IDAHO GEOLOGICAL SURVEY MOSCOW-BOISE-POCATELLO TECHNICAL REPORT 10-2 PRICE AND RODGERS WWW.IDAHOGEOLOGY.ORG Plate 1, Price, K. B., 2009, M.S. Thesis, Idaho State University. Supported by the U.S. Geological Survey, National Cooperative Geological Mapping Program, under assistance award no. 02HQAG003. Description of Map Units 111o2050 43o5000 Geologic Map of the North End of the Big Hole Mountains, Madison and Teton Counties, Idaho Ql Correlation of Map Units Qa Kathleen B. Price and David W. Rodgers 2010 Qt Ql Ql Ql Qls Tyh This Technical Report is a reproduction of a map originally submitted as part of a masters thesis. Its content and format may not conform to IGS standards. Disconformity Tk Price, K.B., 2009, Geology of the northern end of the Big Hole Mountains, Madison and Teton County, Idaho: Idaho State University, M.S. thesis, 120 p. Te Ql 20 Tpdp Tpdp 12 Tyh Tpdp Tcc Qc Tpdp Tco Tk Tpdp Qc Tcc Qc Tk 28 30 Tcb Tk 10 111o2620 43o4642 Tcc Te Tca Tyh Tk Tk 13 Qt Tk Tca Qt Tcc Tca Tcb 27 Qc Tyh Te Tcc Tca Tcc Te 30 Tca Tk Tcc Tca 30 Tcb 27 Tca 28 Ql Qls Tcb Tcb 18 Tcb Tco Ql 30 Tcc Kb Te Ka Kf Tco Qa Tcb Qc Tca 24 20 Qls Te Tyh Te 5 11 5 21 Tcc Ql 10 Tk Tcc 45 TRt Qc TRt Ql 15 32 B Tcb Tca Te Tcb 36 MN Te 4 MILS 302 MILS Temple Peak QUADRANGLE LOCATION 20 1/2 0 1 35 35 .5 1 MILE 0 1 KILOMETER Contour Interval 20 or 40 feet. Anticline Syncline Ka 25 Direction of landslide Geologic mapping was supported by the U.S. Geological Surveys EDMAP program and the Idaho State University, Department of Geosciences. Digital cartography by Kathleen Price and Diana Boyack at Idaho State University, Digital Mapping Laboratory, Department of Geosciences. Topography by photogrammetric methods from aerial photographs taken 1963 and 1973. Field checked 1965 and 1974. Projection: Universal Transverse Mercator, east zone Idaho. 1927 North American Datum. 20 Qc Ql Tcc Tcb Tk Tyh Tca Tco Te Tcc Tcb TRt Tca Te Mm Tpd Tco Tpd Tcc Tcb Tca Tco 8000 Tk Tcc Ql Tcb Tpd Tca Tcc Tco Kf Tcb Tca Tco Kb Ka Kf 6000 5000 Mm 4000 Kf PPMw l Mm 3000 B B 8000 Ql Qc Te Qa 7000 Kf Pp 3000 Tca Tco Tpd Tcb Tca Mm PPMw l TRd Tcc Tcb Tcc Tcb Tca Tco PPMw l Tco TRw 4000 Tk Te Te Tcc Tk Te Tcc Tcb Tca Tco Te Qc Tca TRa Tcb Tcc Tco Te Tcc Tcb Tco PPMw l Ql Te Tco Tcc Tccvc Tcb Tco PPMw l PPMw l Mm Qls Ql Kf PPMw l Kf 5000 TRd Pp PPMw l Kf Mm 4000 3000 Published and sold by the Idaho Geological Survey University of Idaho, Moscow, Idaho 83844-3014 Tertiary conglomerate (Eocene-Miocene) -- Cobble conglomerate. Tan to red, fine-grained, calcareous matrix with subangular to rounded clasts of gray and brown limestone, red and yellow siltstone, and uncommon white quartzite. Clasts range in size from 0.2 inches to 3 feet, but are typically 0.2-4 inches. Matrix is poorly indurated and weathers easily. Forms smooth slopes. Lower contact is a profound angular unconformity placed below the lowest cobble conglomerate. Thickness is 0-100 feet. Frontier Formation (Upper Cretaceous) -- Sandstone. Gray and brown, fine- to coarse-grained sandstone, pebbly and highly glauconitic near top, interbedded with gray and black shale and thin coal beds. Contains lenses of conglomerate throughout the formation; bentonite and white to pink porcellanite beds in lower part. It is easily weathered, friable and covered by colluvium in most places. Forms broad slopes and is poorly exposed in the area. The base is marked by a 50-70 foot, ridge forming, noncalcareous, feldspathic sandstone. Thickness is approximately 4000 feet (Staatz and Albee, 1966a). Aspen Shale (Lower Cretaceous) -- Shale