Sim Kellogg Sheet2 CC

U.S. Department of the Interior Scientific Investigations Map XXXX U.S. Geological Survey Sheet 2 of 2 Pamphlet accompanies map

CORRELATION OF MAP UNITS LIST OF MAP UNITS UPPER EOCENE VOLCANIC ROCKS PROTEROZOIC ROCKS OF BUFFALO PEAKS CENTER INTRUSIVE ROCKS [As used in this report, the terms “stream alluvium” and “fluvial deposits” refer to SURFICIAL DEPOSITS an Andesite sediment transported by running water confined to channels, whereas the terms “sheet- Yla Lamprophyre and andesite dikes (Mesoproterozoic?) wash alluvium” and “sheetflood alluvium” refer to sediment transported by running water vb Volcanic breccia MASS- YXp Pegmatite (Mesoproterozoic and Paleoproterozoic) not confined to channels. The terms “colluvium” and “mass-movement deposits” refers to EOLIAN MOVEMENT tu Upper tuff rock and sediment transported downslope chiefly by gravity. Map units that include Granitic rock, undivided (Mesoproterozoic or Paleoproterozoic) ALLUVIAL AND MASS- AND AND (OR) YXgr debris-flow deposits, such as some of the surficial map units in the map area, probably a Air-fall and ash-flow tuff ANTHROPOGENIC GLACIAL MASS-MOVEMENT MOVEMENT ALLUVIAL GLACIAL WETLAND YXhm Hornblende monzodiorite (Mesoproterozoic or Paleoproterozoic) also include hyperconcentrated-flow deposits. These latter deposits have bedding and DEPOSITS ALLUVIAL DEPOSITS DEPOSITS DEPOSITS DEPOSITS DEPOSITS DEPOSITS DEPOSITS la Lahar deposit sorting characteristics intermediate between those of stream-flow and debris-flow YXhd Hornblende diorite (Mesoproterozoic or Paleoproterozoic) deposits. tl Lower tuff Ygdh Granodiorite of Mount Harvard (Mesoproterozoic) afpt mw ss Qa In descriptions of surficial deposits, the term “clasts” refers to granules and larger bal Basal andesite Qtr Qw Qp Qr particles (>2 millimeter per year [mm] in diameter), while the term “matrix” refers to Ygl Langhoff Gulch Granite (Mesoproterozoic) sand and finer particles (≤2 mm in diameter). The terms “soil” and “soils”, used in this TERTIARY AND Yglf Strongly foliated facies ? report, refer to pedogenic soils formed in surficial deposits. Soil-horizon designations are LATE CRETACEOUS INTRUSIVE ROCKS Qpf Qf those of the Soil Survey Staff (1999) and Birkeland (1999). All colors for soil horizons, ROCKS ASSOCIATED WITH Yge Elephant Rock Granite (Mesoproterozoic) Qgp Qtp sediments, and bedrock in this report are informal field designations] Qpfo EARLY RIO GRANDE RIFTING Ygef Strongly foliated facies Qac Qc Qt Qes SURFICIAL DEPOSITS Late rhyolite porphyry dikes and plugs of Mount Princeton region (late rp Yhy Hybrid mix of Langhoff Gulch Granite and Elephant Rock Granite ANTHROPOGENIC DEPOSITS Oligocene) (Mesoproterozoic) l Olivine-augite lamprophyre dike (late Oligocene?) Ybp Browns Pass Granite of Fridrich and others (1998) (Mesoproterozoic) Qgby Qls af Artificial-fill deposits (latest Holocene) dt Microtonalite (Oligocene?) Qgb ? Qtb QUATERNARY pt Placer-tailings deposits (latest Holocene) Ygrg Granite of Granite (Mesoproterozoic) Qfo Qd Pleistocene rc Hypabyssal rhyolite of Clear Creek (late Oligocene) Qgbo mw Mine-waste deposits (latest Holocene) Ygdm Granodiorite of Mount Elbert (Mesoproterozoic) ? ? ? ? Leucogranite Suite of Mount Antero ss Smelter-slag deposits (latest Holocene) Yqd Quartz diorite (Mesoproterozoic) Qg4 ar Rhyolite dike (early? Oligocene) ALLUVIAL DEPOSITS Ygm Granite of Music Mountain (Mesoproterozoic) Qapb ap Border phase (early Oligocene) Qg3 Qgpb Qpbf Qa Young stream-channel and overbank alluvium (Holocene) Ygs St. Kevin Granite (Mesoproterozoic) ag Main phase (early Oligocene) Qtpb Qgp Outwash gravel of Pinedale glaciation (late Pleistocene) Xgk Kroenke Granite (Paleoproterozoic) Qg2 cg Leucogranite of the California Mine (early Oligocene) Qpf Younger flood gravel and channel deposits of Pinedale glaciation (late Xgy Granite of Mount Yale (Paleoproterozoic) ? ? BASIN-FILL Pleistocene) PRE-RIFT INTRUSIVE ROCKS Qg1 ? DEPOSITS Qpfo Older flood gravel and channel deposits of Pinedale glaciation (late Xdi Diorite (Paleoproterozoic) Granite and granite dikes of North Fork (early Oligocene) QNg Pleistocene) nf ? Xgd Henry Mountain? Granite (Paleoproterozoic) Qgb Outwash gravel of Bull Lake glaciation, undivided (late and middle qmd Quartz monzodiorite (early Oligocene) Nda Xdk Nd Pleistocene) Denny Creek Granodiorite (Paleoproterozoic) Pliocene tm Porphyritic latite dike of Shannon (1988) (early Oligocene?) Ndc Qgby Younger outwash gravel of Bull Lake glaciation (late and middle? and Neogene Xgdm Granodiorite of Methodist Mountain (Paleoproterozoic) Nds Miocene Pleistocene) Rocks of The Mount Aetna Caldera TERTIARY AND LATE Qgbo Older outwash gravel of Bull Lake glaciation (late? and middle (Early Oligocene or Late Eocene) Xgg Foliated granodioritic augen gneiss and granitic gneiss (Paleoproterozoic) CRETACEOUS INTRUSIVE ROCKS Pleistocene) Nb Quartz latite porphyry ring dike Xlg Leucogranite gneiss (Paleoproterozoic) Outwash gravel of pre-Bull Lake age (middle and early Pleistocene) ma OLIGOCENE AND EOCENE VOLCANIC Xgb Gabbro (Paleoproterozoic) ROCKS ASSOCIATED ib Intrusive breccia AND MIXED VOLCANIC, VOLCANICLASTIC, Qg4 Outwash gravel of pre-Bull Lake age, level 4 (middle Pleistocene) WITH EARLY RIO GRANDE RIFTING PALEOPROTEROZOIC ROCKS OF THE AND SEDIMENTARY ROCKS m Monzonite and latite dikes (early Oligocene or late Eocene) ? ? Qapb Gravelly stream alluvium of pre-Bull Lake age (middle Pleistocene) GUNNISON-SALIDA VOLCANO-PLUTONIC BELT l dt lw Late white porphyry (late Eocene) bf rp rc Qgpb Outwash gravel of pre-Bull Lake age, undivided (middle and early? VOLCANIC ROCKS ? ? Xgs Metagabbro of the Gunnison-Salida volcano-plutonic belt Leucogranite Suite of Mount Antero Oligocene Pleistocene) lu Little Union Quartz Latite (late Eocene) ASSOCIATED WITH EARLY nr Xba PRE-RIFT Qg3 Metabasalt ar ap ag Outwash gravel of pre-Bull Lake age, level 3 (middle Pleistocene) RIO GRANDE RIFTING cg Rocks of the Mount Princeton Batholith nt ? INTRUSIVE ROCKS Xvs Metavolcanic rocks, metasedimentary rocks, and metagabbro sills, Qpbf Flood gravel of pre-Bull Lake age (middle Pleistocene) mp Granitic rock of Mount Princeton batholith, undivided (late Eocene) undivided qmd Qg2 Xms bt Rocks of the Mount Aetna Caldera nf Outwash gravel of pre-Bull Lake age, level 2 (middle or early Pleistocene) bqm Aluminous gneiss and schist, calc-silicate gneiss, and quartzite tm Boulder Mountain monzogranite porphyry of Shannon (1988) (early Qg1 Outwash gravel of pre-Bull Lake age, level 1 (early Pleistocene) Oligocene or late Eocene) Xmc bc rd ? ? Muscovite-cordierite schist ib QNg mpf Finer-grained facies ? ma Very old alluvial gravel of Arkansas River (early Pleistocene? or INTERMIXED METASEDIMENTARY tc ab m lw TERTIARY Pliocene) mpk Alkali-feldspar monzogranite AND METAVOLCANIC ROCKS ? rs lu GLACIAL DEPOSITS mpm Equigranular biotite-hornblende monzogranite interior facies YXm PRE-RIFT VOLCANIC, Rocks of the Intermixed metasedimentary and metaigneous rocks (Mesoproterozoic ? ? Qr Rock-glacier