Abstract:
We have applied the CHRONOS model in a pilot study for our GeoMapApp database browser. For implementation we have digitized the bulk of Lamont-Doherty's single channel seismic reflection profiles for the Southern Ocean around Antarctica and for the North Atlantic Ocean. These data were acquired between 1960 and 1980. To this dense set of tracks that commonly image the sediment cover down to the volcanic bedrock of the oceanic crust, we have added relational tables containing biostratigraphic and lithostratigraphic summary information from the early Deep-Sea Drilling Project (Legs 1 to 49). For each drill hole a "chronos" table assigns age and age uncertainty in millions of years to every subsurface depth. From subsurface depth additional links are made to tables that describe the core sections, biozones, the dominant and minor lithologies, key and secondary constituents, carbonate and silica estimates, and sedimentation rate. The initial "chronos" table that assigns age to depth requires decisions of members of our team. Since calibrations might vary from investigator to investigator, users of the database have the ability to enter their own "chronos" tables instead. The eventual goal is to have a participatory user community interactively create and edit the "chronos" tables and rank them with a measure of community-acceptance in order to aid the non-expert. The GeoMapApp WEB browser displays the tracklines on a bathymetry basemap to which basement isochrons can be added. A click on any track brings up the selected reflection profile in a sub-window. Movement of the cursor along the profile displays latitude, longitude, depth, sediment thickness, and basement age. Tools exist to digitize the bedrock reflector or any other reflector of choice and save these values for others. A click on a drill site displays a drill site summary diagram. Selecting a geological time interval (such as 67 + or - 2 my) in a search menu lights up every drill site location on the basemap with colored-symbols representing the dominantly lithology. When the cursor is placed at the drill site, a popup window display additional information relevant to that time interval. Our pilot study is to learn the degree to which such interactive tools aid future syntheses of the Ocean Drilling Project and lead to new discoveries.