Over the past few weeks, we have surveyed the Enriquelo-Plantain Gardens fault along the Jamaica Passage from west (near Jamaica) to east (near Haiti). Traces of coastal bottom faults appear as linear ridges up to 1000 meters high. There are three large basins south of the fault: Moran Basin (60 km long), Navassa Basin (30 km) and Motely Basin (20 km). These basins are bounded by faults to the north and a series of ridges to the south. Huge underwater landslides extend from the southern ridge into the basin. The sediment was dozens of kilometers long, including truck-sized boulders. This suggests that the southern boundary of the fault zone is tectonic and that earthquakes may be the mechanism behind the downslope failure and massive landslide.
Image of the Enriquillo fault showing its linear trajectory, high ridges, seafloor sediment damage, and basins. The image was prepared according to the multibeam bathymetry method. Brown is shallow areas (1,000 meters or less below sea level). Dark green is as deep as 3,000 meters below sea level. Image courtesy of Sylvie Leroy, data collected during the 2012 SIS Ocean Cruise in Haiti.
So far we have recovered 31 Gravity CoreIn the cores, we found a type of turbidite—sediment deposited by fast-flowing turbulent water flowing down a slope—containing iron-rich minerals and organic matter, possibly wood or algae. This is unusual because most of the sediments we get are “calcareous oozes” made up of tiny shelled organisms. Iron-rich minerals in turbidite originate from fault ridges.We’ll learn more when we open the core Lamont-Doherty core repository, but we expect to find more turbidite, which will help understand the seismic history of the region and help better assess the hazards in Jamaica and Haiti.
We assembled the day shift and night shift to take pictures. Front row, left to right: Cecilia McHugh, Vassan Wright, Victor Kabiativa, Jardel Dasent, Richard Kilburn. Back row, left to right: Leonardo Seeber, Matthew Hornbach, Chris Van Hill, Benjamin Freiberg, Brian Agee.
