| Bove, Dana J., Hon, Ken, Budding, Karin E., Slack, John F., Snee, Lawrence W., Yeoman, Ross A. (2001) Geochronology and geology of late Oligocene through Miocene volcanism and mineralization in the western San Juan Mountains, Colorado. Professional Paper 1642. US Geological Survey doi:10.3133/pp1642 | Report (issue) | Volcanism and Mineralization in the Western San Juan Mountains, Colorado U.S. Geological Survey Professional...Volcanism and Mineralization in the Western San Juan Mountains, Colorado By Dana J. Bove, Ken Hon, Karin...volcanism and mineralization in the western San Juan Mountains, Colorado / by Dana J. Bove ... [et al.]...GeologyāSan Juan Mountains (Colo. and N.M.). 4. GeologyāColorado. 5. VolcanismāSan Juan Mountains (Colo...16 16 17 17 20 Figures 1. 2. 3. 4. Map of the San Juan volcanic field, Colorado, showing location of | | | Report (issue) | of revised ages of volcanic units in the San Juan Mountains, Colorado: Recalculated K-Ar age determinations...Generalized volcanic stratigraphy of the San Juan Mountains, Colorado..................................rocks from Tertiary volcanic units of the San Juan Mountains, Colorado..............................4...determinations for the middle to late Tertiary San Juan volcanic field have been recalculated using the...studies outlining the geochronologic history of the San Juan volcanic field were published between 1967 and | | | Journal (article/letter/editorial) | Colorado 8022) Volcanic History of the San Juan Mountains, Colorado, as Indicated by Potassium-Argon...Potassium-Argon Dating ABSTRACT Volcanic rocks in the San Juan Mountains constitute the largest erosional remnant...that extended over much of the southern Rocky Mountains and adjacent areas in Oligocene and later time...the gross petrologic evolution throughout the San Juan remnant of this field was relatively simple, with...original field indicate a similar evolution. In the San Juan field, voluminous early lavas and brecciasāmainly | | | Journal (article/letter/editorial) | central Nevada caldera complex and the central San Juan caldera complex, Colorado* 180/160 Peter B. Larson**...91125, USA Abstract. Oxygen isotope compositions were measured on 129 quartz, feldspar, and biotite phenocrysts...from the Oligocene central Nevada and central San Juan caldera complexes. Most of the ash-flow tufts...ring-fracture eruptions. 6180 values in the central San Juan magmas range from +6.8 to +7.5: These values are...caldera complex, Nye County, Nevada, and the central San Juan caldera complex, Colorado, were chosen for study | | | Journal (article/letter/editorial) | and Mesozoic rocks and overlain by the Miocene San Juan tuff (Larsen and In 1915 Atwood described the...northwest flank of the San miles east of Gunnison (PI. 1, fig. 1; Atwood Juan Mountains in southwestern Colorado...of relatively of it on the south flank of the mountains, 100 fresh Tertiary volcanic rocks are set in...the many of the pebbles and cobbles are rather San Juan region, and "at no time since mid- well rounded...are somewhat more [Eocene] generation of Rocky Mountains" common. (Atwood and Atwood, 1926, p. 621). Some | | | Report (issue) | Related Volcanic Rocks, Southeastern SanJuan Mountains, Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER...and Related Volcanic Rocks, Southeastern San Juan Mountains, Colorado By PETER W. LIPMAN GEOLOGICAL...and related volcanic rocks, southeastern San Juan Mountains, Colorado. (Geological Survey Professional...16:852 1. Volcanism-San Juan Mountains. 2. Volcanic ash, tuff, etc.