DOCSLIB.ORG

Geology, Geochemistry, and Geochronology of the Marigold Mine, Battle Mountain-Eureka Trend, Nevada

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geology, Geochemistry, and Geochronology of the Marigold Mine, Battle Mountain-Eureka Trend, Nevada GEOLOGY, GEOCHEMISTRY, AND GEOCHRONOLOGY OF THE MARIGOLD MINE, BATTLE MOUNTAIN-EUREKA TREND, NEVADA by Matthew T. Fithian ! A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Master of Science (Geology). Golden, Colorado Date ____________________ Signed: _______________________ Matthew T. Fithian Signed: _______________________ Dr. Elizabeth A. Holley Thesis Advisor Signed: _______________________ Dr. Nigel M. Kelly Thesis Co-Advisor Golden, Colorado Date ____________________ Signed: _______________________ Dr. Paul Santi Department Head Department of Geology and Geological Engineering ! ii! ABSTRACT The Marigold mine is located on the northern end of Nevada’s Battle Mountain-Eureka trend, approximately 55 km east-southeast of Winnemucca, Nevada in the Battle Mountain mining district. Marigold defines a N-S trending cluster of economic gold anomalies approximately 7 km long. Marigold has been historically described as a porphyry-related distal disseminated deposit based on the presence of porphyritic intrusions, proximity to known porphyry systems (e.g. Phoenix, Converse, Elder Creek), inferred high Ag:Au ratio, and limited understanding of sulfide mineralogy related to gold mineralization. The aim of this research was to examine the genesis of the gold mineralizing system at Marigold by determining the age of felsic porphyritic intrusions throughout the Marigold mine and the genetic relationship between these intrusions and gold mineralization. Geochronologic data were supplemented by geochemical sampling to understand the effect of the intrusions on the host rock, the effect of alteration on the intrusions, and the geochemical signature of gold ores. In addition to geochronologic and geochemical data, a secondary goal of the project was to determine the ore mineralogy below the redox boundary. The gold deposits at Marigold formed in Ordovician to Permian meta-sedimentary and sedimentary sequences that were intruded by at least 14 plagioclase-biotite-hornblende phyric quartz monzonite porphyry dikes, three of which crosscut the sedimentary host rock packages in the Basalt, Mackay, and Target II open pits. U-Pb isotopic ages from CA-TIMS analysis of zircon grains show that the intrusions were emplaced in the Late Cretaceous (~97.6-92.2 Ma). Geochemical analysis of quartz monzonite intrusions indicates that increased alteration of dike margins is associated with elevated concentrations of gold and gold pathfinder elements such as arsenic, antimony, and thallium, suggesting the introduction of gold post-dates emplacement of Late Cretaceous intrusions. Petrographic analyses of sulfide-bearing rock suggest that two mineralization events occurred at Marigold: a base metal mineralization event (stannite, gersdorffite, argentiferous tennantite, chalcopyrite, pyrite, sphalerite, chromite) and a gold mineralization event (native gold, pyrite, stibnite). No textural evidence was found to suggest the relative timing between gold and base metal mineralization, although porphyry-related base metal mineralizing systems formed during the late Cretaceous elsewhere in the Battle Mountain mining district. Gold occurs natively ! iii! within quartz veinlets and within As-bearing pyrite in unoxidized rock. Electrum, which is common in distal disseminated Ag-Au deposits, was not documented at Marigold. Apatite fission track ages indicate a heating event occurred in the Eocene and are interpreted to represent the age of gold mineralization. The Ag:Au ratio of gold ores is 0.64, which is typical of Carlin-type deposits but significantly lower than many distal disseminated deposits, which have considerably more silver. The deposits at Marigold have no clear genetic affiliation with a porphyry system and display many characteristics similar to Carlin-type deposits. As a result, Marigold should be considered a Carlin-type deposit predominantly hosted by metasedimentary rocks of the Roberts Mountain allochthon. ! iv! TABLE OF CONTENTS ABSTRACT...... ............................................................................................................................. iii LIST OF FIGURES....................................................................................................................... vii LIST OF TABLES ......................................................................................................................... ix ACKNOWLEDGEMENTS ............................................................................................................ x CHAPTER 1 INTRODUCTION.................................................................................................1 1.1 Thesis organization .............................................................................................. 