DOCSLIB.ORG

Deep Crustal Xenoliths from Central Montana, USA: Implications for the Timing and Mechanisms of High-Velocity Lower Crust Formation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Deep Crustal Xenoliths from Central Montana, USA: Implications for the Timing and Mechanisms of High-Velocity Lower Crust Formation Investigations of North America as EarthScope Reaches Its Maturity themed issue Deep crustal xenoliths from central Montana, USA: Implications for the timing and mechanisms of high-velocity lower crust formation Katherine R. Barnhart1, Kevin H. Mahan1, Terrence J. Blackburn2, Samuel A. Bowring2, and Francis O. Dudas2 1Department of Geological Sciences, University of Colorado at Boulder, 2200 Colorado Avenue, Boulder, Colorado 80309, USA 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA ABSTRACT INTRODUCTION seismic velocities (Vp) of >7.0 km/s. Such high-velocity lower crustal layers have been Integration of petrologic, chronologic and Continental crust provides an integrated observed in a variety of settings, particularly petrophysical xenolith data with geophysical record of crustal growth and differentiation in shields and platforms, continental arcs, and observations can offer fundamental insights through time. The lower crust is central to rift zones (Fig. 1) where the material is com- into understanding the evolution of conti- this evolution and its composition and degree monly considered a discrete product of mantle- nental crust. We present the results of a of hetero geneity can have a profound infl u- derived magmatic underplating or intraplating deep crustal xenolith study from the north- ence on the rheology of the lithosphere, yet (Warner, 1990; Kay and Mahlburg-Kay, 1991; ern Rocky Mountain region of the western it is commonly the least constrained part of Eaton, 2006; Karlstrom et al., 2005; Crowley U.S., where seismic experiments reveal an the lithospheric column, because data density et al. 2006; Cornwell et al., 2010; Ridley and anomalously thick (10–30 km), high seismic and seismic constraints generally decrease Richards, 2010). Imbrication of oceanic crust velocity (compressional body wave, Vp > 7.0 with depth. Although the average composi- has also been proposed in some tectonic set- km/s) lower crustal layer, herein referred tion of the lower crust is generally considered tings (e.g., New Zealand; Okaya et al., 2007). to as the 7.x layer. Xenoliths exhumed by to be mafi c, debate continues on this topic as Although high seismic velocity layers are Eocene minettes from the Bearpaw Moun- a result of rare exposure and an incomplete not uncommon, worldwide compilations show tains of central Montana, within the Great and potentially biased record made available that they are generally relatively thin, averaging Falls tectonic zone, include mafi c and inter- through lower crustal xenoliths (e.g., Rudnick 3–8 km (Fig. 1; Christensen and Mooney, 1995; mediate garnet granulites, mafi c hornblende and Taylor, 1987; cf. Hacker et al., 2011). Dis- Rudnick and Fountain, 1995). In contrast, sev- eclogite, and felsic granulites. Calculated crete layers of suspected mafi c lower crust are eral seismic experiments in the Rocky Moun- pressures of 0.6–1.5 GPa are consistent with identifi able as having high compressional wave tain region of Montana and Wyoming (USA), derivation from 23–54 km depths. Samples record diverse and commonly polymeta- morphic pressure-temperature histories Northern Shields & Wyoming Continental Extended including prograde burial and episodes of Orogens Platforms Craton Arcs Rifts Crust decompression. Samples with barometrically 0 determined depths consistent with residence Figure 1. Worldwide compila- within the seismically defi ned 7.x layer have tion of average crustal veloci- 10 calculated bulk P-wave velocities of 6.9–7.8 ties (Vp—compressional body km/s, indicating heterogeneity in the layer. wave) and depths to the Moho Shallower samples have markedly slower 20 by tectonic settings (modifi ed velocities consistent with seismic models. from fi g. 7 in Christensen and New monazite total U-Th-Pb data and a vari- Mooney, 1995). The crustal col- 30 ety of additional published geochronology Moho umn observed by Deep Probe Depth (km) indicate a prolonged and episodic metamor- (Gorman et al., 2002) in central phic history, beginning with protolith ages as Moho Montana (northern Wyoming 40 Moho old as Archean and followed by metamorphic Moho craton) is shown for compari- and deep crustal fl uid-fl ow events ca. 2.1 Ga, son to illustrate the unusual Moho 1.8–1.7 Ga, and 1.5–1.3 Ga. We suggest that 50 thickness of the 7.x layer (black the 7.x layer in this region owes its character fi ll). Moho to a variety of processes, including magmatic 60 underplating and intraplating, associated <5.7 5.7–6.4 6.4–6.8 with multiple tectonic events from the Neo- Vp (km/s) 6.8–7.0 >7.0 >7.8 