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GSA Special Papers
Ultramafic Rocks of the Appalachian Piedmont
Author(s)
Geological Society of America

Volume
231
Copyright:
© 1989 Geological Society of America
Geological Society of America
ISBN print:
9780813722313
Publication date:
January 01, 1989
Book Chapter
Petrology and tectonic affinity of the Baltimore mafic complex, Maryland
Author(s)
Barry B. Hanan
Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
;
Barry B. Hanan
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Published:January 01, 1989
The Baltimore mafic complex in the central Appalachian Piedmont consists of tectonically emplaced layered ultramafic, mafic cumulate, and volcanic rocks. The general stratigraphy of the layered rocks is basal dunite and chromitite grading upward through lherzolite and websterite to hypersthene gabbro and quartz-gabbro at the top. Cyclicity within the cumulus sequence is shown by the presence of upper-level peridotite and the occurrence of olivine gabbro at higher stratigraphic levels. The cumulus crystallization sequence is olivine plus chrome spinel followed by orthopyroxene, clinopyroxene, and plagioclase. Cryptic variation in the composition of the cumulus minerals is shown by olivine Mg97–75,...
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Index Terms/Descriptors
- alkaline earth metals
- Appalachians
- Baltimore Gneiss
- Central Appalachians
- chromitite
- cumulates
- dunite
- emplacement
- gabbros
- Glenarm Series
- igneous rocks
- isotopes
- lherzolite
- lower Paleozoic
- mafic composition
- magmas
- major elements
- Maryland
- metals
- mineral composition
- miscibility gap
- Nd-144/Nd-143
- neodymium
- North America
- Paleozoic
- peridotites
- petrography
- petrology
- Piedmont
- plutonic rocks
- pollution
- Precambrian
- pyroxenite
- rare earths
- recrystallization
- Sr-87/Sr-86
- stable isotopes
- strontium
- structural geology
- tectonics
- textures
- ultramafics
- United States
- volcanic rocks
- websterite
- James Run volcanic arc
Latitude & Longitude
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