4 1.2 Statement of Problem ........................................................................................... 5 1.3 Overview of Carlin-type deposits ........................................................................ 6 1.4 Overview of Distal Disseminated Ag-Au deposits .............................................. 8 1.5 Deposit Classification .......................................................................................... 8 1.6 Geologic Setting ................................................................................................. 10 1.7 Approach and methods....................................................................................... 13 1.7.1 Data collection ....................................................................................... 14 1.7.2 Fieldwork ............................................................................................... 15 1.7.3 Whole rock geochemistry ...................................................................... 15 1.7.4 Mineralogical and textural analysis ....................................................... 16 1.7.5 U-Pb CA-TIMS geochronology ............................................................. 18 1.8 References .......................................................................................................... 20 CHAPTER 2 GEOLOGY, GEOCHEMISTRY, AND GEOCHRONOLOGY OF THE MARIGOLD MINE, BATTLE MOUNTAIN-EUREKA TREND, NEVADA 26 2.1 Regional Geology .............................................................................................. 27 2.2 Deposit Geology ................................................................................................ 29 2.2.1 Marigold Stratigraphy............................................................................. 29 2.2.2 Marigold Structure ................................................................................. 36 2.2.3 Marigold Ore Bodies .............................................................................. 37 2.3 Alteration styles and distribution ....................................................................... 39 2.4 Mineralization .................................................................................................... 44 2.4.1 Base Metal and Silver Mineralization .................................................... 45 2.4.2 Gold Mineralization ............................................................................... 50 ! v! 2.4.3 Paragenesis ............................................................................................. 56 2.4.4 Geochemical Comparison of Mineralization and Alteration Styles ...... 58 2.4.5 Comparison of Alteration and Mineralization Styles Among Host Rock Types ............................................................................................ 62 2.5 U-Pb Geochronology ......................................................................................... 68 2.6 Discussion .......................................................................................................... 70 2.6.1 Magmatism in the Battle Mountain Mining District........................... ... 72 2.6.2 Alteration ............................................................................................... 73 2.6.3 Base metal mineralization ...................................................................... 75 2.6.4 Gold mineralization................................................................................ 76 2.6.5 Controls on gold mineralization ............................................................. 78 2.6.6 Comparison to distal disseminated deposits .......................................... 78 2.6.7 Comparison to Carlin-type deposits ....................................................... 80 2.6.8 Genetic model for the Au deposits at Marigold ..................................... 82 2.7 Conclusions ........................................................................................................ 