IDAHO GEOLOGICAL SURVEY GEOLOGIC MAP 32 MOSCOW-BOISE-POCATELLO LEWIS AND STANFORD

G EOLOGIC MAP COMPILATION OF THE HAMILTON 30 X 60 MINUTE QUADRANGLE, IDAHO

Reed S. Lewis and Loudon R. Stanford 2002

TKa 55 25 Kbgd Qg Yqcw Tg Td 25 TKa Kgdmg ? TKa TKa Kgdmg Td ? Kbgd 60 Tr Kmg Kbgd TKa 55 Kbgd 60 Qal Kmig Yqcw 55 TKa Yqcw Td Ka 60 Yqcw ? 20 50 Kbgd Qg Td 65 Kgdmg 50 Qal TKa 80 Ka 35 75 ? Tr 50 Qg Td Yq 32 Kgd 60 80 Td Kbgd 40 25 46 Kbgd 25 44 40 Kbgd Qg 60 45 TKa 85 38 60 Kmg Td 45 Kmg 60 Td Qg 10 FAULT Kmg 5 70 73 80 80 Yqcw Td 45 60 55 50 Kbgd 63 Kbgd 15 40 64 Tr 83 Td 50 Yqcw Qg Td 58 ? 25 50 20 SPRINGS 40 10 30 73 63 5 35 15 Kdi 35 50 Tr 70 67 WARM 32 42 TKa Kbgd TKa Ka 70 ? ? 73 Kbgd 70 Ka ? 70 78 COLGATE ? Qg ? Kbgd Qg Kht ? Kbgd 50 ? Kmg Ka Ka 45 Td Qg ? Kdi TKa 76 75 Kmg 60 15 Kbgd 47 45 10 Kmg 60 ?

? 53 Ka 20 ? ? 66 TKa 40 35 37 30 Kmg 25 25 55 25 39 ? Qal ? ? Qg 50 ? 79 35

45 ? MONTANA 56 45 Qg Qal TKa Td ? Qg Kmg 50 64 FAULT ? Qg 50 Kbgd 50 Kmg FAULT Kmg 35 34 Kbgd 30 Kbgd ? Tr 75 Yqcw ? 47

? 26 ? 35 ? ELK SUMMIT Qal 26 CREEK Qg 15 Kmig Tr 40 Kmig 35 20 Kdi 10 35 ? TKa 15 10 40 60 Kdi 12 25 15 5 10 TKa 10 35 75 20 Kbgd TKa Kbgd ? Kdi 30 15 ? Qal Kdi TKa ? 10 Kbgd 10 25 65 30 CEDAR Qg Kbgd Tr 5 5 5 25 64 Kdi 20 6025 10 15 Kmg 25 30 88 Tr Tr ? 25 75 10 ? Kbgd 20 20 10 Kdi Trdr 22 42 34 60 Qg 24 35

50 55

56 Kgd Kmig 45 20

30 Qal 34 Kmig Kgd

Trdr Qal 85 Yq Kmig Trdr 35 75 Yqcw 40 Trdr Trdr 53 Trdr 22 32 Kmig Yq Qg 22 22 45 18 Tgp Trdr Trdr Trdr