archean to the Mesoproterozoic. Geosphere; December 2012; v. 8; no. 6; p. 1408–1428; doi:10.1130/GES00765.1; 12 fi gures; 6 tables; 1 supplemental fi le. Received 11 November 2011 ♦ Revision received 24 July 2012 ♦ Accepted 24 July 2012 ♦ Published online 16 November 2012 1408 For permission to copy, contact [email protected] © 2012 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/8/6/1408/3346246/1408.pdf by guest on 27 September 2021 Crustal xenoliths from Montana: Implications for high-velocity lower crust formation and Alberta (Canada) reveal a distinctly thick 115°0′0″W 110°0′0″W 105°0′0″W A Trans-Hudson (10–30 km) lower crustal layer with Vp between Figure 2. (A) Simplifi ed geo- Hearne Province 7.0 and 7.8 km/s (Henstock et al., 1998; Snel- logic of Montana and adja- Orogen son et al., 1998; Clowes et al., 2002; Gorman cent states and provinces. Late BC et al., 2002; Eaton, 2006; Schutt et al., 2008). Cretaceous–early Tertiary age 50°0'0"N Vulcan Low SK The unusual thickness of this high-velocity Precambrian-cored uplifts, 19 Canada N layer, which constitutes as much as half of the the location of seismic experi- AB ″ U.S.A. 0 Medicine ′ 40–60 km crustal column, makes it arguably ments, tectonic boundaries, and Extent of Figure 3 one of the most anomalous regions of continen- the numbers of geochronologic Hat Block 50°0 tal crust in North America. Initial observations constraints on the formation of WA 8,16 indicate that Archean and/or Proterozoic mag- the 7.x layer compiled in Table 1 10 MT 3,9,15,&17 matic underplating events may have played a role are shown. GFTZ—Great Falls ID in contributing to the thickness of high-velocity tectonic zone, LBM—Little Belt OR LBM N material (Gorman et al., 2002: Chamber lain Mountains, TRM—Tobacco ″ GFTZ 0 Root Mountains, BTM—Bear ′ 4 &13 et al., 2003). However, the age and character 5 BTM 45°0 18 & 20 of the lower crust in this region have until now Tooth Mountains, MR—Madi- TRM Wyoming N ″ 1&14 0 remained largely unknown. son Range, BM—Bighorn Province ′ Xenoliths afford a unique opportunity to Mountains, TR—Teton Range, TR 2 BM 45°0 characterize the physical and chemical charac- BH—Black Hills, WRR—Wind 11 teristics of the lower crust, and the data can be River Range, LM—Laramie linked with modern geophysical studies (e.g., Range, SAREX—Southern WRR BH LM Rudnick and Taylor, 1987; Kay and Mahlburg- Alberta Refraction Experiment, 6 12 Kay, 1991). As extensive geophysical data sets TA—Transportable Array. Map NV WY 7 NE become available for the western United States is modifi ed from the Montana 115°0′0″W 3 UT 110°0′0″W 105°0′0″W through large projects such as the National Sci- State Geologic Map (Vuke et al., ence Foundation EarthScope program, it will 2007) and the U.S. Geological Deep Probe Shot Point Billings Array be increasingly important to link these observa- Survey Integrated Geologic SAREX Shot Point CD ROM Recievers tions to compositional, petrologic, and chrono- State Map Database (http:// Deep Probe receivers USARRAY TA stations SAREX receivers Pre Cambrian Exposures logic information in order to both better refi ne pubs.usgs.gov/of/2005/1351/). Geochronologic Constraints from Table 1 the regional tectonic history and the range of (B) Simplifi ed interpretation of composition and petrology corresponding to a the Deep Probe seismic refrac- B particular set of seismic properties. Although tion line with compressional South GFTZ MHB North observations from xenoliths are incomplete, body wave (Vp) speeds (in km/s) Wyoming VL Hearne 0 perhaps unpredictably biased, and depth con- and the location of the 7.x lower straints have limitations, xenoliths commonly crustal layer. The colors and 20 provide the best method of directly sampling velocity thresholds are the same 40 7.x layer relatively modern lower crust. as in the crustal columns of Fig- 60 Moho f Here we report data from crustal xenoliths ure 1. Figure modifi ed from Fig- 80 1 exhumed in Eocene minettes in the Great ure 10 in Gorman et al. (2002). 100 f2 MHB—Medicine Hat block, 120 Falls tectonic zone in central Montana. The VE 5:1 data include thermobarometry and calculated VL—Vulcan low, f1 and f2— (km) Depth Below MSL 140 bulk seismic velocities as well as petrology fl oating refl ectors interpreted –400 –200 0 200 400 600 and monazite geochronology documenting to be relic subducted oceanic Distance North from 49th Parallel (km) a dynamic and polyphase Paleoproterozoic crust. MSL—mean sea level. <5.7 5.7–6.4 6.4–6.8 Vp (km/s) history. We emphasize the heterogeneity in 6.8–7.0 >7.0 >7.8 physical properties and history in the xeno- lith record, and explore the possible means of assembly for the high-velocity lower crustal layer in this region. features of this region that are relevant to this that the upper crystalline crust of the Medicine study are described in more detail in the follow- Hat block is made of ca.
