9706388 McNutt One of the outstanding problems in continental tectonics is the deep structure of continental strike-slip faults. By simple oceanic analogy, they might be vertical fault planes cutting the entire lithosphere and providing a sharp focus for strain between drifting plates. On the other hand, they may sole out into dipping detachments in the lower crust that decouple the motions mapped from surface geology and geodesy from those in the deeper mantle lithosphere. To distinguish between these two end-member models, the PI will conduct a gravity survey of two long transects across the Altyn Tagh, a major continental strike-slip fault separating the Tibet Plateau from the Tarim Basin in southwestern China. The large topographic relief across this fault makes it the ideal place to use very simple gravimetric techniques to determine whether or not the Altyn Tagh cuts the mantle lithosphere and what is the state of stress on the fault. ***