and sandstone. Greenish gray to gray rock composed of white quartz and dark gray chert grains. Fine- to medium-grained, poorly sorted, thick-bedded, well cemented and shows minor cross-bedding. A resistant unit forming prominent ledges. Conformable lower contact which is placed at the bottom of a thin (<15 feet) sandstone ledge just beneath a porcellanite layer. Thickness is approximately 2500 feet (Staatz and Albee, 1966a). Thaynes Formation (Triassic) -- Limestone and calcareous siltstone. Upper half is gray bioclastic limestone underlain by yellowish-gray limey siltstone and sandstone. Lower half is red siltstone underlain by slabby dark-brown fossiliferous silty limestone. Poorly exposed in the map area and generally covered with tan soil. Lower contact is not exposed. Thickness is approximately 800 feet (Staatz and Albee, 1966a). Tpdp TRw Lanphere, M. A., Champion, D. E., Christiansen, R. L.., Izett, G. A., Obradovich, J .D., 2002, Revised ages for tuffs of teh Yellowstone Plateau volcanic field;assignment of the Huckleberry Ridge Tuff to a new geomagnetic polarity event: Geological Society of America Bulletin, v. 114, p. 559-568. Woodside Formation (Triassic) -- Red-brown siltstone, shale, and fine-grained sandstone. Very poorly exposed and generally covered with red soil. Lower contact is not exposed. Thickness is approximately 360 feet (Staatz and Albee, 1966a). TRd Staaz, M. H., and Albee, H. F., 1966a, Description of the stratigraphy, structure, and phosphate and coal deposits of a 215-square mile area at the north end of the Idaho-Wyoming thrust belt, U.S. Geological Survey Bulletin 1205, 122pp. Dinwoody Formation (Triassic) -- Brownish-gray to olive-drab, slabby, thin-bedded dolomitic siltstone. Contains thin partings of fine-grained dolomitic sandstone and silty limestone. Generally covered with gray soil. Lower contact is not exposed. Thickness is approximately 360 feet (Staatz and Albee, 1966a). Pp Phosphoria Formation and related rocks (Permian) -- Black phosphatic shale at top; mudstone, carbonate rock, and sandstone; gray cherty dolomite, mudstone, and sandstone; black phosphorite, mudstone, and shale at base. Weathers tan and is very poorly exposed in the map area. Lower contact is not exposed. Thickness is approximately 300 feet (Staatz and Albee, 1966a). PP l Mw Wells Formation and associated rocks (Permian, Pennsylvanian, and Upper Mississippian) -- Wells Formation is light-gray, finegrained sandstone with gray limestone beds especially in lower part. In places, uppermost part contains chalky-white, very finegrained dolomite and gray chert. The Grandeur Member of the Park City Formation is included with this unit. Lower contact is not exposed but to the south is a brown to gray limestone lying on top of the dark gray, Mississippian, Mission Canyon Limestone. Cumulative thickness is approximately 1500 feet (Staatz and Albee, 1966a). Mm Mission Canyon Limestone (Mississippian) -- Light- to dark-gray, coarse- to fine-grained limestone with some chocolate brown dolomite. Characterized by breccia beds in the upper half composed of gray, medium-grained, angular limestone and lesser chert fragments in a matrix of silty limestone. The lower half is coarsegrained bioclastic limestone and dolomite interbedded with massive limestone. Lower contact is not exposed. Thickness is greater than 3000 feet (Staatz and Albee, 1966a). Staaz, M. H., and Albee, H. F., 1966b, Geologic Map and Sections of the Garns Mountain Quadrangle, Bonneville, Madison, and Teton Counties, Idaho, U. S. Geological Survey Bulletin 