Load more

Recommended publications
  • In the Matter of the Measurement and Apportionment of Thewaters of Thest
    INTERNATIONALJOINT COMMISSION REARGUMENT IN THE MATTER OF THE MEASUREMENT AND APPORTIONMENT OF THEWATERS OF THEST. MARY AND MILK RIVERS ANDTHEIR TRIBUTARIES IN THE UNITED STATES AND CANADA UNDER ARTICLE VI OF THE TREATY OF JANUARY 1 I, 1909, BETWEEN THE UNITED STATES AND GREAT BRITAIN 4 OTTAWA, CANADA MAY 3, 4, AND 5, 1920 WASHINGTON GOVERNMENT PRINTING OFFICE 1921 I. ,I,' #__? .. MAASUKIEMEW,. AM) APPOIITIO~~MEMOF THE WATERS OF THE ST. MARY ANT) MILK RIVERS. INTERNATIONALJOINTCOMMISSION, Ottawa, Canada,, May 9, 1920. The Commission met at 10 o'clock a. m. Present: C. A. Magrath (chairman for Ctinada) €1. A. Powell, K. c., Sir William Hearst. 0. Gardncr (chairman for tLe United States), Clarence D. Clark. Lawrcnce J. Burpee, secretary of the Commission for Canada. Ap earances : CoP . C. S. MacInnes, K. C., counsel for the Dominion of Canada, for the Provinces of Albertaand Saskatchewan, the WesternCanada Irrigation Association, andthe Cypress Hills Water-Users Association. Won. George Turner, counsel for the United States Government. Mr. Will R. Kin chief counsel for the United States Reclamation Service, with Mr. k. J. Egleston, of Helena, Mont., district counsel for the United StatesReclamation Service. with Mr. G. A. Walker of Calgary, for the States Senator from Montana. Mr. A. P. Davis,director of theUnited States Reclamation Service, Washin ton, D.. C. Mr. E. E'. Draf e, director, Reclamation Service of Canada, Ottawa. Mr. C. S. Heidel, hydrographer, engineer's office, State of Montana. Mr. R. J. Burley, irrigation engineer, Department of the Interior, Ottawa. Mr. C. H. Atwood, Water Power Branch, Department of the Inte- rior, Ottawa.
    [Show full text]
  • Volume 7 Number 7
    Volume 8 Number 8 30 December 2020 The Taxonomic Report OF THE INTERNATIONAL LEPIDOPTERA SURVEY ISSN 2643-4776 (print) / ISSN 2643-4806 (online) Review of the Speyeria egleis complex in Montana, with the description of two new subspecies (Lepidoptera: Nymphalidae: Heliconiinae) Steve Kohler 2617 Glen Drive Missoula, MT 59804 ABSTRACT: Four phenotypically and geographically distinct sets of populations of Speyeria egleis are identified in Montana. Two new subspecies are named from northwestern and northcentral Montana. Two existing names are recognized (S. e. macdunnoughi from southwestern Montana, southeastern Idaho and northwestern Wyoming, and S. e. albrighti from central Montana. S. e. near macdunnoughi from Oregon and Washington is discussed. Additional key words: Island ranges, Sweet Grass Hills, Morrell Mountain, Highwood Mountains. ZooBank registration: urn:lsid:zoobank.org:pub:94D912CC-72BA-42EA-A14E-E0F51E1CD498 INTRODUCTION At the present time, thirteen described subspecies of Speyeria egleis (Behr, 1862) are recognized in North America (Pelham 2020). Of these, two occur in Montana, S. e. macdunnoughi (Gunder, 1932) and S. e albrighti (Gunder, 1932). Historically, all Montana egleis populations with a brownish colored under hindwing disc have been assigned to macdunnoughi and all populations with an olive-green colored under hindwing disc have been assigned to albrighti (Ferris and Brown 1981; Kohler 1980). During the course of my study of Montana butterflies, I have identified at least four distinct sets of populations which can be phenotypically and geographically segregated. The purpose of this paper is to define the characters of these four distinctive populations and to describe two new subspecies. DISCUSSION In this study, the two current subspecies of S.
