docthe Geologic Map of the Buena Vista West Quadrangle
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the Geologic Map of the Buena Vista West Quadrangle
OPEN-FILE REPORT 05-8 GEOLOGIC MAP OF THE BUENA VISTA WEST QUADRANGLE, CHAFFEE COUNTY, COLORADO Plate 1 of 2 Booklet accompanies map COLORADO GEOLOGICAL SURVEY DEPARTMENT OF NATURAL RESOURCES DENVER, COLORADO Qpty ! ! ! 33 4-458 ) Xqd 62 4-432/433 v Qfb 4-437 @ 31 18.4 16.4 ¹o o ! ! ! ! U D o¹ Bull Lake alluvial-fan deposits (middle Pleistocene) Qu Quaternary undifferentiated (Shown only on cross section) ¹ ¹ ¹ o o o ¹ ¹ ¹ ¹ Dry Union Formation (Pliocene and Miocene) Tmd Monzonite to trachyte porphyry dikes (Oligocene?) Tv Volcanic (or hypabyssal?) rocks (late Eocene to early Oligocene?) Mount Aetna quartz latite porphyry ring dikes (early Oligocene) Tib Mount Aetna intrusive breccias (early Oligocene) MOUNT PRINCETON PLUTON (late Eocene; 36.6 Ma) Tmpb Mount Princeton border unit (late Eocene) Tmpf Mount Princeton finer-grained quartz monzonite subunit (late Eocene) Tmpk Mount Princeton porphyritic K-feldspar subunit (late Eocene) Tmpm Mount Princeton quartz monzonite interior subunit (late Eocene) Dacite porphyry dikes (Eocene?) PROTEROZOIC ROCKS BERTHOUD PLUTONIC SUITE (1.40 Ga) à Trs à o Trs Qboo ¹ o Td @ Hybrid Dike (Early Proterozoic?) Quartz diorite (Early Proterozoic?) Xgd Granodiorite/quartz monzonite (Early Proterozoic?) Xgdf Granodiorite augen gneiss (Early Proterozoic) Trs 46 Trp D 33 67 Qpo Qbty Qpoo Qpto Qpt à Qbt Tmpm à Trp 5.6 qv Trs 43 Qfo Qtf Shear zone—Ductile shear zones in Proterozoic Rocks Strike and dip of bedding or contacts Qboy Qna 33.4 Qac Qfp o 5 Qk Qi? 8.8 Td SCALE 1:24,000 12 1/2° 222 MILS 1 1/2 1000 0 1 UTM GRID AND 1982 MAGNETIC NORTH DECLINATION AT CENTER OF MAP DIAGRAM IS APPROXIMATE 1000 0.5 2000 3000 4000 0 5000 6000 ) 1 Colorado CONTOUR INTERVAL 40 FEET DATUM IS MEAN SEA LEVEL 4 6 Quadrangle Location 2 3 5 7 8 1 Mount Harvard 2 Harvard Lakes 3 Marmot Peak 4 Mount Yale 5 Buena Vista East 6 Saint Elmo 7 Mount Antero 8 Nathrop ADJOINING 7.5' QUADRANGLES GEOLOGIC MAP OF THE BUENA VISTA WEST QUADRANGLE, CHAFFEE COUNTY, COLORADO By James P. McCalpin and James R. Shannon 2005 Strike and dip of metamorphic foliation and/or gneissic layering Inclined—Showing direction and angle of dip Vertical 4-199 à 7000 FEET 1 KILOMETER Vertical 37 1 MILE 0 Inclined—Showing direction and angle of dip ¹ Qc Geology mapped in 2004 Digital Cartography by Jason C. Wilson MN GN Quartz Vein (post-late Eocene) Qpo 66 Tib Trs à à Qfy Terrace riser ! qv Qboo Fault—Dashed where approximately located, dotted where concealed. U, upthrown side, D, downthrown side Tick mark shows dip of plane. Fault or lanslide scarp—Vertical surface offset, in feet Qk Qk 11.1 15.1 o Qac Tmpm Tib ! Qfp Qbt Tib ? 