Significance of chloritoid-bearing and staurolite-bearing rocks in the Picuris Range, New Mexico

Research Article| September 01, 1978 Significance of chloritoid-bearing and staurolite-bearing rocks in the Picuris Range, New Mexico M. J. HOLDAWAY M. J. HOLDAWAY 1Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275 Search for other works by this author on: GSW Google Scholar Author and Article Information M. J. HOLDAWAY 1Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1978) 89 (9): 1404–1414. https://doi.org/10.1130/0016-7606(1978)89<1404:SOCASR>2.0.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 M. J. HOLDAWAY; Significance of chloritoid-bearing and staurolite-bearing rocks in the Picuris Range, New Mexico. GSA Bulletin 1978;; 89 (9): 1404–1414. doi: https://doi.org/10.1130/0016-7606(1978)89<1404:SOCASR>2.0.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 In the Picuris Range near Taos, New Mexico, the Precambrian Ortega Quartzite and Rinconada Formation are folded together and share a common history. The Ortega contains chloritoid-Al silicate and essentially no staurolite, and the Rinconada contains staurolite-almandine–bearing assemblages with minor graphite. Al silicate–bearing Rinconada rocks locally contain Mn-rich garnet.All the rocks of the area crystallized at temperatures a little above the Al silicate triple point, as indicated by the paragenetic sequence kyanite → andalusite → sillimanite. Analysis of the assemblages in relation to chloritoid, staurolite, and Al silicate stability data, taking into account the mineral compositions and the effect of graphite on fluid composition, shows that all the rocks crystallized at 532 ± 20 °C and about 3,700 b Ptot, but PH2O/Ptot was 0.88 or less in the Rinconada rocks and near 1 in the Ortega rocks. This small difference in PH2O appears to be the most important factor in explaining the juxtaposition of chloritoid and staurolite in the two units. 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.