    [Show full text]
  • Synorogenic Basin Deposits and Associated Laramide Uplifts in the Montana Part of the Cordilleran Foreland Basin System
    SYNOROGENIC BASIN DEPOSITS AND ASSOCIATED LARAMIDE UPLIFTS IN THE MONTANA PART OF THE CORDILLERAN FORELAND BASIN SYSTEM Susan M. Vuke Montana Bureau of Mines and Geology, Butte, Montana ABSTRACT The North American Cordilleran Foreland Basin System extended from the eastern edge of the Cordilleran Sevier fold-thrust belt in western Montana across central and eastern Montana from Jurassic into early Paleo- gene time. In the central and southern Montana part of the system, isolated Laramide basement-cored uplifts and sedimentary basin pairs characterize the main Laramide Province. The thrust/reverse fault-propagated arches and basins of the province developed primarily during Late Cretaceous through earliest Eocene time, although regionally, initiation of uplift may have occurred during Early to middle Cretaceous time in southwest- ern Montana. Associated prominent WNW–ESE- and NE–SW-striking linear features refl ect Laramide reactiva- tion of basement faults that now extend to the surface, or are entirely in the subsurface. They occur throughout the main Laramide Province and are likely genetically related to development of the uplift-basin pairs. The asymmetric Laramide Bighorn and Powder River Basins developed in association with uplift along basin-bounding thrust/reverse faults of the Beartooth and Bighorn basement-cored arches, respectively. Thrust loading associated with uplift along the faults propagated asymmetric synclinal basin folds that accommodated the greatest thicknesses of synorogenic deposits adjacent to the range-bounding faults. In Montana, synorogenic deposits of the Bighorn Basin primarily include the Paleocene Fort Union Formation, and those of the Powder River Basin primarily include the Paleocene Fort Union and Eocene Wasatch Formations.
    [Show full text]
  • Climate Change Impacts on the Island Forests of the Great Plains and the Implications for Nature Conservation Policy
    CLIMATE CHANGE IMPACTS ON THE ISLAND FORESTS OF THE GREAT PLAINS AND THE IMPLICATIONS FOR NATURE CONSERVATION POLICY: THE OUTLOOK FOR SWEET GRASS HILLS (MONTANA), CYPRESS HILLS (ALBERTA – SASKATCHEWAN), MOOSE MOUNTAIN (SASKATCHEWAN), SPRUCE WOODS (MANITOBA) AND TURTLE MOUNTAIN (MANITOBA – NORTH DAKOTA) Norman Henderson (Prairie Adaptation and Research Collaborative) Edward Hogg (Canadian Forestry Service, Edmonton) Elaine Barrow (Adjunct Professor, University of Regina) Brett Dolter (Prairie Adaptation and Research Collaborative) Contact for comments and queries: [email protected] December, 2002 Final Revised Report 1 This study is funded and managed by the Prairie Adaptation Research Collaborative (PARC). Established in 2000 from the Government of Canada’s Climate Change Action Fund, PARC is an interdisciplinary research network established to research the potential impacts of climate change on the Canadian Prairie Provinces and develop appropriate adaptation strategies. PARC also funds and coordinates the training of personnel in climate change adaptation research. PARC is housed at the Information Technology Centre at the University of Regina, Saskatchewan, Canada. The Government of Saskatchewan has also contributed funding for this study. Email: [email protected] Telephone: (306) 337-2300 Fax: (306) 337-2301 Website: www.parc.ca The recommendations and policy analysis presented in this study represent the views of the authors only and does not necessarily reflect the views of their employing agencies. Comments and queries on the study should be directed to the Island Forest Project: [email protected] 2 SUMMARY This study investigates future climate change impacts on ecosystems, with a focus on trees, in 5 island forest sites in the northern Great Plains ecoregion: Sweet Grass Hills (Montana), Cypress Hills (Alberta-Saskatchewan), Moose Mountain (Saskatchewan), Spruce Woods (Manitoba) and Turtle Mountain (Manitoba-North Dakota).
