Geologic interpretation of basement rocks of the Atlantic coastal plain

Terranes and overlap sequences in the Central and Southern Appalachians, an expanded explanation for part of the Circum-Atlantic terrane map

“…It is best represented by a north-northeast-trending positive gravity anomaly having about 30 milligals relief (Johnson, 1973). A mixed pattern of magnetic highs and lows coincides with the envelope of the gravity anomaly (Daniels and Leo, 1985). The nature of the terrane boundaries is unknown.…”

“…STRATIGRAPHY Wells that penetrate basement within the limits of the gravity anomaly have recovered foliated mafic metavolcanic rocks, ultramafic rocks, gabbro, metadiorite, and phyllite (Daniels and Leo, 1985).…”

“…The Sussex terrane may contain substantial amounts of oceanic crustal material. Daniels and Leo (1985); Horton and others (1989a);Johnson (1973) NA43: HATTERAS TERRANE TERRANE BOUNDARIES«The Hatteras terrane of Horton and others (1989a) was first recognized by Daniels and Zietz (1978). This terrane is nowhere exposed and has no distinct geophysical signature relative to the Roanoke Rapids and Spring Hope terranes that bound it to the northwest.…”

“…2) of eastern North Carolina and Virginia is totally covered by Coastal Plain sediments. It is known from drilling to be an amphibolite-facies metamorphic complex containing plutonic rocks (Daniels and Zietz, 1978;Daniels and Leo, 1985). DEFORMATIONAL AND METAMORPHIC EVENTS-The age of amphibolite-facies metamorphism is undetermined.…”

“…IGNEOUS INTRUSIONS-The plutonic rocks, which range in composition from granite to diorite (Daniels and Leo, 1985), have Late Proterozoic Rb-Sr ages of 583 to 685 Ma (Denison and others, 1967;Russell and others, 1981). These ages are similar to those of the lower-grade Carolina terrane and other terranes that have been called Avalonian (Fig.…”