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Michigan Bar District

Past Producer in Sacramento county in California, United States with commodities Gold, PGE, Silver
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Ore body information
  12. Controls for ore emplacement
  13. Economic information about the deposit and operations
  14. Mining district
  15. Bibliographic references
  16. General comments
  17. Reporter information

Geologic information

Identification information

Deposit ID 10310648
Record type District
Current site name Michigan Bar District

Comments on the site identification

  • The Michigan Bar District is a placer-mining locality in and near the Cosumnes River. Mining activity was conducted at several sites between the former settlement of Michigan Bar on the northeast and several miles west and southwest of Bridge House to the area of Sloughhouse.

Geographic coordinates

Geographic coordinates: -121.04481, 38.49953 (WGS84)
Location accuracy 100(meters)
Relative position The Michigan Bar District is about 25 miles east-southeast of downtown Sacramento.

Site location context

Political divisions (FIPS codes)

Sacramento(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Carbondale(quadrangle 1:24,000 scale)

Lodi(quadrangle 1:100,000 scale)

Sacramento(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Cosumnes(hydrologic unit)

San Joaquin(hydrologic accounting unit)

San Joaquin(hydrologic subregion)

California(hydrologic region)

Geographic areas

Country State County
United States California Sacramento

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 008N 008E 36 S2 California

Comments on the location information

  • Location selected for latitude and longitude is the former townsite of Michigan Bar on the USGS 7.5-minute Carbondale quadrangle. Sites of mining, however, extended over various individual locations to the west and south of this location.

Commodities

Commodity Importance
Gold Primary
PGE Critical Secondary
Silver Secondary

Comments on the commodity information

  • Commodity Info: In 1938, a dragline operation dredged 3,411,337 cubic yards of gravel, which yielded 10,018 ounces of gold. In 1948, another operation dredged about 160,000 cubic yards of gravel, which yielded 655 ounces of gold and 66 ounces of silver.
  • Ore Materials: Native gold, native platinum
  • Gangue Materials: Metamorphic rock, igneous rock, quartz (all as clasts)

Materials information

Materials Type of material
Gold Ore
Platinum Ore
Quartz Gangue

Mineral occurrence model information

Model code 119
USGS model code 39a
Deposit model name Placer Au-PGE
Mark3 model number 54

Host and associated rocks

  • Host or associated Host
    Rock type Unconsolidated Deposit > Sand and Gravel
    Stratigraphic age (youngest) Quaternary
  • Host or associated Host
    Rock type Unconsolidated Deposit > Sand and Gravel
    Rock unit name Ione Formation
    Stratigraphic age (youngest) Eocene

Nearby scientific data

(1) -121.04481, 38.49953
ListMap

Economic information

Ore body information

  • General form Irregular

Controls for ore emplacement

  • Mechanical accumulation within stream-channel lag gravels, bars, and point-bar deposits.

Comments on the geologic information

  • REGIONAL GEOLOGY

    The Michigan Bar District is situated within the Great Valley geologic province, which is here represented by the Sacramento Valley. It is adjacent to the westernmost edge of the Sierra Nevada geologic province.

    The Great Valley province is characterized by Cenozoic sedimentary and volcanic rocks, while the Sierra Nevada province is characterized by complex lithologies and structures that were assembled through various plate-tectonic processes.

    In this region, the Sierra Nevada province is composed of belts of Paleozoic-Mesozoic metamorphic complexes that are intruded by various Mesozoic plutons. Together, they compose the basement of the province. This basement is overlain at higher elevations by erosional remnants of Cenozoic volcanic and sedimentary rocks, including gravels. Most of these various lithologies contain gold in places.

    Structurally, the metamorphic rocks and some of the plutonic rocks have been deformed by folding and faulting. The major fault zones typically trend northerly or northwesterly, although in places intrusion of the younger plutons has deformed some of the zones so as to assume other trends as well. In contrast, the overlying Cenozoic rocks are relatively undeformed.

    The rocks of the Great Valley province overlie the basement of the Sierra Nevada where it extends westward underneath the San Joaquin Valley.

    LOCAL GEOLOGY

    The Michigan Bar District is associated with Cenozoic alluvial deposits of the main drainage of the Cosumnes River where it discharges into the Sacramento Valley after passing through the Sierra Nevada basement terranes. The materials in these deposits have been derived by erosion of the various basement and Cenozoic rocks at higher elevations. In places, the basement rocks contain gold within quartz veins and altered rock, while the Cenozoic deposits contain placer gold derived by erosion of these older basement rocks. Erosion of both the gold-bearing basement rocks and the older Cenozoic rocks provided the gold that was eventually deposited in the Cenozoic placer deposits along the Cosumnes River at Michigan Bar and farther downstream toward Sloughhouse. Platinum was probably derived from erosion of ultramafic rocks and serpentinite in the Sierra Nevada basement.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1850

Mining district

District name Michigan Bar District

Comments on the workings information

  • All of the standard placer-mining processes were used in this district including surface, hydraulic, drift, and dredging. Areas of dredge tailings are present locally throughout the district.

Comments on other economic factors

  • Clark (1970) estimated that total production of gold for this district was at least 1,700,000 ounces.

Comments on development

  • Auriferous gravels of the Ione Formation in the Michigan Bar area were hydraulicked extensively in the 1860?s and 1870?s and also exploited in a small way by drift mining. The modern alluvial deposits along the Cosumnes River and some of the older bench gravels adjacent to it, including the Ione Formation, were dredged from before the 1920?s to the 1950?s.

Reference information

Bibliographic references

  • Deposit

    Clark, W. B., 1970, Gold districts of California: California Divisions of Mines and Geology Bulletin 193, p. 90.

  • Deposit

    Carlson, D.W., 1955, Mines and mineral resources of Sacramento County, California: California Journal of Mines and Geology, v. 51, no. 2, p. 134-143.

  • Deposit

    Koschmann, A.H., and Bergendahl, M.H., 1968, Principal gold-producing districts of the United States: U. S. Geological Survey Professional Paper 610, 283 p.

  • Deposit

    Logan, C.A., 1919, Platinum and allied metals in California: California State Mining Bureau Bulletin 85, 120 p.

  • Deposit

    Wagner, D.L. and others, 1981, Geologic map of the Sacramento Quadrangle, California: California Department of Conservation, Division of Mines and Geology Regional Geologic Map Series, Map No. 1A, scale 1:250,000.

General comments

Subject category Comment text
Deposit Gold was recovered from Tertiary and Quaternary alluvial gravels and flood-plain and terrace deposits in and adjacent to the Cosumnes River. The gold-bearing gravels are present mainly in the Eocene Ione Formation and in Pleistocene-Holocene deposits.

Platinum and silver are also present in the alluvial deposits.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-AUG-2006 Higgins, Chris T. California Geological Survey CGS (Formerly CDMG)
Editor 01-SEP-2007 Schruben, Paul G. U.S. Geological Survey Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative California resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.