Trdr 52 18 Tgf Kmig Kgd 16

Tgm 27 Kgd

25 INDEX TO PRIMARY Tgc 20 23 25 MAP SOURCES 19 2. 1. Qal 26 Trdr Ta 30 Tgp Yqcw 34 4. WHISTLING PIG Trdr Tg Tgf 28 21 PLUTON Tg 57 2. Ta 27 18 Qal Kgdmg Qal 40 Trdr 33 40 22 Tgc 35 27 Tgc 15 3. Trdr Yqcw 53 1. 46 Trdr Ta MONTANA 4. Trdr Kmig Trdr Trdr 43 23 Trdr Ta Trdr 67 TKdi 22 1. Dingler, C.M., 1981 Kgd Kgd 20 42 2. Lewis and others, 1992 57 42 12 Trdr 3. Motzer, W.E., 1985 Yq Kmig 55 4. Toth, M.I., 1983a Trdr 60 Trdr Kmig Qg Yq 42 40 Trdr 40 Ta Kmig TKdi Kgdmg INDEX TO ADDITIONAL 53 45 26 Qal MAP SOURCES Trdr 30 45 Tgd Trdr 20 20 31 45 2. 18 7. 5. Trdr TKdi Kgd Kmig PARADISE PLUTON TKdi 50 38 1. 44 59 7. 15 25 1. 35 30 Trdr 43 3. 15 35 25 3. 36 44 58 25 21 Kmig Trdr 30 20 43 25 35 4. 45 20 Kht Kgd 6. 20 40 22 35 Qal Trdr 28 54 25 3. 53 Kgd 20 1. Bittner-Gaber, Enid, 1983. 53 Trdr 75 52 Yqcw 12 20 20 2. Bradley, M.D., 1981. Yq 30 Trdr 12 3. Greenwood, W.R., and D.A. 19 55 Kgd Tgd Morrison, 1973. 35 4. Lund, Karen, 1980. Trdr Trdr 28 5. Nold, J.L., 1968. Tgd Trdr Tgd 6. Toth, M.I., 1983b 45 35 Kgdmg Yq 7. Williams, L.D., 1977. Trdr RUNNING CREEK PLUTON Tgm 32 Tgd SYMBOLS Base map scanned from USGS 1:100,000-scale metric topographic map. MN SCALE 1:100,000 Funded in part by the Mineral Resource Program of the Base map prepared by the U.S. Geological Survey. Compiled from USGS 1:24,000- U.S. Geological Survey Contact: approximately located. GN 1 0 12345 1 0 12 3 scale topographic maps dated 1964-1967. Planimetry revised from aerial photographs o 19 KILOMETERS MILES Digital cartography by Jane S. Freed, Loudon R. Stanford, and Tim Funderburg taken 1974, 1979, and other source data. Revised information not field checked. Map o edited 1980. 1 48 at the Idaho Geological Survey’s Digital Mapping and GIS Lab. Normal fault: approximately located; dotted where concealed; Contour interval 50 meters Projection and 10,000-meter grid, zone 11, Universal Transverse Mercator. Technical review by Karen Lund is gratefully acknowledged. ball and bar on downthrown side. Supplementary contour interval 10 meters Map edited by Roger C. Stewart. 25,000-foot grid ticks based on Idaho coordinate system, west zone. IDAHO 1927 North American datum. Note on printing: The map is reproduced at a high resolution of 600 dots Thrust fault: approximately located; teeth on upper plate UTM grid (GN) and Magnetic declination (MN). per inch. The inks are resistant to run but not to the fading caused by long- National geodetic datum of 1929. Diagram is approximate. QUADRANGLE 50 LOCATION term exposure to light. Strike and dip of bedding. Map version 5-31-02. DESCRIPTION OF MAP UNITS 25 Strike and dip of foliation.

