Hubert Staudigel
Institute For Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California at San Diego - 0225
La Jolla CA 92093-0225

Bill McDonough
Earth and Planetary Sciences
Harvard University
20 Oxford St
Cambridge, MA 02138

Henry Shaw
Geosciences and Environmental Technology, L-201
Lawrence Livermore National Laboratory
Livermore, CA 94551

The Geochemical Earth Reference Model ("GERM") Initiative is a grass-roots effort within the geochemical community aimed at establishing globally relevant geochemical databases that will ultimately lead to a "geochemical reference model" for the Earth. This reference model will include a complete set of chemical data for all major geochemical reservoirs, and the fluxes between them. The GERM effort was initiated during a workshop in Lyon, France in March 1996. This workshop led to a special volume of Chemical Geology (Albarede, et al. 1998) and the development of a regularly updated website (http://EarthRef.org/GERM/) that includes a wide spectrum of useful geochemical data and other information (see also Staudigel et al., 1998).

The aim of the second GERM workshop, held in La Jolla, CA and hosted by the Scripps Institute of Oceanography (SIO) was to foster a multi-disciplinary discussion about the earth as a complex geochemical system. Discussions at the La Jolla workshop successfully integrated geophysics with a wide range of geochemical sub disciplines, including cosmochemistry, and the chemistry of the atmosphere, hydrosphere, and lithosphere. The workshop format was based on keynote presentations followed by extensive discussions that were moderated by discussion leaders (participants and their functions are listed at the end of this note). In addition, smaller "breakout" sessions were held on specific topics relating to the actual development of the web-based GERM. In some sessions a number of groups were established to promote further studies and sharing of samples in order to foster a better understanding of specific reservoirs and fluxes (e.g., the arc environment).

Keynotes lectures and subsequent discussions focused on assessing and improving our understanding of the chemical composition of various reservoirs. We examined the validity, completeness, and strength of the existing data. We exposed and discussed commonly held assumptions concerning the composition of reservoirs.

The nature of the deep Earth was considered in the context of combined geochemical cosmochemical, and geophysical constraints. Many of us recognized the need for models to be internally consistent with respect to all of these data and establishing the uncertainties of each data set was recognized.Discussions on the evolution of the core-mantle system considered the degree of material exchange between these reservoirs today and in the past. The nature of the mantle and its many reservoirs led to discussions of reservoir volumes and compositions today and through time.

Discussions on oceanic crustal data pointed up the need to consider the composition of fresh oceanic crust, as it is extracted from the mantle, as well as the altered oceanic crust that is subducted at arcs. Altered oceanic crust provides the input into island arcs where some of its inventory is extracted to form arc volcanoes and some of it is injected into the mantle where it may provide material for the source regions of some ocean island basalts. Differences between altered and fresh oceanic crust provide an estimate for chemical fluxes between seawater and oceanic crust.

Debate related to the continental crust focused on whether there is a secular evolution in its composition and the "basalt paradox": why the crust does not have a basaltic bulk composition even though these appear to be the primary magmatic additions to the crust. Possible solutions to this paradox include weathering of primary basalt, returning Mg (± Ca and Fe) to the mantle through the oceanic ridge systems, delamination of mafic and ultramafic cumulates from the base of the crust or non-basaltic primary magmatic additions (e.g., Archean tonalites and trondhjemites). In addition, the dominant tectonic setting of crustal growth was variably attributed to plumes (due to the apparent episodic nature of crust formation) or arcs (based on the bulk chemistry of the crust).

Discussions of the chemistry of the oceans and the atmosphere mostly focused on their long-term evolution over the entire history of the earth, and the relationships between seawater isotopic composition and climate.

These scientific discussions led up to a series of working group sessions that focused on how GERM can help improve our understanding of the earth. In particular the workshop emphasized the need for:

• more community participation;
• involvement with other globally relevant initiatives and programs (such as ODP, REM, Margins, RIDGE, JGOFS);
• peer review of materials placed on the GERM web site;
• establishment of well structured data bases using common formats insofar as possible; and
• using GERM as an umbrella organization for fostering and coordinating a variety of community efforts.