    [Show full text]
  • DALLAS L. PECK, Director
    RECONNAISSANCE OF GEOLOGY AND WATER RESOURCES ALONG THE NORTH FLANK OF THE SWEET GRASS HILLS, NORTH-CENTRAL MONTANA By L.K. Tuck U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 93-4026 Prepared in cooperation with the MONTANA BUREAU OF MINES AND GEOLOGY Helena, Montana June 1993 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. Geological Survey DALLAS L. PECK, Director For additional information Copies of this report can write to: be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Books and Open-File Reports Section 428 Federal Building Federal Center 301 South Park, Drawer 10076 Box 25425 Helena, MT 59626-0076 Denver, CO 80225-0425 CONTENTS Page Abstract. .................................. 1 Introduction. ................................ 2 Purpose and scope ............................. 2 Geography of the area ........................... 4 Previous studies. ............................. 5 Numbering system for wells, springs, and stream sites ........... 6 Quality assurance ............................. 7 Water-quality standards .......................... 7 Acknowledgments .............................. 9 General geology ............................... 9 Stratigraphy. ............................... 9 Structure ................................. 19 Water resources ............................... 19 Ground water. ............................... 19 Unconsolidated aquifers ......................... 22 Alluvium. ............................... 22 Interstratified sand and gravel in glacial
    [Show full text]
  • Appendix B. Detailed Inventory of Existing Characteristics
    Appendix B. Detailed Inventory of Existing Characteristics Table of Contents Natural Setting 1 Geography and Topography 1 Climate 2 Geology 3 Groundwater 4 Vegetation 5 Fish and Wildlife 5 Natural Hazards 7 People and Communities Toole County History 8 Communities 12 Population 15 Community Health 18 Personal Income 19 Housing 20 Public Education, Local Services, and Amenities 23 Public Education 23 Public Safety and Emergency Services 24 Health Care 25 Senior Services 26 Youth Services 26 Public Transportation Services 26 Culture and Recreation 26 Infrastructure 28 Transportation Systems 28 Water Systems 31 Sewer Systems 33 Solid Waste 33 Toole County Facilities 34 Economy and Local Government 36 Economy 36 Local Government Revenue 40 Land Use and Planning 41 Land Ownership 41 Land Use 41 Local Planning 44 Sources 46 The Natural Setting Geography and Topography Toole County is situated on the far western reaches of the North American Great Plains and east of the Continental Divide and high mountains of Glacier National Park. Most of the county consists of rolling to flat level terrain, characterized by drainages and shallow lake depressions. The Sweet Grass Hills are a mountainous area in the northeastern portion of the county. The area is known as an island mountain range because it is distinctly separated from any larger chain of mountain ranges. Elevations in the county range from about 2,900 feet at Lake Elwell (Tiber Reservoir) to 6,983 feet at West Butte in the Sweet Grass Hills. Toole County falls into three main watershed basins – the Marias, Willow, and the Upper Milk. The Marias River is the major river in the county and a major tributary to the Missouri River in Montana.
    [Show full text]
  • Gros Ventre/White Clay Place Names
    1 Gros Ventre/White Clay Place Names Second Edition, 2013 Compiled by Allan Taylor, Terry Brockie, and Andrew Cowell, with assistance from John Stiff Arm Copyright: Center for the Study of Indigenous Languages of the West (CSILW), University of Colorado, Boulder CO, 2013. Note: Permission is hereby granted by CSILW to all Gros Ventre individuals and institutions to make copies of this work as needed for educational purposes and personal use, as well as to institutions supporting the Gros Ventre language, for the same purposes. All other copying is restricted by copyright laws. 2 Introduction: This is a list of Gros Ventre/White Clay/A’ani place names. Specifically, it includes all names in the Gros Ventre language that we have been able to find. The places are listed in alphabetical order by their English name, and then the Gros Ventre name(s) are given, in italics. After the italic entries, the Gros Ventre names are separated into segments to show the meanings of the different parts of the word. The linguistic abbreviations used are explained at the end of this publication. There are also references to the sources where the original name was documented in many cases. The list of these sources is also at the end of the paper. The majority of these names were documented by Allan Taylor, professor of Linguistics, University of Colorado, during his work with the Gros Ventre Tribe from the 1960s through the 1990s (abbreviation of the form T II.164 refer to Taylor’s Dictionary, Volume II, page 164). Terry Brockie and Andrew Cowell (also a professor at the University of Colorado) worked to find other names no longer known by the Gros Ventre people, but which were recorded by people such as Fred Gone (who gathered the story of the “Seven Visions of Bull Lodge”) and George Bird Grinnell, an early naturalist who lived in the late 1800s and early 1900s and worked with several Plains Indian tribes.