83 2.8 References Cited ................................................................................................ 84 CHAPTER 3 DEPOSIT AND REGIONAL SCALE EXPLORATION IMPLICATIONS AND SUGGESTIONS FOR FUTURE WORK ................................................ 93 3.1 Regional-scale suggestions for future work .............................................. 97 3.2 Concluding statement ................................................................................ 98 3.3 References Cited ....................................................................................... 98 APPENDIX A CROSS SECTIONS ......................................................................................... 100 APPENDIX
Load more

Recommended publications
  • Annual Information Form for the Year Ended December 31, 2018 Dated As of March 22, 2019 BARRICK GOLD CORPORATION
    Barrick Gold Corporation Brookfield Place, TD Canada Trust Tower Suite 3700, 161 Bay Street, P.O. Box 212 Toronto, ON M5J 2S1 Annual Information Form For the year ended December 31, 2018 Dated as of March 22, 2019 BARRICK GOLD CORPORATION ANNUAL INFORMATION FORM TABLE OF CONTENTS GLOSSARY OF TECHNICAL AND BUSINESS TERMS 4 REPORTING CURRENCY, FINANCIAL AND RESERVE INFORMATION 10 FORWARD-LOOKING INFORMATION 11 SCIENTIFIC AND TECHNICAL INFORMATION 14 THIRD PARTY DATA 15 GENERAL INFORMATION 15 Organizational Structure 15 Subsidiaries 16 Areas of Interest 18 General Development of the Business 18 History 18 Significant Acquisitions 18 Strategy 19 Recent Developments 21 Results of Operations in 2018 22 NARRATIVE DESCRIPTION OF THE BUSINESS 26 Production and Guidance 26 Reportable Operating Segments 26 Barrick Nevada 27 Pueblo Viejo (60% basis) 28 Lagunas Norte 29 Veladero (50% basis) 29 Turquoise Ridge (75% basis) 30 Acacia Mining plc (63.9% basis) 31 Pascua-Lama Project 32 Mineral Reserves and Mineral Resources 33 Marketing and Distribution 46 Employees and Labor Relations 47 Competition 48 Sustainability 48 Operations in Emerging Markets: Corporate Governance and Internal Controls 49 Board and Management Experience and Oversight 50 Communications 51 - i - Internal Controls and Cash Management Practices 51 Managing Cultural Differences 52 Books and Records 52 MATERIAL PROPERTIES 52 Cortez Property 52 Goldstrike Property 58 Turquoise Ridge Mine 63 Pueblo Viejo Mine 69 Veladero Mine 76 Kibali Mine 86 Loulo-Gounkoto Mine Complex 93 EXPLORATION
    [Show full text]
  • Annual Reportannual 2016 Barrick Goldbarrick Corporation of Owners Of
    Barrick Gold Corporation Annual Report 2016 Barrick Gold Corporation A Company of Owners Annual Report 2016 Our Vision is the generation of wealth through responsible mining – wealth for our owners, our people, and the countries and communities with which we partner. We aim to be the leading mining company focused on gold, growing our cash flow per share by developing and operating high-quality assets through disciplined allocation of human and financial capital and operational excellence. “ In 2016, we further strengthened our balance sheet and generated record free cash flow through a disciplined and rigorous approach to capital allocation. Going forward, digital technology and innovation will play an increasingly important role across our business as we seek to grow the long-term value of our portfolio with a focus on growing margins and returns over production volume.”Kelvin Dushnisky, President Our Assets are located in geopolitically stable regions with an increasing focus on our five core mines in the Americas. Proven and Probable Mineral Reserves6 As at Production Cost of Sales AISC1† Tonnes Grade Contained Golden Sunlight Hemlo December 31, 2016 (000s ozs) ($/oz) ($/oz) (000s ozs) (gm/t) (000s ozs) Turquoise Ridge JV Goldstrike 20% Cortez Goldstrike 1,096 852 714 70,685 3.55 8,077 19% ~70% of 2016 production Cortez 1,059 901 518 151,002 2.11 10,220 Pueblo Viejo 13% from core mines at Cost of Sales$793/oz Pueblo Viejo (60%) 700 564 490 85,821 2.93 8,087 1 8% and AISC $606/oz Lagunas Norte Lagunas Norte 435 651 529 70,670 1.86 4,218 Other Gold Mines: Porgera JV, Papua New Guinea Veladero 544 872 769 252,125 0.83 6,749 Kalgoorlie JV, Australia Acacia, Tanzania Other Copper Mines: Core mines sub-total 3,834 793 606 631,283 1.85 37,473 Zaldívar Copper JV 10% Jabal Sayid JV, Saudi Arabia Veladero Lumwana, Zambia Total Barrick 5,517 798 730 2,006,898 1.33 85,950 †Please see page 84 of the 2016 Financial Report for corresponding endnotes.
