DOCSLIB.ORG

Factors Controlling the Internal Facies Architecture of Kimberlite Pipes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Factors Controlling the Internal Facies Architecture of Kimberlite Pipes 10th International Kimberlite Conference, Bangalore - 2012 10IKC-246 FACTORS CONTROLLING THE INTERNAL FACIES ARCHITECTURE OF KIMBERLITE PIPES Kurszlaukis, S., Fulop, A. De Beers Canada Inc., Toronto, Canada Under close examination, most if not all diatreme and maar crater with several lobes. kimberlite pipes show a multitude of facies types For our study we are investigating kimberlite suggesting that the pipes were emplaced under pipes of the Jurassic Attawapiskat Kimberlite an episodic reoccurrence of eruptive phases, often Field in northern Ontario, Canada. The Field is with intermittent phases of volcanic quiescence. comprised of 23 known kimberlite pipes, one of The majority of these facies can be related to either which is Victor Mine. Next to Victor, 8 pipes a change in the fragmentation behavior of the (Bravo-1, Delta-1, India-1, Tango Extension, magma during emplacement or are a result of Whiskey, X-Ray, Yankee and Zulu) were drilled changing conditions during sedimentation of sufficiently in order to understand the internal volcaniclastic deposits, as well as their alteration facies architecture that is controlling diamond and compaction after deposition. distribution within a specific pipe. Victor itself is An additional factor controlling pipe facies actually comprised of several pipes (Webb et al., architecture is the degree of mobility of the loci 2004; van Straaten et al., 2009, 2011): Victor of explosions in the explosion chambers of the Southwest, Southeast and Victor North. The latter root zone or root zones at the base of the maar- occurrence is a product of several amalgamated diatreme volcano (Ort and Núñez-Carrasco, pipes: Victor Northwest and Victor Main, all of 2009). In a growing pipe the root zone moves which have a complex internal facies architecture downwards and with that movement the overlying that resulted from the emplacement of different diatreme enlarges both in size and diameter phases of kimberlite over an extended span of (Lorenz and Kurszlaukis, 2007). However, during time. the life span of the volcano, the explosion chamber During the study of the maar diatreme can also move upwards, back into the lower volcanoes we realized that the facies architecture diatreme, where renewed explosions result in the of a number of pipes showed repetitive patterns. destruction of older deposits and their structures These patterns are not controlled by a change in (White and Ross, 2011). the nature of the country rocks, since all pipes Next to vertical shifts of explosion belong to the same kimberlite field and the country chambers, the loci of explosions can also move rock strata is a Paleozoic sedimentary cover laterally along the feeder dyke or dyke swarm. sequence that had a thickness of about 500 m at This mobility of explosion chambers results in a the time of emplacement and that shows very little highly complex facies architecture where a pipe lateral lithological variation throughout the field. can be comprised of several separate root zones In the case of the Attawapiskat kimberlite pipes, that are overlain by an amalgamated, crosscutting the distribution of volcanic facies within a Extended Abstract 1 10th International Kimberlite Conference, Bangalore - 2012 kimberlite pipe is rather controlled by the degree the energy released in a subsequent emplacement of shifting of the explosion chambers and their cycle, earlier tephra that filled the pipe may be respective feeder vents during the emplacement completely ejected, leaving little or even no history of a pipe. A variation of pipe sizes also evidence of its existence. However, if late eruptive allows us to investigate the facies architecture of cycles start with relative low energy explosions, different structural levels of a pipe, straddling from then earlier tephra in the pipe can survive this lower diatreme to deposits that filled the syn- and event and serves as a witness to earlier volcanic post-emplacement crater. Hence, our study activity in the pipe. Depending on the explosive includes processes that are both primary and force position of the explosion chamber in the pipe resedimented. By having an understanding of the and vent geometry, the existing tephra becomes processes, we could also distinguish deposits that variably affected by the renewed volcanic activity. were modified in their original structure during In steep-sided and small pipes it is rather the emplacement of younger phases. easy for a subsequent eruption to either fully eject The examples from the Jurassic earlier tephra deposits filling the pipe or Attawapiskat kimberlite field show that some completely homogenize and mix it. The latter case kimberlite pipes were excavated during initial is indicated by massive deposits and grain-in-grain strong explosions forming several 100 m deep mixing of different types of juvenile pyroclasts. craters. Towards the end of