-San Juan Mountains. I. Title. II. Series:.... . . . . . . . . . . . . . . . . . . . . . . San Juan caldera cluster . . . . . . . . . . . . . . . | | | Journal (article/letter/editorial) | com/locate/gca Oligo-Miocene maļ¬c intrusions of the San Juan Volcanic Field, southwestern Colorado, and their...locating and analyzing maļ¬c magmas in the San Juan Mountains of Colorado, the largest erosional remnant...Mountain ignimbrite ļ¬are-up. The āļ¬are-up inā the San Juan Volcanic Field (SJVF) has several potential explanations...Geosciences, Univer- sity of Texas San Antonio, 1 UTSA Circle, San Antonio TX 78249, United States. Tel...This study is focused on maļ¬c rocks from the San Juan Mountains of southwestern Colorado to examine if the | | | Report (volume) | Precambrian Melasyenite of Ute Creek, San Juan Mountains, Colorado11 Chemistry, Petrology, and Strontium... Precambrian Melasyenite of Ute Creek, San Juan Mountains, ColoradoChemistry, Petrology, and Strontium...SURVEY GEOLOGY BULLETIN 1311-C Hornblende-biotite melasyenite, exposed in an erosional window through...___________ 2. Analytical data and K-Ar ages of biotite from melasyenite of C5 Ute Creek____________...GEOLOGY PRECAMBRIAN MELASYENITE OF UTE CREEK, SAN JUAN MOUNTAINS, COLORADO CHEMISTRY, PETROLOGY, AND STRONTIUM | | | Report (issue) | map of the Howardsville 7.5-minute quadrangle, San Juan and Hinsdale Counties, Colorado by Robert G. Luedke...related quadrangles studies in the western San Juan Mountains of southwestern Colorado .................. Aeromagnetic map of part of the western San Juan Mountains region showing location of the Howardsville...5-minute quadrangle, located in the western San Juan Mountains of southwestern Colorado (fig. 1), includes...included in a comprehensive study of the San Juan Mountains region by Larsen and Cross (1956) . Detailed | | Lipman, P. W., Fisher, F. S., Mehnert, H. H., Naeser, C. W., Luedke, R. G., Steven, T. A. (1976) Multiple ages of mid-Tertiary mineralization and alteration in the western San Juan Mountains, Colorado. Economic Geology, 71 (3) 571-588 doi:10.2113/gsecongeo.71.3.571 | Journal (article/letter/editorial) | STEVEā¢ Abstract Ore depositsin the western San Juan Mountains formed intermittently in middle to late Tertiary...volcanoesand also after formation of the Uncompahgre,San Juan, Silverton, and Lake City calderas. The richest...its evolution(BurbankandLuedke, Tā¢Iā¢. westernSan Juan Mountainsare amongthe 1968, 1969; Stevenet al.,...Plata Mountains(Fig. 1), and Geologic Setting anotherin the middleto late Tertiary relatedto the San Juanvolcanic...Juanvolcanic field. Thesetwo majorepochs The San Juan volcanicfield is the largestsingle volcanicfield | | | Report (issue) | geologic map of the Silverton 7.5-minute quadrangle, San Juan County Colorado by Robert G. Luedke1 and Wilbur...related quadrangles studied in the western San Juan Mountains of southwestern Colorado .................. Aeromagnetic map of part of the western San Juan Mountains region showing location of the Silverton...5-minute quadrangle, located in the western San Juan Mountains of southwestern Colorado (fig. 1), includes...within the quadrangle, became the county seat of San Juan County when the county was formed in 1876 (Henderson | | | Report (volume) | Geology of the Mount Wilson Quadrangle Western San Juan Mountains Colorado By CALVIN S. BROMFIELD GEOLOGICAL...Tertiary_ _ _ _ ___ ____________ __ __ _____ _____ San Juan Formation___________________________________ Silverton...major intrusive rocks to igneous rocks of western San Juan Mountains_____________________________________..._________________ Comparison of eastern San Miguel Mountains with laccolithic centers of the Colorado...Butterfly mine________________________________________ San Juan claims_______________________________________ | | | Report (volume) | Bulletin 843 A BRIEF REVIEW OF THE GEOLOGY OF THE SAN JUAN REGION OF SOUTHWESTERN COLORADO BY WHITMAN CROSS...greenstone______________.