    [Show full text]
  • Carlin-Type Gold Deposits in Nevada: Critical Geologic Characteristics and Viable Models
    ©2005 Society of Economic Geologists, Inc. Economic Geology 100th Anniversary Volume pp. 451–484 Carlin-Type Gold Deposits in Nevada: Critical Geologic Characteristics and Viable Models JEAN S. CLINE,† University of Nevada, Las Vegas, 4505 Maryland Parkway, Box 454010, Las Vegas, Nevada 89154-4010 ALBERT H. HOFSTRA, Mineral Resources Program, U.S. Geological Survey, Mail Stop 973, Box 25046, Denver, Colorado 80225 JOHN L. MUNTEAN, Nevada Bureau of Mines and Geology, Mail Stop 178, University of Nevada, Reno, Nevada 89557-0088 RICHARD M. TOSDAL, AND KENNETH A. HICKEY Mineral Deposit Research Unit, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4 Abstract Carlin-type Au deposits in Nevada have huge Au endowments that have made the state, and the United States, one of the leading Au producers in the world. Forty years of mining and numerous studies have pro- vided a detailed geologic picture of the deposits, yet a comprehensive and widely accepted genetic model re- mains elusive. The genesis of the deposits has been difficult to determine owing to difficulties in identifying and analyzing the fine-grained, volumetrically minor, and common ore and gangue minerals, and because of postore weathering and oxidation. In addition, other approximately contemporaneous precious metal deposits have overprinted, or are overprinted by, Carlin-type mineralization. Recent geochronological studies have led to a consensus that the Nevada deposits formed ~42 to 36 m.y. ago, and the deposits can now be evaluated in the context of their tectonic setting. Continental rifting and deposi- tion of a passive margin sequence followed by compressional orogenies established a premineral architecture of steeply dipping fluid conduits, shallow, low dipping “traps” and reactive calcareous host rocks.
    [Show full text]
  • Responsible Mining
    Responsibility Report 2013 Responsible Mining Barrick Gold Corporation is the world’s leading gold producer with a portfolio of 25 owned and operated mines and development projects in five continents. Barrick Responsibility Report 2013 Contents Section 1 2013 Overview 03 About Barrick 08 Responsible Mining 09 CEO Letter Section 2 Material Issues 12 Material Issues Performance Summary 26 Social and Economic Development 15 Materiality Process 31 Workplace Safety 17 Anti-Corruption and Transparency 36 Water Management 20 Human Rights 39 Energy Use and Climate Change 23 Community Engagement 43 Biodiversity Section 3 Additional Information Governance Employees 46 Governance Structure 86 Employees and Human Rights 50 Our Strategy and Management Approach 89 Employee Development 55 Our Stakeholders 92 Occupational Health and Wellness 56 External Commitments 95 Labour Organizations 59 Government Affairs 96 Emergency Response 60 Security and the Voluntary Principles 97 Employee Awards 62 Supply Chain Society 64 Products 98 Community Safety and Security 65 Independent Assurance 100 Indigenous Peoples 68 Significant Issues in 2013 107 Resettlement Environment 108 Artisanal Mining 72 Environmental and Social Impact Assessment 74 Waste and Materials 78 Mine Closure 80 Land and Wildlife Management 83 Energy Profile 84 Air Emissions Section 4 Data Tables 110 Environment 129 Safety and Health 132 Community 135 Employees Section 5 GRI Index 142 GRI Index Section 1: 2013 Overview Barrick Responsibility Report 2013 01 Section 1 2013 Overview 03 About Barrick 08 Responsible Mining 09 CEO Letter 02 Barrick Responsibility Report 2013 Section 1: 2013 Overview About Barrick Barrick is committed to leadership in responsibility reporting, because it gives our stakeholders transparent, comparable, and externally assured information on our commitment to, and progress on, mining responsibly.
    [Show full text]
  • 2019 Program
    Our Sponsors Exhibitors Nevada State Bank, a division of Zions Bancorporation (ZB, N.A.), is a full service bank offering a complete range of consumer, private and business banking services with branches statewide. Founded in 1959, Nevada State Bank serves On January 1, 2019 a new Barrick was born out of the merger between Barrick 20 communities across the state of Nevada. For more information on Nevada Gold Corporation and Randgold Resources. Barrick’s vision is to be the world’s State Bank, call 775.393-2325 or access www.nsbank.com. most valued gold mining business by finding, developing and owning the best assets, with the best people to deliver sustainable returns for our owners, partners and communities. Access at www.barrick.com Newmont is a leading gold and copper producer. Founded in 1921, the Company has approximately 24,700 employees and contractors who work at Welcome to operations and advanced development projects in five countries around the COUNTRY Financial is a marketing name for COUNTRY Life Insurance Company®, world. Newmont’s purpose is to create value and improve lives through COUNTRY Mutual Insurance Company® and their respective subsidiaries, sustainable and responsible mining. Visit us at www.newmont.com located in Bloomington, IL. COUNTRY Financial serves about one million house- holds and businesses throughout the United States and offers a wide range of Humboldt County’s insurance and financial products and services. Nevada Outdoor School (NOS) is a local nonprofit organization with a mission to inspire exploration of our natural world, responsible stewardship of our habitat Annual Economic Outlook Cyanco is the only company 100% dedicated to safety, reliability and efficiency, and dedication to community.
