Geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana
<p>The 7.5′ Strawberry Butte quadrangle in Meagher County, Montana near the southwest margin of the Little Belt Mountains, encompasses two sharply different…
Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.
LIST OF MAP UNITS Alluvium (Holocene) Alluvium and colluvium, undivided (Holocene) Colluvium (Holocene) Landslide deposits (Holocene and Pleistocene) Terrace gravel (Holocene? and Pleistocene) Old alluvium (Holocene? or Pleistocene) Older gravel (Pleistocene? and Neogene?) Sedimentary rocks (Miocene and Oligocene)—Shown as MIOGS in Reynolds and Brandt, 2005, 2007 Basalt (Oligocene)—Shown as OGb in Reynolds and Brandt, 2005, 2007 Biotite hornblende dacite (Eocene)—Shown as EObhd in Reynolds and Brandt, 2005, 2007 Biotite hornblende monzonite (Eocene)—Shown as EObhm in Reynolds and Brandt, 2005, 2007 Park Shale (Upper and Middle Cambrian) Meagher Limestone (Middle Cambrian) Wolsey Shale (Middle Cambrian) Flathead Sandstone (Middle Cambrian) Belt Supergroup, part (Mesoproterozoic) Newland Formation (Mesoproterozoic) Newland Formation, upper part (Mesoproterozoic) Newland Formation, lower part (Mesoproterozoic) Granite gneiss (Paleoproterozoic) Granite gneiss and biotite gneiss undivided (Paleoproterozoic) Biotite hornblende diorite (Paleoproterozoic) EXPLANATION Contact—Dashed where approximately located, short dashed, where inferred, dotted where concealed Boundary of mapped surficial material or feature—Approximately located Fault—Dashed where approximately located, short dashed, where inferred, dotted where concealed Normal Fault—Ball and bar on downthrown block; dashed where approximately located, short dashed where inferred, dotted where concealed; red arrow indicates fault attitude showing dip Anticline—Dashed where approximately located, short dashed where inferred, dotted where concealed; arrow shows direction of plunge Syncline—Dashed where approximately located, short dashed where inferred, dotted where concealed Bed or vein of iron-silicate gossan Outcrop of iron oxide gossan zones—In bedrock of the Newland Formation Area of iron-oxide-stained bedrock, bedrock fragments and soil—Near zones of sulfide mineralization Area of colluvial boulders, blocks and cobbles of iron-silicate gossan—Derived from nearby zones of sulfide mineralization Area of alluvial and colluvial boulders, cobbles, and blocks—Derived from Paleozoic strata east of the quadrangle or from Flathead Sandstone on Black Butte Zone of brecciated and sheared rock adjacent to fault Horizontal bedding Inclined bedding—Showing strike and dip Vertical bedding—Showing strike Overturned bedding—Showing strike and dip Inclined shear fracture—Showing strike and dip Inclined layering in layered gneiss or schist—Showing strike and dip Inclined slickensides—Showing bearing and plunge Location and age of dated rocks—Showing sample number and radiometric age Selected locality of trace fossils in Flathead Sandstone Prospect pit in iron oxide gossan zone Exploration trench in iron oxide gossan zone Qt Ql Qc Qa p b f w m bhd Ynu Ynl Xgg
Xbd QNg bhm N s Qac Qoa Figure 3. Tectonic map of west-central Montana showing principal faults, major tectonic elements, intrusive and extrusive igneous rock bodies, Tertiary strata and major areas of Quaternary sediments. Thrust sheets and igneous units listed in descending succession of inferred increasing age within tectonic elements (for example, autochthons and parautochthons). Red rectangular outline shows the location of the Strawberry Butte 7.5´ quadrangle (modified from Reynolds and Brandt, 2005, figure 2, sheet 1). 