 | | Report (issue) | | Qiiartzite-Schist Sequence Along Coal Creek to Idaho Springs Formation Front Range, Colorado By JOHN D. WELLS, DOUGLAS...metavolcanic(?) rocks_______ Microcline - quartz - plagioclase - biotite gneiss (microcline gneiss)________________________..._______ Microcline - quartz - plagioclase - biotite gneiss and hornblende gneiss (microcline gneiss and...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 |  | | 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...granite, a red, coarse-grained, porphyritic, microcline granite, was emplaced. Late difierentiates from |  | | 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 |  | | 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 (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...Lithologic succession of layered rocks_______ Microcline gneiss ________________________ Biotite gneiss |  | | 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...pegmatite_______________________________ Microcline gneiss (microcline-quartz-plagioclase-biotite gneiss)___...of the Idaho Springs district____________ In pocket 2. Geologic sections of the Idaho Springs district |  | | Report (issue) | | QlJADRANGLE (TOGETHER 'VITH THE EMPIRE DISTRICT) COLORADo· BY JOSIAH E. SPURR AND GEORGE H. GARREY WITH..................._.......... . Distribution in Colorado .................................................................. _. . . . . . 93 Origin of microcline. _.. _.. _. _............ _. _.. _. _.. 93 Secondary.... . . . . . . . . . . . . . . . . . . . 97 Idaho Springs auriferous area. __ ............. _.. _. _....Boulder County.............. . . . . . . . . . . . ......... . ....... . 103 Ores in Gilpin County .... |  | | 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...Quartz-plagioclase gneiss___________-______-________________ Microcline-quartz-plagioclase-biotite gneiss.__________________...2. Triangular diagram showing composition of microcline gneiss___________________________________________ |  | | 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 |  | | Journal (article/letter/editorial) | | REGIONAL METAMORPHISM IN THE NORTHERN FRONT RANGE, COLORADO Abstract: Rubidium-strontium dating of wholerock...rocks give a concordant age of 1.71 ± 0.07 b.y. Microcline and plagioclase from a concretion pegmatite yield...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...andalusite, sillimanite-muscovite, and sillimanite-microcline zones have been recognized (Braddock, 1966). |  | | 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) | | REYNOLDS AREA LAWSON-DUMONT DISTRICT CLEAR CREEK COUNTY COLORADO By J. E. Harrison and B. F. Leonard ...REYNOLDS AREA LAWSON-DUMONT DISTRICT, CLEAR CREEK COUNTY, COLORADO By J. E. Harrison and B. F. Leonard...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 |  | | 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) | | Lithium-Bearing Pegmatite in the Clear Creek District, CLEAR CREEK COUNTY, COLORADO In all of Colorado's Front...lithiumbearing pegmatite has been rediscovered in the Clear Creek district on the east flank of Mt. Evans. This...TILANDER Chevron U.S.A., Inc. 700 South Colorado Boulevard Denver, Colorado 80201 pears to dip steeply to the...pegmatite. Amphibolite, probably of the Idaho Springs Formation, encloses the pegmatite. The country rock...size) pegmatite composed of plagioclase, quartz, microcline (perthite), and muscovite. Two subvarieties of |  | | 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............................................... Microcline gneiss............................................................................... Boulder Creek Granite........................................ |  | | 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) | | 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...Amphibolite___________________________________ 8. Microcline gneiss_______________________________ 9. Granite...THE LAWSONDUMONT-FALL RIVER DISTRICT, CLEAR CREEK COUNTY, COLORADO By C. C. HAWLEY and FRANK BAKER |  | | Report (volume) | | 931-O NICKEL DEPOSIT NEAR GOLD HILL BOULDER COUNTY, COLORADO BY E. N. GODDARD AND T. S. LOVERING Strategic............ 351 Idaho Springs formation.............................. 352 Boulder Creek granite..........Generalized geologic map of the vicinity of Gold Hill, Colorado, showing-the regional setting of the Copper King...King mine, Boulder County, Colorado..... In pocket Figure 37. Index map of Colorado showing the location... NICKEL DEPOSIT NEAR GOLD HILL, BOULDER COUNTY, COLORADO By E. N. Goddard and T. S. Levering ABSTRACT |  | | Report (issue) | | Empire Quadrangle Grand, Gilpin, and Clear Creek Counties ColOrado. By WILLIAM A. BRADDOCK .,..,., GEOLOGICAL...gneiss ________________________ -- ___ Microcline gneiss (microcline-quartz-plagioclase-bioti te gneiss)...diorite of St. Marys Lake__________________ Bo.ulder Creek Granite__________________________ Quartz diorite...in the Empire quadrangle, Grand, Gilpin, and Clear Creek Counties, Colo __ In pocket 3. Foliation and...-----Triangular plot of quartz, plagioclase, and microcline in the granitic part of migmatite from biotite |  | | Journal (article/letter/editorial) | | C. Alsrracr Microcline perthites from Precambrian pegmatites in the l'ront Range, Colorado, have been...sholvs fairly well exposed vertical contacts The microcline-orthoclase transition, the only major manifestation...Outside the contact a.ureole and microcline commonly consists of clear crystals with typical crosshatched...occasionally be observed. Both the nature of the microcline-orthoclase transition and its distance from the...Heat flow calculations further indicate that the microcline-orthoclase transition may occur at temperatures |  | | 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...those which have been correIated with the Idaho Springs formation and closely associatedmigmatite. Cord.ierite:Sterrett...of the mine on the north bank of Thirty-one Mile Creek. The outcrop is about 500 feet east of the Copper...bank of Dicks Gulch about 2 miles west of Currant Creek. The other minerals of the gneiss are qtartz, muscovite |  | | Journal (article/letter/editorial) | | G R A N IT E S OF T H E FR O N T R A N G E , COLORADO: T H E IN D IA N C R EE K PLUTONS BY MARGARET...batholith............................... Indian Creek granite-Indian Creekplutons............................................................ Idaho Springs formation................................................................................. Indian Creek plutons...........................................ILLUSTRATIONS Figure Page 1. Front Range batholiths in Colorado.............................................. |  | | Report (volume) | | Economic Geology of the Idaho Springs District Clear Creek and Gilpin Counties, Colorado GEOLOGICAL (=) I...Geology of the Idaho Springs District Clear Creek and -i ;i ?i Gilpin Counties, Colorado By ROBERT H. MOENCH..._______________ Mines and prospects in the Idaho Springs district ________________ Previous studies....gneiss and pegmatite.-------------_-_I-__':!_---_ Microcline gneiss. _________________________L___ J.______...Genesis of the veins____________ Sequence of ore formation.___. Hypogene zoning.____________ Environment |  | | 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) | | Precambrian Rocks of the Southern Front Range, Colorado ABSTRACT Rb-Sr analyses of whole-rock samples...areas in the southern part of the Front Range, Colorado, yield ages of 1,781 ± 66 and 1,722 ± 50 m.y....igneous and metamorphic events of the Front Range in Colorado. Analyses of minerals separated f r o m t w o...origin. These rocks west of Golden, Colorado, were named " I d a h o Springs F o r m a t i o n " by Ball (1908)...and Boos (1957) extended the use of " I d a h o Springs Series" to the south, including the Blue Ridge |
|
