9633114 Collins This project supports researchers from Woods Hole Oceanographic Institution in Massachusetts to conduct a series of experiments at two sites in the North Atlantic Ocean to understand the processes involved in growth of the Mid-Atlantic Ridge. Specifically, the investigators will measure the reflected and refracted arrivals of seismic energy from small explosive charges near the bottom over sections of the mid-ocean ridge spreading center which have known, previously sampled, rock compositions. They will then apply the results of their seismic experiment to a) identify and b) map rock types across these two sections of the Mid-Atlantic Ridge, to test existing models for subsurface ridge structure. The technique will, if successful, provide the first 3-dimensional map of the structure of a slow-spreading mid-ocean ridge, which is predicted to differ in several key aspects from the faster-spreading mid-ocean ridge systems previously studied in this manner in the Pacific Ocean. The experiment will, also, provide the first field test of the use of high resolution seismic velocity data to discriminate among gabbros, serpentinites and basalts in the upper kilometer of an active spreading center. Again, if successful this will provide an opportunity to map regions of unknown surface lithology using the seismic technique alone. ***
