Basement Controls on Lineament-Block Tectonics of Coastal Plain Province in Virginia: ABSTRACT

Abstract

Linear features in the coastal plain of Virginia were interpreted from Landsat images and analyzed to define the geologic framework of the underlying basement. The lineaments were digitized, and length-weighted frequency distributions were calculated at 5° intervals on a 10-km2 grid. Statistically significant peaks (> 95%) and troughs (< 5%) within each cell were identified. These significant trends identify 13 major lineament zones, which in turn were compared with structural domains recognized from a combined interpretation of geophysical, subsurface form-surfaces, and basement well-log data. Correlation between lineament frequency, aeromagnetic, and gravity data was tested on a regionwide and smaller domain basis. The major lineament zones divide the western part of the area into north-south and northeast-southwest bound rhomboidal blocks. The eastern part is characterized by north-south and northwest-southeast bound rectangular blocks, quite different from the regional Appalachian grain. The lineament zones are documented to parallel basement domain boundaries because subsurface structure, lithologic and stratigraphic changes, and steep geophysical gradients occur along their extent. Some End_Page 1450------------------------------ lineament zones clearly cut across several stratigraphic levels, indicating Mesozoic and Cenozoic reactivation of favorably oriented preexisting basement faults. The depositional control of sedimentary units, fracture propagation due to basement-block tectonics, and apparent reversals of fault movement observed at the surface are also suggested in a conceptual model. End_of_Article - Last_Page 1451------------