the end of the ODP program the greatly improved quality of the cores permitted the useful employment of core scanning devices that measure density, magnetic susceptibility, P-wave velocity, natural gamma radiation, color, and magnetic polarity. These digital measurements are in addition to pore water chemistry, physical properties, microbiological samples, biostratigraphy, and other measurements that were standard in the days of DSDP. In ODP the shipboard scientific party grew to as many as 30 scientists who operated the machines, did the descriptions, made the measurements, and carried out the scientific studies. Their efforts over 12-hour shifts, 7 days/week, on a 56-day expedition constitute an aggregate 9 to 10 man-years of work achieved during the at-sea time. These expeditions are very productive efforts.
The substantial improvements made in the recovery and documentation of the recovered section came in parallel to improvements in how we used the holes that were drilled. Logging of the holes has come very close to keeping pace with developments in the industry. Other measurements such as heat flow and vertical velocity profiles have also been commonly made. Perhaps one of the most elegant innovations in down-hole instrumentation has been the circulation obviation retrofit kit (CORK), a device that seals off one or more sections of the drill hole and allows measurements of the chemical and physical nature of the waters in that section to be made over time. Thus, the holes themselves can become deep-sea observatories or laboratories for chemistry, microbiology, and seismology.
As our knowledge of the deep-sea environment and the scientific questions we address expands, our technical capabilities continue to improve. Now with the Integrated Ocean Drilling Program (IODP) we have also been able to go beyond the limitations first accepted as necessary in the early days of DSDP. We have drilled in the ice-covered region of the high Arctic and brought back a startling record of climate change associated with the CO2 rich atmosphere of the Eocene. We have drilled on the very shallow shelf off New Jersey and the reefs of Tahiti to delve into the history of sea level changes and its impact on the sedimentary architecture of shallow water environments. And we are beginning an ambitious program of exploring the tectonic, depositional, and hydrologic environment of convergent margins. We no longer have to drill lacking the well control provided by a riser and will hopefully extend the water depth in which we can operate in the riser (or “well control”) mode beyond the present 2,500 m.
The envisioned scope of the great exploration that awaited us in the beginning days of scientific ocean drilling has been exceeded. Not only have we applied crucial tests to the plate tectonic theory but also we have created a whole new scientific field—paleoceanography. Through the exploration of the deep-sea environment we have also expanded the science we address far beyond that envisioned in the early days of DSDP. The chemistry and hydrology of water in the sediments and the crust are now thought to play a key role in the chemistry of the oceans and the weathering of the basalt both near the ridge axes and far off the axes into the older crust. The structure of the oceanic crust itself is gradually being revealed as we penetrate deeper into the basaltic sections. And we are just beginning to realize the great importance of microbes in the ocean environment. These are just some of the aspects of scientific ocean drilling that continue to intrigue the scientific mind and expand both the science and the scientific community that use scientific ocean drilling to increase the scope of our knowledge.
Coffin, M.F. and J.A. McKenzie. 2001. Earth, Oceans and Life: Scientific Investigation of the Earth System Using Multiple Drilling Platforms and New Technologies, Initial Science Plan, 2003-2013. Integrated Ocean Drilling Program, Texas A&M University, College Station, Texas.
Gornitz, V. 2009. Encyclopedia of Paleoclimatology and Ancient Environments. Springer, The Netherlands.