 | | Report (issue) | | Qiiartzite-Schist Sequence Along Coal Creek to Idaho Springs Formation Front Range, Colorado By JOHN D. WELLS, DOUGLAS...Boulder Creek Granite and the quartz monzonite_ __________-__-__---_----_--_-_---_-Boulder Creek Granite...the Coal Creek areaIn pocket FIGUBE 1. Index maps of the Coal Creek area, Eldorado Springs, Ralston Buttes...cordierite. 12 4. Triangular diagram of Boulder Creek Granite.______________________ 13 5. Triangular...QUARTZITE-SCHIST SEQUENCE ALONG COAL CREEK TO IDAHO SPRINGS FORMATION, FRONT RANGE, COLORADO By JOHN D. WELLS, DOUGLAS |  | | Journal (article/letter/editorial) | | PEGMATITES OF EIGHT MILE PARK, FREMONT COUNTY, COLORADOXT E. Wrrr. HerNnrcu, Department of Mineralogy...to twelve miles west of Canon City, Fremont County, Colorado, includes about 30 square miles that lie at...separate paper. 420 PEGMATITES OF EIGHT MILE PARK, COLORADO 42r area are flanked on the east by hogbacks...granite, Idaho Springs schist, and injection gneiss. The oldest, the Idaho Springs formation, consists...formed by large scale lit-par-lit intrusion of Idaho Springs biotite schists by granite, aplite, and pegmatite |  | | Report (volume) | | of the Freeland-Lamartine District, Clear Creek County, Colorado GEOLOGICAL SURVEY BULLETIN This report...of the Freeland-Lamartine District, Clear Creek County, Colorado By J. E. HARRISON and J. D. WELLS GEOLOGY...GEOLOGY AND ORE DEPOSITS OF CLEAR CREEK, GILPIN, AND LARIMER COUNTIES, COLORADO GEOLOGICAL SURVEY BULLETIN...Pre-Cambrian rocks...____________________________ _ Idaho Springs formation___________________________ Biotite-quartz...mine. CONTENTS V Page FIGURE 3. Index map of Colorado showing the location of the FreelandLamartine |  | | Report (issue) | | Geology of Precambrian Rocks Central City District Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 474-C Prepared... Geology of Precambrian Rocks Central City District Colorado By P. K. SIMS and D. J. GABLE SHORTER CONTRIBUTIONS...1918Geology of Precambrian rocks, Central City district, Colorado, by P. K. Sims and D. J. Gable. Washington, U...district, Colorado. 1964. (Card2) 1. Geology, Stratigraphic Pre-Cambrian. 2. Geology Colorado Gilpin Co...Gilpin County, Colorado. 2. Geologic sections of the Central City district, Gilpin County, Colorado. 3. |  | | Report (issue) | | QlJADRANGLE (TOGETHER 'VITH THE EMPIRE DISTRICT) COLORADo· BY JOSIAH E. SPURR AND GEORGE H. GARREY WITH..................._.......... . Distribution in Colorado ................................................. . . . . . . . . . . . . . . . . . . . 97 Idaho Springs auriferous area. __ ............. _.. _. _....Boulder County.............. . . . . . . . . . . . ......... . ....... . 103 Ores in Gilpin County ............................... . 103 Orcs in Clear Creek County ............................ . 103 Ores from |  | | Report (volume) | | (A) Geology of Precambrian rocks, Idaho Springs district, Colorado, by Robert H. Moench. (B) Geology...and iron content of rocks from the Red Mountain Formation, Alabama, by Richard P. Sheldon. (E) Investigations... Geology of Precambrian Rocks, Idaho Springs District, Colorado By ROBERT H. MOENCH CONTRIBUTIONS...of the Idaho Springs district____________ In pocket 2. Geologic sections of the Idaho Springs district...mapped by present and previous workers in the Idaho Springs district ____________________ ----- ________ |  | | Journal (article/letter/editorial) | | PRECAMBRIAN ROCKS OF THE HALL VALLEY AREA, FRONT RANGE, COLORADO BY ERNEST E. WAHLSTROM AND OK JOON KIM ABSTRACT...The Hall Valley area, in northwestern Park County, Colorado, contains