10.2 Qna Qboy 28.2 Qpoo Contact—Approximately located Qpo Qboy Qbto 62 U 3.3 4.9 Tib Qbt MAP SYMBOLS Qk 35.1 Qf Tib Biotite-garnet felsic and biotite-hornblende intermediate gneiss and amphibolite (Early Proterozoic?) Qal Qboo Qboy Xb Qk 60.0 Tib LAYERED BIOTITE AND FELSIC AND HORNBLENDIC GNEISS COMPLEX (1.74 Ga) Qboo Qpbo 16.7 4.9 Tib Qac o o o o Ãà 0°45´ 13 MILS Pegmatite (Early to Middle Proterozoic?) Xqd Td Qboy à ) 4-199 4B-120 Biotite granite (Early to Middle Proterozoic?) ROUTT PLUTONIC SUITE-DENNY CREEK EQUIVALENT (1.66 Ga) Tmpk Qta Base from U.S. Geological Survey, 1982 Lambert Conformal Conic projection, 1927 North American Datum 10,000-foot grid based on Colorado coordinate system, central zone 1,000-meter Universal Transverse Mercator grid ticks, zone 13 Qfb Mount Aetna ring shears (early Oligocene) Qna Qfy o @ oo Tib o o ! o ! Ãà Tmpm ) Pinedale alluvial-fan deposits (late Pleistocene) Xhy Qal 55 Qrg Qfp ! o o @ ¹ ! ¹ @ ! ! o ov o o ¹ ! ¹ ¹ ¹ o ! Qpoo Qpoo Tmpk Qta Alluvial-fan deposits, older (late to middle Pleistocene) ROUTT PLUTONIC SUITE (1.70 TO 1.66 Ga) Qfy 58 Tl Qfo YXp v Tmpk à à à UD Qta à Qn Qbty Qfp Qfy 61 Alluvial-fan deposits, younger (Holocene to late Pleistocene) YXg Qbt 68 37 Qbo Qboy Trp 22 Qfy Tdd Qpoy Qpt Tib 67 Alluvial-fan deposits, undivided (Holocene to middle Pleistocene) MISCELLANEOUS MAGMATISM (late Eocene) Qal Qpoo Qk Trs D 28 Qf Qna vv o Qta à Trp » Qrg @ Qrgo Qtf ! Qboo U ) Td Qal ! ! Xb Ãà o o oo Ql Ãà Qrg 48 Alluvium and colluvium, older (middle to late Pleistocene) ! Tmd Tmpm 4B-199A 53 Qboy D Qbo Tib Qta » Qaco @ 4-119/120 ) Qs Qrg Alluvium and colluvium, undivided (Holocene and late Pleistocene) Trs @ Qtf Qrg Qfy @ Trp Qrg Qta Qnt Qtf Qac @ Qrgo Ql Landslide deposits, undivided (Holocene to middle Pleistocene) @ Ãà Td @ A U ! ! Qrgo Qpt U Qal Qbty Qpt Tmpm Qls Rhyolite porphyry dikes (Late Oligocene?) ! ! Qpbt? Trp Colluvium (Holocene and late Pleistocene) @ Tib Qc Trp ! Qbo Trs Tmpk Tmpk Qboo Tib Trs Nussbaum(?) alluvium (early Pleistocene) ! Tib à 38 D @ Qac Qbto 52 @ U Qn @ D Nebraskan(?) alluvium (early Pleistocene) ! Ãà Trs Tl ! @ ! à Tmd Trs Trp ! ) Qal Qbo Tmpm Qna ! à à 4-4A Qboo Tmpm Trs Qls ! Tib Kansan(?) alluvium (early Pleistocene) Tma Qls Ãà à Ãà Trs Tib Qk Spessartite lamprophyre dikes (Miocene?) Qk? ! Tib 67 Illinoian(?) alluvium (early Pleistocene) MOUNT AETNA CAULDRON (early Oligocene; 34.4 Ma) Tdd Trs o 84 Qi Tl ! ÃÃTmaà Tl Bull Lake outwash deposits, undivided (middle Pleistocene) MISCELLANEOUS MAGMATISM (early Oligocene?) ! Trs Tib ½ @ à Qc Qpoo à Xb Qk Qbo Qc Tv à Qfy Qf 75 Qt 78 ¹ @ Tib oà Ãà à Pinedale outwash deposits, undivided (late Pleistocene) RIFT-RELATED BIMODAL MAGMATISM (late Oligocene-Miocene) 85 Qls D Trs Qpo IGNEOUS ROCKS Qboo Qfy ») à Uà U Tma 63 4B-450 D Tma Trs à Qac Tmpm 52 14 à Qbt Tmpm Xgdf ¹Ã à 79 81 81 51 Tmpb Stream-channel, flood-plain, and low-terrace alluvium (Holocene) Qboy Qk Ãà à Ão Xgdf ¹o ¹ 64 ¹ à Qfp Qpbt Xqd 53 Qc Qboo Qaco ¹ @ Tmpf Qal Td Qboo 51 @ Qfy Lacustrine deposits, undivided (Holocene) SEDIMENTARY ROCKS à Xb à à Tmpf Ql Qboo Qpoo Ãà Tmpm Qbty 9.8 Qac Qfy Tmpm Qfy 18 Qboy Qboo 73 Qbty Solufluction deposits (Holocene and late Pleistocene) 24.6 @ 30 à 9.2 42 Qpt Qs ! v o 30 à 47 Tmpf Qbto Tib Trs ¹ 32 Tmpb Qpty Talus fan deposits, undivided (Holocene) 35.4 Qpt Qpto Qtf ! Qfp 18 Qboy 12 Tmpb Qfy Qac Talus deposits, undivided (Holocene) ! Qac Qc 82 Qboo ! 