From pattern to process on the deep ocean floor: A geographic information system approach.

摘要

This dissertation explores a synergism between the disciplines of physical geography and marine geology. A major emphasis is the manipulation of geological data with conventional geographic techniques in order to optimize the information content of the data and the resulting interpretations.; Marine geological data collected along the crest of the East Pacific Rise at {dollar}9spcirc12spprime{dollar}-54{dollar}spprime{dollar}N with the Argo I deep-towed, photographic/acoustic vehicle are processed and displayed in a geographic information system (GIS). GIS and statistical analyses establish the abundance, widths, and spatial distribution of crustal fissures, as well as the spatial distribution of hydrothermal vents and the relative age distributions of lava flows. The distributions of these fine-scale features provide spatial and temporal constraints for a qualitative process model in which individual 5-15 km-long segments of the ridge are in different phases of a volcanic-hydrothermal-tectonic cycle.; Simple numerical models from fracture mechanics are used to estimate the depths of the fissures observed along the East Pacific Rise crest from measurements of their widths. The results suggest that wide cracks are presumably the deepest, are primarily eruptive, and may be associated with the inflation of an axial magma chamber. Narrow cracks are presumably the shallowest, are primarily tectonic, and are associated with far-field plate stresses.; The successful demonstration of GIS as an enabling technology for science, begs the question of "the science of GIS." The ongoing "tool versus science" debate regarding GIS is summarized and interpreted. The implications are discussed regarding the increased effectiveness of GIS in either capacity as tool or science.; Realization of the multidimensionality and problem-solving potential of a GIS, revealed the need for the expansion of a primarily land-based GIS research agenda to the development of systems focusing more on the marine environment. GIS application domains and data models are discussed in light of the unique characteristics of deepsea oceanographic data that a GIS is particularly suited to handle and optimize. The scope of GIS functionality for oceanography is assessed in terms of strengths and weaknesses. A case study of a deepsea geological application is presented, with reference to specific successes and challenges.