ABSTRACT: Seismic Facies and Baisn History Related to Sea Level Cycles and Tectonism: Paola Slope Basin, Eastern Tyrrhennian Margin

F. Trincardi, M. Canu, M. Field, W. Normark

The influence of local tectonics and eustatic sea level change on basin sedimentation patterns is particularly well illustrated in the slope basins of the eastern Tyrrhennian margin. Basin history here is dominated by a high sediment influx during the Pliocene and Quaternary and a complex sea level history of eustatic changes combined with those resulting from differential vertical movements between the subsiding Tyrrhennian abyssal plain and the uplifting Calabrian arc.

Paola basin, a small (70 × 30 km), confined basin typical of the region, is bounded on the seaward side by a slope ridge formed from folded and sheared Pliocene-Pleistocene deposits. Syndepositional

growth of the ridge induced continual change in sedimentation patterns by alternately providing pathways and barriers to sediment flows. Sedimentary facies that ponded behind the slope ridge include channel and associated levee deposits and slumps indicated by mounded, channelized, wedge-shaped, and chaotic reflectors. Vertical changes in facies defined by seismic character suggest a significant increase in the influx of turbidity currents to the basin floor during the Pleistocene.

The distribution of facies interpreted to be coarse grained indicate that during lowstands of sea level numerous ephemeral points of sediment entry existed along the basin margin. Morphologic lows are filled with either coarse-grained channel and mounded deposits or with onlapping plane-parallel turbidite deposits. Highstands of sea level, in contrast, flooded the basin and resulted in a widely distributed blanket of thinly draped sediment.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990