the emplacement, the The Bravo-1 pipe is such an example in the eruptive style became less explosive, resulting in Attawapiskat kimberlite field. a rather low-energy fragmentation behavior of the In larger pipes or pipes that are to some magma with a very low ability to fragment country extent flaring towards the surface, it is more rock. During this phase the deep craters are filled difficult for a renewed eruption to fully eject with hot pyroclastic deposits that often have a earlier tephra from the pipe. The stronger an remarkable low content of country rock xenoliths. explosion is the more overlying tephra will be The final phase of an eruptive cycle is often affected. Less energetic explosions will result in marked by low-energy spatter fragmentation that eruptions that pierce in the form of a feeder vent produces welded pyroclastic deposits or even lava through the overlying tephra pile to exit to the lakes. Late intrusions of coherent kimberlite sheets surface or, in weak explosions, will not be able to into older kimberlite tephra filling the pipe are a leave the explosion chamber in the root zone or common theme in the Attawapiskat kimberlite may get stuck in the lower portion of the diatreme pipes. This emplacement behavior can be repeated as failed tephra jets. In the latter case these weak if a new pulse of magma enters the pipe at its explosions will still alter the original structure in bottom. Depending on the time gap in between the lower diatreme, where they destroy bedding the ascending kimberlite pulses, older tephra in and homogenize the pipe infill. These failed tephra the pipe is entirely, partly or not at all jets will mix with the surrounding tephra already consoli­dated. In either case mixing of cognate filling the pipe and may, in some cases, be still volcaniclastic pyroclasts or juvenile pyroclasts of traceable by their diagnostic petrographic features different nature testify the emplacement of and variations in diamond content. kimberlite within a pipe as repetitive, cyclic If the explosion sites in the root zone are events. laterally immobile then older deposits, which were It is apparent that these eruptive cycles, from originally forming mostly horizontal layers on the highly explosive to low energy fragmentation and respective crater floors, become tilted and down coherent intrusion can be repeated several times rafted towards the centre of the pipe. This is firstly during the emplacement of a pipe. Depending on a function of simple compaction of the tephra, Extended Abstract 2 10th International Kimberlite Conference, Bangalore - 2012 which will be more pronounced in the central If the explosion sites are stagnant, for portion of a pipe due to its larger depth extent of example due to the strong influx of external water the underlying tephra column compared to the from an aquifer into the root zone, then the margins of the pipe. In addition, the consumption ongoing explosions will widen the root zone. The of existing tephra in the lower portion of a pipe wider a root zone the less impact an explosion due to renewed eruptions originating in the root has on the country rocks, since the root zone is zone also causes tilting and down rafting of filled by down sagged kimberlite tephra. Hence formerly horizontal beds towards the deep central these explosions will not further grow the pipe part of a kimberlite pipe. by the excavation of country rock but will rather This cyclic emplacement behavior combined mix and recycle tephra of the overlying diatreme with tilting due to compaction and down rafting with newly fragmented tephra from kimberlite forms an internal symmetric facies architecture intruding the bottom of the root zone. This with a cone-in-cone like arrangement of volcanic scenario of a stagnant root zone leads to a pipe deposits. The Victor NW pipe is an example where that flares upwards from the bottom of the pipe these emplacement sequences are repeated over with a tephra infill that is typically low in xenolith time. content and is highly homogenous in nature. Vertical shifts of the explosion sites within Victor Main, which is to some extent flaring from the root zone can also add complexity to the an artesian aquifer at the interface between internal pipe architecture. Pipe growth occurs basement and overlying Paleozoic sediments, is when the explosion chambers move downwards an example for such a pipe. and the overlying diatreme expands both towards If aquifers or hydrologically active faults depth and laterally. In basaltic maar-diatreme become depleted during volcanic activity, volcanoes this continuous downward growth intruding magma can pass the site of earlier process is typically achieved when a vertical fragmentation and forms intrusive sheets higher hydrologically active fault is cut by the feeder within the diatreme or forms spatter that may dyke of the volcano resulting in thermohydraulic reconstitute to lava on the maar crater floor (as explosions. In the Attawapiskat area the seen in Victor NW, Delta and India kimberlite hydrological situation is different in that pipes).
