 | | Report (issue) | | Sequence Along Coal Creek to Idaho Springs Formation Front Range, Colorado By JOHN D. WELLS, DOUGLAS M...____ Boulder Creek Granite and the quartz monzonite_ __________-__-__---_----_--_-_---_-Boulder Creek...1. Index maps of the Coal Creek area, Eldorado Springs, Ralston Buttes, and Blackhawk quadrangles..-_________...andalusite and cordierite. 12 4. Triangular diagram of Boulder Creek Granite.______________________ 13 5. Triangular...SEQUENCE ALONG COAL CREEK TO IDAHO SPRINGS FORMATION, FRONT RANGE, COLORADO By JOHN D. WELLS, DOUGLAS M |  | | 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...Granitic rocks 1230 Migration of elements 1230 Boulder Creek granodiorite and Silver Plume granite 1233 |  | | Report (issue) | | PRELIMINARY REPORT ON THE ECONOMIC GEOLOGY OF GILPIN COUNTY, COLORADO. By EDSON S. BASTIN and JAMES M. HiLL.1 INTRODUCTION...economic geology of Gilpin County and adjacent portions of Clear Creek and Boulder counties, Colo., summarizes...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...humidity. The principal mining centers are, in Gilpin County, Central City, Blackhawk, Nevadaville, Eussell |  | | 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 (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 ____________________ ----- ________ |  | | 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 |  | | Journal (article/letter/editorial) | | REGIONAL METAMORPHISM IN THE NORTHERN FRONT RANGE, COLORADO Abstract: Rubidium-strontium dating of wholerock...A large part of the Precambrian terrane of the Colorado Front Range consists of schists and gneisses which...(Fig. 1). West of Golden, Colorado, these were named the Idaho Springs Formation by Ball (1906). The Idaho...garnet, staurolite, andalusite, sillimanite-muscovite, and sillimanite-microcline zones have been recognized...local extensive recrystallization. Granodiorite of Boulder Creek type and quartz diorite were emplaced during |  | | Report (volume) | | the Freeland-Lamartine District, Clear Creek County, Colorado GEOLOGICAL SURVEY BULLETIN This report...the Freeland-Lamartine District, Clear Creek County, Colorado By J. E. HARRISON and J. D. WELLS GEOLOGY...OF CLEAR CREEK, GILPIN, AND LARIMER COUNTIES, COLORADO GEOLOGICAL SURVEY BULLETIN 1032-B This report...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) | | 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 |  | | Report (issue) | | QlJADRANGLE (TOGETHER 'VITH THE EMPIRE DISTRICT) COLORADo· BY JOSIAH E. SPURR AND GEORGE H. GARREY WITH............................ ___ ... . Biotite-sillimanite schist ........................................................_.......... . Distribution in Colorado ................................................. . . . . . . . . . . . . . . . . . . . 97 Idaho Springs auriferous area. __ ............. _.. _. _...._,_........................ 102 Extension from Boulder beyond Leadville .. , ...... _._._............ |  | | 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 (issue) | | REYNOLDS AREA LAWSON-DUMONT DISTRICT CLEAR CREEK COUNTY COLORADO By J. E. Harrison and B. F. Leonard UNITED...REYNOLDS AREA LAWSON-DUMONT DISTRICT, CLEAR CREEK COUNTY, COLORADO By J. E. Harrison and B. F. Leonard This...REYNOLDS AREA LAWSON-DUMONT DISTRICT, CLEAR CREEK COUNTY, COLORADO CONTENTS Page Abstract .....................units.................................... Idaho Springs formation................... Biotite-quartz-plagioclase...Sisters groups of claims. The area is in Clear Creek County, Colo., about three-fourths of a mile south of |  | | 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 Formati...ILLUSTRATIONS Page PLATE 1. Geologic map of the Eldorado Springs quadrangle..___.__In pocket FIGURE 1. Index map |  | | Journal (article/letter/editorial) | | SOME MINERAL OCCURRENCES IN THE GUFFEY REGION, COLORADO* Jeuos E. Bnven, []niversity of Michigan, Ann...north-central Fremont County and southeast Park County in the Front Range of central Colorado. Its center is...tentatively identified as sillimanite." Pods of coarse-grained magnetite-quartz-sillimanite rock, as much as 25...those which have been correIated with the Idaho Springs formation and closely associatedmigmatite. Cord.ierite:Sterrett...centimeters, partly or completely altered to fibrous sillimanite occur randomly oriented in injection gneiss on |  | | Report (volume) | | Uranium Deposits of the Caribou Area, Boulder County Colorado GEOLOGICAL SURVEY BULLETIN This report...Uranium Deposits of the Caribou Area, Boulder County Colorado By F. B. MOORE, W. S. CAVENDER, and' E...units_____ - - _________________ . Idaho Springs formation --______________ Boulder Creek granite____..