Geology of the Whitehall area, Montana

Geology of the Whitehall area, Montana

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Bibliographic Details
Author / Creator:Alexander, Roger G.
Imprint:[Red Lodge? Mont.] Yellowstone-Bighorn Research Association, 1955.
Description:111 pages illustrations, maps (some folded).
Language:English
Series:Yellowstone-Bighorn Research Project contribution 195
Yellowstone Bighorn Research Association. Yellowstone-Bighorn Research Project contribution ; 195.
Subject:
Geology -- Montana -- Whitehall area.
Geology.
Format: Print Book
URL for this record:http://pi.lib.uchicago.edu/1001/cat/bib/3216180
Hidden Bibliographic Details
Notes:Issued also as thesis, Princeton University.
Includes bibliographical references (pages 108-111).
Summary:The Whitehall area is located in southwestern Montana north of the Jefferson River and northward from the Tobacco Root Mountains. The area lies near the southeastern border of the Boulder batholith and near the junction of three Rocky Mountain tectonic provinces, each of which has unusual structural and stratigraphic features having important bearing on the geologic history of the Whitehall district. The area contains sedimentary rocks of all systems; volcanic rocks of late Cretaceous - Paleocene age; and intrusive rocks of Eocene age. During the late pre-Cambrian time a major fault-scarp crossed the southern part of the area, following the line of high-angle fault which separated the Tobacco Root Highland on the south from the down-dropped Beltian geosyncline-of-sedimentation on the north. Following Beltian sedimentation, both in the main trough and in the Lombard-Harlowton embayment, gentle epeirogenic movements affected the area during Paleozoic to Middle Cretaceous time. Strong Laramide mountain-building movements were felt in the Whitehall area, including several puses of deformation and intrusion during Upper Cretaceous, Paleocene and Eocene time. Late Creaceous doming within a part of the area definately caused local truncation of all strata down through a portion of the Mississippian Madison Limestone, and possibly down to the upper part of the pre-Cambrian Greyson shale. Following this erosion 9000 or more feet of volcanic rocks were deposited. Then (Paleocene?) compression (from the northwest) formed several folds, which are oriented northeast-southwest, probably because of local drag along a southwestward extension of the Lombard thrust-fault. This folding involved pre-Cambrian, Paleozoic, and Mesozoic formation and was an integral part of the folding and thrusting which affected the whole Beltian trough of northwestern Montana. During the later phases of this period of compression, basic magma, rising from depth, exerted a vertical force-component which broke the local crustal rocks into a number of differentially-tilted blocks or plates separated from each other by high-angle reverse faults. Shortly afterward (probably in the early Eocene) the area was intruded at depth by marginal portions of the Boulder batholith, and as a concluding phase of this igneous activity small masses of the intrusive extended upward toward the surface, with mesothermal mineralization occurring in the surficial rocks of the area. Eocene streams developed a pre-Oligocene mature topographic surface showing a local differential reflief of at least 4,100 feet, and durin ghte Oligocene and Miocene epochs more than 1,000 feet of Bozeman beds accumulated in these Eocene valleys. By early Pliocene time the area had a gently rolling surface developed in part by pedimentary cutting of the pre-Oligocene upland rocks, and in part by truncation of the Tertiary valley fills. Subsequent (Pliocene -Recent) erosion has partially re-excavated the Eocene valleys; has cut deep canyons (where the Jefferson and North Boulder were superposed); and has developed several sets of benches or minor pedimentary surfaces along the valley-sides.
Table of Contents:
  • Abstract
  • Introduction
  • General statement
  • Previous work
  • Field work
  • Acknowledgments
  • Stratigraphy
  • Late pre-Cambrian Belt series
  • General statement covering previous work
  • General statement regarding Belt formations Whitehall map area
  • Greyson shale
  • LaHood formation
  • Origin and paleogeography of the LaHood formation
  • The LaHood formation as a near-shore facies
  • Area of deposition
  • Source area
  • Post LaHood, Pre-Flathead (Cambrian) history
  • Cambrian system
  • General statement
  • Flathead sandstone
  • Wolsey shale
  • Meagher limestone
  • Park shale
  • Pilgrim limestone
  • Dry Creek shale
  • Devonian system
  • General statement
  • Jefferson formation
  • Three Forks shale
  • Mississippian-Pennsylvanian systems
  • Madison group
  • Amsden formation
  • Quadrant formation
  • Permian system
  • Phosphoria formation
  • Jurassic system
  • General statement
  • Ellis group
  • Morrison formation
  • Cretaceous system
  • General statement
  • Cretaceous-Tertiary systems
  • Livingston formation
  • General statement
  • Livingston formation near Whitehall
  • Significance of Livingston volcanics
  • Tertiary system
  • Bozeman formation
  • General statement
  • Distribution near Whitehall
  • Characteristics of the Bozeman formation near Whitehall
  • Conclusions as to origin
  • Igneous rocks
  • General statement
  • Orthoclase-gabbro
  • General statement
  • Mineralogy
  • Basalt sills and dikes
  • General statement
  • Mineralogy
  • Relation to stratigraphy
  • Diorites and granodiorite
  • General statement
  • Mineralogy
  • Latite porphyry
  • General statement
  • Mineralogy
  • Syenite
  • General statement
  • Mineralogy
  • Sequence of intrusion
  • Mineralization
  • Regional setting
  • Mienralization in Whitehall area
  • General statement
  • Golden Sunlight mine
  • West side of southern end of Bull Mountain
  • Scattered localities
  • Conclusions
  • Structure
  • Regional structure
  • General statement
  • Eastern Rocky Mountain structural province
  • Beltian geosynclinal province
  • Boulder batholith area
  • Tobacco Root batholith
  • Structure of the Whitehall map area
  • General statement
  • Western area
  • General statement
  • Block-Border Faults
  • Igneous rocks
  • Eastern area
  • General statement
  • South Boulder block
  • North Boulder block
  • LaHood block
  • Eureka block
  • Cave and East Canyon blocks
  • Sappington block
  • Tectonic history of Whitehall region
  • Pre-Cambrian
  • Early pre-Cambrian
  • Late pre-Cambrian
  • Paleozoic
  • Mesozoic
  • General statement
  • Laramide revolution
  • General statement
  • Late Cretaceous local uplift
  • Extrusion of Livingston volcanics
  • Folding due to northwest-southeast compression Paleocene
  • Cause of the folding
  • Block movements (Paleocene) to Eocene
  • Tensional block movements
  • Post Laramide deformation
  • Physiography
  • Development of topography in Eocene time
  • Valley filling during Oligocene and Miocene time
  • Late Tertiary-Quaternary erosion
  • Canyon cutting
  • Erosion surface development
  • Appendix
  • Stratigraphic Section No. 1 LaHood formation
  • Stratigraphic Section No. 2 LaHood formation
  • Stratigraphic Section No. 3 LaHood formation
  • Stratigraphic Section No. 4 LaHood formation
  • Stratigraphic Section No. 5 Lower Paleozoics
  • Stratigraphic Section No. 6 Livingston formation
  • Stratigraphic Section No. 7 Livingston formation
  • Stratigraphic Section No. 7 Livingston formation
  • Stratigraphic Section No. 8 Livingston formation
  • Stratigraphic Section No. 9 Livingston formation
  • Stratigraphic Section No. 10 Livingston formation
  • Stratigraphic Section No. 11 Livingston formation
  • Stratigraphic Section No. 12-16 Bozeman formation
  • Bibliography.
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