A multi-scale investigation into seafloor topography of the northern Mid-Atlantic Ridge based on geographic information system analysis

Tomasz Niedzielski,Åge Høines,Mark A Shields,Thomas D Linley,Imants G Priede

doi:10.1016/j.dsr2.2013.10.006

Abstract

The Mid Atlantic Ridge (MAR) has been identified as an important component of the lower bathyal (800−3500m depth) benthic biogeographic province in the North Atlantic Ocean. We performed a multi-scale characterization of seafloor topography of the MAR. In the basin-scale analysis, we have used the 30″ General Bathymetric Chart of the Oceans (GEBCO) grid to estimate the area of different components of lower bathyal habitat in the main North Atlantic basin and to produce a corresponding depth–area relationship. The regional-scale investigation is based on swath bathymetry surveys which show the flanks to MAR to comprise a series of sediment-draped flat plains (37.65% of area) with intervening gentle slopes ranging from 5° to 30° (56.70% of area) and slopes steeper than 30° (5.65% of area). The steep slopes have significant areas of hard substrate (70%) comprising bare cliff faces and rock outcrops. Within the local-scale approach, detailed surveys of such steep areas were done by multi-beam sonar and cameras mounted on a Remotely Operated Vehicle (ROV). In several locations, the terrace-like seafloor topography has also been identified. Overall, it has been shown that the MAR lower bathyal is 95% covered with soft sediment.

Highlights

The general form of the world's ocean basins and the presence of a mid-ocean ridge in the Atlantic Ocean have been known for over 100 years (Murray and Hjort, 1912)
The total area of lower bathyal depths in the North Atlantic Ocean is 8,109,116 km2 of which 50% is on the continental margins and 46% on the Mid Atlantic Ridge (MAR) (Priede et al, 2013a)
It should be noted that the Extended Mid Atlantic Ridge Lower Bathyal Province” (EMARLBP) definition used in this study includes seamounts based on the lower flanks of the MAR so our area estimate is larger than would be derived from strict adherence to the 3500 m contour around the MAR (Watling et al, 2013)

Summary

Introduction

The general form of the world's ocean basins and the presence of a mid-ocean ridge in the Atlantic Ocean have been known for over 100 years (Murray and Hjort, 1912). A major step forward was the availability of global satellite altimeter-derived bathymetry (Smith and Sandwell, 1997) with 2′ grid resolution. This has subsequently been enhanced by combining with other data sets to create global grids at 1′ (GEBCO released in 2003) and 30′′ resolution (GEBCO released in 2009). Using the 1′ grid, Costello et al (2010) estimated the areas of seabed in all world's oceans identifying mid-ocean ridges, seamounts and slopes.

Methods

Results

Conclusion