Generalized Thermal Maturity Map of Alaska

The files in this directory are those that were used to create the Generalized Thermal Maturity Map of Alaska (USGS Miscellaneous Investigations Map I-2494), published in 1996. These files are necessary for importing the map in digital form into a Geographical Information System. Output files in several formats also are included in this directory; these can be used any time a digital version of the complete map is needed.
The map is based, in large part, on the vitrinite-reflectance (VR) and
conodont color-alteration-index (CAI) data in USGS Open-File Report 92-409, an
updated version of which also is included on this CD-ROM.

Alaska is a complex amalgamation of tectonic blocks with diverse histories. Sedimentary basins that are formed on these blocks both before amalgamation and as a result of collisions between them record the tectonic history of this complex region. Thermal-maturity data-indicators of maximum burial temperatures-provide important constraints both on basin evolution and on terrane amalgamation. To help elucidate these relations, and to provide constraints for hydrocarbon assessments, the U.S. Geological survey (USGS) has compiled thermal-maturity data from Alaska for many decades. This report is a digital release of our current understanding of thermal-maturity patters in Alaska.

The 10 ARC/INFO coverages used to construct the map, together with the directory "INFO" (needed by ARC/INFO to support the coverages), are found in the "coverages" subdirectory. These coverages can be used by any GIS capable of importing files in ARC/INFO format.

Export version of these coverages are found in the subdirectory "export files." These files can be imported into ARC/INFO with the "import" command.

Shapefile versions of 9 of the ARC/INFO coverages are found in the subdirectory "shapefiles." Each shapefile actually consists of three files, with extensions .shp, .shx., and .dbf; all are needed for importation into a GIS supporting the shapefile format.

Inset figures and text, as well as the map title, headers, and latitude-longitude ticks, were created as a separate file. This file is available in Adobe Illustrator 6.0 format (insets.ill) and in Encapsulated PostScript format (insets.eps) in the subdirectory "insetfigures."

The subdirectory "miscfiles" contains many important files needed to use these coverages in ARC/INFO or another GIS.