INTEGRATING STRUCTURAL, PETROLOGIC, GEOCHRONOLOGIC, AND GEOPHYSICAL DATA FOR TECTONIC ANALYSIS OF CONTINENTAL CRUST

Crustal cross-sections and isobaric sections are essential for investigating the evolution of continental crust, and crustal processes through time. These natural laboratories reveal the complex interaction of deformation, metamorphism, and material properties that represent the critical input data for the geological and geophysical models. It is essential to compile data from a number of such exposures as a general resource for future workers. However, the integration of textural, structural, spatial, mineralogical, and compositional data tends to involve user-specific requirements, such that new data sets (involving new field excursions, new samples, and new analyses) are typically undertaken for each new research initiative. This is inefficient and increasingly impractical. We present examples from isobaric sections in northern Canada (deep crust) and the southwestern USA (mid crust) that show the types of data needed to characterize 4-dimensional tectonic processes in these terrains, and also the types of data that must be archived in order to be useful to future researchers. The granulite facies East Athabasca area, Saskatchewan, provides a view of the deep crust (1.0-1.2 GPa) from ~2.5 Ga to at least 1.9 Ga. Proterozoic rocks in the southwestern USA provide a view of the middle crust (0.4-0.6 GPa) from at least 1.65 Ga to 1.4 Ga. Both terrains preserve multiple deformation and metamorphic events during prolonged residence in the crust, and both regions are characterized by heterogeneity at scales from the map to the thin section. Different parts of the tectonic history are preserved in different lithologies and structural settings, and older structures are reactivated by younger events, all leading to a blurred composite view of crustal evolution. Integrated structural, petrologic, and in-situ geochronologic data are essential to deconvolute the tectonic history and to create time slices of crustal configuration and crustal behavior. For present and future analysis of these linked data sets, it is critical that raw data be integrated with raw images and map interpretations in a way that the data can be resampled and reinterpreted without bias. Analysis and archiving of linked data sets must involve the same tools in order to insure data storage and value to future workers.