Strike of vertical foliation. INTRODUCTION Qal Alluvium (Quaternary)—Stream deposits in modern drainages; gravel, silt, and TKdi Biotite-hornblende diorite, quartz diorite, and tonalite (Cretaceous and sand. Eocene?)—Abundant narrow dikes and composite bodies of gray to black 20 Strike and dip of mylonitic foliation. diorite, quartz diorite, and tonalite. Fine- to medium-grained equigranular The map was compiled primarily from four sources: Lewis and others 1992, Qg Glacial deposits (Quaternary)—Poorly sorted and poorly stratified, unconsolidated rocks are dominant over porphyritic varieties. Bearing and plunge of lineation. Toth 1980, Motzer 1985, and Dingler 1981. Geologic edge-match deposits principally of glacial origin. Includes till in lateral and ground 10 discrepancies between sources were reconciled where possible in the moraines as well as outwash and modern stream alluvium. Ka Andesite dikes (Cretaceous)—Dark gray, weakly porphyritic to equigranular Mylonite. compilation; the field work necessary to resolve remaining problems was fine-grained dikes that consist primarily of plagioclase, biotite, quartz, and 25 Tr beyond the funded scope of this project. Intrusive rocks are classified Rhyolite dikes (Eocene)—Tan-weathering, aphanitic to very fine-grained hornblende. Bearing and plunge of small fold axis. according to IUGS nomenclature using normalized values of modal quartz phaneritic rock that contains less than 10 percent phenocrysts of potassium 20 Bearing and plunge of asymmetrical small fold showing feldspar and quartz. Kdi Hornblende diorite (Cretaceous)—Dikes and small bodies of fine- to medium- (Q), alkali feldspar (A), and plagioclase (P) on a ternary diagram (Streckeisen, counterclockwise rotation viewed down plunge. 1976). grained equigranular (pyroxene-) biotite-hornblende diorite and quartz Trdr Rhyodacite and rhyolite dikes and plugs (Eocene)—Rhyodacite and subordinate diorite. rhyolite, typically porphyritic, with phenocrysts of orthoclase or sanidine, plagioclase, quartz, biotite, and hornblende. Kgd Biotite and muscovite-biotite granodiorite and granite (Cretaceous)—Slightly REFERENCES porphyritic to equigranular granodiorite and granite containing 2-5 percent Ta Andesite dikes (Eocene)—Dark gray nonfoliated dikes characterized by sparse biotite and varied amounts of muscovite. Weakly developed primary flow Bittner-Gaber, Enid, 1983, Geology of selected migmatite zones within the CORRELATION OF MAP UNITS hornblende and plagioclase phenocrysts in an aphanitic matrix. foliation present. Local development of a mylonitic foliation, particularly Bitterroot lobe of the Idaho batholith, Idaho and Montana: University of at higher elevations. Includes the Bear Creek pluton of Toth (1983b). Tg Granite (Eocene)—Biotite granite. Stock in northeast corner is light gray, fine Idaho Ph.D. dissertation, 173 p. grained, and muscovite-bearing. It lacks perthitic feldspar typical of Eocene Kmg Muscovite-biotite granite (Cretaceous)—Medium-grained, equigranular Bradley, M.D., 1981, Geology of northeastern Selway-Bitterroot Wilderness area, granite in the region, but is similar chemically (K O > Na O; SiO > 72%). Qal HOLOCENE 2 2 2 muscovite-biotite granite and granodiorite. Muscovite is in books that locally Idaho and Montana: University of Idaho M.S. thesis, 51 p. Dingler, C.M., 1981, Reconnaissance glacial geology of the Selway-Bitterroot Tgp coarsen to 1 cm in diameter. QUATERNARY Porphyritic granite (Eocene)—Gray to pinkish gray, fine- to medium-grained Wilderness and surrounding lower elevations, Idaho and Montana: University Qg porphyritic hornblende-biotite granite. Phenocrysts are orthoclase feldspar. PLEISTOCENE Kbgd Biotite granodiorite (Cretaceous)—Medium- to fine-grained, equigranular to of Idaho M.S. thesis, 184 p. Mapped as a chill zone capping the Whistling Pig pluton (Lund, 1980; slightly porphyritic biotite granodiorite. Hornblende-bearing and tonalitic Greenwood, W.R., and D.A. Morrison, 1973, Reconnaissance geology of the Motzer, 1985). near some contacts with metasedimentary