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Compositional diversity in late Cenozoic mafic lavas in the Rio Grande rift and Basin and Range province, southern New Mexico

1992; Geological Society of America; Volume: 104; Issue: 8 Linguagem: Inglês

10.1130/0016-7606(1992)104 2.3.co;2

1943-2674

Elizabeth Y. Anthony, Jerry M. Hoffer, W. KENT WAGGONER, Weiping Chen,

Geological and Geochemical Analysis

Research Article| August 01, 1992 Compositional diversity in late Cenozoic mafic lavas in the Rio Grande rift and Basin and Range province, southern New Mexico ELIZABETH Y. ANTHONY; ELIZABETH Y. ANTHONY 1Department of Geological Sciences, University of Texas at El Paso, El Paso, Texas 79968-0555 Search for other works by this author on: GSW Google Scholar JERRY M. HOFFER; JERRY M. HOFFER 1Department of Geological Sciences, University of Texas at El Paso, El Paso, Texas 79968-0555 Search for other works by this author on: GSW Google Scholar W. KENT WAGGONER; W. KENT WAGGONER 1Department of Geological Sciences, University of Texas at El Paso, El Paso, Texas 79968-0555 Search for other works by this author on: GSW Google Scholar WEIPING CHEN WEIPING CHEN 1Department of Geological Sciences, University of Texas at El Paso, El Paso, Texas 79968-0555 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1992) 104 (8): 973–979. https://doi.org/10.1130/0016-7606(1992)104 2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ELIZABETH Y. ANTHONY, JERRY M. HOFFER, W. KENT WAGGONER, WEIPING CHEN; Compositional diversity in late Cenozoic mafic lavas in the Rio Grande rift and Basin and Range province, southern New Mexico. GSA Bulletin 1992;; 104 (8): 973–979. doi: https://doi.org/10.1130/0016-7606(1992)104 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract This study reports major- and trace-element compositions of late Cenozoic (5 Ma and younger) mafic volcanic rocks from southern New Mexico. Stratigraphic sampling is reported for two of the volcanic fields, the Potrillo and the Jornado del Muerto volcanic fields; reconnaissance sampling, for an additional seven fields. These are among the first chemical analyses for some of these volcanic fields, and they provide insight into the dynamics of melt generation in this continental rift zone.The lavas fall into two groups: (1) an alkaline suite of basanite, alkali basalt, and trachybasalt with low SiO2 and high abundances of incompatible elements (TiO2, Nb, Rb, and Sr); (2) a subalkaline suite of subalkali basalts with high SiO2 and low abundances of the incompatible elements. Compositions of volcanic rocks from the Geronimo volcanic field, the Taos Plateau volcanic field, and the transition zone in central New Mexico are similar to those reported in this study, confirming that these are general characteristics of lavas throughout the region. For many of the large fields, the volcanic rocks belong exclusively to one compositional group or the other. Furthermore, there appear to be no patterns to the distribution of these compositional groups; for example, the Potrillo volcanic field, which is composed exclusively of alkaline lavas, and the Jornado del Muerto volcanic field, which is dominantly subalkaline, both occur in the axis of the Rio Grande rift. We see no evidence for evolution in melt chemistry during the past 5 m.y.In the Potrillo volcanic field, for which we have the best documentation of stratigraphic changes in composition, incompatible elements increase upsection and are correlated with decreasing Mg number, suggesting that magmas underwent differentiation before their final ascent. Phenocrystic olivine and plagioclase, which are liquidus phases at low pressure, imply a shallow depth for this crystallization event.Processes responsible for chemical divergence between the alkaline and subalkaline groups occurred at an early stage of magmatic evolution. Correlation between incompatible-element enrichment and silica undersaturation suggests that variable degrees of partial melting played a significant role in the generation of the two lava types. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.