Geology of the western boundary of the Charlotte Belt at Brookneal, Virginia

Abstract

The western boundary of the Charlotte Belt near Brookneal, Virginia lies midway along a 100 km length of the boundary previously mapped by reconnaissance methods only (Jonas, 1928). This study concludes that the metavolcanic Chopawamsic Formation of northern and central Virginia is the extension of the Charlotte Belt. The Charlotte Belt is bounded to the west by the metasedimentary Evington Group that extends from northern Virginia southward into the Smith River Allochthon as the Fork Mountain Schist. In Brookneal, the boundary between the eastern metavolcanic and western metasedimentary units is obscured by the intrusion of the 470 Ma Melrose Granite. The abrupt change in lithology and multiple fault generation across the granite indicates that the boundary between the metasedimentary and metavolcanic units is tectonic.

Unconformably overlying both the metavolcanic and metasedimentary units is the Arvonia sequence, previously not documented in the southern Virginia Piedmont.

The Brookneal terrane has undergone three metamorphic events and localized hydrothermal retrogression. The metamorphism is tied in sequence to seven folding episodes. The metamorphism and deformation are results of the regional Taconic event, the late-Acadian event which terminates to the west in Brookneal, and the fault localized Alleghanian event, each of which resulted in faulting.