Load more

Recommended publications
  • The Roots of Middle-Earth: William Morris's Influence Upon J. R. R. Tolkien
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2007 The Roots of Middle-Earth: William Morris's Influence upon J. R. R. Tolkien Kelvin Lee Massey University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Literature in English, British Isles Commons Recommended Citation Massey, Kelvin Lee, "The Roots of Middle-Earth: William Morris's Influence upon J. R. R. olkien.T " PhD diss., University of Tennessee, 2007. https://trace.tennessee.edu/utk_graddiss/238 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Kelvin Lee Massey entitled "The Roots of Middle-Earth: William Morris's Influence upon J. R. R. olkien.T " I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in English. David F. Goslee, Major Professor We have read this dissertation and recommend its acceptance: Thomas Heffernan, Michael Lofaro, Robert Bast Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Kelvin Lee Massey entitled “The Roots of Middle-earth: William Morris’s Influence upon J.
    [Show full text]
  • Sulphur Isotope Geochemistry of the Ores and Country Rocks at the Almadcn Mercury Deposit, Ciudad Real, Spain*
    Gemhimrca 0 Comochmica Acln Vol. 56, pp. 3765-3780 OOl6-7037/92/$5.00 + 00 Copyright 0 1992 PerpamonPress Ltd. Printed tn U.S.A. Sulphur isotope geochemistry of the ores and country rocks at the AlmadCn mercury deposit, Ciudad Real, Spain* FRANCIS SAUP~~and MICHEL ARNOLD Centre de Recherches Pstrographiques et GCochimiques, BP 20, 54501 Vandoeuvre-l&s-NancyCedex. France (Received June 7, 1991: accepted in revised form April 15, 1992) Abst~ct-Seventy-four new S isotope analyses of ore minerals and country rocks are given for the Hg deposit of Almad&. The spread of the cinnabar &34Sis narrow within each of the three orebodies, but the 634S average values differ sufficiently between them (mean 634S: San Nicolas = 0.2 rt I. l%, San Francisco = 8.1 + 0.7%0, San Pedro = 5.9 f 1.0%0) to indicate three different mineralization episodes and possibly processes. The unweighted mean for all cinnabar samples is 5.6%0 and the S source is considered to be the host-rocks, either the Footwall Shales (634S = 5.5%0) or the spilites (S34S = 5.1 rt 1.3%0). For geometric and chronologic reasons, the former seem the best potential source. However, the high ?js4S values of the San Francisco cinnabar cannot be explained without addition of heavy S from reduction of seawater sulphate. Orderly distributions ofthe 634Svalues are observed in all three orebodies: ( 1) their increase from the stratigraphic bottom to the top in the San Pedro orebody is explained by a Rayleigh process, and (2) the maxima in the centres of the San Francisco and San Nicolas orebodies are explained by mixing of the S transporting hydrothermal fluids with seawater within the sediments.
    [Show full text]
  • Wayne P. Barnett Principal Consultant
    Resume Wayne P. Barnett Principal Consultant Profession Principal Structural Geologist Education Doctor of Philosophy in the School of Geological Sciences, University of KwaZulu-Natal, South Africa, 2007 Master of Science in Structural/Engineering Geology, University of Cape Town, South Africa, 1997 Certificate in Rock Mechanics, Chamber of Mines of South Africa, 2002. Bachelor of Science with Honours in Geology, University of Cape Town, 1995 Registrations/ Professional Geologist (APEGBC #43273), Professional Affiliations Natural Scientist (SACNASP #400237/04) Specialisation Structural Geology; Kimberlite Geology; Engineering Geology; 3D Computer-based Geological Modelling and GIS. Expertise Wayne is a Principal Consultant with 24 years of experience in the mining and exploration industry. He has been employed over a period of eight years as a mining operations-based geotechnical engineer and applied structural geologist. Subsequently, Wayne has performed the role of consulting structural geology specialist in mining and exploration in Africa, North America, South America and Asia. Consequently he specialises in defining the structural geology of mining projects in order to properly characterize the rock mass for geotechnical engineering applications - for scoping to pre-feasibility studies, as well as problem-solving in active mining operations. Wayne is a geological modelling expert and undertakes and provides training in structural and geotechnical drill core logging, open pit and underground mapping, geological data management, data QA/QC, and statistical analysis of structural data. He has provided formal applied structural geology training to over 1000 geologists and engineers internationally. These versatile skills have also allowed him to provide practical, goal-focussed structural consulting in diamond, precious and base metal exploration and resource characterization on numerous projects and active operations on all major mining-active continents; for understanding controls on mineralization and targeting purposes.