foliated highgrade Precambrian metamorphic...argument against continued use of the terms Idaho Springs formation and Swandyke gneiss for the metasedimentary...migmatization and granitization. (7) A body of Boulder Creek granodiorite was intruded into the northeast portion...Granitic rocks 1230 Migration of elements 1230 Boulder Creek granodiorite and Silver Plume granite 1233 Pegmatite |  | | Report (volume) | | Part of the Morrison Quadrangle Jefferson County, Colorado GEOLOGICAL SURVEY BULLETIN 1251-E Geology...Part of the Morrison Quadrangle Jefferson County, Colorado By D. J. GABLE CONTRIBUTIONS TO GENERAL GEOLOGY...rocks along the mountain front due west of Denver, Colorado UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON...PART OF THE MORRISON QUADRANGLE JEFFERSON COUNTY, COLORADO By D. J. GABLE ABSTRACT The Morrison quadrangle...This sequence, which is typical of the Idaho Springs Formation, was intruded, in Precambrian time, by |  | | Report (volume) | | in Colorado GEOLOGICAL SURVEY BULLETIN 1422-D Nomenclature of Precambrian Rocks in Colorado By...Ogden, 1912Nomenclature of Precambrian rocks in Colorado. (Contributions to stratigraphy) (Geological Survey...Pre-Cambrian. 2. Geology, Stratigraphic Nonmenclature Colorado. I. Title. II. Series. HI. Series: United States... ILLUSTRATION Page FIGURE 1. Map of parts of Colorado and adjoining States showing distribution of Precambrian...1. Classification of Precambrian rock units in Colorado............................. D4 in CONTRIBUTIONS |  | | Report (issue) | | Beryllium Area, Park and Jefferson t:-1 Counties, Colorado g ~ s:p ~ I> li:tl ~ GEOLOGICAL SURVEY PROFESSIONAL...Flats) Beryllium Area, Park and Jefferson Counties, Colorado By C. C. HAWLEY GEOLOGY AND ORE DEPOSITS OF THE...SOUTHERN TARRYALL REGION PARK AND JEFFERSON COUNTIES, COLORADO GEOLOGICAL SURVEY PROFESSIONAL PAPER 608-A A...rocks~ ____ ~ _______________________ _ Idaho Springs Formation ___________________ _ Amphibolite and hornblendite...hornblendite _______________ _ Boulder Creek{?) Granodiorite ______________ _ Silver Plume(?) Granite |  | | Report (volume) | | Geology of the Eldorado Springs Quadrangle Boulder and Jefferson , Counties, Colorado C_-J / By JOHN D. WELLS...___ Boulder Creek Granodiorite__________________________ Inclusions in the Boulder Creek Granodiorite_________...Sandstone_____--__--__-_-___---____________ Lykins Formation.__________________________________ Mesozoic r...rocks__________________________________________ Ralston Creek Formation.. __________________________ Morrison Form...ILLUSTRATIONS Page PLATE 1. Geologic map of the Eldorado Springs quadrangle..___.__In pocket FIGURE 1. Index map |  | | Report (issue) | | PRELIMINARY REPORT ON THE ECONOMIC GEOLOGY OF GILPIN COUNTY, COLORADO. By EDSON S. BASTIN and JAMES M. HiLL.1 INTRODUCTION...the economic geology of Gilpin County and adjacent portions of Clear Creek and Boulder counties, Colo.,...Mountains. It is the oldest lode-mining region in Colorado, and its discovery in 1859 was the occasion of...productive portions of Gilpin County and small adjacent parts of Boulder and Clear Creek counties, all within...Gilpin County, Central City, Blackhawk, Nevadaville, Eussell Gulch, Perigo, and Apex; in Clear Creek County |  | | Report (volume) | | Geology of the Platte Canyon Quadrangle Colorado By WARREN L. PETERSON CONTRIBUTIONS GEOLOGICAL TO...quadrangle. _ In pocket FIGURE 1. Index map of Colorado showing location of the Platte Canyon quadrangle...GEOLOGY GEOLOGY OF THE PLATTE CANYON QUADRANGLE, COLORADO By WARREN L. PETERSON ABSTRACT The Platte Canyon...Front Kange in