__ _ __________________________ Needle Mountains group... __.._. __ __________________________...rocks__-____---_-______--__-_______--_______Needle Mountains area______ _ ____________________________ Granite...andesite__________ _-_______________________________ San Juan tuff__ _________________________________________________...ILLUSTRATIONS Page PLATE 1. Geologic map of the San Juan region, Colorado _________ In pocket 2. Relief | | | Journal (article/letter/editorial) | trachytic inclusions, Carpenter Ridge Tuff, Central San Juan volcanic field, Colorado Michael J. Dorais I *...GA 30605, USA a Department of Geology and Geophysics,Rice University, Houston, TX 77251, USA ReceivedOctober...indicative of an alkaline parentage. Sanidine and biotite contain up to 8 and 5 wt% BaO respectively. In...Sciences, Indiana University, Bloomington, IN 40705, USA Offprint requests to : M.J. Dorais the compositions...erupted from the Bachelor Caldera of the Central San Juan volcanic field, Colorado. The U.S.G.S. has extensively | | | Journal (article/letter/editorial) | previousattemptsindependentage control on the (An2o_4o), quartz,biotite,andhornblende (Fig. 1A). host rock and postorerockshas...sodicplagioclase, reville district,in the southeastern San Juan Mountains sultingin a rapakivitexture. This areawasinter...alteration and associatedlocal ore eastern San Juan Mountains,were localizedalong interpretedas a simplelava...containingphenocrysts of plagioclase(p), sanidine(s), biotite (b), and resorbed quartz (q). See Table 1, no... 1 Quartz latite of South Mountain 70L-134 Biotite Sanidine 2 Altered rock 71L-49 Aluniteā¢ 8.52 | | | Journal (article/letter/editorial) | CarbonIsotopeStudiesof the StonyMountain Complex,WesternSan Juan Mountains, Colorado* RICHARDW. FORESTER ANDHUSH P. TAYLOR...is composedof an outer diorite, a main massof biotite gabbro,and an inner diorite. This compositestockand...compositestockand most of the surroundingcountryrocks of the San Juan volcanicfield in the vicinity of the Silvertoncalderahave... hydrothermalā¢sO exchangeis feldspar-pyroxene-biotite-magnerite-quartz. Hydrogen isotopeanalysesof sericites...centers, the Stony Mountain stock, in the western San Juan in order to understandbetter the problemsof interaction | | | Journal (article/letter/editorial) | THE SAN JUAN MOUNTAINS, COLORADO.' IN the course of a recent examinationof the Needle Mountains quadrangleby...regionis near the southwesternlimits of the San Juan Mountains of southernColorado,which are made up largely...is knownlocallyas the Needle Mountains,and whichlies in partsof San Juan and La Plata counties, the youngerlava...complex,and in the laboratoryspecimensof the Needle Mountains rocks were compared with those collected by the...mineralsappearto be in excess GREENSTONE SCHISTS IN SAN JUAN MOUNTAINS 503 of the lightersilicates;what feldsparthereis | | | Report (issue) | measurements from the Lake City caldera area, San Juan Mountains, Colorado by V. J. S. Grauch and Mark R...2SR-6 2 Location map of the calderas of the San Juan volcanic 4 field LIST OF TABLES Table 1. List...samples from the Lake City caldera area, San Juan Mountains, Colorado (Figure 1). These samples were...part of the San Juan volcanic field (Figure 2). The volcanic history of the San Juan Mountains spans approximately...Lake City caldera area. Located in the western San Juan volcanic field, the Lake City caldera neighbors | | | Journal (article/letter/editorial) | of Mines, University of Nevada, Reno, NV 89557, USA Abstract. The key to mantled feldspar genesis is...mafic-rich rock is produced, typically with hornblende, biotite, and relatively calcic plagioclase, in which pre-mixing...Mafic inclusions Not reported Clotty mafics Clotty biotite Mafic inclusions and clots Diabasic inclusions...Not reported Diabasic inclusions Biotite schlieran Fine-grained biotite ? Clotty mafics Diabasic inclusions...Mtn., AZ Little Chief Mtns, CA Santa Rita