Las Cruces Country III最新文献

{"title":"Oxygen isotope variations in Paleogene volcanic rocks from southern New Mexico: Insight on crustal contamination and magmatic sources","authors":"M. Hoffman, G. Michelfelder","doi":"10.56577/ffc-69.189","DOIUrl":"https://doi.org/10.56577/ffc-69.189","url":null,"abstract":"This study reports oxygen isotope values determined by laser fluorination of mineral separates from basalt through rhyolite composition volcanic rocks erupted from the Rubio Peak and Bell Top formations and the Uvas Volcanic Field. Plagioclase phenocrysts from the Uvas Basalts are altered and have δ18O values of 12.87‰. Pyroxene phenocrysts from the basalts are considered magmatic with δ18O values of 4.29–5.64‰; quartz contains δ18O values of 2.10–7.52‰ and is only found as amygdule filling crystals. Phenocrysts from the Rubio Peak Formation basalts and andesites contain δ18O values of 4.88-5.40‰. Two rhyolite samples from the Bell Top Formation are ash flow tuffs from the Kneeling Nun Tuff and Cooney Canyon Tuff. Plagioclase and quartz phenocryst δ18O values are restricted, ranging from 6.69–6.73‰ and 8.01–8.23‰, respectively. Biotite phenocrysts from these samples exhibit a greater range in δ18O values, from 5.21– 6.18‰. Calculated magmatic δ18O values for the Uvas basalts and Rubio Peak andesites range between 6.12 and 6.40‰ corresponding to fractional crystallization of a primary mantle melt, while Bell Top Formation volcanic rocks exhibit higher δ18O magmatic value of 8.60‰, representing partial melting of a granitic composition crustal source. 189","PeriodicalId":253436,"journal":{"name":"Las Cruces Country III","volume":"39 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":"130865843","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":"Masson Farm Geothermal Greenhouses at Radium Springs: Third�day (C) Road Log from Las Cruces to Geothermal Greenhouses of the Masson Farm at Radium Springs","authors":"J. Witcher, G. Mack","doi":"10.56577/ffc-69.47","DOIUrl":"https://doi.org/10.56577/ffc-69.47","url":null,"abstract":"","PeriodicalId":253436,"journal":{"name":"Las Cruces Country III","volume":"47 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":"130987087","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":"Superposed reverse and normal faults in the central Florida Mountains, southwestern New Mexico, and their implications for post-Cretaceous crustal deforamtion","authors":"T. Lawton, C. Clinkscales","doi":"10.56577/ffc-69.119","DOIUrl":"https://doi.org/10.56577/ffc-69.119","url":null,"abstract":"A bstrAct — At Mahoney Park in the Florida Mountains of southwestern New Mexico, field relations demonstrate several generations of faults that offset basement and the Paleozoic section. The oldest faults have reverse separation; they strike east–west and northwest–south-east. The reverse-separation faults emplaced basement granite over Ordovician strata and Silurian dolostone over Devonian Percha Shale. Younger normal faults with approximate east-west strikes cut basement and strata as young as middle to late Eocene. A major NW-trending, moderately dipping normal fault, termed here the Mahoney Park fault, is either contemporary with the steep faults or post-dates them. The steep faults do not cut the Mahoney Park fault, which emplaces Paleozoic sedimentary rocks on footwall basement syenite and offsets the trace of a major reverse-separation basement fault, the South Florida Mountains fault. The Mahoney Park fault is not expressed in surficial deposits flanking the range, whereas north-trending, range-bounding faults form subdued scarps of several meters on the northwest flank of the range. Regional geologic relations suggest that reverse-separation faults are Late Cretaceous to middle Eocene, both predating and postdating deposition of the middle Paleocene to early Eocene Lobo Formation. Rhyolite and granite dikes with U-Pb and 40 Ar/ 39 Ar ages on groundmass, biotite, and hornblende that range from ~32–25 Ma are emplaced along east-west faults in the Little Hatchet Mountains of southwestern New Mexico and the northern part of the Florida Mountains. The dike ages indicate that the east-west normal faults were active in the Oligocene prior to development of north-trending Basin and Range faults. Some of the extensional faults demonstrably reacti- vated Laramide reverse faults. The Mahoney Park fault may be time equivalent with the Oligocene faults or alternatively may represent an intermediate phase of post-Oligocene, pre-Basin and Range faulting. Exploitation of some Laramide shortening structures by the east-west faults suggests that north-south extension resulted from gravitational collapse of a high-elevation plateau in Oligocene time.","PeriodicalId":253436,"journal":{"name":"Las Cruces Country III","volume":"75 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":"122588980","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":"Constraining timing of