USGS Visual Identifier

GEOLEX

Summary of Citation: Pikes Peak

Publication:
Cross, C.W., 1894, Description of the Pikes Peak sheet [Colorado]:
   U.S. Geological Survey Geologic Atlas of the United States,
   Pikes Peak folio, no. 7, 5 p.
Usage in Publication:
Pikes Peak granite*

Modifications: Geologic Province: Dominant Lithology:
 First used
 Southern Rocky Mountain region
 Granite

Summary:
First published use of name. No type locality designated. Geologic map. Not mapped as a separate unit but as part of a unit designated "granite and gneiss" of Archean age. These rock types make up most of map occurring in Teller Co, and Park Co, CO in Southern Rocky Mountain region. Is principally a single type of granite at Pikes Peak--a very coarse grained, red biotite-granite or granitite. Potash feldspar, microcline, and orthoclase predominate over granite and biotite. The feldspars are often intergrown after perthite with plagioclase, quartz, and biotite. Zircon, apatite, and allanite are accessory minerals. Red color, a pigment of hydrous iron oxide, impregnates the feldspars. Biotite content increases near Platte River area and in several places in southwest part of district.
Summary of Citation: Pikes Peak

Publication:
Matthews, E.B., 1900, The granitic rocks of the Pikes Peak
   quadrangle: Journal of Geology, v. 8, no. 2, p. 214-240
Usage in Publication:
Pikes Peak type*

Modifications: Geologic Province: Dominant Lithology:
 Revised
Overview
 Southern Rocky Mountain region
 

Summary:
A large part of the area mapped in the Pikes Peak folio, El Paso Co, CO in the Southern Rocky Mountain region, is a single type of granite characterized by large pink or gray feldspar and quartz grains. Some of the feldspar phenocrysts are several inches in diameter. The fresh unaltered granites are coarse-grained aggregates of quartz, perthitic feldspar, and biotite with occasional accessory hornblende or fluorite, microscopic apatite, zircon, titanite, magnetite, rutile, hematite, limonite, epidote and allanite. Texture varies from that in which feldspar is only slightly larger than quartz to one where feldspar stands out in large imperfectly formed porphyritic crystals. The most important feldspar is microcline. Considered to be the oldest granite in the report area. Is cut by many dikes of Summit type (first used) and by finer grained rocks of Cripple Creek type (first used). Rock disintegrates before it is decomposed. Effect of weathering extends 2 or 3 ft beneath the surface. Forms thick talus and granite. Of Algonkian age. Small geologic sketch map.
Summary of Citation: Pikes Peak

Publication:
Scott, G.R., 1963, Bedrock geology of the Kassler quadrangle,
   Colorado, IN Geology of the Kassler quadrangle, Jefferson
   and Douglas Counties, Colorado: U.S. Geological Survey
   Professional Paper, 421-B, p. B71-B125
Usage in Publication:
Pikes Peak granite*

Modifications: Geologic Province: Dominant Lithology:
 Mapped 1:24k (Kassler quad, Douglas and Jefferson Cos, CO)
 Denver basin
 Granite

Summary:
Is Precambrian lithodeme mapped in northwestern Douglas Co, CO (Southern Rocky Mountain region). Is only formal Precambrian lithodemic unit in quad. Occurs along southern edge of quad. Consists of two separately mapped units: (1) coarse-grained moderate reddish-orange granite composed of microperthite, quartz, and biotite and (2) granite pegmatite, crystal-lined miarolitic cavities, vein-like pegmatites, and pegmatized border zone. Outcrops as rounded cubical shapes due to weathering along joints. Mineralogy of three samples listed (table, p.84). In contact with Precambrian metamorphic rocks.
Summary of Citation: Pikes Peak

Publication:
Peterson, W.L., 1964, Geology of the Big Spring quadrangle,
   Kentucky: U.S. Geological Survey Geologic Quadrangle Map,
   GQ-261, 1 sheet, scale 1:24,000
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Mapped 1:24k (Platte Canyon quad, Douglas and Jefferson Cos, CO)
 Southern Rocky Mountain region
 Granite