    [Show full text]
  • Kimberlite Wall Rock Fragmentation Processes: Venetia K08 Pipe Development
    1 Kimberlite Wall Rock Fragmentation Processes: Venetia K08 Pipe Development The final publication is available at www.springerlink.com - 10.1007/s00445-011-0499-3 W.P. Barnett (1,2) , S. Kurszlaukis (3), M. Tait (1), P. Dirks (4) (1) Mineral Resources Management, De Beers Group Services, P/Bag X01, Southdale 2135, South Africa (2) present address: SRK Consulting, Suite 2200, 1066 West Hastings Street, Vancouver V6E3X2, BC, Canada ([email protected]; +17782388038) (3) Kimberlite Petrology Unit, De Beers Canada Inc., Toronto, Ontario, Canada (4) School of Earth and Environmental Sciences, James Cook University, Townsville, Australia Abstract Current kimberlite pipe development models strongly advocate a downward growth process with the pipe cutting down onto its feeder dyke by means of volcanic explosions. Evidence is presented from the K08 kimberlite pipe in Venetia Mine, South Africa, which suggests that some pipes or sub-components of pipes develop upwards. The K08 pipe in pit exposure comprises >90 vol.% chaotic mega-breccia of country rock clasts (gneiss and schist) and <10 vol.% coherent kimberlite. Sub-horizontal breccia layers, tens of metres thick, are defined by lithic clast size variations, and contain zones of shearing and secondary fragmentation. Textural studies of the breccias and fractal statistics on clast size distributions are used to characterize sheared and non-sheared breccia zones, and to deduce a fragmentation mechanism. Breccia statistics are compared directly with the statistics of fragmented rock produced from mining processes in order to support interpretations. Results are consistent with an initial stage of brecciation formed by upward-moving collapse of an explosively pre-conditioned hangingwall into a subterranean volcanic excavation.
    [Show full text]
  • Treasures of Middle Earth
    T M TREASURES OF MIDDLE-EARTH CONTENTS FOREWORD 5.0 CREATORS..............................................................................105 5.1 Eru and the Ainur.............................................................. 105 PART ONE 5.11 The Valar.....................................................................105 1.0 INTRODUCTION........................................................................ 2 5.12 The Maiar....................................................................106 2.0 USING TREASURES OF MIDDLE EARTH............................ 2 5.13 The Istari .....................................................................106 5.2 The Free Peoples ...............................................................107 3.0 GUIDELINES................................................................................ 3 5.21 Dwarves ...................................................................... 107 3.1 Abbreviations........................................................................ 3 5.22 Elves ............................................................................ 109 3.2 Definitions.............................................................................. 3 5.23 Ents .............................................................................. 111 3.3 Converting Statistics ............................................................ 4 5.24 Hobbits........................................................................ 111 3.31 Converting Hits and Bonuses...................................... 4 5.25
    [Show full text]
  • The Philippines Illustrated
    The Philippines Illustrated A Visitors Guide & Fact Book By Graham Winter of www.philippineholiday.com Fig.1 & Fig 2. Apulit Island Beach, Palawan All photographs were taken by & are the property of the Author Images of Flower Island, Kubo Sa Dagat, Pandan Island & Fantasy Place supplied courtesy of the owners. CHAPTERS 1) History of The Philippines 2) Fast Facts: Politics & Political Parties Economy Trade & Business General Facts Tourist Information Social Statistics Population & People 3) Guide to the Regions 4) Cities Guide 5) Destinations Guide 6) Guide to The Best Tours 7) Hotels, accommodation & where to stay 8) Philippines Scuba Diving & Snorkelling. PADI Diving Courses 9) Art & Artists, Cultural Life & Museums 10) What to See, What to Do, Festival Calendar Shopping 11) Bars & Restaurants Guide. Filipino Cuisine Guide 12) Getting there & getting around 13) Guide to Girls 14) Scams, Cons & Rip-Offs 15) How to avoid petty crime 16) How to stay healthy. How to stay sane 17) Do’s & Don’ts 18) How to Get a Free Holiday 19) Essential items to bring with you. Advice to British Passport Holders 20) Volcanoes, Earthquakes, Disasters & The Dona Paz Incident 21) Residency, Retirement, Working & Doing Business, Property 22) Terrorism & Crime 23) Links 24) English-Tagalog, Language Guide. Native Languages & #s of speakers 25) Final Thoughts Appendices Listings: a) Govt.Departments. Who runs the country? b) 1630 hotels in the Philippines c) Universities d) Radio Stations e) Bus Companies f) Information on the Philippines Travel Tax g) Ferries information and schedules. Chapter 1) History of The Philippines The inhabitants are thought to have migrated to the Philippines from Borneo, Sumatra & Malaya 30,000 years ago.