extension in the southern Rio Grande Rift and basin and range using apatite and zircon (U-Th)/He thermochronology","authors":"J. Biddle","doi":"10.56577/ffc-69.127","DOIUrl":"https://doi.org/10.56577/ffc-69.127","url":null,"abstract":"A bstrAct — We sampled rocks for zircon (ZHe) and apatite (AHe) (U-Th)/He thermochronology from seven mountain ranges across the Rio Grande rift-Basin and Range transition zone in southeastern Arizona, southern New Mexico, and western Texas. Individual AHe ages (n=23) range from 8–26 Ma, and ZHe ages (n=42) range from 19–649 Ma. Samples from the Basin and Range province, west of the Cookes Range and the Florida Mountains (southwestern New Mexico), have a small spread in ZHe ages, whereas samples from the southern Rio Grande rift yield a wide range of ZHe ages that is related to a corresponding spread in effective uranium (eU). Forward and inverse modeling suggests that cooling from temperatures >200°C in the southeastern Basin and Range may have been due to a combination of tectonic exhumation and mid-Cenozoic igneous activity, whereas extension in the southern Rio Grande rift exhumed rocks from depths corresponding to temperatures <200°C. However, basins in the southern Rio Grande rift are up to 3 km deep, whereas the southeastern Basin and Range is characterized by basins with less than 700 m of basin fill. While further work is needed to fully understand the effects of normal faulting vs. igneous activity on thermochronologic data in southwestern New Mexico, these observations may be a reflection of different styles of extension in each region, separated by a N–S trending boundary in southern New Mexico. Core complex style extension involving low-angle normal faults and mid-crustal detachments are common within the Basin and Range. In contrast, extension in the southern Rio Grande rift may have been accomplished through high-angle faults, which would favor the formation of deep basins, but which did not exhume","PeriodicalId":253436,"journal":{"name":"Las Cruces Country III","volume":"46 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":"126923759","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":"Geology of the Do�a Ana Mountains, south-central New Mexico: A summary","authors":"W. Seager, G. Mack","doi":"10.56577/ffc-69.71","DOIUrl":"https://doi.org/10.56577/ffc-69.71","url":null,"abstract":"Located a few kilometers north of Las Cruces in south-central New Mexico, the Dona Ana Mountains are part of a late Tertiary fault block that extends from the northern Franklin Mountains to San Diego Mountain. Uplift along the Jornada fault on its eastern side and subsidence along the Robledo fault into the northern Mesilla half graben has resulted in a ~15° westward tilt of the Dona Ana block. Early Pliocene to Quaternary axial-fluvial and piedmont-slope deposits, paleocanyon fill, and pediment veneers onlap bedrock around the perimeter of the range. Two easterly trending, dike-filled faults or fracture zones, both downthrown to the south, divide the range into three structural blocks. The northern, structurally highest block primarily consists of easterly trending, folded and thrust-faulted upper Pennsylvanian and Lower Permian sedimentary rocks, deformed during the latest Cretaceous-early Tertiary Laramide orogeny. The Permo-Pennsylvanian strata are intruded by the Summerford Mountain syenite sill. The central block exposes a thick sequence of southerly dipping, upper Eocene andesite and dacite lava flows and volcaniclastic rocks assigned to the Palm Park Formation. Deeply eroded remnants of the Dona Ana caldera constitute the structurally lowest, southern block. Eruption of the ~36 Ma Dona Ana Rhyolite, an ash-flow tuff sequence at least 440 m thick, triggered caldera collapse. Post-caldera fallout tuffs and ash-flow tuffs hundreds of meters thick accumulated within the caldera, most notably in the Red Hills graben, where chaotic megabreccia, rhyolite flows, and rhyolite dome-flow complexes and other intrusives were emplaced. Rhyolite and syenite sheets or dikes were emplaced along the northern margin of the caldera, as well as along faults that earlier had broken both caldera tuffs and post-caldera rocks. The Summerford Mountain sill may have extended below both the northern and central blocks, as well as beneath the Dona Ana caldera, where it may have been the source of felsite to syenite dikes at the northern margin of and within the caldera. Because it is buried by younger rocks or alluvium, the western, southern, and eastern limits of the caldera are unknown. However, the western boundary may have been hinged rather than broken, as suggested by the gradual westward decrease in the number and thickness of dikes along the northern margin of the caldera. 71","PeriodicalId":253436,"journal":{"name":"Las Cruces Country III","volume":"10 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":"114872120","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}