The Assessment Unit is the fundamental unit used in the World Petroleum Resources Project. The Assessment Unit is defined within the context of the higher-level Total Petroleum System. The Assessment Unit is shown here as a geographic boundary interpreted, defined, and mapped by the geologist responsible for the province and incorporates a set of known or postulated oil and (or) gas accumulations sharing similar geologic, geographic, and temporal properties within the Total Petroleum System, such as source rock, timing, migration pathways, trapping mechanism, and hydrocarbon type. The Assessment Unit boundary is defined geologically as the limits of the geologic elements that define the Assessment Unit, such as limits of reservoir rock, geologic structures, source rock, and seal lithologies.
This shapefile includes arcs and polygons that describe U.S. Geological Survey defined 33 geologic provinces of the Circum-Arctic (north of the Arctic Circle). Each province has a set of geologic characteristics distinguishing it from surrounding provinces. These characteristics may include the dominant lithologies, the age of the strata, and the structural style. Some provinces include multiple genetically-related basins. Resource-assessments are conducted by research scientists of the U.S Geological Survey's World Petroleum Resource Project by means of a combination of Total Petroleum System analysis based on available geologic information, and statistical analysis of production and exploration information. Total Petroleum Systems are defined in provinces considered for assessment analysis. Total Petroleum Systems are subdivided into Assessment Units. Assessment results from the analysis of assessment units and total petroleum systems are aggregated and allocated to geologic provinces. Summary results are presented as attributes of this shapefile`.