Approximately 1,800 geophysical logs and 100 measured sections provided data for several types of isopleth maps of the Westwater Canyon and Brushy Basin Members of the Upper Jurassic Morrison Formation in the southern San Juan basin, New Mexico. These types of maps include: isopach, sandstone:mudstone ratio, percent sandstone, net sandstone, and average number of mudstone interbeds per 100 ft (30 m) of section. We also constructed a paleotopographic map on the base of the Westwater Canyon and a structure contour map on the base of the Upper Cretaceous Dakota Sandstone.

These maps illustrate depositional unit geometry, sandstone depocenter distribution, and large-scale lithofacies variations within the units. The Westwater Canyon is thinner and less sandy over paleotopographic highs and is thicker and sandier along paleotopographic lows, which suggests active structural control of facies distribution during deposition. Sedimentation of the Brushy Basin Member was also affected by some of the same active structural elements. Detailed reflection seismic studies have defined basement faults that were periodically reactivated since the Precambrian. These faults exerted a significant influence on depositional patterns in the Morrison Formation.

Primary uranium ore in the Westwater Canyon Member is restricted to sandstone depocenters associated with east-southeast-trending isopach thicks. Remnant ore deposits are relict primary deposits that lie in oxidized ground updip from a regional oxidation-reduction (redox) interface. Sedimentologic controls seem to be similar to those for primary ore, and in general these deposits have been preserved from oxidation by stratigraphic variations and by structures. Redistributed ore deposits are also concentrated in the vicinity of isopach thicks, but in rocks with relatively low sandstone:mudstone ratios. However, the location of redistributed ore is much more closely related to the position of the regional redox interface. The geographic form of this interface was influenced regionally a d locally by Laramide structures.

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