Contourite and Turbidite Features in the Middle Caspian Sea and Their Connection to Geohazards Derived from High-Resolution Seismic Data

Abstract

High fluvial input combined with specific topographic and oceanographic settings in the Caspian Sea create favorable conditions for contourite deposition. For the first time in its middle portion, contourite deposits have been observed in high-resolution seismic profiles. Various types of contourite drifts and mixed depositional systems have been revealed on the lower slope and in the adjacent basin, some of which are accompanied by sediment wave fields. The deposition of contourites or turbidites and their lateral distribution is controlled by sea-floor topography and oceanographic processes, as well as the modern activity of gravity flows downslope on the western Caucasian slope and in the channel system on the Mangyshlak Sill. The contourite drifts and sediment wave fields form several contourite depositional systems, which seem to merge in the Caspian contourite depositional complex. This occurs near the foot of slopes of the Derbent Basin and is related to the counterclockwise circum-Caspian current in the Middle Caspian Sea. The fact that the Caspian Sea is the largest lake in the world makes this region a significant area for research into the “lake contourites” issue. The Caspian Sea is an important oil-producing area, and sedimentary processes related to the contourite and turbidite can be a source of potential geohazards in the construction and exploitation of underwater engineering structures

Submarine geohazards on the northwestern continental margin of the South China Sea and their mechanism

“…When the relative sea level falls, the continental shelf becomes partially exposed and many sediments flow into deep water. This gravity flow erodes the seabed and forms channels (Vincent et al, 2013; Yutsis et al, 2022). When the relative sea level rises, the early channels sink into the seabed, forming buried channels.…”

“…This gravity flow erodes the seabed and forms channels (Vincent et al, 2013;Yutsis et al, 2022). When the relative sea level rises, the early channels sink into the seabed, forming buried channels.…”