Geologic analysis and evaluation of ERTS-A imagery for the state of New Mexico

There are no author-identified significant results in this report

Geologic analysis and evaluation of ERTS-A imagery for the State of New Mexico

There are no author-identified significant results in this report

Geological analysis and evaluation of ERTS-A imagery for the state of New Mexico

The author has identified the following significant results. Coverage of approximately one-third of the test site had been received by January 31, 1973 and all of the images received were MSS products. Images recorded during the first two months of the ERTS-1 mission were of poor quality, owing largely to high ground reflectance. Later images were of better quality and MSS bands 5 and 7 have proven to be particularly useful. Features noted during visual inspection of 9 1/2 x 9 1/2 prints include major structural forms, vegetation patterns, drainage patterns, and outcrops of geologic formations having marked color contrasts. The Border Hills Structural Zone and the Y-O Structural Zone are prominently reflected in coverage of the Pecos Valley. A study of available maps and remote sensing material covering the Deming-Columbus area indicated that the limit of detection and the resolution of MSS products are not as good as those of aerial photographs, geologic maps, and manned satellite photographs. The limit of detection of high contrast features on MSS prints is approximately 1000 feet or 300 meters for linear features and about 18 acres for roughly circular areas

Geologic analysis and evaluation of ERTS-A imagery for the State of New Mexico

The author has identified the following significant results. Many circular to elliptical features have been identified on the ERTS-1 images, only some of which can be accounted for by existing data. A small number of circular features are adjacent to existing ore deposits, but such relationships should not be emphasized unless other supporting data exists. Circular features may be tectonically or geomorphically controlled, or a combination of the two. A limited number are man-made. A preliminary listing of features which may have circular expression are listed. Photographic examples of identified and unidentified circular features will be included in the final report along with a thorough discussion and analysis. Comparisons will be made with existing gravity and magnetic data

Earth resources evaluation for New Mexico by LANDSAT-2

The author has identified the following significant results. The Middle Rio Grande project has not yet progressed to the point where mineral exploration sites can be chosen; however, there does appear to be some correlation between the known structure and mineral deposits and the LANDSAT lineament map. A circular feature identified in the southern Magdalena Mountains on LANDSAT-1 imagery agrees well with the location of a newly proposed caldron complex. Several recognized and unrecognized circular features were identified on imagery of the Mogollon-Datil volcanic field. A check of aeromagnetic maps for New Mexico found that the circular features on the LANDSAT imagery showed up as areas of generally high magnetic intensity

Geologic analysis of ERTS-1 imagery for the State of New Mexico

There are no author-identified significant results in this report

Provenance of Cretaceous through Eocene strata of the Four Corners region: Insights from detrital zircons in the San Juan Basin, New Mexico and Colorado

Cretaceous through Eocene strata of the Four Corners region provide an excellent record of changes in sediment provenance from Sevier thin-skinned thrusting through the formation of Laramide block uplifts and intra-foreland basins. During the ca. 125–50 Ma timespan, the San Juan Basin was flanked by the Sevier thrust belt to the west, the Mogollon highlands rift shoulder to the southwest, and was influenced by (ca. 75–50 Ma) Laramide tectonism, ultimately preserving a >6000 ft (>2000 m) sequence of continental, marginal-marine, and offshore marine sediments. In order to decipher the influences of these tectonic features on sediment delivery to the area, we evaluated 3228 U-Pb laser analyses from 32 detrital-zircon samples from across the entire San Juan Basin, of which 1520 analyses from 16 samples are newly reported herein. The detrital-zircon results indicate four stratigraphic intervals with internally consistent age peaks: (1) Lower Cretaceous Burro Canyon Formation, (2) Turonian (93.9–89.8 Ma) Gallup Sandstone through Campanian (83.6–72.1 Ma) Lewis Shale, (3) Campanian Pictured Cliffs Sandstone through Campanian Fruitland Formation, and (4) Campanian Kirtland Sandstone through Lower Eocene (56.0–47.8 Ma) San Jose Formation. Statistical analysis of the detrital-zircon results, in conjunction with paleocurrent data, reveals three distinct changes in sediment provenance. The first transition, between the Burro Canyon Formation and the Gallup Sandstone, reflects a change from predominantly reworked sediment from the Sevier thrust front, including uplifted Paleozoic sediments and Mesozoic eolian sandstones, to a mixed signature indicating both Sevier and Mogollon derivation. Deposition of the Pictured Cliffs Sandstone at ca. 75 Ma marks the beginning of the second transition and is indicated by the spate of near-depositional-age zircons, likely derived from the Laramide porphyry copper province of southern Arizona and southwestern New Mexico. Paleoflow indicators suggest the third change in provenance was complete by 65 Ma as recorded by the deposition of the Paleocene Ojo Alamo Sandstone. However, our new U-Pb detrital-zircon results indicate this transition initiated ∼8 m.y. earlier during deposition of the Campanian Kirtland Formation beginning ca. 73 Ma. This final change in provenance is interpreted to reflect the unroofing of surrounding Laramide basement blocks and a switch to local derivation. At this time, sediment entering the San Juan Basin was largely being generated from the nearby San Juan Mountains to the north-northwest, including uplift associated with early phases of Colorado mineral belt magmatism. Thus, the detrital-zircon spectra in the San Juan Basin document the transition from initial reworking of the Paleozoic and Mesozoic cratonal blanket to unroofing of distant basement-cored uplifts and Laramide plutonic rocks, then to more local Laramide uplifts.National Science Foundation (NSF grant EAR-1649254

Floodwater farming, discontinuous ephemeral streams, and Puebloan abandonment in southwestern Colorado

Geoarchaeological study on the southern piedmont of Sleeping Ute Mountain in southwestern Colorado indicates the presence of discontinuous ephemeral streams that were the foci of episodic Puebloan occupation between A.D. 600s and 1280. Characterized by arroyos, discontinuous ephemeral streams contain alternating aggrading and degrading reaches and are well suited for ak chin floodwater agriculture. Episodic Puebloan abandonment of the southern piedmont correlates with periods of drought but does not appear to be linked to stream entrenchment. We question a priori assumptions of droughts correlated to stream entrenchment and urge caution in the use of drought-arroyo models for settlement shifts in alluvial flood plains without supporting stratigraphic or geomorphic evidence