Ijamsville Formation and Marburg Schist (MDif-ms;3)

State	Maryland
Name	Ijamsville Formation and Marburg Schist
Geologic age	Late Precambrian (?)
Lithologic constituents	Major Metamorphic > Metasedimentary > Metaclastic > Phyllite Minor Metamorphic > Metasedimentary > Metaclastic > Metasiltstoneincludes meta-argillite Metamorphic > Metasedimentary > Metaclastic > Metasandstone > Metagraywacke Metamorphic > Schist > Mica-schist > Muscovite-schistmuscovite-chlorite-albite-quartz schist Metamorphic > Metasedimentary > Metaclastic > Slate Incidental Metamorphic > Metasedimentary > Metaclastic > Quartzite
Comments	secondary unit description from USGS Geologic Names Lexicon (ref MD004): Marburg Schist of Jonas and Stose (1938) is here reinstated as Marburg Formation. Fisher (1978) abandoned Marburg and included its rocks within Ijamsville Phyllite. Ijamsville is distinctive purple phyllite, whereas the Marburg is a lithologically mixed unit and therefore is reinstated as a separate, mappable unit. Rank term is changed to Formation because it consists predominantly of phyllite, paragonite phyllite, muscovite phyllite, siltstone, greenstone, quartzite, and graywacke. It also now includes some rocks previously called Pleasant Grove Schist (here abandoned), because it has been determined that Pleasant Grove was composed of sheared Mather Gorge Formation, Prettyboy Schist, and Marburg Formation. Age of Marburg is changed to Late Proterozoic and Early Cambrian.
References	Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000. In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/. USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/ https://ngmdb.usgs.gov/Geolex/search
NGMDB product	NGMDB product page for 16548
Counties	Frederick - Howard - Montgomery

State

Maryland

Name

Ijamsville Formation and Marburg Schist

Geologic age

Late Precambrian (?)

Lithologic constituents

Major

Metamorphic > Metasedimentary > Metaclastic > Phyllite

Minor

Metamorphic > Metasedimentary > Metaclastic > Metasiltstoneincludes meta-argillite

Metamorphic > Metasedimentary > Metaclastic > Metasandstone > Metagraywacke

Metamorphic > Schist > Mica-schist > Muscovite-schistmuscovite-chlorite-albite-quartz schist

Metamorphic > Metasedimentary > Metaclastic > Slate

Incidental

Metamorphic > Metasedimentary > Metaclastic > Quartzite

Comments

secondary unit description from USGS Geologic Names Lexicon (ref MD004): Marburg Schist of Jonas and Stose (1938) is here reinstated as Marburg Formation. Fisher (1978) abandoned Marburg and included its rocks within Ijamsville Phyllite. Ijamsville is distinctive purple phyllite, whereas the Marburg is a lithologically mixed unit and therefore is reinstated as a separate, mappable unit. Rank term is changed to Formation because it consists predominantly of phyllite, paragonite phyllite, muscovite phyllite, siltstone, greenstone, quartzite, and graywacke. It also now includes some rocks previously called Pleasant Grove Schist (here abandoned), because it has been determined that Pleasant Grove was composed of sheared Mather Gorge Formation, Prettyboy Schist, and Marburg Formation. Age of Marburg is changed to Late Proterozoic and Early Cambrian.

References

Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.

In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/.

USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/

https://ngmdb.usgs.gov/Geolex/search

NGMDB product

NGMDB product page for 16548

Counties

Frederick - Howard - Montgomery