Study of Deep-Sea Furrows: Physical Characteristics, Mechanisms of Formation and Associated Environmental Processes

Abstract

Abstract : A field of sedimentary furrows was discovered on the abyssal plain at the base of the Sigsbee Escarpment during a 1999 deep-tow survey of the continental slope in the Bryant Canyon area of the northwestern Gulf of Mexico. The furrows are long, relatively narrow depressions in the seafloor that are generally oriented parallel to the escarpment. Furrows associated with deep-water currents have been found along the Blake Bahama Outer Ridge (Hollister et al., 1974; Lonsdale and Spiess, 1977; Tucholke, 1979; Flood and Hollister, 1980; Flood, 1983), the Bermuda Rise (Embley et al., 1980), and several other localities (see review by Flood, 1983). Though such observations exist, they have by necessity been limited to relatively small areas and only few individual furrows have been studied in detail. The massive areal extent of Sigsbee Escarpment furrow field (10,000 km2) and the detail with which the field has been imaged are unprecedented. Their character indicates the occurrence of previously unrecognized strong bottom water flow in the gulf and it highlights the important influence flow has on slope and rise sedimentary processes. Many questions about the nature of the furrows and their relationships to currents and other environmental processes exit. For example: What are the dimensions and morphologic features of the furrows? What is their mechanism of formation? What is their significance for the lower slope/rise sedimentary processes? What is the nature and cause of associated water flow? As a first step toward answering such questions, we have begun examining existing 3-D seismic data and deep-tow data.