1205, plate 1, scale 1:31,680 6000 Ka Member A, Carlton Creek Volcanics (Upper Miocene) -- Rhyolite lava flow. Gray to lavender with areas of pink and brown, crystalrich, flow-banded, densely welded lava flow. Contains 15-20% fine-grained phenocrysts of euhedral plagioclase, quartz, sanidine, pyroxene and minor Fe/Ti oxides. Matrix is light colored and glassy. Flow bands are 0.1-2 inches thick, continuous, and horizontal to convoluted. Tan to pale yellow pumice is present at top of member. Unconformable lower contact placed at the base of lowest volcanic rock which overlies sedimentary rocks. 40Ar/39Ar analysis on groundmass did not yield an interpretable result. Thickness is 0400 feet. TRt Tk Kb Member B, Carlton Creek Volcanics (Upper Miocene) --Dacite ignimbrite. Dark gray and red, thinly laminated, crystal-rich, densely welded, rheomorphic tuff. Contains 10-15% phenocrysts of plagioclase, uncommon quartz, Fe/Ti oxides, and rare pyroxene. Flow planes are convolute and relatively continuous. Platy cleavage or jointing is sub-perpendicular to the ground surface. Lower contact is placed above tan pumice and below a rarely exposed red and black flow breccia. Forms slopes and low ledges that weather into small hoodoos. Thickness is generally less than 100 feet. Ankareh Shale (Triassic) -- Red to purple calcareous siltstone and shale; has greenish-white polka-dot mottling in several layers. Poorly exposed and commonly covered by red soil. No basal exposure is found here. Thickness is approximately 540 feet (Staatz and Albee, 1966a). 7000 TRt TRw Anders, M. H., Saltzman, J., and Hemming, S .R., 2009, Neogene tephra correlations in eastern Idaho and Wyoming: Implications for Yellowstone hotspot-related volcanism and tectonic activity; Geol. Soc..America Bull. v. 121; p. 837-856. Member C, Carlton Creek Volcanics (Upper Miocene) -- Dacite ignimbrite. Black to dark gray, devitrified, crystal-poor, lithic-poor welded tuff. The rock contains 2% euhedral, very fine-grained phenocrysts of plagioclase, magnetite, rare pyroxene and zircon. Plagioclase forms laths or stubby tabular crystals. Pyroxene is altered and rimmed with Fe/Ti oxides. The glassy matrix contains microlites of strongly trachytic plagioclase, rare pyroxene and magnetite. Laminated flow planes and prominent jointing parallel to the banding are distinctive. Flow planes are discontinuous and commonly parallel to the ground surface. Dark gray, thin, devitrified layer overlies a red to black, altered, discontinuous flow breccia. Upper half forms cliffs and ledges and the lower half forms a colluvial slope. Lower contact marked by a red to black, altered, flow breccia overlain by a discontinuous, thin, dark gray, devitrified layer. 40Ar/39Ar analysis on sanidine indicates an age of 6.62±0.08Ma. Thickness is approximately 400 feet in the type area but ranges from 0-400 feet in map area. TRa 8000 Qls Tccvc Tcc References Cited Platy zone, Pony Creek dacite lava flow -- Dense, dark gray, and platy with rare white pumice. Forms steep ledges 3-10 feet high and alternating slopes. Fractures into angular blocks about 3 feet across and 0.5-2 inches thick. Bear River Formation (Lower Cretaceous) -- Shale, sandstone, limestone, clay and marl. Sandstone is gray with fine-grained white quartz and dark gray chert grains, and is commonly cross-bedded. Generally forms ledges. Shale is greenish gray, light gray and black, carbonaceous with a few thin seams of coal-like material. Other lithologies are generally gray with thin to medium beds. The base of this unit is not