US-Switzerland Cooperative Research: Seismic Modeling of Reflective Structures in the Alps and Implications for Orogenic Structure

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This award supports Professor Larry Brown and others of Cornell University to collaborate in geophysics with Professor Jean-Jacques Wagner of the Laboratory of Petrophysics, University of Geneva, and Professor Raymond Oliver, Institute of Geophysics, University of Lausanne. The objective of their joint research is to develop new, more detailed geologic models of orogenic structure by computer modeling of deep seismic data recently collected across the Alps by the Swiss researchers, with support from the Swiss National Science Foundation. The combination of exposure, thorough mapping, availability of multiple seismic lines, and tectonic history make the Alps perhaps the most promising starting point for more quantitative comparative studies of deep structure of orogens as revealed from reflection profiling. Later, the Swiss results will be compared with similar deep structures in Paleozoic and Precambrian orogenic belts in the U.S., which were surveyed under a multi-institutional deep seismic program operated by Cornell University on behalf of COCORP (the Consortium for Continental Reflection Profiling.) Deep seismic reflection profiling has become a standard tool in the investigation of crustal structure. Yet debate persists concerning the actual cause of deep reflectivity. An important development in this field is the relatively recent acquisition of seismic surveys across young mountain belts where a) structures are particularly well exposed and b) reflection patterns can be traced to considerable depth. The Alpine system is perhaps the best example of such a system. Preliminary three dimensional seismic modeling by the Swiss of known Alpine structures, and their extrapolations to depth have proven to be an effective interpretational tool in providing a quantitative test of hypothesized structure in this active region. By analogy, considerable light may be shed upon the crustal architecture of older mountain belts where deep structural interpretations have been more cryptic. Thus this work may make the Alps a prototype for intercontinental collisions and a laboratory for calibration of deep seismic reflection data elsewhere.