Interim Geologic Map of the West Part of - Utah Geological Survey

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Panguitch quadrangle) of several voluminous calc-alkaline, subduction-relatedvolcanic centers and underlying source plutons that characterized the West fromOligocene to Miocene time at this latitude (Lipman and others, 1972; Rowley andDixon, 2001); Fleck and others (1975) and Rowley and others (1994a) reportedseveral K-Ar ages of 21 to 30 Ma on rocks of the coeval vent facies; at least 1000feet (300 m) thick in the map area in the northern Markagunt Plateau (Andersonand Rowley, 1987) (and at least 6000 feet [2000 m] thick farther north; Rowleyand others, 2005), but pinches out radially from an east-trending string ofstratovolcanoes along the southern part of the Marysvale volcanic pile.TbvBear Valley Formation, undivided (lower Miocene to upper Oligocene) – Whiteto light-gray, yellowish-gray, and olive-gray, moderately to well-sorted, fine- tomedium-grained volcaniclastic sandstone; sand is about 60% quartz, and theremainder is feldspar, biotite, hornblende, augite, and relict pumice replaced byzeolite; cement is mostly zeolite (clinoptilolite) (Anderson, 1971); sandstone ischaracterized by high-angle cross-beds indicative of eolian deposition; thickeolian sand was derived from the south and west and accumulated in a low-reliefbasin bounded on the north by an east-trending fault scarp possibly associatedwith the 25 Ma Spry intrusion (Anderson, 1971; Anderson and others, 1990a);also contains lesser interbedded lava flows, volcanic mudflow breccia,conglomerate, and ash-fall and ash-flow tuff beds, especially in the upper part ofthe formation; where mapped as part of the Markagunt megabreccia, sandstonefacies (Tbvs) and ash-flow tuff facies (Tbvt) are mapped separately; Fleck andothers (1975) reported two K-Ar ages of 24.0 ± 0.4 Ma and 23.9 ± 0.5 Ma fromthe upper part of the formation; an incomplete section of Bear Valley strata isonly 100 feet (30 m) thick in the Panguitch quadrangle (Moore and Straub, 1995)and about 400 feet (120 m) thick in the Cottonwood Mountain quadrangle, but theformation is in excess of 1000 feet (300 m) thick on the northern MarkaguntPlateau (Anderson, 1971); the unit is as much as about 260 feet (80 m) thick inthe Red Hills (Maldonado and Williams, 1993b).Tbvb Bear Valley Formation mudflow breccia (lower Miocene to upper Oligocene) –Pale-yellowish-brown breccia composed of pebble- to cobble-size clasts, mostlyof intermediate composition volcanic rocks and lesser amounts of tuff andtuffaceous sandstone; as much as about 800 feet (245 m) thick in the CottonwoodMountain quadrangle.Quichapa Group (lower Miocene to upper Oligocene) – Regionally consists of threedistinctive ash-flow tuffs: in ascending order, the Leach Canyon Formation, CondorCanyon Formation, and Harmony Hills Tuff (Mackin, 1960; Williams, 1967; Andersonand Rowley, 1975; Rowley and others, 1995); the lower two formations erupted from theCaliente caldera complex, but the Harmony Hills Tuff likely erupted from the easternBull Valley Mountains (Rowley and others, 1995).Tqh Harmony Hills Tuff (lower Miocene) – Resistant, pale-pink to grayish-orangepink,crystal-rich, moderately welded, dacitic ash-flow tuff; contains about 50%phenocrysts of plagioclase (63%), biotite (16%), horneblende (9%), quartz (7%),39
pyroxene (5%), and sanidine (trace) (Williams, 1967); exposed in ParowanCanyon where it overlies the Bauers Tuff Member of Condor Canyon Formationand reinterpreted by lead-author Biek to underlie the Isom Formation that is partof the Markagunt megabreccia; source of Harmony Hills Tuff unknown butisopachs are centered on Bull Valley (Williams, 1967), suggesting that it wasderived from the east Bull Valley Mountains, probably from an early, much morevoluminous eruptive phase of the Bull Valley/Hardscrabble Hollow/Big Mountainintrusive arch, as suggested by Blank (1959), Williams (1967), and Rowley andothers (1995); consistent with this interpretation is the fact that the 40 Ar/ 39 Arplateau age of the Harmony Hills is 22.03 ± 0.15 Ma (Cornell and others, 2001),nearly identical to that of those intrusions; as much as 50 feet (15 m) thick.Tqcb Bauers Tuff Member of Condor Canyon Formation (lower Miocene) –Resistant, light-brownish-gray to pinkish-gray, densely welded, rhyolitic ash-flowtuff; contains about 10 to 20% phenocrysts of plagioclase (40-70%), sanidine (25-50%), biotite (2-10%), Fe-Ti oxides (1-8%), and pyroxene (
Page 1 and 2: ! !! !!! ! ! !! ! ! ! !! ! !! !! !