Summary:
Is Precambrian(?) lithodeme mapped in western Douglas and southeastern Jefferson Cos, CO (Southern Rocky Mountain region). Is only formally named unit in quad. On map explanation, unit is shown to be older than Precambrian(?) foliated basic dike unit and younger than all other informal Precambrian? lithodemic units; contact with older rocks is sharp. Outcrops over southwestern one-third of quad. Mapped separately as pink coarse-grained seriate granular granite unit; faintly mottled light-gray and light pinkish-gray medium-grained seriate granular to porphyritic quartz monzonite unit in gradational contact with granite unit; and as inclusions of gneisses, intruded and enveloped by fine-grained alaskite. Crops out in smooth, rounded masses. Cut by dikes of fine-grained alaskite; dikes are less than an inch up to 10 ft thick. Pegmatites are common in Pikes Peak; they range from 1 to several hundred ft across but most are 5-50 ft in maximum dimension. In places contains thin, dark, curved layers (or veins) that contain abundant allanite as well as feldspar, quartz, biotite, and fluorite. Pikes Peak also contains many inclusions of metasedimentary rock and migmatite.
Summary of Citation: Pikes Peak

Publication:
Hawley, C.C., Huffman, A.C., Jr., Hamilton, J.C. and Rader,
   L.F., Jr., 1966, Geologic and geochemical features of the
   Redskin Granite and associated rocks, Lake George beryllium
   area, Colorado, IN Geological Survey research 1966: U.S.
   Geological Survey Professional Paper, 550-C, p. C138-C147
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Southern Rocky Mountain region
 

Summary:
A granite formerly called the late facies of the Pikes Peak Granite is separated from the Pikes Peak and named Redskin Granite. The Pikes Peak occurs in the north and northeast parts of the Lake George area, Park Co, CO in the Southern Rocky Mountain region. The granite is coarse grained, subequigranular to porphyritic, and at most places massive to very faintly foliated but potassic feldspars are markedly aligned in a primary foliation locally. Pikes Peak is cut by dikes or irregular masses of pegmatite, aplite-pegmatite, fine-grained granite, and granite porphyry. Is classified as epizonal because of its discordant contacts, massive structure, and local miarolitic nature. Isotopic ages reported from previous reports of 980, 1,000, 1,060, and 1,080 m.y. Geologic map. Chemical analyses.
Summary of Citation: Pikes Peak

Publication:
Bryant, B.H., 1974, Reconnaissance geologic map of the Conifer
   quadrangle, Jefferson County, Colorado: U.S. Geological Survey
   Miscellaneous Field Studies Map, MF-597, 1 sheet, scale
   1:24,000
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Mapped 1:24k (Conifer quad, Douglas and Jefferson Cos, CO)
 Southern Rocky Mountain region
 Granite

Summary:
Is Precambrian Y [Middle Proterozoic] lithodeme mapped in west-central Jefferson Co, CO (Southern Rocky Mountain region). Is youngest Precambrian unit in quad. On Correlation of Map Units is shown to unconformably underlie Pleistocene older alluvium unit and to be younger than Silver Plume Quartz Monzonite (Precambrian Y). Unit is mapped in southwestern part of quad. Pikes Peak is described as coarse-grained white to moderate-orange-pink biotite and hornblende-biotite granite with a grain size of 0.5 to 2 cm. Forms large slabby outcrops and a thin very permeable sandy soil. Rb-Sr age is about 1,040 m.y. (Hedge, 1970, USGS P.P. 700-B, p.86-89).
Summary of Citation: Pikes Peak

Publication:
Bryant, B.H., 1974, Reconnaissance geologic map of the Pine
   quadrangle, Jefferson County, Colorado: U.S. Geological Survey
   Miscellaneous Field Studies Map, MF-598, 1 sheet, scale
   1:24,000
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Mapped 1:24k (Pine quad, Jefferson Co, CO)
 Southern Rocky Mountain region
 Granite
Granodiorite
Quartz monzonite

