As we all know, the deep sea contains fantastic records of ancient oceanic conditions. The deep sea also holds clues about the continents. In this case, we can use deep sea sediments to better understand how Earth surface systems respond to climatic fluctuations. The inherent relief between continental and ocean plates drives the transfer of sediment from the shoreline to the deep ocean. A grain of sand lodged from a decomposing rock in the mountains may spend a long time making its way down a river system, or being swashed around at the coast, but ultimately the deep sea is the final resting place. In other words, this is as low as it can go. Combine this with a high volume of sediment over time and the result is an accumulation (sometimes several kilometers thick) for geologists to examine.
Studies of sediment transfer within this context has been coined “source-to-sink” and involve the integration of several Earth science disciplines including sedimentology, geomorphology, hydrology, mineralogy/petrology, geochemistry, marine geophysics, and others. A big chunk of my current research is a collaborative source-to-sink project between Stanford University and the U.S. Geological Survey. We are focused on the sediment records housed in the deep marine basins of the California Continental Borderland region offshore southern
Using multibeam bathymetry, seismic-reflection profiles, and core samples, we can map the distribution and flux of continentally-derived sediment in these basins. The image above is a seismic-reflection profile from the
So, what are we finding out in these studies? A radiocarbon-dated Ocean Drilling Project core in
Ultimately, the record of sediment transfer that is stored in the deep sea (modern or ancient) will tell us a great deal about what was happening on the continent regarding the interactions of tectonism, climate, and Earth surface processes.
1 Perspective image created in GeoMapApp, a fantastic freeware program for exploring the world’s bathymetric database. Download here: http://www.marine-geo.org/geomapapp/
2 Normark, W.R., D.J.W. Piper, and R. Sliter, 2006, Sea-level and tectonic control of middle to late Pleistocene turbidite systems in
3 Bathymetry of the northeastern
4 Barron, J.A., L. Huesser, T. Herbert, and M. Lyle, 2003, High-resolution climatic evolution of coastal northern
4 Romans, B.W. and Normark, W.R., 2006, Distribution and rates of terrigenous sediment accumulation on the Hueneme submarine fan in the late Holocene (4.3 ka – present),