Subsurface geology of the upper Cretaceous Kirtland and Fruitland formations of the San Juan Basin, New Mexico and Colorado
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Abstract
The San Juan Basin is an asymmetrical structural basin in northwestern New Mexico and southwestern Colorado. The basin contains sedimentary rocks ranging from Cambrian through Recent in age and attaining a maximum thickness between 14,000 and 15,000 feet. The Upper Cretaceous sedimentary rocks exceed 8,000 feet in thickness and can be divided into two groups: the lower Upper Cretaceous which is composed of the non marine and non-marine rocks and the upper Upper Cretaceous which is composed of the non-marine Kirtland and Fruitland Formations. The Kirtland Shale is subdivided into the lower shale, Farmington Sandstone, and upper shale members.
The rocks of the Kirtland and Fruitland Formations consist of fluviatile and flood plain deposits and range in thickness from 1750 feet in the northwest part of the basin to 0 feet on the eastside of the basin. The thinning of the Kirtland and Fruitland Formations from west to east is primarily the result of erosion following tilting of the San Juan Basin area toward the west after either part or all of the upper shale member had been deposited. The overlying Ojo Alamo Sandstone rests on progressively older rocks across the basin overstepping the under lying upper shale member, Farmington Sandstone Member, Fruitland Formation, and finally resting on the Lewis Shale on the east side of the basin. The source area for the rocks of the Kirtland and Fruitland Formations was probably to the north or northwest of the San Juan Basin area.
The Kirtland and Fruitland rocks have produced minor amounts of oil and gas. The Fruitland Formation contains large coal deposits some of which are currently being strip mined near Fruitland, New Mexico
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Subsurface geology of the upper Cretaceous Kirtland and Fruitland formations of the San Juan Basin, New Mexico and Colorado |
| Series title | Open-File Report |
| Series number | 64-53 |
| DOI | 10.3133/ofr6453 |
| Year Published | 1964 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Description | Report: 93 p.; 12 Plates: 48.29 x 25.08 inches or smaller |
| Country | United States |
| State | Colorado, New Mexico |
| Other Geospatial | San Juan Basin |