Colorado (fig. 1). The quadrangle is accessible from the north by county roads that lead...Highway 285 and Colorado Highway 124, from the south by a county road that joins Colorado Highway 67, and |  | | Journal (article/letter/editorial) | | Geological Survey, Vermillion, S. D. Paleozoic Colorado land mass extended from northern Black Hills nearly...transgression lasting to mid-Turonian (embracing Graneros formation). Basin downwarping recurred during Laramide and...across South Dakota. Wisconsin glaciation and formation of Missouri River are later than the old age valleys...west-north-west of Rapid City, and in other places. Rapid Creek, with well-developed intrenched meanders, is cut...State Geological Survey, Vermittion, S. D. A formation of chert and volcanic ash crops out east of Sioux |  | | Report (issue) | | General Geology of the Harold D. Roberts Tunnel, Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 831-B General... General Geology of the Harold D. Roberts Tunnel, Colorado By CHARLES S. ROBINSON, LAWRENCE A. WARNER, and...ENGINEERING GEOLOGY OF THE HAROLD D. ROBERTS TUNNEL, COLORADO GEOLOGICAL SURVEY PROFESSIONAL PAPER 831-B......................................... Boulder Creek Granite...........................................Morrison Formation. Dakota Group............ Benton Shale.............. Niobrara Formation. Pierre Shale |  | | Journal (article/letter/editorial) | | by BRUCE R. DOE U.S. Geological Survey, Denver, Colorado INTRODUCTION T H E isotopic composition of lead...shallow. A large triangular region comprising the Colorado Plateau and the Basin and Range province has not...sampled because the possible mode of origin is not clear-cut, although some data by Stern, Newell, Kistler...Mountains Front Range Little Glass Mountain Clear Lake area Santa Lucia Mountains Southern California...Albion stock, feldspar (Ta 1) Vitrophyre, Willow Creek Member, Bachelor Mountain Rhyolite (Re 1) Welded |  | | Journal (article/letter/editorial) | | system in basalt. 2. The Eldora stock--Idaho Springs Formation contact zone: a conductive thermal regime...stock and Precambrian gneiss of the Idaho Springs Formation, Colorado, where previous geochronological,...collected from the stock and from the Idaho Springs Formation at the contact and at increasing distances...never at depths greater than 1 km. The Idaho Springs Formation consists predominantly of alternating felsic-...felsic, mafic and pegmatitic phases of the Idaho Springs Formation, were taken along the aforementioned traverse |  | | Journal (article/letter/editorial) | | completely their use i~l age determination. Discordant zircon ages are nearly all of the kind that wou[id result...phenomenon i~ lacking. The problem of discordant zircon ages has been treat,td as one of loss of lead,...at a constant rate over the entire history of a zircon, and Tilton {3] showed thalt continuous diffusion...showed that zircon from saprolite had U-Pb ages that were no more discordant than zircon ages from tile...[11 ] examined the related thorium-lead system in zircon and showed thai in many places the thorium-lead |  | | Report (volume) | | the Lawson-DumontFall River District Clear Creek County Colorado By C. C. HAWLEY and FRANK BAKER MOORE...northwestern part of the important Central City-Idaho Springs mineralized area UNITED STATES GOVERNMENT PRINTING...section of the Lawson-Dumont-Fall River district, Clear County, Colo. 2. ~ap showing major faults (veins) of...THE LAWSONDUMONT-FALL RIVER DISTRICT, CLEAR CREEK COUNTY, COLORADO By C. C. HAWLEY and FRANK BAKER...is in Clear Creek County, Colo., just west of the highly productive