INTEGRATING GEOLOGY AND GEOPHYSICS (AND SMALL AND LARGE SCIENCE): A CHALLENGE FOR EARTHSCOPE AND FOR NSF

The Earthscope initiative will be a milestone for our understanding of the North American continent (and continents in general), potentially shaping the nature of Earth Science research for decades. In order to maximize the return, we need to scrutinize the experiences of large geology-geophysics collaborations, such as the CDROM or Canadian lithoprobe, as well as the interaction of “small” and “large” science within the context of a mega-project. Earthscope has, at its core, the geophysical initiative to image the lithosphere, but the image is almost everywhere a composite one, integrating a long history, diverse processes, and changing boundary conditions. Distinguishing the present dynamics from the past kinematics has been a major challenge for CDRom and Lithoprobe. It is critical for geologists to be involved at every stage, from designing the experiment to interpreting results. The most critical collaborators are those who have worked on surface exposures in the same region. These people are best suited to add the fourth dimension, tectonic history, to the geophysical image. The “natural laboratory”, surface exposure, is critical for interpreting the geophysical results. Xenoliths provide essential samples, but are generally without context. Isobarically cooled terranes may be particularly important; they provide a map view of specific levels of the crust at the highest resolution. Work in such terranes has revealed, perhaps more than anything else, heterogeneity in both space and time. A major challenge is to interpret the multi-scale, time integrated, heterogeneity at the surface in the specific context of remote geophysical images. Geology-geophysics collaborations focused on the Earthscope experiments must be paired with geology-geophysics collaborations in carefully chosen natural laboratories; each type of work provides relevance and context for the other. Some of the most important of these studies, both geological and geophysical, are essentially “small science”. Consistent funding, unbiased evaluation, and the ultimate integration with the larger initiatives are fundamental challenges that have been, and are still being, addressed in the past and present collaborations that form the precursors to Earthscope.