This dataset consists of a polygon coverage and associated attribute data derivedfrom the onshore portion of the 1996 "Generalized
Thermal Maturity Map ofAlaska" compiled by M.J. Johnsson and D.G. Howell, which was published as Plate 1in US Geological
Survey Bulletin 2142: "Thermal Evolution of Sedimentary Basins in Alaska".The published map summarizes vitrinite
reflectance and conodont alteration index data(both measure the thermal maturity of rocks) into generalized units that can
be showncartographically at 1:2,500,000. This digital dataset includes the 8 map units indicated on theoriginal map. (5 thermal
maturity levels; 2 rock or sediment type; 1 "no data").The data quality of the generalized information is retained,
with an attribute valuefor "certainty" whose value choices are "questioned" or "certain". Additional
dataretained in a look-up table are the maximum and minimum vitrinite reflectance andconodont alteration index values assigned
to each thermal maturity level.This coverage is not intended to be a complete representation of the printedmap. It does NOT
include the following features: locations of individualvitrinite or conodont sample data points (these data are available
in: Johnsson andothers, 1992, USGS Open File Report 409, 3 diskettes); faults; offshore maturity data(from dredge and well
samples); cities, glaciers, wells; inset maps and subsurfacecontours for the Colville basin and Cook Inlet; the correlation
chart, text orreferences printed on the map.
other Citation Details
Cinergi keyword enhanced at Tue Jan 17 12:59:42 UTC 2017
purpose:
This coverage is intended to provide digital features (polygons) representinggeneralized thermal maturity units in Alaska
for use in small-scale spatial analysis(statewide) with similar coverages such as geologic units,vegetation types, soils,
etc.Johnsson, M.J., Pawlewica, M.J., Harris, A.G., and Valin, Z.C., 1992, Vitrinitereflectance and conodont color alteration
index data from Alaska: Data to accompanythe Thermal Maturity Map of Alaska: U.S. Geological Survey Open File Report 92-409,
3Macintosh-formatted 3 1/2" high density (1.44 Mb) diskettes.