Drilling for Deep-Time GeoSystems Workshop (DOSECC)

A workshop to explore the need and feasibility of a continental drilling program for GeoSystems research was held on Aug 23-24, 2005 in Arlington , VA. GeoSystems is an interdisciplinary, community-based effort focusing on research of Earth’s climate and linked systems in ‘deep’ (pre-Quaternary) time. The workshop, supported by DOSECC (Drilling, Observation and Sampling of the Earth’s Continental Crust), identified how drilling will benefit GeoSystems science, and developed a spectrum of example drilling programs to explore resources needed for each. The workshop gathered together scientists with expertise in drilling for deep-time climate objectives together with scientists with expertise in physical and cyber-facilities key for data archival and synthesis, as well as interested observers from the National Science Foundation.

The need for drilling for GeoSystems science was clearly reiterated to complement surface geologic studies. Drilling is key to GeoSystems research because the subsurface is the best source of long, continuous and pristine paleoclimatic records at high temporal resolution, especially in continental environments and marine intervals older than the Cretaceous. Drilling enables researchers to control sampling of critical geologic intervals and sample high-resolution sections, to sample unweathered section suitable for an array of geochemical analyses, and to focus multidisciplinary efforts on a common sedimentary record. Furthermore, drilling provides a means to collect a spatial array of records and bring them back to a common archival point for later study.

One of the key issues discussed at the workshop was development of a spectrum of typical GeoSystems drilling programs. The group decided that the types of drilling programs needed for GeoSystems research will have multiple scales. At one end of the spectrum are relatively inexpensive projects requiring only a single or a few shallow holes (~100-200 m holes, drilling costs around $50k per hole plus logistics) designed to sample a ‘big scientific impact’ interval or a classic boundary sequence. At the other end of the spectrum are larger drilling campaigns consisting of multiple 1+ km holes (drilling costs of about $500k per hole) to sample significant periods of geologic time, similar to Lamont-Doherty’s Newark Basin Drilling Project. These larger programs could have objectives that include sampling high-resolution continuous sedimentary section, developing better chronostratigraphy, and understanding normal (but different than modern) earth system operations over long periods of the geologic record. Between these two end-members are programs that might require moderate levels of geographic coverage or drilling depths (e.g. 0.5 to 1 km). Example scientific programs were assembled so that workshop participants could realistically assess the costs and infrastructure needs. Typical drilling programs are envisioned to range from 3 to 5 years in length. Most participants felt that holes drilled as part of a multi-hole program should be distributed over multiple years rather than completed in a single field season. Such a ‘distributed drilling’ approach enables study of preliminary results that might sharpen planning for subsequent holes.

Clearly a full continental drilling program will require significant investment, because the science costs (both routine measurements made on core and specific tasks pertinent to the scientific problem) were estimated to cost 1-2 times the drilling expense. Estimated costs for a full large program (e.g. 5 km of core) is around $6-8M for a 4-year project. Developing this level of funding will require time, but is viewed to be so critical to GeoSystems science that we need to begin plans now.

The spectrum of drilling programs obviously affects the total cost of a GeoSystems drilling program and the infrastructure needed. It was clear that much of the needed infrastructure is already available. DOSECC already has drill rigs and coring tools that could handle the 100-1000+ m depth range. NSF core storage facilities capable of handling both unconsolidated sediments and lithified material are currently funded although no facility has yet been designated as a permanent storage facility. Geophysical equipment for site survey is available in the community, although additional equipment and personnel support may be needed for geophysical data acquisition. Facilities for logging and mobile core-scan facilities to measure physical properties need to be acquired. Standard types of laboratory measurements, including geochronology, need to be identified so that these costs can be allocated in addition to the costs for the specific science objectives of each project.

While a GeoSystems drilling program is not yet imminent, it is clear that drilling will be a critical component of GeoSystems science. The GeoSystems community should thus expect to be called upon to help develop both a drilling program and the science to justify it.

Many thanks to the following workshop participants, whose expertise were critical to make the workshop a success: Cinzia Cervato (Iowa State U.), Shirley Dutton (Texas Bureau of Economic Geology), Ed Goolish (NASA Astrobiology Institute), Bill Hay (emeritus, University of Colorado), Lee Kump (Pennsylvania State University), Mitch Lyle (Boise State U.), Tim Lyons (University of California, Riverside), Ken Miller (Rutgers University), Isabel Montanez (University of California, Davis), Dennis Nielsen (DOSECC office), Paul Olsen (Columbia University), Mark Schmitz (Boise State University), Lynn Soreghan (University of Oklahoma), and Ken Verosub (University of California, Davis)

Mitch Lyle and
Lynn Soreghan, co-convenors