Geology of the Gila Wilderness-Silver City area最新文献

{"title":"Soil-geomorphic setting and change in prehistoric agricultural terraces in the Mimbres area, New Mexico","authors":"J. Sandor, J. Hawley, Robert H. Schiowitz, P. L. Gersper","doi":"10.56577/ffc-59.167","DOIUrl":"https://doi.org/10.56577/ffc-59.167","url":null,"abstract":"A BSTRACT — Soil-geomorphic relationships at some prehistoric agricultural terrace sites in the Sapillo and Mimbres Valleys in southwestern New Mexico were investigated to learn about agricultural management in this semiarid mountainous region, evaluate soil productivity, and determine long-term effects of agriculture on the physical environment. The sites, farmed during the Mimbres Classic period (AD 1000 to 1130), occur within certain geomorphic settings, implying strategies to optimize local climatic and hydrologic conditions for runoff agriculture. The landscape was modified by terracing, which served to reduce runoff velocity, increase soil moisture, and thicken naturally thin soil A horizons. Comparison of these prehistoric agricultural soils with nearby uncultivated soils that are similar in geomorphic setting and degree of development show that significant differences in soil properties still exist, nearly nine centuries after farming ceased. Soil changes resulting from the prehistoric agriculture mostly involved degradation, including accelerated erosion, compaction, and reduced concentrations of nutrients such as nitrogen and phosphorus. Despite soil degradation, maize growth in these soils indicates favorable productivity with nitrogen inputs and improved soil conservation.","PeriodicalId":382579,"journal":{"name":"Geology of the Gila Wilderness-Silver City area","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127666862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoclimatic implications of stable oxygen and carbon isotopes of lacustrine and pedogenic calcite from the Gila Conglomerate (Plio-Pleistocene), Mangas Basin, west-central New Mexico","authors":"G. Mack, N. Tabor","doi":"10.56577/ffc-59.159","DOIUrl":"https://doi.org/10.56577/ffc-59.159","url":null,"abstract":"A BSTRACT — Stable carbon and oxygen isotopes of lacustrine (ancient lake Buckhorn) and pedogenic calcite of the Gila Formation (Plio-Pleistocene) in the Mangas Basin, west-central New Mexico, provide information about paleoclimate when compared to similar data from coeval strata in the southern Rio Grande rift near Las Cruces and in the Basin and Range of southeastern Arizona, as well as to modern calcite predicted to precipitate at the sites of the ancient strata. The pedogenic and lacustrine δ 18 O values from the ancient strata are more positive than those calculated for corresponding modern sites, implying the existence of air masses whose precipitation was enriched in 18 O and/or greater evaporation of lake and soil water during Plio-Pleistocene time compared to today. Although δ 18 O values of pedogenic calcite are similar among the ancient strata, the δ 13 C values of the Gila Formation are more negative, suggesting a higher proportion of C 3 plants in the Mangas Basin commen-surate with cooler and wetter conditions at higher elevation. Differences in δ 13 C values of pedogenic calcite within the Mangas basin may have resulted from higher water table and concomitant higher percentage of C 3 plants on the river floodplain than on the alluvial fans. The δ 18 O and δ 13 C values of lake-center ooid limestones of the Gila Formation are more positive than those of the other ancient strata, which could have occurred if lake Buckhorn received precipitation enriched in 18 O, had higher rates of evaporation, and/or precipitated limestones during times of diatom and/or algal blooms. In contrast, lake-margin ooid and ostracode limestones of the Gila Formation have significantly lower values of δ 18 O and δ 13 C compared to the other ancient sites and to the lake-center limestones of the Gila Formation. The low δ 18 O values imply that lake-margin sites may have been influ- enced by water from high-elevation catchments and/or by geothermal waters entering lake Buckhorn via a buried fault, while precipitation of lacustrine calcite during periods of low biological productivity could have produced the low δ 13 C values.","PeriodicalId":382579,"journal":{"name":"Geology of the Gila Wilderness-Silver City area","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132471461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-bearing properties of selected geologic materials in mining areas of Grant County, New Mexico","authors":"L. C. Kilner","doi":"10.56577/ffc-59.199","DOIUrl":"https://doi.org/10.56577/ffc-59.199","url":null,"abstract":"","PeriodicalId":382579,"journal":{"name":"Geology of the Gila Wilderness-Silver City area","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124083330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for large-scale Laramide tectonic inversion and a mid-Tertiary caldera ring fracture zone at the Lightening Dock geothermal system, New Mexico","authors":"J. Witcher","doi":"10.56577/ffc-59.177","DOIUrl":"https://doi.org/10.56577/ffc-59.177","url":null,"abstract":"Stratigraphy in a recent intermediate depth (2100 ft) geothermal test hole is interpreted along side previous deep (7001 to 7404 ft depth) exploration holes to study large-scale structural controls for the Lightning Dock geothermal system and refine the stratigraphic and structural characterization of the shallow reservoir. Laramide compression and large-scale tectonic inversion of a northwest-trending Late Jurassic-Early Cretaceous extensional structure at the Lightning Dock geothermal site represents deformation that may exceed Neogene extensional processes in magnitude and duration and provide potential for a significant volume of shattered rock. Also, volcanic stratigraphy supports the hypothesis of Elston et al. (1983) for a midTertiary caldera ring fracture zone in the vicinity the geothermal area. Northeastand north-trending Neogene normal faults that cross cut older structures provide additional preparation of fractured ground. A north-trending Pleistocene normal fault may reopen older fractures that are favorably oriented and allow concentration and upward flow of deep-seated geothermal fluids. Because the Lightning Dock geothermal system is “blind” and has no surface manifestations, a better understanding of structures buried beneath Neogene alluvial basin fill may have application in geothermal exploration to find similar “blind” geothermal systems elsewhere in southern New Mexico and southeastern Arizona. FIGURE 1. Shaded relief topographic location map of the Lightning Dock geothermal area.","PeriodicalId":382579,"journal":{"name":"Geology of the Gila Wilderness-Silver City area","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123752011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}