    [Show full text]
  • Airborne and Ground Electrical Surveys of the Edwards and Trinity Aquifers, Medina, Uvalde, and Bexar Counties, Texas
    43 Airborne and Ground Electrical Surveys of the Edwards and Trinity Aquifers, Medina, Uvalde, and Bexar Counties, Texas By Bruce D Smith1, David V. Smith1, Jeffrey G. Paine2, and Jared D. Abraham1 1U.S. Geological Survey, MS 964, Box 25046, Denver Federal Center, Denver, CO 80225, 2Bureau of Economic Geology, Jackson School of Geological Sciences, The University of Texas at Austin, Univ. Station, Box X, Austin, TX 78713 ABSTRACT Helicopter electromagnetic (HEM) and magnetic surveys were flown in the Seco Creek area, (Medina and Uvalde Counties, TX, 2002) and in Northern Bexar County (TX, 2003). The purpose of these surveys was to map structure and lithology of the Edwards and Trinity aquifers consisting of the catchment zone (Glen Rose, Trinity Group), recharge zone (Devils River, Edwards Group), and confined zone. The latter survey concentrated on Camps Stanley and Bullis, which are located mostly on the Glenn Rose. The south- ern part of Camp Bullis includes the faulted contact between the Edwards Group (recharge zone) and the catchment (Glenn Rose). Ground geophysical surveys at Seco Creek, conducted by the USGS in April 2002, consisted of total field magnetics, dc resistivity and shallow terrain conductivity measurements. In May 2003, BEG (Bureau of Economic Geology) acquired ground electrical conductivity measurements at 379 locations. Re-mapping of the geology along the nine geophysical lines was done at the same time. The shallow ground conductivity interpretations were supplemented by time domain EM (TDEM) soundings by the USGS. Ground-based measurements demonstrate that (a) mapped geologic units consisting of Cretaceous age limestones and dolomitized limestones, marls, mudstones, shales, and Quaternary alluvial deposits have differences in apparent conductivity, (b) geologic structures such as faults and karst can have detectable apparent conduc- tivity signatures, and (c) conductivity measurements can be combined with geologic maps and outcrop stud- ies to identify hidden contacts, covered strata, and unmapped structural features.