Summary:
Is Precambrian Y [Middle Proterozoic] lithodeme mapped in southern Jefferson Co, CO (Southern Rocky Mountain region). Is youngest Precambrian unit in quad. On Correlation of Map Units is shown to unconformably underlie Tertiary gravel unit and to be younger than Silver Plume Quartz Monzonite (Precambrian Y). Occurs in most of southern half of quad. Is divided into two map units, a granite unit and granodiorite and quartz monzonite unit. Granite is described as coarse-grained white to moderate-orange-pink biotite and hornblende-biotite granite with a grain size of 0.5-2 cm; contains a few dikes and inclusions of aplite and a few pods and dikes of pegmatite; forms large slabby outcrops and thin sandy soil except along fracture zones where outcrops are smaller and angular, and soil is deeper. Granodiorite and quartz monzonite unit is described as coarse-grained, light-greenish-gray, commonly porphyritic biotite and biotite-hornblende; contains potassic feldspar grains 0.5-2 cm; contacts with granite unit are gradational. Rb-Sr age is about 1,040 m.y. (Hedge, 1970, USGS P.P. 700-B, p.86-89).
Summary of Citation: Pikes Peak

Publication:
Tweto, Ogden, 1977, Nomenclature of Precambrian rocks in Colorado,
   IN Contributions to stratigraphy: U.S. Geological Survey
   Bulletin, 1422-D, p. D1-D22
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Overview
 Southern Rocky Mountain region
 

Summary:
Is the chief rock of large composite Pikes Peak batholith. Name has been applied to many different compositional facies and intrusive bodies in batholith but properly should be restricted to coarse-grained granite or rank changed. Listed with granitic rocks of circa 1,000 m.y. (Precambrian Y) age group in Southern Rocky Mountain region.
Summary of Citation: Pikes Peak

Publication:
Marvin, R.F. and Dobson, S.W., 1979, Radiometric ages; compilation
   "B", U.S. Geological Survey: Isochron/West, no. 26, p. 3-32
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Isotopic dating
 Southern Rocky Mountain region
 

Summary:
Four samples taken in vicinity 38 deg 52 min N, 105 deg 07 min W, Teller? and El Paso Cos, CO in the Southern Rocky Mountain region and dated by Pb-alpha method (on zircon). First sample dated as 1,290 +/-145 m.y. old. Age too old for 1,000-m.y.-old Pikes Peak Granite; age may be result of xenocrystic contamination. Second, third, and fourth samples dated as 1,050 +/-115 m.y. old, 995 +/-110 m.y. old, and 1,055 +/-115 m.y. old respectively. Age of Pikes Peak Granite is approximately 1,000 m.y. Ages published by Marvin (1968).
Summary of Citation: Pikes Peak

Publication:
Tweto, Ogden, 1987, Rock units of the Precambrian basement in
   Colorado, IN Geology of the Precambrian basement in Colorado:
   U.S. Geological Survey Professional Paper, 1321-A, p. A1-A54,
   (incl. geologic map, scale 1:1,000,000)
Usage in Publication:
Pikes Peak Granite*

Modifications: Geologic Province: Dominant Lithology:
 Overview
 Southern Rocky Mountain region
 

Summary:
Is a pink to pale-orange, coarse-grained, massive, homogeneous granite that is part of Pikes Peak batholith, Southern Rocky Mountain region, CO. Disintegrates into a coarse, orange-red grus. Many rocks of the batholith (Mount Rosa, Windy Point, and Redskin Granites and related rocks) are excluded from the Pikes Peak Granite. The batholith occupies an area of about 3,100 km sq (1,200 mi sq) in the southern Front Range and is inferred to extend over a larger area in the subsurface. The Rb-Sr age of the batholith is about 1,020 m.y. Pikes Peak Granite is of Middle Proterozoic age.