rocks. Associated pegmatite and Selway-Bitterroot Wilderness area: Idaho Bureau of Mines and Geology aplite dikes and sills are common. Tgf Fine-grained granite (Eocene)—Cream colored biotite leucogranite. Commonly Pamphlet 154, 30 p. Trdr Tg Tgp Tgf Tgm Tgc Tr contains miarolitic cavities. Graphic and myrmekitic textures are abundant. Lewis, R.S., R.F. Burmester, R.W. Reynolds, E.H. Bennett, P.E. Myers, and R.R. Kht Tonalite (Cretaceous)—Medium-grained hornblende-biotite tonalite and quartz Reid, 1992, Geologic map of the Lochsa River area, northern Idaho: Idaho Mapped as a textural phase of the Whistling Pig pluton (Lund, 1980; Motzer, diorite. Strongly developed flow foliation and a down-dip flow lineation Trdr 1985). Geological Survey Geologic Map 19, scale 1:100,000. EOCENE TERTIARY defined by biotite and hornblende. Lund, Karen, 1980, Geology of the Whistling Pig pluton, Selway-Bitterroot Tgm Wilderness, Idaho: University of Colorado M.S. thesis, 115 p. Tgd Ta Medium-grained granite (Eocene)—Pink, medium-grained, biotite-hornblende Kgdmg Megacrystic granodiorite (Cretaceous)—Granodiorite, granite, and tonalite granite to quartz syenite. Miarolitic cavities are common. Mapped as a containing poikilitic potassium feldspar megacrysts 3 to 8 cm long. Muscovite- Motzer, W.E., 1985, Tertiary epizonal plutonic rocks of the Selway-Bitterroot textural phase of the Whistling Pig pluton (Lund, 1980; Motzer, 1985). bearing in southwest part of quadrangle (Toth, 1983), and hornblende- Wilderness, Idaho County, Idaho: University of Idaho Ph.D. dissertation, TKa TKdi 467 p. Tgc bearing and foliated in northwest part (Lewis and others, 1992). Coarse-grained granite (Eocene)—Pink, coarse-grained, biotite-hornblende Nold, J.L., 1968, Geology of the northeastern border zone of the Idaho batholith, granite to quartz syenite. Grain size averages greater than 5 mm. Sparse to Ka Kmig Migmatite (Cretaceous)—Migmatite consisting of 20-95 percent granitic rocks Montana and Idaho: University of Montana Ph.D. dissertation, 159 p. Kgd Kbgd Kmg no miarolitic cavities. Mapped as a textural phase of the Whistling Pig intruded into quartzofeldspathic schist and gneiss, amphibolite, biotite Streckeisen, A.L., 1976, To each plutonic rock its proper name: Earth-Science Kdi CRETACEOUS pluton (Lund, 1980; Motzer, 1985). Kdi quartzite, and calc-silicate gneiss. Studied in detail by Bittner-Gaber (1987). Reviews, v. 12, p. 1-33. Kmig Toth, M.I., 1983a, Reconnaissance geologic map of the Selway-Bitterroot Tgd Hornblende-biotite granodiorite (Eocene)—Medium-grained equigranular to Yqcw Calc-silicate gneiss and quartzite of Wallace Formation (Middle Proterozoic)— Wilderness, Idaho County, Idaho, and Missoula and Ravalli counties, Kht Kgdmg porphyritic monzogranite and granodiorite. Porphryritic rocks have light Includes centimeter-scale, layered, hornblende-diopside-quartz plagioclase Montana: U.S. Geological Survey Miscellaneous Field Studies Map MF- pink potassium feldspar phenocrysts 6 mm long in a medium-grained gneiss, garnet-diopside quartzite, amphibolite, and minor amounts of garnet- 1495-B, scale 1:125,000. groundmass. Mapped as the Paradise pluton by Toth (1983a, 1983b). biotite schist and gneiss. Toth, M.I., 1983b, Structure, petrochemistry, and origin of the Bear Creek and Paradise plutons, Bitterroot lobe of the Idaho batholith: University of Colorado Yqcw TKa Andesite dikes (Cretaceous and Eocene?)—Dark gray, sparsely porphyritic to Yq Quartzite (Middle Proterozoic)—White quartzite and micaceous granofelsic MIDDLE Ph.D. dissertation, 337 p. equigranular fine-grained dikes of uncertain age. Equivalent to either Ta or quartzite, commonly interlayered with pelitic schist. Quartz (31-97 percent) Yq PROTEROZOIC Williams, L.D., 1977, Petrology and petrography of a section across the Bitterroot Ka units. is found as granoblastic grains 2-4 mm across and in elongate platy grains lobe of the Idaho batholith: University of Montana Ph.D. dissertation, 219 parallel to the schistosity. p.

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