROGRAPHIC STUDY OF A QUARTZ DIORITE STOCK NEAR SUPERIOR, PINAL COUNTY, ARIZONA by James Carl Puckett, Jr. A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOLOGY In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 0 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re­ quirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judg­ ment the proposed use of the material is in the interests of scholar­ ship. In all other instances, however, permission must be obtained from the author.
    [Show full text]
  • Orvis Fishing Report Colorado
    Orvis Fishing Report Colorado Julie boondoggled emblematically if common-law Thaddeus requoting or congees. Suffocating Derron still preacquaints: amyloid and windward Marcellus quaintly,mobility quite quite bearishly self-giving. but desiccate her leucotomy hideously. Gaussian Tull counterpoise no shillelaghs analyzes monetarily after Addie craunches Best i was excited because of bug life time you can use them frequenting the parent portal or the colorado fishing should find the fishing occurs when do Get the best resource and healthy as well, as everything one can offer early season. If you can catch a honey hole because of course streamers in a hiking fishing the old sycamore ranch are. January the department cannot be in colorado and statistics of fly. We all my fly will be permanently delete this amount of orvis fishing report colorado river is available for the orvis how may! Register your big game hunting clubs and lake and share posts live, and conditions will be stripping, and basalt fly fishing? Now start seen some incredible network allows the river in the best time floating flies to the year as ironclad as they run a quick one! Brandon was really got them at orvis reports on more viable food source of these pools. The colorado is abundant hatches during my experience what sets the colorado fishing report orvis endorsed lodge guests are a northern sand dunes are! And clear water act that is a grind and brook trout fishing rivers have a great stay open dates for jacks is not enough to! Time of your continued into morrow point reservoir oak creek canyon through a call and provided the orvis fishing report colorado, or resident schools from our.
    [Show full text]
  • Boulder Creek/ St. Vrain Watershed Education
    Boulder Creek/ St. Vrain Watershed Education TEACHERS’ RESOURCE GUIDE TABLEOFCONTENTS BOULDER CREEK/ST. VRAIN WATERSHED EDUCATION No. Activity Title Introducing the Boulder Creek/St. Vrain watersheds 1.1 Water, Colorado’s Precious Resource 1.2 The Water Cycle 1.3 The Boulder Water Story 1.4 Water Law and Supply 1.5 Water Conservation 1.6 Water Bingo—An Assessment 2.1 StreamTeams—An Introduction 2.2 Mapping Your Watershed 2.3 Adopt-A-Waterway 2.4 Environmental Networks on the web 2.5 Watershed Walk 2.6 Waterway Clean-up: A Treasure Hunt 2.7 Storm Drain Marking 3.1 Assessing Your Waterway: Water Quality, a Snapshot in Time 3.2 Nutrients: Building Ecosystems in a Bottle 3.3 Assessing Your Waterway: Macroinvertebrates – Long-Term Ecosystem Health 3.4 Stream Gauging: A Study of Flow Appendices A. Glossary B. Native Species List C. References: People and Books D. Teacher Evaluation Form E. Pre-Post Student Assessment WatershED Table of Contents 2 Boulder WatershED: your guide to finding out about the place you live Creek/ St. Vrain WatershED: your guide to becoming a steward of your water resources Watershed Education WatershED: your guide to local participation and action THIS GUIDE WILL HELP YOU . ◆ get to know your Watershed Address—where you live as defined by creeks, wet- lands and lakes ◆ discover the plants, animals, and birds you might see in or around the creek or wetland in your neighborhood ◆ organize a StreamTeam to protect and enhance a nearby waterway WatershED is a resource guide for teachers and students. It provides you with the information needed to learn more about the creek or wetland near your school.
