The objective of this research is an intensive study of the crust in the transition zone from the stable Colorado Plateau to the extended Basin and Range province. We will rely primarily on recently collected seismic reflection data - data collected as a "piggyback" experiment to the U.S. Geological Survey PACE (Pacific to Arizona Crustal Experiment) refraction survey in Arizona -- although the data will be supplemented and integrated with existing COCORP (Consortium on Continental Reflection Profiling) data. The four areas of proposed research include: 1) a P-wave structural interpretation of the transiton zone emphasizing the lower crust and Moho, 2) an analysis of the unusually reflective upper crust seen on indsutry and COCORP data, as well as the new data, 3) a study of wide-angle and fan profiles collected in the piggyback experiment and 4) analysis and interpretation of 3- component data from the new experiment with an emphasis on crustal composition derived from P and S velocities. The piggyback reflection data are uniquely suited to study the transition zone because of the excellent data quality and close trace spacing of the survey.