    [Show full text]
  • Upper Milk River Watershed Hydrology Report
    Upper Milk River Watershed Water Supply and Water Use Study Report: 2006 – 2009 Montana Department of Natural Resources DNRC Report: WR 3.A.4.j UMR Upper Milk River Helena, Montana November, 2012 Table of Contents Introduction .................................................................................................................................... 1 General Basin Description ............................................................................................................... 3 Streamflow Data and Stream Gaging Stations ............................................................................... 4 Upper Milk River Watershed Streamflow Characteristics by Subbasin and Stream Reach ........... 6 Livermore Creek .......................................................................................................................... 6 South Fork of the Milk River ....................................................................................................... 8 Middle Fork of the Milk River ................................................................................................... 10 Milk River Main Stem ................................................................................................................ 12 Flow Contributions of Milk River Tributaries to Western Crossing .......................................... 14 North Fork of the Milk River Streamflow Characteristics ......................................................... 15 Streamflow and Water Supply Conditions During the Study ......................................................
    [Show full text]
  • Eocene Potassic Magmatism of the Milk River Area, Southern Alberta
    ERCB/AGS Open File Report 2012-01 Eocene Potassic Magmatism of the Milk River Area, Southern Alberta (NTS 72E) and Sweet Grass Hills, Northern Montana: Overview and New Data on Mineralogy, Geochemistry, Petrology and Economic Potential ERCB/AGS Open File Report 2012-01 Eocene Potassic Magmatism of the Milk River Area, Southern Alberta (NTS 72E) and Sweet Grass Hills, Northern Montana: Overview and New Data on Mineralogy, Geochemistry, Petrology and Economic Potential A.S. Rukhlov1 and J.G. Pawlowicz2 1 British Columbia Geological Survey (formerly of Alberta Geological Survey) 2 Energy Resources Conservation Board Alberta Geological Survey March 2012 ©Her Majesty the Queen in Right of Alberta, 2012 ISBN 978-1-4601-0073-8 Energy Resources Conservation Board/Alberta Geological Survey (ERCB/AGS) and its employees and contractors make no warranty, guarantee or representation, express or implied, or assume any legal liability regarding the correctness, accuracy, completeness or reliability of this publication. Any software supplied with this publication is subject to its licence conditions. Any references to proprietary software in the documentation, and/or any use of proprietary data formats in this release, do not constitute endorsement by ERCB/AGS of any manufacturer's product. If you use information from this publication in other publications or presentations, please give due acknowledgement to ERCB/AGS. We recommend the following reference format: Rukhlov, A.S. and Pawlowicz, J.G. (2012): Eocene potassic magmatism of the Milk River area, southern Alberta (NTS 72E) and Sweet Grass Hills, northern Montana: overview and new data on mineralogy, geochemistry, petrology and economic potential; Energy Resources Conservation Board, ERCB/AGS Open File Report 2012-01, 88 p.
    [Show full text]
  • Milk River Transboundary State of the Watershed Report 2Nd Edition
    Messages from the Watershed Council Chairs Milk River Watershed Council Canada Milk River Watershed Alliance Our family has been living and ranching within the Milk River Watershed since 1885. Around 1910 Jacob Pattison, my Sustainability is a very important part of how we work with the land. To gain a better grandfather, arrived at Vandalia, Montana knowledge of our watershed not only defines our roots as a community but better defines to work with the dam on the Milk River. I where we are heading in the future. This report reflects the successes and challenges now live a couple miles downstream from facing all three political jurisdictions in our watershed. that project. Many times I have wondered about the work, dreams, and visions many This report serves as a guidepost; a reflection of the research, monitoring and stewardship have had for the future of this great state. required to manage the common resources for future generations. The majority of Alberta’s endangered species occur in the Milk River Watershed due to the stewardship of our As the Chairman of the Milk River forefathers and will continue with our help in the future. Watershed Alliance, I welcome you to the beauty, splendor, and majesty of our We want this report be read, referenced and used as a resource for watershed home. Our team calls the Milk River “the residents and the scientific community. The future is ours to give to our kids, life line of the hi-line”, as it sustains many let’s make it a good one. communities as it meanders through John A.