deposits (early Holocene and latest Pleistocene?) VOLCANICLASTIC, AND Mount Princeton Batholith and Paleoproterozoic) cn Paleogene mpp Augite-bearing granodiorite porphyry SEDIMENTARY ROCKS Till (late to early Pleistocene) Xb Biotite gneiss mpb Border phase Eocene and Xhc Hornblende gneiss, amphibolite, and calc-silicate gneiss wm UPPER EOCENE bqm mpf mpk mpm mpp Qtp Till of Pinedale glaciation (late Pleistocene) Eocene and Paleocene mp Paleocene Intrusive ? VOLCANIC ROCKS OF Intrusive Intermediate and Felsic Rocks Xhg Hornblende gneiss and amphibolite tr mpb Intermediate and Felsic Rocks Qtb Till of Bull Lake glaciation (late and middle Pleistocene) sb BUFFALO PEAKS CENTER Eocene ? ? ? ai Intrusive andesite (late Eocene?) an Qtpb Till of pre-Bull Lake age (middle and early Pleistocene) ra cr ql va vb tu ? ? ? ALLUVIAL AND MASS-MOVEMENT DEPOSITS gp Gray porphyry group, undivided (Eocene or Paleocene) la a ai Qf Fan deposits (Holocene and late Pleistocene) gj tl Johnson Gulch Porphyry (Eocene) bal a ? gj gs er Qac Alluvium and colluvium, undivided (Holocene to middle? Pleistocene) gs Sacramento Porphyry (Eocene) Regional ? md Qfo Old fan deposits (late and middle Pleistocene ) er Eagle River Porphyry (Eocene?) Paleogene And wf di Late Cretaceous Rocks ? MASS-MOVEMENT DEPOSITS gl gl Lincoln Porphyry (Eocene or Paleocene) gp Qc Colluvium (Holocene to middle? Pleistocene) ? di Diorite of Buckskin Gulch (Eocene? or Paleocene?) gt Qt Talus deposits (Holocene to middle? Pleistocene) ? ? ? Paleocene Km tlg wf Felsic plutons and dikes of Fridrich and others (1998) (Eocene) Qls Landslide deposits (Holocene to early? Pleistocene) md Monzodiorite porphyry (Eocene?) Kdi Kwg EOLIAN AND ALLUVIAL DEPOSITS Kw Kd Late Kad Cretaceous CRETACEOUS Qes Eolian sediments and alluvium, undivided (Holocene to middle? Regional Paleogene and ? ? ? ? Pleistocene) PALEOZOIC SEDIMENTARY ROCKS Late Cretaceous Intrusive Rocks Unconformity MASS-MOVEMENT AND (OR) GLACIAL DEPOSITS gt Granite porphyry of Tumble Hill (Paleocene) Qtr Talus and rock-glacier deposits, undivided (Holocene and late tlg Twin Lakes Granodiorite (Paleocene) PERMIAN Pleistocene) Lower Permian Figure 9. View to north of Buffalo Peaks, which are composed mostly of Pm Qd Diamicton (Pleistocene) Early white porphyry group (Paleocene or Late Cretaceous) Upper Pennsylvanian Kw andesite flows, andesite breccias, lahars, and welded tuff deposited on WETLAND DEPOSITS Kdi Diorite sill (Paleocene or Late Cretaceous) Mesoproterozoic granite. The peak on the left is West Buffalo Peak (4,062 m; Qw Wetland deposits (Holocene and late Pleistocene) 13,326 ft) and the peak on the right is East Buffalo Peak (4,054 m; 13,330 ft). m Rhyodacite and dacite plugs and dikes (Paleocene or Late Cretaceous) Qp Peat deposits (Holocene and late Pleistocene) Kd Middle Km Hornblende monzonite, monzodiorite, and gabbro (Paleocene or Late EXPLANATION me Pennsylvanian PENNSYLVANIAN BASIN-FILL DEPOSITS Cretaceous) Nd Dry Union Formation (lower Pliocene? and Miocene) Contact—Dashed where approximately located, short dash where inferred. Queried Kwg mc Whitehorn Granodiorite (Late Cretaceous) where identity or existance is questionable Nda Volcanic-ash beds (late Pliocene? and Miocene) b Kad Andesite dike (Late Cretaceous?) Lower Fault—Dashed where approximately located. Dotted where concealed. Tick shows bc k Ndc Clay subfacies (Miocene) 65 Pennsylvanian PALEOZOIC SEDIMENTARY ROCKS dip value and direction Disconformity Nds Mls Middle and Slide-block subfacies (Miocene) Pm Maroon Formation (Lower Permian to Middle Pennsylvanian) Normal fault—Dashed where approximately located, short dash where inferred, Ml Lower MISSISSIPPIAN Nb dotted where concealed. Bar and ball on downthrown side. Traces of inferred Browns Canyon Formation (Miocene or upper Oligocene) m Disconformity Mississippian Minturn Formation (Middle Pennsylvanian) faults were identified on lidar imagery OLIGOCENE AND EOCENE VOLCANIC Dd me Evaporite facies Reverse fault—Dashed where approximately located, dotted where concealed. Dc AND MIXED VOLCANIC, VOLCANICLASTIC, Upper Devonian DEVONIAN mc Rectangles on upthrown block Dp AND SEDIMENTARY ROCKS Coffman Member Disconformity VOLCANIC ROCKS ASSOCIATED u Middle and Lower Pennsylvanian, Mississippian, Devonian, Ordovician, Lineament—As observed on lidar imagery u Of Upper Ordovician WITH EARLY RIO GRANDE RIFTING and Cambrian rocks, undivided Anticline—Trace of axial plane bf Vesicular basaltic-andesite flow (upper Oligocene) b Belden Formation (Middle and Lower Pennsylvanian) Ofh Disconformity Syncline—Trace of axial plane; dotted where concealed Or nr Oh Middle Ordovician ORDOVICIAN Topaz rhyolite flow of Nathrop Volcanics, including basal vitrophyre bc Quartz-pebble conglomerate and sandstone member Mu (lower Oligocene) Quartzite layer—A Paleoproterozoic quartzite layer (qz) in units Xhg, Xvs, and Disconformity k nt Tuff and tuffaceous breccia of Nathrop Volcanics (lower Oligocene) Kerber Formation (Lower Pennsylvanian) Xms that is interpreted as being a metachert. Consists of light- to dark-gray, very Lower Ordovician fine- to fine-grained quartz-magnetite-hematite rock. Quartzite beds are as thick Om Om MI PRE-RIFT VOLCANIC, VOLCANICLASTIC, Leadville Limestone (Lower Mississippian)—Queried where the as 8 m and hundreds of meters long Disconformity AND SEDIMENTARY ROCKS identification is not certain Oms Mls Quartzite of Sheep Mountain Breccia zone—Marked by sheared to granulated deformation fabric in bedrock Upper Cambrian CAMBRIAN bt Bonanza Tuff (lower Oligocene) ds 25 bc Badger Creek Tuff (lower Oligocene or upper Eocene) Mu Mississippian?, Devonian, Ordovician, and Cambrian rocks, undivided Inclined bedding—Showing strike and dip (Mississippian? to Cambrian) Unconformity rd Rhyodacite flow and tuff (lower Oligocene or upper Eocene) 20 Overturned bedding—Showing strike and dip Dc Chaffee Group, undivided (Lower Mississippian? and Upper Devonian) 40 tc Tallahassee Creek Conglomerate (lower Oligocene and upper Eocene?) Inclined foliation—Showing strike and dip PROTEROZOIC ROCKS Dd Dyer Dolomite (Lower Mississippian? and Upper Devonian) ab Basalt, andesite, and latite flows, and associated plugs (upper Eocene) Vertical foliation—Showing strike INTRUSIVE ROCKS INTERMIXED Dp Parting Sandstone (Upper Devonian) METASEDIMENTARY rs Rhyodacite lava of Salida East (upper Eocene?) A Sample or site location—Letter correlates with field number (see table 1 in Or Ordovician rocks, undivided pamphlet) ? AND METAVOLCANIC ROCKS Lava Creek B ash bed Yla cn Capping andesite porphyry of Triad Ridge of Thirtynine Mile Andesite SL–MM06–91 Ofh Fremont Dolomite and Harding Sandstone, undivided (Upper and Middle Location of Lava Creek B ash bed—Identified at two localities by Scott (1975): (1) MESOPROTEROZOIC (upper Eocene) Ygdh Ygl Yglf Yge Ygef Yhy Ybp Ygrg Ygdm Yqd Ygm Ygs Ordovician) on the east side of the Arkansas River, about 8 km northwest of Buena Vista, wm Wall Mountain Tuff (upper Eocene) Of Fremont Dolomite (Upper Ordovician) where the ash overlies bouldery flood gravel of unit Qpbf, and (2) at one locality YXp YXhm YXhd tr Tuff of Triad Ridge (upper Eocene) by Scott and others (1975) on the west side of the Arkansas River about 4 km Xgk Oh Harding Sandstone (Middle Ordovician) southwest of Nathrop where the ash overlies deposits of unit Qg3. Ash has a YXgr sb Trout Creek slide block (Eocene?) 