A PETROLOGIC AND GEOCHRONOLOGIC DATABASE OF PLUTONS FOR STUDYING THE 4-D EVOLUTION OF CONTINENTS: A GIS BASED GEOINFORMATICS PROGRAM

Studies of magmatic processes in geoscience research provide fundamental information on the physical and chemical evolution of continents through time. Diverse tectonic processes of collision, extension and transpression leave a rich geologic record saturated with igneous rocks amenable to GIS based data management. Because this record of continental growth is often the result of multiple events, large, high-resolution datasets are required to address questions of rates and periodicity of such events. We are constructing a GIS based database architecture on plutons and their ages from the Appalachian orogen to discover new relationships between magmatism, crustal evolution and other geologic records preserved in both space and time. In the Appalachian orogen, thermal perturbations are recognized in the plutonic record through its cyclical activity over 750 Ma of earth history. We anticipate such a database will yield correlations between other geologic processes (e.g. style of thrusting, basin development, cooling rates, paleogeothermal gradients, tectonic setting) and will provide a firm basis for a national database on plutons.

We have created a template for Attributes that quantitatively describe field, bulk and mineralogic properties of plutons. The database architecture has been constructed to analyze data at different scales (km - µm). For example, a database of field observations allows for characterization of rock fabrics and textures, while bulk rock data permit assessment of geochemical and isotopic heterogeneities within plutons. At a mineral scale our database provides a structure for both mineral chemistries, and the isotopic record for the crystallization and cooling histories of plutons. For example, SIMS based U/Pb analyses of zircon can be retrieved, viewed, and queried. We also include in our GIS based compilation, errors associated with scale and map transposition, as well as analytical measurements, through metadata links.

This hierarchical data system (cascade of scales) provides us a powerful tool to manage and analyze large amounts of geologic data. The use of a GIS and its associated databases as a geologic tool has allowed us to model the spatial and temporal correlation of magmatic activity to the evolution the Appalachian orogen.