Central City and Idaho Springs districts |  | | Journal (article/letter/editorial) | | District LARIMER COUNTY, COLORADO MARK I. JACOBSON 1350 E . Easter Avenue Littleton, Colorado 80122 B L U...This is one of the few pegmatite districts in Colorado where nei ther all the pegmatites have been studied...of the Crystal Mountain district, Larimer County, Colorado. Location The Crystal Mountain district is...Collins and Loveland within the Front Range of Colorado. Most of the district's pegmatites are found north...the Big Thomp son Canyon and south of Buckhorn Creek. This area can be located on the Crystal Mountain |  | | Report (volume) | | . 234 " y { " ,-t .. .~,:",. I " , COLORADO "or.! _ +, (~ STATE OF .~ :'(' COL~ADO /... BULLETIN 40 RADIOACTIVE MINERAL OCCURRENCES OF COLORADO AND BlaLlllGRAPHY by James L. Nelson-Moore,...Energy COLORADO GEOLOGICAL SURVEY DEPARTMENT OF NATURAL RESUURCES STATE OF COLORADO DENVER, COLORADO 1978...ete 11 st r ng of rad i aaet 1ve occurrences 1n Colorado, with a comprehensive blbi iography and bibliographic...association of radium, uranium. and vanadIum on the Colorado Plateau sparked several periods of exploratIon |  | | Report (issue) | | Some High-Grade Cordierite Gneisses, Front Range, Colorado Dolores J. Gable U.S. Geological Survey, Denver...SOCIETY OF AMERICA, INC. Colorado Building P.O. Box 1719 Boulder, Colorado 80302 Printed in the United...65 65 66 67 ... Vlll CORDIERITE GNEISSES, COLORADO FRONT RANGE Factors determining the mineral assen1blages...75 77 81 85 FIGURES l. Map of Front Range, Colorado ............... ................. .......... ...cordierite-bearing rocks in central part of Front Range, Colorado ................................. ....... ... |  | | Report (issue) | | ALONG THE FRONT RANGE FROM DENVER TO BOULDER, COLORADO Clay Minerals Society 39th Annual Meeting and...Geological Survey Open-File Report 02-413 Denver, Colorado 2002 U.S. DEPARTMENT OF THE INTERIOR GALE A........................ 11 The clay industry in Colorado ..................................... 13 Rubey.......................................... 47 Idaho Springs and Central City mining districts .......................... 67 Nederland; mining in Boulder County .............................. 67 Boulder Canyon |  | Stark, J. T., Johnson, J. H., Behre, C. H. Jr., Powers, W. E., Howland, A. L., Gould, Don B. (1949, January) Geology and Origin of South Park, Colorado. GSA Memoir 33. Geological Society of America doi:10.1130/mem33 | Report (issue) | | Memoir 33 GEOLOGY AND ORIGIN OF SOUTH PARK, COLORADO BY J. T . STARK, J. H. JOHNSON, C. H. BEHRE,..... ................................ . Idaho Springs formation ......................... . ......................... . ...................... Maroon formation . . . .. ... ..... . . . .................. .......................... ............ Morrison formation .......... . .................. .. .............Dakota formation ... ............... .............. . ............... . .......... Benton formation ... |  | | Report (issue) | | Crystalline Rocks, Park and Jefferson Counties, Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER 608-B General...Crystalline Rocks, Park and Jefferson Counties, Colorado By C. C. HAWLEY and R. A. WOBUS GEOLOGY AND ORE...TARRYALL REGION, PARK AND JEFFERSON COUNTIES, COLORADO GEOLOGICAL SURVEY PROFESSIONAL PAPER 608-B...Tarryall region, Park and Jefferson Counties, Colorado) (Geological Survey Professional Paper 608-B)...Stratigraphic Pre-Cambrian. 2. Geology-Colorado Park Co. 3. Geology Colorado Jefferson Co. 4. GraniteColorado |
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