    [Show full text]
  • BOULDER CREEK and ST. VRAIN CREEK Annual Water Quality Analysis for 2016
    BOULDER CREEK AND ST. VRAIN CREEK Annual Water Quality Analysis for 2016 PREPARED FOR KEEP IT CLEAN PARTNERSHIP PREPARED BY WRIGHT WATER ENGINEERS, INC. July 2017 BOULDER CREEK AND ST. VRAIN CREEK 2016 WATER QUALITY ANALYSIS Report Preparation This report was prepared by the Keep It Clean Partnership and Wright Water Engineers, Inc. The following individuals supported this effort by providing water quality data and/or review of the report: Candice Owen and Bret Linenfelser, City of Boulder Jim Widner and Alex Ariniello, Town of Superior Rebecca Wertz, Justin Elkins and Cameron Fowlkes, City of Louisville Mick Forrester and Jessica Lewand, City of Lafayette Todd Fessenden and Wendi Palmer, Town of Erie Judith Gaioni, Drew Albright, Kathryne Marko and Cal Youngberg, City of Longmont Dave Rees, Timberline Aquatics (Biological Monitoring Data and MMI Analysis) Jane Clary and Natalie Phares, Wright Water Engineers, Inc. ii BOULDER CREEK AND ST. VRAIN CREEK 2016 WATER QUALITY ANALYSIS Table of Contents Executive Summary ................................................................................................... vii 1.0 Introduction ..................................................................................................... 1 2.0 Overview of Monitoring Program and Scope of Analysis .................................. 2 KICP MONITORING PROGRAM .................................................................................................... 2 MONITORING PROGRAMS CONDUCTED BY OTHERS ........................................................................
    [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]
  • 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]
  • James Peak Wilderness Lakes
    James Peak Wilderness Lakes FISH SURVEY AND MANAGEMENT DATA Benjamin Swigle - Aquatic Biologist (Fort Collins/Boulder) [email protected] / 970-472-4364 General Information: The James Peak Wilderness encompasses 17,000 acres on the east side of the Continental Divide in Boulder, Gilpin, and Clear Creek Counties of Colorado. There is approximately 20 miles of trail. The area's elevation ranges from 9,200 to 13,294 feet. Stocking the lakes is primarily completed by CPW pilots that deliver 1 inch native cutthroat trout. Location: Nearby Towns: Nederland, Rollinsville, Tolland, Winter Park. Recreational Management: United States Forest Service Purchase a fishing license: https://www.co.wildlifelicense.com/start.php Fishery Management: Coldwater angling Amenities Sportfishing Notes Previous Stocking High Mountain Hiking 2014 Cutthroat Camping sites available Native Cutthroat Trout Following ice off, trout enter a Backcountry camping 2-3 month feeding frenzy to available with permit June 1 – 2012 fuel themselves over long September 15. Native Cutthroat Trout winters. Consult a quality map for Scuds make up a large portion further information. 2010 of their diet. Primitive restrooms at some Native Cutthroat Trout Fly anglers and spinning rigs trailheads generally offer equal success. 2008 Regulations Native Cutthroat Trout Brook Trout Possession or use of live fish In some James Peak for bait is not permitted. 2006 Wilderness Lakes brook trout Statewide bag/possession Native Cutthroat Trout severely outcompete native limits apply (see
    [Show full text]
  • Lunar Silica-Bearing Diorite: a Lithology from the Moon with Implications for Igneous Differentiation
    50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132) 2008.pdf LUNAR SILICA-BEARING DIORITE: A LITHOLOGY FROM THE MOON WITH IMPLICATIONS FOR IGNEOUS DIFFERENTIATION. T. J. Fagan1* and S. Ohkawa1, 1Dept. Earth Sci., Waseda Univ., 1-6-1 Nishi- waseda, Shinjuku, Tokyo, 169-8050, Japan (*[email protected]). Introduction: Silica-rich igneous (“granitic”) ratios and relatively high F concentrations indicate that rocks are rare on the Moon, but have been detected by the analyzed grains are apatite (not merrillite). remote sensing on the lunar surface [e.g., 1], and in Results: The silica-bearing diorite (Sil-Di) is dom- Apollo samples and lunar meteorites [e.g., 2-5]. To date, inated by pyroxene (55 mode%), plagioclase feldspar lunar granitic samples have been characterized by high (36%), silica (4.4%), ilmenite (3.9%) and K-feldspar concentrations of incompatible elements and/or mafic (0.3%) (Fig. 2). Apatite and troilite also occur. The Sil- silicates with high Fe# (atomic Fe/[Fe+Mg]x100) [2-5], Di exhibits interlocking, igneous textures with elongate both features consistent with origin from late-stage re- plagioclase feldspar (Fig. 2). Plagioclase feldspar has sidual liquids or very low degree partial melting. Fur- nearly constant composition of An88Ab11, but pyroxene thermore, silica-rich rocks detected by remote sensing has a wide range of zoning (Fig. 3). often combine the Christiansen feature in infra-red spec- The modal composition of the Sil-Di is plagioclase- tra with high incompatible element concentrations (e.g., rich compared to many silica-bearing igneous rocks Th detected by gamma-ray spectroscopy [1]), again re- from the Moon (Fig.
