Procedures_Used: The linework was digitized in 1997 from a paper copy of the 1996 map at the U.S. Geological Survey's Alaska Section (Geologic Division) facilities in Anchorge, AK. The original Transverse Mercator projection of the map (Central Meridian: 100*W; Scale factor: 0.926; Reference ellipsoid:(6371204m, 63712004m)) was converted to an Albersequal-area coverage in ARC/INFO (version 7.1.2). The resulting coverage did not align exactly with an Albers equal-area coverage of the Alaskan coastline, so a rubber-sheeting operation was performed using points along the coastline and major rivers to match an Albers equal area projection. Map unit (polygon) locations and attributes were checked by the person responsible for the digitizing, and spot-checked by one reviewer reviewer, by comparing a printed copy of the coverage to the published map. Metadata were collected using document.aml v. 7.1.1, distributed by ESRI, Inc.
Revisions: None completed or planned.
Reviews_Applied_to_Data: See Procedures_Used.
Related_Spatial_and_Tabular_Data_Sets: MATURITY.DAT (see Entity_and Attribute_Information). The item "MATURITY" can be used to establish relates.
Other_References_Cited: Johnsson, M.J., and Howell, D.G., compilers, 1996, Generalized Thermal Maturity of Alaska, U.S. Geological Survey Miscellaneous Investigations Map I-2494. Scale 1:2,500,000.
Johnsson, M.J., and Howell, D.G., Eds., 1996, Thermal Evolution of Sedimentary Basins in Alaska-U.S. Geological Survey Bulletin 2142, U.S. Government Printing Office, Washington, D.C., 131p.
Johnsson, M.J., Pawlewica, M.J., Harris, A.G., and Valin, Z.C., 1992, Vitrinite reflectance and conodont color alteration index data from Alaska: Data to accompany the Thermal Maturity Map of Alaska: U.S. Geological Survey Open File Report 92-409, 3 Macintosh-formatted 3 1/2" high density (1.44 Mb) diskettes.
Notes: The completeness and quality of the generalized maturity data in the digital coverage is that of the published 1996 map, which itself summarized data released in 1992 and collected prior to that date (mainly since 1980). No recent data have been added. The geographic accuracy of the published map has been slightly degraded by the rubber-sheet operation.
MATURITY.PAT COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? 1 AREA 4 12 F 3 - 5 PERIMETER 4 12 F 3 - 9 MATURITY# 4 5 B - - 13 MATURITY-ID 4 5 B - - 17 MATURITY 4 4 C - - 21 CERTAINTY 2 2 C - -Possible 'MATURITY' values defined as:
U = Undermature M1 = Mature I M2 = Mature II O = Overmature S = Supermature Ig-M = Igneous-Metamorphic Qs = Quaternary sediments (unconsolidated) ND = No data
Possible 'CERTAINTY' values defined as:
C = Certain Q = Questioned
MATURITY.DAT COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME INDEXED? 1 MATURITY 4 4 C - - 5 RO-MIN 4 4 N 2 - 9 RO-MAX 4 4 N 2 - 13 CAI-MIN 4 4 N 2 - 17 CAI-MAX 4 4 N 2 -
Record MATURITY RO-MIN RO-MAX CAI-MIN CAI-MAX 1 U 0.10 0.60 1.00 1.00 2 M1 0.61 1.30 1.50 2.00 3 M2 1.31 2.00 2.50 3.00 4 O 2.01 3.50 3.50 4.00 5 S 3.51 5.00 4.50 4.50 6 Ig-M 5.01 8.00 5.00 8.00 7 Qs 0.00 0.01 0.00 0.10