exposed here, but in other areas is placed at the bottom of the green-gray sandstone overlying the Cretaceous Draney Limestone (not found in mapped area). Thickness is approximately 900 feet (Staatz and Albee, 1966a). Datum is mean sea level. Tk Glassy zone, Pony Creek dacite lava flow -- Dense, black, and glassy with a conchoidal fracture. Contains zones of intense perlitic texture. Perlite diameters are generally 0.1-0.2 inches but can be as much as 1 inch. Forms slopes covered with angular to rounded cobbles and boulders and low, rounded ledges. Kb Layout by Kathleen Price at the Idaho State University, Digital Mapping Laboratory, Department of Geosciences. A 5000 3000 Strike and dip of foliation 43o4230 111o2150 7000 4000 Kf National Geodetic Vertical Datum of 1929 35 Te 5000 Strike and dip of bedding (Garns Mtn, Temple Peak, 40 feet: Packsaddle Lake, Wright Creek, 20 feet) Control by USGS, NOS/NOAA, and USC&GS. 8000 6000 25 SCALE 1:24,000 1 A 7000 Garns Mtn. 25 25 Tco Thrust fault: teeth on hanging wall, dashed where approximately located, dotted where concealed. Base map from USGS 7.5 series: Temple Peak 1979, Garns Mtn. 1978, Packsaddle Lake 1965, and Wright Creek 1965. 111o2620 6000 Normal fault: bar and ball on hanging wall, dashed where approximately located, dotted where concealed. PPMw l 35 20 PPlMw 43o4230 Packsaddle Lake IDAHO PPMw l Tcb Tcc 18 Tcb Wright Creek UTM Grid and 1965 Magnetic North Declination at Center of Map Te 45 Tcc TRw 111o1728 17.5o 0o13 35 Qc Tca 28 Mississippian Symbols 45 TRa a Lower Mississippan Tcc Tca PPMw l 8 TRd Upper Mississippian Paleozoic 45 Kf 21 Qc Pp Pennsylvanian 45 25 Te Te Qa 29 35 Mm ? Qc 35 50 18 Lower Pennsylvanian Tpdp 25 GN 45 Mm 18 Permian Te 50 19 20 Lower Permian Unit Contact, dashed where approximately located, dotted where concealed. 45 Tca Qc 45 Tcb Tcc Qls ? 30 Tcc 12 10 Tpdg Qls Kf 55 45 Qls Lower Triassic Triassic 15 65 Tcc Te Upper Triassic Tco Tk Tk Mesozoic 43o4518 Tco 34 Qls 4 Dacite of Pony Creek (Upper Miocene) -- Dacite lava flow. Black to dark gray, massive, vesicular trachytic lava flow with 10% phenocrysts, 2% quartz xenocrysts, 20% vesicles, and 68% vitrophyric, microcrystalline matrix. Fine-grained phenocrysts include 70% euhedral to subeuhedral laths of plagioclase, 25% euhedral to anhedral augite, and 5% anhedral opaque minerals. Vesicles are 0.02-0.1 inches in diameter, aligned, show glass rims, and have rare laths of plagioclase protruding into them. Quartz xenocrysts are about 0.1-0.2 inches in diameter. Locally divided into two zones based upon textural differences. Lower contact is a disconformity marked by the first appearance of vitrophyric lava. 40Ar/39Ar analysis on sanidine indicates an age of 6.59±0.02 Ma . Thickness ranges from 0-1400 feet. Tyh Mm Tcc Lower Cretaceous 29 Qc Tk Cretaceous Kf ? ? Upper Cretaceous Tuff of Edie School (Upper Miocene) -- Rhyolite ignimbrite. Dark gray, violet, or lavender, crystal-rich, densely welded tuff. Contains 10-20% phenocrysts of plagioclase, quartz, sanidine, augite, serpentinized and oxidized pyroxene, magnetite and zircon. Phenocrysts are most abundant in a rare, dark purple to black, devitrified basal zone. Common flattened lithophysae are 3-4 inches in diameter. Forms slopes, rounded hoodoos, and rarely steep cliffs. Fractures into cubical blocks about 1 ft long and is strongly weathered in most places. Lower contact is generally a disconformity marked by the first appearance of purple, crystal-rich tuff. Age is 6.57 Ma (Anders et al., 2009). Thickness is 0-500 feet. Carlton Creek