COMPILATION OF A PRECAMBRIAN BASEMENT MAP AND GEODATABASE OF SOUTH DAKOTA

The primary goal of this project is to generate a new geologic map of the Precambrian basement of South Dakota and secondly, the creation of a Precambrian geodatabase using Geographical Information System (GIS) software that will serve as a unique research tool for additional studies into this very important region.

The Precambrian geology and tectonic evolution of the Northern Great Plains remains speculative. A blanket of Phanerozoic rocks covers much of the area and restricts basement mapping to the use of drill core, geophysical evidence, and comparatively small exposures such as the Black Hills, South Dakota. The Precambrian basement of South Dakota consists of five major tectonic elements that are the building blocks of the central North American continent. These are the Wyoming and Superior cratons (Archean) and the Trans-Hudson, Central Plains, and Penokean Orogens (Proterozoic).

This project is part of a much broader effort to understand the lithospheric characteristics of the Great Plains. It is important to compile existing information on basement lithologies, structures, and tectonic boundaries before further studies are undertaken. This compilation differs from previous works because of the wide scope of information it includes and the use of GIS to analyze the data. For the first time, many older maps are being updated to a digital format that can be supplemented with recently published datasets. Some of the types of data included in this geodatabase are: digitized basement maps, newly published gravity and magnetic grids, historical earthquake epicenters, surface geology, available basement drill hole data (lithology, ages, and geochemistry), Shuttle Radar Topography Mission (SRTM) data, and available seismic profiles. The GIS analysis was essential for classifying basement geology using such variegated information. The result is a much more accurate map than could be produced by subjective interpretations.