Mtns, AZ San Francisco Mtns, MO Albany qtz syenite, NH Cedar Mtns | | Ringrose, Christopher R., Harmon, Russell S., Jackson, Simon E., Rice, Clive M. (1986) Stable isotope geochemistry of a porphyry-style hydrothermal system, West Silverton District, San Juan Mountains, Colorado, U.S.A. Applied Geochemistry, 1 (3) 357-373 doi:10.1016/0883-2927(86)90021-1 | Journal (article/letter/editorial) | hydrothermal system, West Silverton District, San Juan Mountains, Colorado, U.S.A. CHRISTOPHER R . RINGROSE...intrudes Tertiary volcanic rocks of pre- and post-San Juan Caldera age along the western margin of the Silverton...INTRODUCTION STABLE isotope evidence from the San Juan Volcanic Field in C o l o r a d o has demonstrated...Mountain intrusive complex in the western San Juan Mountains (FORESTERand TAYLOR, 1980) and the Sunnyside...the Silverton Caldera, which together with the San Juan and Uncompahgre Calderas, comprises a caldera | | | Journal (article/letter/editorial) | 40Ar/39Archronology of Oligocene volcanic rocks, San Juan Mountains, Colorado* MARVIN A. LANPHERE U.S. Geological...revisedform February 25, 1988) Abstract-The central San Juan caldera complex consists of seven calderas from...relations. Weighted-mean age-spectrum plateau ages of biotite and sanidine are the most precise with standard...be achieved at 27 Ma. New data indicate that the San Luis caldera is the youngest caldera in the central...ages suggested that the calderas of the central San Juan caldera complex developed during a period of about | | | Report (issue) | PRELIMINARY GEOLOGY OF THE SAN LUIS PEAK QUADRANGLE AND ADJACENT AREAS SAN JUAN VOLCANIC FIELD, SOUTHWESTERN...Snowshoe Mountain Tuffs, and associated calderas---!! San Luis caldera complex---- -----------------------------------12...FIGURES 1. 2. 3. 4. Index map of the central San Juan Mountains------ --29 Areas of mapping responsibility...geologic map of the San Luis Peak quadrangle (oversize) Correlation of map units, San Luis Peak quadrangle...calderas, and radiometric ages in the central San Juan Mountains --- ----32 2.Preliminary revised stratigraphic | | | Report (issue) | 1981-1982. index of Colorado geology 1975-1980. San Juan Basin, New Mexico, Colorado, CREEDE RESEARCH...deposition in the Creede mining district, San Juan Mountains, Colorado: II. Age of mineralization. Lanphere...High-resolution 40Ar/ 39Ar geochronology, central San Juan caldera complex, Colorado [abs.]. Lipman and others...others, 1970, Volcanic history of the San Juan Mountains, Colorado, as indicated by potassium-argon dating...others, 1967, Age of volcanic activity in the San Juan Mountains, Colorado. -6- Index GEOLOGY, Creede | | | Report (issue) | the Rio Grande from north of Weminuche meadows, San Cristobal quadrangle. The upper cliff-forming flow...Alboroto rhyolite. Geology and Petrology of the San Juan Region Southwestern Colorado By ESPER S. LARSEN...OF THE WORK A study of the geology of the San Juan Mountains was begun by Whitman Cross in 1895. The project...following table. Early work in the western San Juan Mountains Quadrangle Field work Workers La Plata (folio...Clements, O. W. Stose, and R. .D. George. Ncocllo Mountains 1900,1901- Whitman Cross and Ernest (folio 131) | | | Report (issue) | Rocks Associated With the Creede Caldera San Juan Mountains Colorado GEOLOGICAL SURVEY PROFESSIONAL PAPER...VOLCANIC ROCKS ASSOCIATED \VITH THE CREEDE CALDERA SAN JUAN MOUNTA~NS COLORADO I I I R esu rgent dome...Rocks Associated With the Creede Caldera San Juan Mountains Colorado By JAMES C. RATTE and THOMAS A....volcanic stratigraphy of the Page central San Juan Mountains, Colorado___ H3 2. Map showing intertonguing...ROCKS ASSOCIATED WITH THE CREEDE CALDERA, SAN JUAN MOUNTAINS, COLORADO By JAMES C. RATTE and THOMAS |
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