    [Show full text]
  • The Diamond a Pamphlet Describing the Most Reliable Indications And
    MICROFILMED BY KEUFFEL Si ESSER COMPANY 15G1 N. Danville St., Arlington, Va. 22201 REEL NO. /// REDUCTION RATIO iX. MICROFILMED FOR t/^/Kev^r-fy ^f t*/ C*1s*h k«. CONTENTS STARTS ENDS u II r^ p; 4.W^*Vk J J>7 J+J Iff* I ! THE DIAMOND,^ A ramphlet describing the most reliable indications and the principal minerals associated with the DIAMOND IN SOUTH AFRICA, WITH HINTS TO PROSPECTORS IN SEARCH OF - THESE GEMS. [ILLUSTRATED WITH MAP AND SECTIONS. I V by DAVID DRAPER, F.G.S., and MINETT E. FRAMES. PRICE 5s. JoHANNESBURfl : MATTHEWS & WALKER, PRINTERS 1898. mm .;•-,.-:, /> J. : Mr. W&WEm DR4PBR, Fellow of the Geological Society of London. Member Fed. Inst.Mming Engineers"Forth of England. Member Geogr. Soc. of Holland. Hon. Secretary Geological Society of South Africa Curator Chamber of Mines Mineral Collection London Office : No. 448, MANSION HOUSE CHAMBERS, No. 11, QUEEN VICTORIA ST. South African Address : Box 460, JOHANNESBURG. Office: CHAMBER of MINES, AND Mr. 1€ Who has been for many years connected with Diamond and Gold Mining m the Free State and Transvaal, will inspect and report upon Mineral Properties in any portion of South Africa. DIAMONDS A SPECIALITY. Extracts from Local Press Reports " Mr. Draper identified the specimens fr m Riotf„nf^;„ i • iferous, in February, 1897."-*«»« IT^XZ^g, &£ {&?»* "The lessees of Rietfontein . were invited to not fo« n i to their a tonishn,, n , they wereins.rucMed ,™ by a S « tXt ""I search for the precious mineral, whose Kietfontem) to efforts tknnl . T i 6 gratifying!, successful, ano ' haie placed bey !„,? do^bt !,* ex^ence of Wi,Th "T a ,rue diamondiferous pipe in tL T^^l]^^*%;*£ The owners have acknowledged that Mr.
    [Show full text]
  • Nandewar Mineral and Petroleum Resources and Potential, Nandewar Western Regional Assessment
    NSW WESTERN REGIONAL ASSESSMENTS Nandewar Mineral and Petroleum Resources and Potential NAND07 FINAL April 2004 RESOURCE AND CONSERVATION ASSESSMENT COUNCIL NSW WESTERN REGIONAL ASSESSMENTS Nandewar MINERAL AND PETROLEUM RESOURCES AND POTENTIAL Roger McEvilly, Kirstine Malloch, John Watkins,Victor Tadros, Leslie Wiles, Julie Moloney, Ricky Mantaring Project Number NAND07 RESOURCE AND CONSERVATION ASSESSMENT COUNCIL INFORMATION C Crown Copyright (April 2004) NSW Government ISBN 1 74029 207 3 This project has been funded and coordinated by the Resource and Conservation Division (RACD) of the NSW Department of Infrastructure, Planning and Natural Resources, for the Resource and Conservation Assessment Council (RACAC) Preferred way to cite this publication: McEvilly R P, Malloch K R, Watkins JJ, Tadros VN, Wiles LA, Moloney J, Mantaring A R, 2004, Nandewar Mineral and Petroleum Resources and Potential, Nandewar Western Regional Assessment. Resource and Conservation Assessment Council, 250pp. For more information and for information on access to data, contact: Resource and Conservation Division, Department of Infrastructure, Planning and Natural Resources P.O. Box 39 SYDNEY NSW 2001 Phone: 02 9228 6586 Fax: 02 9228 6411 Email: [email protected] Key authors: Roger McEvilly, Kirstine Malloch, John Watkins, Victor Tadros, Leslie Wiles, Julie Moloney, Ricky Mantaring. Disclaimer While every reasonable effort has been made to ensure that this document is correct at the time of printing, the State of New South Wales, its agents and employees, do not assume any responsibility and shall have no liability, consequential or otherwise, of any kind, arising from the use of or reliance on any of the information contained in this document.
    [Show full text]
  • Application of Seismic Refraction Tomography to Karst Cavities
    29 Application of Seismic Refraction Tomography to Karst Cavities Jacob R. Sheehan1, William E. Doll1, David B. Watson2, Wayne A. Mandell3 1Battelle, 105 Mitchell Rd, Suite 103, Oak Ridge, TN 37830 2Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831 3 U.S. Army Environmental Center, 5179 Hoadley Rd, Aberdeen, MD 21010 ABSTRACT For three years we have used synthetic and field data to investigate the effectiveness of commercial refraction tomography codes on both simple and complex subsurface velocity structures, with the ultimate goal of determining the suitability of the method for karst problems. The results of these studies indicate that refraction tomography is able to resolve karst features under some conditions. The analysis of field data acquired on the Oak Ridge Reservation, TN shows low velocity zones on three parallel seismic lines. These zones are located at similar depths and fall on a line that is parallel to geologic strike, leading to an interpre- tation of a possible karst conduit. This feature has velocities of about 1500-2000 m/s in a matrix of 3000- 4000 m/s, reasonable velocities for a mud filled void in saprolite at these depths. Drilling of this feature is anticipated in the near future. Analysis of a seismic line taken over the known mud-filled cavity shows a low velocity feature with a location consistent with drilling results. The velocity of the feature is about 1000 m/s, a value that is a little lower than that found for the features discussed above. Synthetic modeling some- times generates results similar to the field results, but often fails to image cavities as well, or at all.