Volcanics (Upper Miocene) -- Dacite lava flows and ignimbrites. Formerly mapped by Staatz and Albee (1966a, b) as part of the Kirkham Hollow Volcanics, but herein defined as a new formation containing 4 members. Type section is on the northeast slope of Carlton Creek in Sec. 17 &18, T5N, R43E, Wright Creek Quadrangle, Madison County, Idaho for Members A, B, and C. Type section for the dacite of Pony Creek is located near the Pony Creek drainage in Sec. 34, T6N, R44E. Thickness at the type locality is approximately 600 feet; elsewhere it ranges from 0-900 feet. Tyh Tcc Mm Tca Qc Qa 16 Tk Qls Tk Te Tca Qc Tco Mm Tcc Tcc Tyh Qc 15 Qls Tca Tyh Tcc 25 21 PP l Mw 15 Qc Tcc Tcb Qc Tyh Tcc Tcc Ppm Tcc Tcc 12 Ppu Tk Qls 21 Tcc Te Tyh Qls Tco Tco Tcb Tcb Tca Tk 30 35 Qc Tca 30 Tcb Tyh Tcc Qa Qls Tcc Oligocene TRd Qc 18 17 Tcc 28 TRw Qa Tco Tca TRt B Tk Qls Qc Tk TRa Ql Tk 14 Tcc Tcb Ql Te Disconformity Tk Te Qls Tcc Qc Tcb Tcc Tuff of Kilgore (Pliocene) -- Rhyolite ignimbrite. Pink to gray, crystalpoor, densely welded tuff. Phenocrysts of plagioclase, quartz, sanidine, augite, magnetite and zircon compose 2-7% of the rock. Diagnostic textures include common lithophysae from 0.1-1 inch in diameter, maroon pumice, and black, gray and maroon obsidian pieces from 0.5-4 inches. Forms ledges and slopes. Disconformable lower contact placed below the lowest crystal-poor tuff. Age is 4.49 Ma (Anders et al., 2009). Thickness is 0-100 feet. Ka Kb Te Tk Tcc Tcb Qt Tcc Tpdp Tpdp Qls Tk Unconformity Kf Tpdp Tpdg Tpdg Qls 43o4737 15 Tcc 32 Tk Tcc Tca Ql Ql Tk Tpdp Huckleberry Ridge Tuff (Pliocene) -- Rhyolite ignimbrite. Compound cooling unit of tan, gray, and lavender, densely welded, eutaxitic, crystal-rich, devitrified tuff. Contains phenocrysts of 5% quartz, 10% sanidine and 5% sodic plagioclase, sparse opaque oxides (magnetite), clinopyroxene and fayalite olivine. Changes upsection from phenocryst-rich to phenocryst-poor. Welded pumice is dark and scoriaceous or light colored and compact. Weathers into distinctive rectangular blocks of varying sizes. Found on lower elevation slopes in the north and west of map area. Lower contact is an angular unconformity defined by the first appearance of crystalrich, light-colored tuff. Age is 2.06 Ma (Lanphere et al., 2002). Thickness is 0-200 feet. Eocene 111o1728 32 Te Ql Tyh Tk Tpdg Loess (Pleistocene) -- Light tan to dark brown, homogenous eolian deposits of angular silt and clay grains. Composed mostly of calcite and quartz but also contains clay minerals, biotite, muscovite, zircon, feldspar and amphibole. Typically covers slopes below 6500-7000 in elevation. Thickness is 0-40 feet (Staaz and Albee, 1966a). Tyh Unconformity Ql 25 Landslide deposits (Holocene and Pleistocene) -- Chaotically mixed boulder- to silt-sized rock debris. Thickness is 0-50 feet. Tertiary Miocene Unconformity Tpdg Tpdp Tcc Qls Cenozoic Tca Tk Colluvium (Holocene and Pleistocene) --Tan, gray, brown, and redbrown, unconsolidated, angular silt- to boulder-sized debris found on steep slopes and uncommonly on flats. Thickness is 0-25 feet. Tcb Tpdg Tyh Qc Pliocene Tpdp Tpdg 15 Tcc Qc Ql Qt Travertine (Holocene) --Tan to white, porous, finely layered limestone deposited in small mounds by hydrothermal activity. Thickness is 0-30 feet. Quaternary Te Tpdg Tcc Pleistocene Disconformity Tpdp 32 20 Alluvium (Holocene) -- Unconsolidated clay, silt, sand, and gravel below modern streams. Thickness is generally less than 15 feet. Ql Tk Tpdg Qc Tk Qls Tpdg Tpdp Tyh Qc Holocene Qa
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