    [Show full text]
  • Cypress Hills Ethnohistory and Ecology: a Regional Perspective
    CYPRESS HILLS ETHNOHISTORY AND ECOLOGY: A REGIONAL PERSPECTIVE By Robson Bonnichsen University of Maine at Orono and Stuart J. Baldwin University of Alberta Archaeological Survey of Alberta Occasional Paper No. 10 December, 1978 Prepared for: Published by: Archaeological Survey Alberta Culture of Alberta Historical Resources Division OCCASIONAL PAPERS Papers for publication in this series of monographs are produced by or for the four branches of the Historical Resources Division of Alberta Culture: the Provincial Archives of Alberta, the Provincial Museum of Alberta, the Historic Sites Service and the Archaeological Survey of Alberta. Those persons or institutions interested in particular subject sub-series may obtain publication lists from the appropriate branches, and may purchase copies of the publications from the following address: Alberta Culture The Bookshop Provincial Museum of Alberta 12845 - 102 Avenue Edmonton, Alberta T5N OM6 Phone (403) 452-2150 Objectives These Occasional Papers are designed to permit the rapid dissemination of information resulting from Historical Resources' programmes. They are intended primarily for interested specialists, rather than as popular publications for general readers. In the interests of making information available quickly to these specialists, normal production procedures have been abbreviated. The cover illustration shows the geographic relationships of the major blocks of the Cypress Hills remnant plateau and the more impor­ tant outliers. Note the radial drainage of this prairie area. ABSTRACT Students of the northwestern plains archaeological region have very limited and scattered amounts of historical and ethnographic records available to them for study. This lack has prompted us to develope a new organizational framework which synthesizes ethnohistoric data gathered from previous literature, archaeological assemblages and avail­ able ecological data.
    [Show full text]
  • FIRST FOSSIL MAMMALS from the ... -.: Palaeontologia Polonica
    FIRST FOSSIL MAMMALS FROM THE UPPER CRETACEOUS EAGLE FORMATION (SANTONIAN, NORTHERN MONTANA, USA), AND MAMMAL DIVERSITY DURING THE AQUILAN NORTH AMERICAN LAND MAMMAL AGE BRIAN M. DAVIS, RICHARD L. CIFELLI, and JOSHUA E. COHEN Davis, B.M., Cifelli, R.L., and Cohen, J.E. 2016. First fossil mammals from the Upper Creta- ceous Eagle Formation (Santonian, northern Montana, USA), and mammal diversity during the Aquilan North American Land Mammal Age. Palaeontologia Polonica 67, 101–126. Mammalian faunas in North America experienced dramatic change during the Cretaceous, with earlier faunas characterized by eutriconodontans, symmetrodontans, and unspecial- ized therians giving way to a major diversification of therian lineages by the Campanian– Maastrichtian. The Aquilan North American Land Mammal Age (NALMA), originally based on the well-studied fauna of the Milk River Formation (Santonian) of southern Alberta, re- cords the start of this transition. Notable are first appearances of pediomyoid marsupialiforms and the eutherian Paranyctoides, and last occurrences of eutriconodontans and symmetrodon- tans. The Campanian Wahweap Formation has yielded a similar fauna, but until now the John Henry Member of the Straight Cliffs Formation was the only other unit of known Santonian age from which fossil mammals have been recovered, leaving this transitional interval rep- resented by limited sampling. The Eagle Formation in central and northern Montana is con- sidered to be laterally equivalent to the Milk River Formation, with northernmost exposures correlated to the upper Santonian, based on palynomorphs and magnetostratigraphy. Here, we describe the first fossil mammals known from the Eagle Formation. A relatively small rock sample yielded a rich, diverse assemblage including two genera of spalacotheriid symmetro- donts, several “alphadontid” marsupialiforms and the large pediomyoid Aquiladelphis, and at least two eutherians including Paranyctoides.
    [Show full text]