    [Show full text]
  • Deep Groundwater and Potential Subsurface Habitats Beneath an Antarctic Dry Valley
    ARTICLE Received 21 May 2014 | Accepted 2 Mar 2015 | Published 28 Apr 2015 DOI: 10.1038/ncomms7831 OPEN Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley J.A. Mikucki1, E. Auken2, S. Tulaczyk3, R.A. Virginia4, C. Schamper5, K.I. Sørensen2, P.T. Doran6, H. Dugan7 & N. Foley3 The occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional- scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18 km of the valley. A connection between these two basins was not detected to the depth limitation of the AEM survey (B350 m). 1 Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA. 2 Department of Geosciences, Aarhus University, Aarhus 8000, Denmark. 3 Department of Earth and Planetary Sciences, University of California, Santa Cruz, California 95064, USA. 4 Environmental Studies Program, Dartmouth College, Hanover, New Hampshire 03755, USA. 5 Sorbonne Universite´s, UPMC Univ Paris 06, CNRS, EPHE, UMR 7619 Metis, 4 place Jussieu, Paris 75252, France.
    [Show full text]
  • 2004 Annual Report
    BARRICK GOLD CORPORATION BARRICK Annual Report Annual 2004 2004 Annual Report Annual Barrick is one of the world’s largest gold mining companies, with operating and development properties in the US, Canada, Australia, Peru, Chile, Argentina and Tanzania. What’s next: Growth. Our vision is to be the world’s best gold mining company Building Mines. Building Value. by fi nding, developing and producing quality reserves in a profi table and socially responsible manner. Barrick shares are traded on the Toronto, New York, London and Swiss stock exchanges and the Paris Bourse. You can contact us toll-free within Canada and the United States: 800-720-7415 email us at: [email protected] BARRICK GOLD BARRICK visit our investor relations website: www.barrick.com TT39748-BAR39748-BAR CoverCover andand Spine.inddSpine.indd 1 33/16/05/16/05 11:01:59:01:59 PMPM Delivering Growth. Building Mines Ltd. ada, Barrick’s pipeline of gold development projects is unrivaled in size, quality, and immediacy. Three new mines will be in production in 2005, Cannting: of Bowne another in early 2006, with two more to follow in subsequent years. Forward-Looking Statements Certain information contained or incorporated by reference in this Annual Report 2004, including any information as to our future financial or operating performance, constitutes “forward-looking statements”. All statements, Building Value other than statements of historical fact, are forward-looking statements. The words “believe”, “expect”, “anticipate”, “contemplate”, “target”, “plan”, “intends”, “continue”, “budget”, “estimate”, “may”, “will”, “schedule” and similar expressions identify forward-looking statements. Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable by us, are Barrick is targeting a 12% compound annual growth rate in inherently subject to significant business, economic and competitive uncertainties and contingencies.