Page 3 and 4: MAP UNIT DESCRIPTIONSQUATERNARYAllu
Page 5 and 6: Qafc Coalesced fan alluvium of Paro
Page 7 and 8: glacial deposits and features that
Page 9 and 10: (Tbhv) and Dakota (Kd and Ktd) Form
Page 11 and 12: typically mapped where lava flows d
Page 13 and 14: that range in age from Miocene to H
Page 15 and 16: fronts (except at Dry Valley, immed
Page 17 and 18: the quadrangle; no fault that postd
Page 19 and 20: Qbw, QbwcWater Canyon lava flow and
Page 21 and 22: others, 2007); lava flow is typical
Page 23 and 24: Mahogany Hill, about 500 feet (150
Page 25 and 26: lava flow (Tbbm) that conceal the u
Page 27 and 28: TERTIARYpreserved in down-dropped b
Page 29 and 30: and Rowley and others (in preparati
Page 31 and 32: field (or possibly coeval batholith
Page 33 and 34: hidden by shadow; we tentatively as
Page 35 and 36: esistant crystal-poor rhyolite tuff
Page 37 and 38: thickness uncertain but outcrop pat
Page 39: divide between Red Creek and Little
Page 43 and 44: unconformityThe Leach Canyon Format
Page 45 and 46: unconformityMa (Best and others, 19
Page 47 and 48: interval, and a lower limestone int
Page 49 and 50: Figure 3. View northwest to North V
Page 51 and 52: dark-yellowish-orange, grayish-pink
Page 53 and 54: TKgc Grand Castle Formation, undivi
Page 55 and 56: track (the latter found by Eric Rob
Page 57 and 58: noted by Moore and Straub (2001) an
Page 59 and 60: shoreface, beach, lagoonal, and est
Page 61 and 62: water deposits of Cenomanian age (N
Page 63 and 64: 62Figure 7. Cedar Mountain Formatio
Page 65 and 66: leached white under the Cretaceous
Page 67 and 68: ACKNOWLEDGMENTSThis geologic map is
Page 69 and 70: Anderson, R.E., and Christenson, G.
Page 71 and 72: Biek, R.F., Rowley, P.D., Hayden, J
Page 73 and 74: field guide (The Mackin Volume): Ut
Page 75 and 76: 2001, Cretaceous and early Tertiary
Page 77 and 78: Hacker, D.B., Rowley, P.D., Blank,
Page 79 and 80: Kurlich, R.A., III, 1990, Geology o
Page 81 and 82: Maldonado, F., and Moore, R.C., 199
Page 83 and 84: Flagstaff-Green River basins [abs.]
Page 85 and 86: elation to other igneous centers in
Page 87 and 88: Schulman, E., 1956, Dendroclimatic
Page 89: Van Kooten, G.K., 1988, Structure a
Page 92:
113°00'112°00'15BV20R i v e rCCNP
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Interim Geologic Map of the West Part of - Utah Geological Survey

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