TRIPSANAS, EFTHYMIOS, WILLIAM BRYANT, DEBORA BERTI, Texas A&M University; and ARMAND SILVA, University of Rhode Island, Providence Rhode Island

Forty-eight jumbo piston cores up to 20 meters long have been recovered in an attempt to reconstruct the paleosedimentological events that were acting in the Bryant Canyon area. Detailed descriptions and x-radiographs were made from seven cores located on the slope, the flanks and the thalweg of the canyon. Seven sedimentological units were identified from the cores that strongly correlated with detailed bulk density profiles. The recovered sediments extended to early Wisconsinan in age. Five of the sedimentological units are related to sea level fluctuations, whereas two others reveal the influence of slope instabilities caused by salt diapir activity. Well-developed turbidites deposited during the early Wisconsinan glacial period indicate that Bryant Canyon was active during this period. Overlaining hemipelagic sediments reveal a sea-level rise during the middle Wisconsinan. Gravity flows, limited above the Y-5 layer, indicate severe halokinetic processes taking place over the area. The late Wisconsinan glacial period is characterized by alternating deposition of hemipelagic sediments, deposition from nepheloid layers andor by very diluted sediment flows. The lack of turbidites indicates that portions of Bryant Canyon were blocked by diapirs. Finally, highly laminated zones, containing rhythmites more than 6 meters thick, were observed in the upper and lower glacial units. The rhythmites are the result of deposition by nepheloid layers, and/or by tails of turbidity currents, uniform deposition of sediments entrained in river plumes and detached turbidity currents or are aeolian in nature.

TRIPSANAS, EFTHYMIOS, WILLIAM BRYANT, DEBORA BERTI, and ARMAND SILVA

AAPG Search and Discovery Article #90908©2000 GCAGS, Houston, Texas