    [Show full text]
  • Geology of the Crater of Diamonds State Park and Vicinity, Pike County, Arkansas
    SPS-03 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director STATE PARK SERIES 03 GEOLOGY OF THE CRATER OF DIAMONDS STATE PARK AND VICINITY, PIKE COUNTY, ARKANSAS by J. M. Howard and W. D. Hanson Little Rock, Arkansas 2008 STATE OF ARKANSAS ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director STATE PARK SERIES 03 GEOLOGY OF THE CRATER OF DIAMONDS STATE PARK AND VICINITY, PIKE COUNTY, ARKANSAS by J. M. Howard and W. D. Hanson Little Rock, Arkansas 2008 STATE OF ARKANSAS Mike Beebe, Governor ARKANSAS GEOLOGICAL SURVEY Bekki White, State Geologist and Director COMMISSIONERS Dr. Richard Cohoon, Chairman………………………………………....Russellville William Willis, Vice Chairman…………………………………...…….Hot Springs David J. Baumgardner………………………………………….………..Little Rock Brad DeVazier…………………………………………………………..Forrest City Keith DuPriest………………………………………………………….….Magnolia Becky Keogh……………………………………………………...……..Little Rock David Lumbert…………………………………………………...………Little Rock Little Rock, Arkansas 2008 i TABLE OF CONTENTS Introduction…………………………………………………………………………..................... 1 Geology…………………………………………………………………………………………... 1 Prairie Creek Diatreme Rock Types……………………………….…………...……...………… 3 Mineralogy of Diamonds…………………….……………………………………………..……. 6 Typical shapes of Arkansas diamonds…………………………………………………………… 6 Answers to Frequently Asked Questions……………..……………………………….....……… 7 Definition of Rock Types……………………………………………………………………… 7 Formation Processes.…...…………………………………………………………….....…….. 8 Search Efforts……………...……………………………...……………………...………..….
    [Show full text]
  • Coding Manual 5.0
    Coding Manual 5.0 MINFILE Coding Manual Version 5.0 Information Circular 2007- 4 Table of Contents Welcome to the new 2007 MINFILE Coding Manual. This manual is a guide to the collection and entry of data into the MINFILE database. It compliments the MINFILE/pc User's Manual, which provides instructions on installing, operating, and using the MINFILE/pc program. Online help is also available from the online coding card. For comprehensive information concerning the MINFILE/pc program refer to the MINFILE/pc User's Manual. 1. INTRODUCTION 2. GENERAL INFORMATION 3. OCCURRENCE IDENTIFICATION 3.1 Coding Activity 3.2 MINFILE Number 3.3 Name 3.4 Status 3.5 NTS Map 3.6 BC Map 3.7 Mining Division 3.8 Location 3.8.1 Latitude/Longitude 3.8.2 UTM Zone 3.8.3 UTM Northing 3.8.4 UTM Easting 3.9 Elevation 3.10 Location Certainty 3.11 Canmindex Number 3.12 National Mineral Inventory (NMI) Number 3.13 Date Coded/Coded by 3.14 Date Revised/Revised by 3.15 Field Check 3.16 Comments - Identification 4. MINERAL OCCURRENCE file:///C|/HardcopyManual/01_codetoc.htm (1 of 4)2007-09-20 4:09:02 PM Coding Manual 5.0 4.1 Commodities 4.2 Mineralogy 4.2.1 Comments - Mineralogy 4.3 Alteration Type 4.4 Deposit Character 4.5 Deposit Classification 4.6 Deposit Type 4.7 Age of Mineralization 4.8 Isotopic Age 4.9 Material Dated 4.10 Dating Method 4.11 Deposit Configuration 4.11.1 Shape 4.11.2 Shape Modifier 4.11.3 Deposit Dimension 4.12 Attitude 4.13 Comments - Structural and Age 5.
    [Show full text]