Specific progress on some of these issues included an agreement to set up a joint office for GERM and the geophysical Reference Earth Model (REM) at Scripps Institution of Oceanography in fall 1998 (Staudigel and Masters) and to establish contacts with the MARGINS initiative (Bebout). Considerable progress was made toward the coordination of the GERM database effort with other ongoing efforts to compile databases for specific reservoirs. Along these lines, C.H. Langmuir (Lamont), A. Hofmann (Max Planck Institute) and C. Hawkesworth (Open University), will be compiling geochemical data for MORB, Ocean Islands, and Island Arcs, respectively.

The GERM workshop succeeded in bringing together expertise from very diverse fields of earth science, with the common focus of improving our understanding of the make-up of the planet and the processes that control its interactions. Much progress was made on advancing the GERM initiative, but it is very obvious that this effort needs the continued support by the geochemical community. In return, the effort offers the community the opportunity a basis for identifying key issues that need resolution, a convenient resource for data compilations and abstractions, and a forum for bringing together earth scientists with different backgrounds to work on common geochemical problems.

Conference Participants and Their Functions

(KN Keynote Speaker, DL Discussion Leader, CON Convener. PO poster presentation, GE GERM editor, GSt Steering Committee)

Albarede, F. (CON, GSt, PO)
Anderson, D. (DL, GSt, PO)
Arthur, M. (KN)
Barth, M. (PO)
Bebout, G. (GE, PO)
Bohrson, W.
Brandon, A. (KN)
Butterfield, D. A.
Calderwood, A. (PO)
Castillo, P. (PO)
De Paolo, D. (KN)
Derry, L. (DL, GSt)
Dixon, J.
Donnelly, K. (PO)
Edmond, J. (GE)
Elliott, T. (GE, PO)
Farquhar, J.
Fessenden, J.
France-Lanord, C. (PO)
Galy, A. (PO)
Godderis, Y. (PO)
Goldstein, S. L. (KN)
Hanan, B. B.
Hart, S. R. (KN)
Hawkesworth, C. (KN)
Holland, H. D. (KN)
Jacobsen, S. (GE)
Janney, P. (PO)
Jochum, K. (PO)
Jones, G. (PO)
Keeling, R. (GE)
Kurtz, A. (PO)
LaGatta, A. (PO)
Langmuir, C. (GE)
Ludden, J.
Masters, G. (CON)
McDonough, W. (DL, CON, GSt, PO)
Michael, P. (PO)
Muehlenbach, K. (PO)
Nielsen, R. (GE)
O'Neill, H. (KN)
Pearce, J. (PO)
Phipps-Morgan, J. (KN, PO)
Rahn, A.
Reid, M.
Rose, E. (PO)
Rudnick, R. (GE, PO)
Shaw, H. F. (CON, GSt)
Spivack, A. (DL)
Staudigel, H. (CON, GSt, PO)
Su, Y. (PO)
Veizer, J. (GE, PO)
Vervoort, J. (PO)
White, W. (GSt)
Zindler, A. (GE, GSt)

Acknowledgements

The GERM workshop was mostly funded by the National Science Foundation, as part of the CSEDI program. Additional funding was provided by the Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanography, and by Micromass Instruments.

Albarede, F., Blicher-Toft, J., Staudigel, H. and White, W.M. (eds), 1998, Geochemical Earth Reference Model (GERM), Special Issue of Chemical Geology, Vol 145, p 1563-491.

Staudigel, H., Albarede, F., Blicher-Toft, J., Edmond, J., McDonough, W., Jacobsen, S. B., Keeling, R., Langmuir, C. H., Nielsen, R. L., Plank, T., Rudnick, R., Shaw, H. F., Shirey, S., Veizer, J. and White, W.M., 1998, Geochemical Earth Reference Model (GERM): description of the Initiative., Chemical Geology, 145: 153-160.