10 KILOMETERS 10 MILES Area of Figure 3 MONTANA FAULT CARR WOODS CREEK RIDGE SMITH VALLEY EAST SIDE FAULT LOST FORK PLUTON CREEK FAULT NORTH FAULT LACCOLITH ZONE ZONE MOUNTAIN SHEEP MOUTAIN FLANK VALLEY LOGAN FAULT CAMUS CREEK FAULT BIG BALD MOUNTAIN LACCOLITH BOULDER BALDY PLUTON FORT PLUTON BASIN THRUST FAULT FAULT CREEK TENDERFOOT NEVADA CREEK FAULT DECOLLEMENT FAULT FAULT ZONE RANGE FAULT DRYWOLF LACCOLITH WAITE ZONE MOOSE ZONE CREEK FAULT CASTLE MOUNTAINS PLUTON ZONE CREEK FAULT PARK QUARTZITE WESTERN END ANCESTRAL CENTRAL MONTANA UPLIFT DRY FAULT HOOVER White Sulphur Springs Utica Neihart 111°00' 110°00' 110°30' 111°22' 47°00' 46°30' 46°45' R Quaternary and Pliocene(?) sediment in veneers on older rocks—Locally includes Miocene and Oligocene sedimentary rocks in valley of Smith River Miocene and Oligocene sedimentary rocks—Locally includes Eocene(?) sedimentary rocks at base Oligocene basalt Oligocene(?) and Eocene rhyolite with breccia blocks of Paleozoic sedimentary rocks Eocene intrusive rocks—In plutons, laccoliths, and large sills of the autochthon and parautochthon Eocene and Cretaceous intrusive rocks penetrating the Moors Mountain thrust sheet Paleozoic sedimentary rocks of the frontal fold-and-fault belt Neoproterozoic diorite sill in Moors Mountain thrust sheet Mesoproterozoic metasedimentary rocks of the Moors Mountain thrust sheet Mesozoic sedimentary rocks of the paratochthon—Become contiguous with the autochthon in T8N, R19E Paleozoic sedimentary rocks of the paratochthon—Become contiguous with the autochthon in T8N, R19E EXPLANATION [Thrust sheets and igneous units listed in descending succession of inferred increasing age; some Quaternary and Tertiary deposits are not shown] R R R Mesozoic sedimentary rocks of the autochthon Paleozoic sedimentary rocks of the autochthon; locally includes Eocene sills and dikes Mesoproterozoic metasedimentary rocks of the paratochthon Lewis and Clark tectonic zone—Boundaries inferred Stratigraphic boundary Major high-angle normal fault—Bar and ball on downthrown block Major fault with complex displacement—Including normal, strike-slip and reverse movement through geologic time Major high-angle reverse fault—R on upthrown block Edge of major thrust sheet—Sawteeth on upper plate Edge of decollement surface at base of frontal fault and fold belt Fault—Dotted where concealed by Cenozoic units or water Neoarchean metamorphic rocks of the autochthon Paleoproterozoic metamorphic rocks of the autochthon Mesoproterozoic metasedimentary rocks of the autochthon MOORS B A K CANYON LEWIS AND CLARK TECTONIC ZONE THRUST VOLCANO VOLCANO VALLEY FAULT MOUNTAIN Figure 2. Shaded relief map of the Strawberry Butte 7.5´ quadrangle (red rectangle) and adjacent areas showing features referred to in the accompanying pamphlet. Selected streams, blue; roads and vehicle trails, black and gray lines respectively; quadrangle names, green; Lewis and Clark National Forest exterior boundary, dashed and orange lines. There are private inholdings within the boundaries of the National Forest shown on this map. 5 MILES 5 KILOMETERS 1:200,000 Creek Black Butte Creek Black Butte Strawberry Butte Coxcombe Butte Moose Mountain Allan Park Sheep Creek Bar Green Mountain Williams Mountain Monument Peak Iron Mountain Belt Park Quartzite Ridge Buckingham Reservoir Newlan Creek Reservoir Sheep Creek Moose Creek Creek Sheep Newlan Creek Newlan Creek Tenderfoot Eagle Smith River Rabbit Creek Adams Creek Creek Pole Creek CASC AD E OU NT Y MEAG HE R OU NT Y Rim ro k R d g e 111°7’30” 47° 46°52’30” 46°45’ 46°37’30” 111° NATIONAL FOREST LEWIS AND CLARK Creek U.S. Geological Survey National Elevation Dataset (NED) 10-meter resolution elevation data, accessed on 07-25-2016 Lake 110°45’ 110°52’30” Ch ar o al
G u h Sheep Mountain MONUMENT PEAK BUBBLING SPRINGS BELT PARK BUTTE SHEEP MTN STRAWBERRY BUTTE MOOSE MTN WHITETAIL RESERVOIR COXCOMBE BUTTE COXCOMBE BUTTE CHARCOAL GULCH MONUMENT PEAK BUBBLING SPRINGS BELT PARK BUTTE SHEEP MTN STRAWBERRY BUTTE MOOSE MTN WHITETAIL RESERVOIR CHARCOAL GULCH BUBBLING SPRINGS SHEEP MTN STRAWBERRY BUTTE MOOSE MTN WHITETAIL RESERVOIR COXCOMBE BUTTE COXCOMBE BUTTE CHARCOAL GULCH Figure 1. Generalized physiography of west-central Montana, showing location of the Strawberry Butte and adjacent 7.5´ quadrangles referred to in the text and annotated with names of selected topographic and cultural features; orange shading indicates highlands and green indicates lowlands. Missouri River 20 MILES 20 KILOMETERS Niehart White Sulphur Springs 111°30’ 111° 110°30’ 47° 46°30’ Adel Mountains Castle Mountains Elkhorn Mountains Spokane Hills Dry Range Park Hills Little Belt Mountains Smith River Valley Townsend Valley Sheep Mountain Strawberry Butte Moose Mountain Judith River basin Helena Valley M s s o u r
