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Sand Compositional Changes as a Key For Sequence-Stratigraphic Interpretation: the Pleistocene Tiber River Deltaic Succession (Italy)

Daniel Tentori
California State University, Northridge

The use of variation in sand composition as a tool in sequence stratigraphy is still in an early stage and requires more case studies to test its effectiveness in sequence interpretation. Depositional cycles and sequence boundaries are well defined for late Quaternary wave-dominated Tiber delta deposits that crop out along the Lazio coastal margin near Rome, Italy.

The aim of this study is to define the relative contribution of autogenic and allogenic processes on the late Quaternary Ponte Galeria sequence and petrofacies development, as well as compositional trends from base to top of the succession. Integration of sand provenance with sequence stratigraphic interpretation will better constrain the contribution of tectonic uplift in the source region (e.g., higher sediment lithic proportions), volcanism (e.g., higher volcanic lithic proportions), and eustacy and coastal reworking (e.g., higher quartz content) in controlling the evolution of the Ponte Galeria depositional sequences.

Thirty sand samples collected from the Tiber River and its tributaries will be analyzed to evaluate the contribution of the geologic units that crop out in the drainage basin to the Tiber River sediment composition. Compositional effects of littoral transport and magnitude of wave and current reworking along the coastline will be determined on 7 samples collected from the coastal zone. A resulting model of compositional trends along the modern river and river mouth will help to interpret detrital modes determined for 29 sand specimens sampled from two measured and correlated sections in the Pleistocene barrier-island and wave- dominated deltaic successions associated to the Paleo-Tiber River.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013