Geology topics

F. Trincardi

Publications and source records attributed to F. Trincardi.

3 recordsLinked to original sources

USGS2005

High-resolution surveys for geohazards and shallow gas: NW Adriatic (Italy) and Iskenderun Bay (Turkey)

The need for quantifying and understanding the distribution of shallow gas is both of academic interest and of relevance to offshore facilities. The combination of seafloor mapping, subbottom profiling, and multi-channel seismic data can provide information on regions of possible shallow gas, where the gas impacts the acoustic properties of the host material and the seafloor. In this paper, we present two case studies - one academic and one industry - that evaluate the distribution of shallow gas in two field areas in the Mediterranean. In the first case study, geophysical data from Iskenderun Bay, southeastern Turkey, indicate the presence and distribution of shallow gas. Pockmarks on the seafloor are associated with acoustic wipeout in the shallow subbottom data. Although deeper seismic data do not show bright spots or other indicators of possible gas, instantaneous frequency analysis clearly shows laterally restricted anomalies indicating gas-rich zones. The interpretation of possible shallow gas resulted in moving a proposed drilling location to a nearby area characterized by fewer (but still present) shallow gas signatures. In the second case study, cores acquired in the Po Delta, Adriatic Sea, provide quantitative ground-truthing of shallow gas - as suggested by geophysical data - and provide minimum estimates of the percentage of gas in the subsurface. Cores targeted on anomalous subbottom data yielded up to 41,000 ppm methane; cores with anomalous gas content are associated with thick recent flood deposits which may effectively isolate reactive terrigenous organic matter from biologic and physical re-working. ?? Springer 2005.

Marine Geophysical Research↗

USGS1992

Collapse and flow of lowstand shelf-margin deposits: An example from the eastern Tyrrhenian Sea, Italy

The upper slope of the eastern Tyrrhenian Sea margin has a complex morphology shaped by Quaternary tectonism and by sedimentation phases controlled by changing sea levels. Sediment slides of widely varying size and shape are common in Quaternary deposits of the upper slope, particularly where gradients are steep. Our study of a large sediment failure in lowstand prograded coastal deposits west of Cape Licosa indicates that the nature of shelf-margin deposition is an additional important control on failure. The failure zone has a mobilization surface showing in-situ deformation in the sediment above it; an upper failure surface; a head scarp; and a zone of ponded sediment debris downslope from the exposed surface of failure. The basal mobilization surface is roughly parallel to the seafloor and coincident with a major downlap surface. The failed section is less that 20 m thick and local in extent, but deformation on the basal mobilization surface extends outside the immediate area of the failure. Directly downslope of the slide scarp are internally stratified mounds that show no evidence of deformation or movement. Most of the prograded deposit experienced in-situ deformation that evolved into the collapse of part of the sediment pile above the mobilization surface. A portion of the mobilized sediment flowed a few kilometers basinward and accumulated at the base of a slope-parallel ridge. Sediment failure occurred on the Licosa shelf margin following a major pulse of coastal sedimentation along the lowstand shoreline. On many continental margins, sea-level lowering is thought to be an important cause of failure unconsolidated sediment deposited during previous high-stand conditions. The Licosa slide demonstrates that sea-level fall has another, equally important but indirect, role in sediment failure. As sea level falls and reaches its lowstand position, streams are at their peak efficiency and a coarsening-upward clastic coastal wedge is rapidly emplaced at relatively steep gradients on the shelf margin, and these are conditions that inherently favor sediment instability and failure.

Marine Geology↗

USGS1988

Sediment waves on the tiber prodelta slope: Interaction of deltaic sedimentation and currents along the shelf

A regressive depositional sequence has been prograding on the northeastern Tyrrhenian Shelf since the establishment of the present high stand of sea level. Thickness and distribution of this prograding sequence are chiefly controlled by the Tiber Delta sediment source and the oceanographic conditions on the shelf. Wavy bedforms characterize the Tiber prodelta slope between 35 and 100 m water depth. On 3.5 kHz subbottom profiles, these bedforms show the same morphology and internal depositional geometry as most of the deep-water examples of sediment waves. ?? 1988 Springer-Verlag New York Inc.

Geo-Marine Letters↗