R e r Smit h R ive r North Fork Sm ith R e r S o u t h
F o r k S mith R iver Musselsh ell
Ri ve r Judith River Big Belt
Mounta ins Ca n y o n
F er ry
Lake ? ? ? ? Qa Qc Ql Qt b bhd Ynu Ynl Xgg
Xbd QUATERNARY TERTIARY CAMBRIAN MESOPROTEROZOIC PALEOPROTEROZOIC Holocene Oligocene Upper Cambrian Middle Cambrian BELT SUPERGROUP (part) Pleistocene Pliocene(?) and Miocene Fault contacts Unconformity Unconformity Unconformity Intrusive contacts CORRELATION OF MAP UNITS Eocene p m f w WSP9–99 31.71 Ma Qoa QNg N s bhm Qac WSP8b–99 31.87 Ma WSP9–99 31.71 Ma WSP8a–99 32.04 Ma Ynu Qa Ql m f Ynu Ynl Ynu Qa f m Qa m f f f f Qt Qa Qa Qa Xgg Xgg Xgg Xgg Xgg Xgg f f f f f Ql Ql w Qa Xbd Xbd m Qa Qt Qa w f f f QNg Ynl QNg Ynu QNg f Xgg
FAULT FAULT VOLCANO VALLEY BLACK BUTTE CREEK ZONE ZONE Qac N s N s N s N s Qa b b Qa b N s N s N s N s b bhm bhd bhd bhd b Qac QNg f Qa Qa Qa p p f Qc Ql Qc Qoa N s Ynl
BLACK BUTTE CREEK ZONE FAULT Geologic Map of the Strawberry Butte 7.5’ Quadrangle, Meagher County, Montana By Mitchell W. Reynolds and Theodore R. Brandt CONVERSION FACTORS centimeter (cm) millimeter (mm) meter (m) kilometer (km) Multiply Length By To obtain inch (in.) inch (in.) foot (ft) mile (mi) U.S. Customary Units to International System U.S. Department of the Interior U.S. Geological Survey ://doi.org/10.3133/sim3379 ISSN 2329-132X (online) For more information concerning this publication, contact Center Director, USGS Geosciences and Environmental Change Science Center Box 25046, Mail Stop 980 Denver, CO 80225 (303) 236-5344 Or visit the Geosciences and Environmental Change Science Center Web site at ://gec.cr.usgs.gov/ ScienceBase citation: Reynolds, M.W., and Brandt, T.R., 2017, Data release for the geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana: U.S. Geological Survey data release, ://doi.org/10.5066/F73J3B61. Suggested citation: Reynolds, M.W., and Brandt, T.R., 2017, Geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana: U.S. Geological Survey Scientific Investigations Map 3379, pamphlet 16 p., 2 sheets, scale 1:24,000, ://doi.org/10.3133/sim3379. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. This database, identified as SIM 3379, has been approved for release and publication by the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the database is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. This map or plate is offered as an online-only, digital publication. Users should be aware that, because of differences in rendering processes and pixel resolution, some slight distortion of scale or color may occur when viewing it on a computer screen or when printing it on an electronic plotter, even when it is viewed or printed at its intended publication scale. Base from U.S. Geological Survey Strawberry Butte 1:24:000-scale, 1967 Revised by U.S. Forest Service Strawberry Butte 1:24,000-scale, 1995 Projection and 1,000-meter grid Universal Transverse Mercator ticks, zone 12 10,000-foot ticks, Montana coordinate system, central zone 1927 North American Datum Geology mapped by Mitchell W. Reynolds in July 1998 and July 1999; assisted by Sandra A. Reynolds Digital topographic base map, digital compilation, and geographic information systems (GIS) database prepared by Theodore R. Brandt Color design of map and figures by Mitchell W. Reynolds Scientific Investigations Map 3379 Sheet 1 of 2 Pamphlet accompanies map CONTOUR INTERVAL 40 FEET NATIONAL GEODETIC VERTICAL DATUM OF 1929 APPROXIMATE MEAN DECLINATION, 2016 QUADRANGLE LOCATION SCALE 1:24 000 1 MILE 1/ 2 7000 FEET 1 KILOMETER TRUE NORTH MAGNETIC NORTH 12° MONTANA Publishing support provided by Denver Publishing Service Center Edit and digital layout by J.A. Herrick Manuscript approved for publication March 15, 2017 To learn about the USGS and its information products visit ://www.usgs.gov/ 1-888-ASK-USGS A' B' A B C'