    [Show full text]
  • Tectonics and Seismicity of the Southern Washington Cascade Range
    Bulletin of the Seismological Society of America, Vol. 86, No. 1A, pp. 1-18, February 1996 Tectonics and Seismicity of the Southern Washington Cascade Range by W. D. Stanley, S. Y. Johnson, A. I. Qamar, C. S. Weaver, and J. M. Williams Abstract Geophysical, geological, and seismicity data are combined to develop a transpressional strain model for the southern Washington Cascades region. We use this model to explain oblique fold and fault systems, transverse faults, and a linear seismic zone just west of Mt. Rainier known as the western Rainier zone. We also attempt to explain a concentration of earthquakes that connects the northwest-trend- ing Mount St. Helens seismic zone to the north-trending western Rainier zone. Our tectonic model illustrates the pervasive effects of accretionary processes, combined with subsequent transpressive forces generated by oblique subduction, on Eocene to present crustal processes, such as seismicity and volcanism. Introduction The southern Washington Cascades contains Mt. Rain- Geology of Western Washington ier, the most massive of the volcanoes in the Cascade Range magmatic arc (Fig. 1). Mr. Rainier is part of the triangle of The Puget Sound region and the western flank of the large stratovolcanoes in southem Washington that includes Cascade Range in southwestern Washington occupy a com- Mount St. Helens and Mt. Adams. Mount St. Helens expe- plex tectonic setting along the margin of two distinct crustal rienced a cataclysmic eruption in 1980 and is apparently blocks. Crust in the eastern block beneath the southwest younger than Mt. Rainier and Mt. Adams, both of which Washington Cascades is composed of Mesozoic and older exhibit more rounded profiles than the pointed, pre-1980 accreted terranes, volcanic arcs, and underplated magmatic Mount St.
    [Show full text]
  • DEPARTMENT of ENVIRONMENTAL ENGINEERING and EARTH SCIENCES Department of Environmental Engineering and Earth Sciences Chairperson: Dr
    DEPARTMENT OF ENVIRONMENTAL ENGINEERING AND EARTH SCIENCES Department of Environmental Engineering and Earth Sciences Chairperson: Dr. Marleen Troy Faculty Professors: Murthy, Troy, Whitman Associate Professors: Frederick Assistant Professor: Finkenbinder, Karimi, Karnae Lecturers: Kaster, McMonagle Laboratory Manager: McMonagle Office Assistant: Garrison The Department of Environmental Engineering and Earth Sciences (EEES) offers the following degree programs: the B.S. in Civil Engineering, the B.S. in Environmental Engineering; the B.S. in Environmental Science; the B.S. in Geology; and the B.A. in Earth and Environmental Science. EEES envisions future accreditation of the Civil Engineering program by EAC-ABET. The Environmental Engineering program is accredited by the EAC-ABET. The engineering programs incorporate a strong background in the fundamentals of engineering with a blend of science and advanced engineering courses. The Environmental Science program combines a foundation in the related sciences and primary earth reservoirs (water, land, air, and life) with concentrations in either Earth Science or Biology. The Geology program provides a comprehensive curriculum that includes the fundamentals of geology with courses responsive to the needs of industrial employment sectors. The Geology program meets the academic requirements for Pennsylvania State professional licensure. All EEES programs emphasize the value of integrative learning in the classroom, laboratory and field. Modern laboratories are well-equipped to support a wide range of courses and research experiences. Easy access to exceptional off-campus sites provides training in field methods that augment the curricula. A dedicated computer laboratory for geospatial technology (Geographic Information System, Global Positioning System, Remote Sensing) supports all EEES programs and research/project activities in the science and engineering fields.
    [Show full text]
  • Growth and Erosion of Fold-And-Thrust Belts with an Application to the Aconcagua Fold-And-Thrust Belt, Argentina G
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, B01410, doi:10.1029/2002JB002282, 2004 Growth and erosion of fold-and-thrust belts with an application to the Aconcagua fold-and-thrust belt, Argentina G. E. Hilley1 and M. R. Strecker Institut fu¨r Geowissenschaften, Universita¨t Potsdam, Potsdam, Germany V. A. Ramos Department de Geologia, Universidad de Buenos Aires, Buenos Aires, Argentina Received 1 November 2002; revised 26 August 2003; accepted 11 September 2003; published 23 January 2004. [1] The development of topography within and erosional removal of material from an orogen exerts a primary control on its structure. We develop a model that describes the temporal development of a frontally accreting, critically growing Coulomb wedge whose topography is largely limited by bedrock fluvial incision. We present general results for arbitrary initial critical wedge geometries and investigate the temporal development of a critical wedge with no initial topography. Increasing rock erodibility and/or precipitation, decreasing mass flux accreting to the wedge front, increasing wedge sole-out depth, decreasing wedge and basal decollement overpressure, and increasing basal decollement friction lead to narrow wedges. Large power law exponent values cause the wedge geometry to quickly reach a condition in which all material accreted to the front of the wedge is removed by erosion. We apply our model to the Aconcagua fold-and-thrust belt in the central Andes of Argentina where wedge development over time is well constrained. We solve for the erosional coefficient K that is required to recreate the field-constrained wedge growth history, and these values are within the range of independently determined values in analogous rock types.
