EARTHTIME: A COMMUNITY-BASED EFFORT TOWARDS HIGH-PRECISION SEQUENCING OF EARTH HISTORY

The EARTHTIME project (http://www.earth-time.org) is now two years old with over 200 participants from 30 countries. In that time there has been remarkable progress in bringing together geochronologists, stratigraphers, and paleontologists/evolutionary biologists with a common appreciation of the value and power of a highly resolved record of earth history. We have sponsored three workshops, a short course, and several topical sessions at international meetings.

The geochronology communities are engaged in a major effort to eliminate inter-technique and inter-laboratory biases, the main limitations to the goal of the initiative. EARTHTIME prepared, calibrated and began distributing a mixed 205Pb-233U-235U-tracer solution for use in high-precision U-Pb geochronology, and several zircon standards were prepared and distributed. Use of these materials will eliminate much of the inter-laboratory bias. In Ar-Ar geochronology, we have sponsored distribution of multiple samples, including large quantities of the Fish Canyon sanidine as a preferred monitor.

The EARTHTIME project continues to foster cooperation between geochronologists and stratigraphers/paleontologists. It encourages approaches such as CONOP-9 that can produce composite sequences for thousands of first- and last-appearance events of fossil taxa together with other time-stratigraphic events, including dated tephra-falls. When integrated with high-precision geochronology, these composite sequences can break barriers to resolving power imposed by traditional zones and stages, and will allow, for example, continuous serial estimates of species richness as a function of time.

EARTHTIME is developing an active program of education and public outreach and increasing awareness within the geoscience community. The outreach effort led by the R@dius Project at the Denver Museum of Nature and Science has created a 30-minute geochronology video, curricula, and live data casts between EARTHTIME researchers and middle school students. The momentum of EARTHTIME is building, but progress towards the ultimate goal of a highly resolved temporal framework for the past 600 Ma remains dependent upon community involvement.