Tectonic evolution of the Baltimore Gneiss anticlines, Maryland

Puncoviscana folded belt in northwestern Argentina: testimony of Late Proterozoic Rodinia fragmentation and pre-Gondwana collisional episodes

“…7, 8 and 10 according to the tectonic synthesis for the southern Appalachian orogen proposed by Muller and Chapin (1984), Horton et al (1989) and Condie (1990). This sector has traditionally been interpreted as a succession of compressional events in Paleozoic times from an accretional terrane system.…”

Geologic interpretation of basement rocks of the Atlantic coastal plain

“…North of the Spotsylvania Lineament, a heterogeneous terrane of Piedmont metamorphic rocks lies adjacent to the edge of the Coastal Plain and is largely occupied by a Paleozoic package of rocks called the Glenarm Supergroup (usage of Muller and Chapin, 1984). In the Maryland Piedmont it consists of the sequence comprising the Setters Formation, Cockeysville Marble, and the much larger Wissahickon Group, all of which overlie the Proterozoic Baltimore Gneiss.…”

“…In the Maryland Piedmont it consists of the sequence comprising the Setters Formation, Cockeysville Marble, and the much larger Wissahickon Group, all of which overlie the Proterozoic Baltimore Gneiss. The Glenarm rocks are complexly deformed with the gneiss into a series of mantled domes (Muller and Chapin, 1984). In Virginia the Wissahickon Group is the dominant lithology.…”

“…East and southeast of the Baltimore gneiss domes lies an allochthonous terrane of highly varied lithologies which includes metagabbro and metaperidotite of the Baltimore Mafic Complex, metavolcanic rocks of the James Run Formation and metaplutonic rocks of the Relay Quartz Diorite and Port Deposit gneisses, and other rocks (Muller and Chapin, 1984). The numerous bodies of metamorphosed gabbro and peridotite in the Virginia-Maryland-Pennsylvania-Delaware Piedmont are regarded by Drake and Morgan (1981) as allocthonous fragments of a dismembered ophiolite.…”

“…Two of the deeper wells in New Jersey have been described in more detail and are consistent with Glenarm rocks: the New Brooklyn well (72, plate 4) in which sillimanite bearing quartz-plagioclase-biotite-muscovite schist and gneiss was reported, and the Butler Place test well (73, plate 4) which returned dolomitic marble (US Geological Survey, 1967). Dolomitic marbles are characteristic of both the Cockeysville marble from the Baltimore area and the Inwood marble from Manhattan Island in New York City, (Muller and Chapin, 1984;C. Baskerville, personal communication, 1985).…”