| This thesis presents the results of an integrated geophysical and geological study of a "Gilbert-type", fjord-head delta at Zeballos, British Columbia. The primary objective of the study was to elucidate the architecture, stratigraphy, sedimentology, and evolution of a high energy, fjord-head delta.;A ground penetrating radar survey and air photo interpretation revealed the presence of two deltas: an elevated, incised, late Pleistocene delta and a Holocene delta graded to present sea level. Both deltas comprise topset, foreset, and bottomset units. A time domain electromagnetic (TDEM) survey, a ground penetrating radar (GPR) survey, borehole data, and gravel pit exposures provided information on the structure of both deltas. They indicated that the deltaic deposits coarsen upward from silt in the bottomset unit to gravel in the topsets. The TDEM survey also revealed a highly irregular, buried bedrock surface, ranging from 20 to 190 m in depth, and delineated saltwater intrusion into the delta sediments. Late Quaternary relative-sea level changes at Zeballos were inferred from the architecture of the two deltas.;Sediments of the delta plain are divisible into seven lithofacies, from bottom to top: (1) facies A: gravelly sand/sandy gravel, (2) facies B: single sand beds, (3) facies C: stratified organic-rich silt and sand, (4)facies D: organic-rich silt, (5) facies E: silt and sand beds/laminae, (6) facies F: silt bed(s), (7) facies G: peat. The vertical succession of lithofacies in section is repeated laterally across the delta plain, from distributary channels, to sand flats, to tidal marsh. (Abstract shortened by UMI.). |