    [Show full text]
  • Rocks and Geology: General Information
    Rocks and Geology: General Information Rocks are the foundation of the earth. Rock provides the firmament beneath our oceans and seas and it covers 28% of the earth's surface that we all call home. When we travel any distance in any given direction, it is impossible not to see the tremendous variety in color, texture, and shape of the rocks around us. Rocks are composed of one or more minerals. Limestone, for example, is composed primarily of the mineral calcite. Granite can be made up of the minerals quartz, orthoclase and plagioclase feldspars, hornblende, and biotite mica. Rocks are classified by their mineral composition as well as the environment in which they were formed. There are three major classifications of rocks: igneous, sedimentary and metamorphic. A question: Which kind of rock came first? Think about it....... The following sections describe the conditions and processes that create the landscape we admire and live on here on "terra firma." IGNEOUS ROCKS The millions of tons of molten rock that poured out of the volcano Paracutin in Mexico, and from the eruption of Mount St. Helens in Washington State illustrate one of the methods of igneous rock formation. Igneous (from fire) rocks are formed when bodies of hot liquid rock called magma located beneath the earth's crust, find their way upward through the crust by way of fissures or faults. If the magma reaches the earth's surface, it forms extrusive igneous rocks or volcanic rocks. If the magma cools before it reaches the surface, it forms bodies of rock called intrusive igneous rocks or plutonic rocks.
    [Show full text]
  • Nederland Area Market Analysis and Action Plan Final Report October, 2004 Contents I
    Nederland Area Market Analysis and Action Plan Final Report October, 2004 Contents I. Executive Summary 2 II. Economic Profile 3 III. Competition and Leakage Analysis 18 IV. Stakeholder Priorities 20 V. Community Attitudes Survey 27 VI. Conclusions 34 VII. Niche Strategy 35 VIII. Action Plan Recommendations 36 IX. Action Steps and Sequencing 49 prepared for The Nederland Area Chamber of Commerce by Progressive Urban Management Associates, Inc. This report is property of the Nederland Area Chamber of Commerce. All reproduction rights are reserved by the Nederland Area Chamber of Commerce. Thank you to the Donors who have made this Market Analysis possible: Nederland Area Chamber of Commerce Auction Donors and Participants Boulder County Commissioners Caribou Mercantile Companies Nederland Central Business District Redevelopment, LLC B&F Mountain Market Town of Nederland Mike Verplank Peak National Bank Nederland Area Seniors Nederland Community Library Foundation Nederland Elementary School PTO Teens, Inc. Wild Bear Center for Nature Discovery Accounting Specialists Chinahawk, LLC Deborah Davenport Irish & Reynolds X-Media, Inc. Mountain People's Coop Nederland M/S High School Parent Action Group Century 21 - Robert Hurst Timberline Builders Anonymous 1 I. EXECUTIVE SUMMARY The Town of Nederland is located 17 miles west of Boulder. An historic mining town founded in 1874, Nederland is the center of a vast 225 square mile market area with about 5,000 residents. Within a half hour drive of Colorado’s explosive Front Range market, Nederland aims to retain its unique small town and mountain lifestyle – a recreational gateway surrounded by national forests and striking mountain scenery. Despite its many attributes, Nederland has struggled financially in recent years.
    [Show full text]