40Ar/39Ar mean age of 639±2 ka (Lanphere and others, 2002) Om Bishop ash bed Xgy Xdi Xgd Xdk Xgdm Manitou Dolomite, upper part (Lower Ordovician) SL–MM06–91 YXm ra Rhyodacite porphyry flow, ash, and mud-flow deposit of Van Alstine and Location of Bishop ash bed—Identified at one locality by Scott and others (1975) Om Xgg Xlg Xgb PALEOPROTEROZOIC ROCKS PALEOPROTEROZOIC Cox (1969) (upper or middle Eocene) Manitou Dolomite, including Upper Cambrian Taylor Pass Member of on the west side of the Arkansas River, about 7 km southwest of Nathrop, where OF THE GUNNISON-SALIDA cr Calico rhyodacite lava of Shannon (1988) (upper? Eocene) Myrow and others (2003) (Lower Ordovician and Upper Cambrian) the ash overlies deposits of unit Qg2. Ash has a 40Ar/39Ar age of 759±2 ka VOLCANO-PLUTONIC BELT Oms Manitou Dolomite (Lower Ordovician and Upper Cambrian) and (Sarna-Wojcicki and others, 2000) ql Quartz-latite porphyry flow (upper? Eocene) Sawatch Quartzite (Upper Cambrian), undivided Water body XbaXvs Xms Xmc Xb Xhc Xhg Xgs va Volcaniclastic conglomerate and ash (upper? Eocene) ds Dotsero Formation and Sawatch Quartzite, undivided (Upper Cambrian) Divisions of Quaternary, Neogene, and Paleogene time used in this report1

Period or Epoch Age For more information concerning this publication, contact: subperiod Center Director, USGS Geosciences and Environmental Change Science Center Box 25046, Mail Stop 980 Holocene 0–11.5 ka Denver, CO 80225 (303) 236-5344 Quaternary late 11.5–132 ka Or visit the Geosciences and Environmental Change Science Center Web site at: Pleistocene middle 132–788 ka early 788 ka–2.588 Ma COLORADO Geologic Map of the Upper Arkansas River Valley Region, North-Central Colorado http://gec.cr.usgs.gov/ Digital files available at https://doi.org/10.3133/simXXXX or Pliocene 2.588–5.332 Ma Neogene DENVER To learn about the USGS and its information products visit http://pubs.usgs.gov/sim/XXXX Miocene 5.332–23.03 Ma http://www.usgs.gov/ GIS files are available for this report as a data release from ScienceBase at Oligocene 23.03–33.9 Ma By 1-888-ASK-USGS https://doi.org/10.5066/XXXXXXX Paleogene Eocene 33.9–55.8 Ma For product and ordering information visit: Paleocene 55.8–65.5 Ma http://store.usgs.gov/ Suggested citation: Kellogg, K.S., Shroba, R.R., Ruleman, C.A., Bohannon, R.G., Premo, W.R., Cosca, M.A., Moscati, R.J.,and Brandt, T.R., 2017, Geologic map of the 1Ages of time boundaries are those of the U.S. Geological Survey Geologic Names Karl S. Kellogg, Ralph R. Shroba, Chester A. Ruleman, Robert G. Bohannon, Wayne R. Premo, Michael A. Cosca, Richard J. Moscati, and Theodore R. Brandt upper Arkansas River valley region, north-central Colorado: U.S. Geological Survey Committee (2010) except those for the late-middle Pleistocene boundary and middle- ISSN 2329-132X (online) early Pleistocene boundary, which are those of Richmond and Fullerton (1986). Ages are Scientific Investigations Map XXXX, pamphet XX p., scale 1:50,000, expressed in ka for kilo-annum (thousand years) and Ma for mega-annum (million years). MAP LOCATION 2017 https://doi.org/10.3133/simXXXX https://doi.org/10.3133/simxxxxx.