    [Show full text]
  • Future Volcanism at Yellowstone Caldera: Insights from Geochemistry of Young Volcanic Units and Monitoring of Volcanic Unrest
    2012 Annual Meeting & Exposition Issue! SEPTEMBER 2012 | VOL. 22, NO. 9 A PUBLICATION OF THE GEOLOGICAL SOCIETY OF AMERICA® Future volcanism at Yellowstone caldera: Insights from geochemistry of young volcanic units and monitoring of volcanic unrest Inside: Preliminary Announcement and Call for Papers: 2013 GSA Northeastern Section Meeting, p. 38 Preliminary Announcement and Call for Papers: 2013 GSA Southeastern Section Meeting, p. 41 VOLUME 22, NUMBER 9 | 2012 SEPTEMBER SCIENCE ARTICLE GSA TODAY (ISSN 1052-5173 USPS 0456-530) prints news and information for more than 25,000 GSA member read- ers and subscribing libraries, with 11 monthly issues (April/ May is a combined issue). GSA TODAY is published by The Geological Society of America® Inc. (GSA) with offices at 3300 Penrose Place, Boulder, Colorado, USA, and a mail- ing address of P.O. Box 9140, Boulder, CO 80301-9140, USA. 4 Future volcanism at Yellowstone GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, caldera: Insights from geochemistry regardless of race, citizenship, gender, sexual orientation, of young volcanic units and religion, or political viewpoint. Opinions presented in this monitoring of volcanic unrest publication do not reflect official positions of the Society. Guillaume Girard and John Stix © 2012 The Geological Society of America Inc. All rights reserved. Copyright not claimed on content prepared Cover: View looking west into the Midway geyser wholly by U.S. government employees within the scope of basin of Yellowstone caldera (foreground) and the West their employment. Individual scientists are hereby granted permission, without fees or request to GSA, to use a single Yellowstone rhyolite lava flow (background).
    [Show full text]
  • Module 12 Basin Geology Community Sailing Center
    Geology of the Champlain Basin & Watersheds How did the landscape around me form and how will it impact where I can sail? Module 12 : LSR Ch. 3&4 Grade Level Module created by: Elementary - Middle School Subject Areas Earth Systems, Geology, History, Water Cycle Duration Preparation time: 15 minutes Lesson Time: 2 hours 45 minutes Part I: 30 minutes Part II: 30 minutes Part III: 15 minutes Part IV: 45 minutes Part V: 30 minutes Setting This module is best implemented outdoors where students can see the landscape in the area where they live and interpret how it can contribute to what’s happening around them. You can implement Part III, and IV in the classroom. Part I is best conducted where they will be sailing or in a place where they can see different landforms. Use a map of your local area to support student observations. Part II is best completed outdoors where students are able to manipulate rocks first hand. Skills Making Observations and Drawing Conclusions, Analysis, Recording Qualitative Data, Map Making Sailing Skills Preparation, Wind Awareness, Interpreting the Landscape to Determine Weather Patterns, Sailing a Course Vocabulary Sedimentary Rocks, Sedimentary Layers, Rock Types, Mountain-Building, Plate Tectonics, Erosion, Weathering, Watershed, Water Cycle, Pollution, Wind Shadows Standards Science & Engineering Practices • Analyzing and interpreting data • Obtaining, evaluating, and communicating information Crosscutting Concepts • Patterns • Cause and effect • Energy and Matter: Cycles Summary Students use map-making to aid their understanding of their surrounding landscape and community. They will explore concepts relating to sedimentary rocks, mountain-building, erosion, and watersheds. They gain a new perspective on their community and environment by building a watershed and drawing conclusions about the effects of pollution and the water cycle.
    [Show full text]