Hartford and Deerfield Basin Framework Mineralogies: Independent Evidence for Provenance, Current Directions, and Tectonic History
M. Vetter, G. R. Brakenridge
Petrographic studies of sands and muds on a basinwide scale can document regional sand-dispersal patterns, changes in those patterns through time, and reconstructions of inferred tectonic history. Several Triassic-Jurassic marginal rifts of eastern North America provide adequate exposures for sample locations designed to document changes up section (through time) as well as lateral and longitudinal directions (through paleogeographic landscapes). The basins in question are located in the Connecticut Valley half graben; our samples are distributed over its 116-km length and 28-km width. The samples consist of fine and coarse arkoses, arkosic conglomerates, fanglomerates, mudstones, and siltstones. Point counting of sand grains in thin sections stained for orthoclase and pl gioclase will allow quantitative characterizations of the Qm (monocrystalline quartz), Qp (polycrystalline quartz), P (plagioclase), K (orthoclase), Lv (volcanic lithic fragments), and Ls (sedimentary and metasedimentary lithic fragments) components of the rocks. Such results can: (1) test the previous provenance inferences made on the basis of local current direction indicators and pebble compositions, and (2) identify mineralogically distinct strata or zones for possible correlation with subsurface samples.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.