________________...Point mine______-________-___ ________________ _ Idaho mine___________ ___________________ Gold mine_____...Plate 35. Geologic map of the Caribou area, Boulder County, Colo. 36. Composite map of the Caribou mine |  | | 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...metamorphic schists of the Precambrian Idaho Springs Formation, which is sandwiched from the south by |  | | 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 ................................. ....... ... |  | | 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...State Geological Survey, Vermittion, S. D. A formation of chert and volcanic ash crops out east of Sioux...the Northern States Power Plant, indicates a formation at least 60 feet thick, composed of chert, containing |  | | Report (issue) | | Quadrangle Grand, Gilpin, and Clear Creek Counties ColOrado. By WILLIAM A. BRADDOCK .,..,., GEOLOGICAL SURVEY...of plagioclase, quartz, and microcline in the Boulder Creek Granite_________________________ Triangular...________________________ Modal compoEition of Boulder Creek Granite_________________________________...CIPW norms of various Tertiary rocks from the Idaho Springs and Central City areas__ 19. Chemical compositions...QUADRANGLE, GRAND, GILPIN,, AND CLEAR CREEK COUNTIES, COLORADO " By WILLIAM ABSTRACT The Empire quadrangle |  | | 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 (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 |  | | Report (issue) | | Geology and Ore Deposits of the Front Range Colorado By T. S. LO\'ERING and E. N. GODDARD GEOLOGICAL...in cooperation with the Colorado State Geological Survey Board and the Colorado Metal Mining Fund ~ oopr...Metamorphic rocks ________________________ _ Idaho Springs formation _______________ _ Swandy ke hornblende..._ Quartz diorite and associated hornblendite_ Boulder Creek granite _________________ _ Pikes Peak granite...stratigraphic relations __ Fountain formation ________________ _ Ingleside formation ________________ _ Lyons sandstone |  | | Report (issue) | | Washington Zinc ore, Friedensville, Pa. Banded iron-formation, Palmer, Mich. 6. Ribbon asbestos ore, Quebec...Peninsula, Mich. 10. Porphyry molybdenum ore, Colorado 11. Zinc ore, Edwards, N.Y. 12. Manganese nodules... Poncha Springs, Colo. 14. Tungsten ore, North Carolina Rutile in Precambrian Sillimanite-Quartz Gneiss...Gneiss and Related Rocks, East-Central Front Range, Colorado By SHERMAN P. MARSH and DOU1GLAS M. SHERIDAN GEOLOGY...and geochemical study of rutile-bearing rocks in Colorado and a description of their occurrence elsewhere |  | | Report (issue) | | Geology and Ore Deposits of the Boulder County Tungsten District Colorado GEOLOGICAL SURVEY PROFESSIONAL... Geology and Ore Deposits of the Boulder County Tungsten District Colorado By T. S. LOVERING and OGDEN TWETO...with the State of Colorado through the Colorado Geological Survey Board and the Colorado Metal Mining Fund...Pre-Cambrian rocks_____________________________ Idaho Springs formation_ _______________ Distribution ___..._____ Age_ __________________________________ Boulder Creek granite and related rocks. ____ Distribution |  | | Report (issue) | | METAMORPHIC ROCKS OF THE CENTRAL FRONT RANGE. COLORADO By Dolores J. Gable ' Edited bv William. D............................................ 11 Sillimanite-Free Biotite Gneiss ................................................................... 13 Sillimanite-biotite gneiss.................................................................. 13 Garnet-sillimanite-biotite gneiss.............................................................. 14 Cordierite-sillimanite-biotite gneiss ............................. |
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