61 71 24 81 Qfy Qt ! o Qpt Tmpm ! 65 Tib Qpt 86 Qpbt oo Talus deposits, active (middle to late Holocene) Pre-Bull Lake outwash deposits (early Pleistocene) ! 47 Qpbt o 19 87 Qboy Qc Qpbt o o oo Qac Tmpb Tmpf Tmpk 70 Qpoy Qfy à à à D U Tmpf Qta Qpbo af ! o 38 D U Rock glacier deposits, older (late Pleistocene) Bull Lake outwash deposits, older (middle Pleistocene) ! Tdd 88 80 Qrgo ALLUVIAL AND COLLUVIAL DEPOSITS 79 o Rock glacier deposits, undivided (Holocene) Qboo Qboy Qboo 47 ¹ Tmpf Qrg Qpoo Qpoy 115 ¹ 75 33 Tmpb Pre-Bull Lake till, undivided (early Pleistocene) COLLUVIAL DEPOSITS ! ¹ o 39 73 55 ¹ Qpbt Bull Lake outwash deposits, younger (late middle Pleistocene) 5.9 v à 39 Bull Lake till, older (middle Pleistocene) Qboy Qpoo Qal Qpoo Qi 4 Tmpb à 33.4 51 Qi Qac 33.4 ¹ 44 Qfp à Qk 75 à Qls Qbto Qal Qboy 50 71 41 Ãà 25 22 Bull Lake till, younger (late middle Pleistocene) Pinedale outwash deposits, older (late Pleistocene) Qpoy Qac ! à 15 ) Tmpb Qbty Qpoo Qpoo ! ¹ 4-223 @ ¹ Bull Lake till, undivided (middle Pleistocene) Qfy Qk Xbg Tmpb 49 Qbt Pinedale outwash deposits, younger (late Pleistocene) Qpoy ! 64 ¹ 39 33 Qpoo Qpoy Qk Qaco37 o @ à Qls Tdd Pinedale till, older (late Pleistocene) Qbo Qpo ¹ ¹ ¹Ã à ¹Ã Qls Qpto Qpoy Qpoy Qal Qpoy Qbty Qfb 22.3 11.2 Tdd @ @ ¹ 63 Qpoo Qpoo 44 Qls? Qpoo Qpoo 18.4 64 Qbo Qboy Qac Qls? Xb Pinedale till, younger (late Pleistocene) ALLUVIAL DEPOSITS Qpoo ) Qc Qpty Qfy Qal 50 61 Pinedale till, undivided (late Pleistocene) PERIGLACIAL AND LACUSTRINE DEPOSITS Tdd 38 Qbty ) 54 Xb Qpo Qal Tdd Xgdf ¹ Qk Xb Xb Tdd YXg Qpt Qk Qbty Qc Xbg Xqd Xgdf 34 Qpoy 49 Neoglacial till (Holocene) Qboy 27 Xgdf 75 49 60 51 Qna Xgdf Qc YXg Tdd 59 Qnt 42 4-454 52 4-425 4B-490A Qpoo ) Xqd ) 43 Qbty Qpto 42 76 29 ) ! 55 55 o 63 46 83 ! 4-409 63 Xgd 49 Xb ) Xqd 60 YXp o 54 54 Qpoo Qk Qbo ¹ ùà à ¹Ã ¹ ¹ oà ûà à » ù » à ¹Ã ¹ ¹ ¹ à ¹ ¹Ã ù ¹ Xgdf o ! 4A-90/91 53 à ! ! ¹ ¹ ) ¹ à ¹ ù ¹¹ ¹o oà o ¹ o¹ 30 ! @ ¹ 79 ! à Xb 52 à A' 27 )844B-271 46 Qpty 55 70 Xqd Qac Qk ! 41 ! ! @ ¹Ã» Qna 63 ! ! 61 58 Qn Artificial fill (latest Holocene) GLACIAL DEPOSITS 34 Xqd ! ! Qbto 38 af ! ! ! ! @ @ ¹ ! Qpbt ! ! ! HUMAN-MADE DEPOSITS Qal ¹ Xgd Xgd Xgd Qna ! ! Qf 55 YXg o 30 ! ! ! Qfy ¹ Qac ! @ Xb Qna Xgd Qna Qbto Xbg Xhy Qf af Xgd Qc 66 SURFICIAL DEPOSITS o @ Qbto YXg 69 Xgd Qna YXg o ¹ Xqd Qal Xgd Qf o Qk 22 Xgd Qna Xqd 57 Qk Qac 63 o ¹ ¹ Qbo Qc Xqd 40 Xgd ¹ ¹ ¹ 21 Qpoo ½ 25 Qk o 62 Xgd Qna Xgd Xgd o ¹ 53 ) Qboy Qfb Xb Qboo v 4A-67/68 Qna 22 o o 31 52 ¹ ¹Ã à Ãà Xgdf The complete description of map units and references are in the accompanying booklet. Units shown as a fraction indicate a thin layer of the upper unit occurs over the lower unit. o ¹ LIST OF MAP UNITS Sample location for whole rock chemistry, assay, and geochemistry Abandoned prospect » Abandoned mine shaft Abandoned adit A A' Alignment of cross section