Collaborative Research: Have Ridge Volumes Changed Over the Past 160 Ma?

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Kominz0418076This project describes and quantifies the long-term pattern of eustatic sea level change during the last 120 million years using plate tectonic reconstructions of the ocean basins. Estimates of Cretaceous eustatic sea level as a result of changing ocean ridge volume and the data on which they were based have been a cornerstone of many studies of stratigraphy, tectonics and climatology. Recent improvements global databases and controversy surrounding the older results allow a new, more systematic assessment and new calculations of ridge volumes through time. This project is generating plate tectonic reconstructions for 14 time intervals back to 120 Ma. New age vs. depth relations for seafloor are determined including: 1) Sediment unloading; 2) Pure age vs. depth relation; and 3) Observed age vs. depth relation. These anomalous features take up ocean volume and impact sea-level change. These calculations include estimates of changing area of continents through stretching of continental crust due to breakup, and of compression and shortening of continental crust to determine their effect on ocean volume. The impact of oceanic volcanism in the form of large igneous provinces hot spots is estimated. Broader Impacts:Understanding the history of eustatic sea level change is fundamental to the study of stratigraphy, sequence stratigraphy, facies analysis, paleogeography, hydrocarbon formation and accumulation, global climate change, the evolution of the cryosphere, the changing composition of the atmosphere and biogeography. The effects of sea level fluctuations touch nearly every aspect of sedimentary geology and Earth System evolution.At least 5 students (both undergraduate and PhD) are active participants in the research and in dissemination of the results at regional and national meetings. The paleogeographic maps are resources for the scientific community both as base maps for future research and as teaching tools. Data and results compiled for this study are available to the public through data base storage available on the world wide web or at cost on CD.(Collaborative Project with 0418395/Scotese/University of Texas at Arlington)