Transition from Staurolite to Sillimanite Zone, Rangeley Quadrangle, Maine

Research Article| March 01, 1974 Transition from Staurolite to Sillimanite Zone, Rangeley Quadrangle, Maine CHARLES V. GUIDOTTI CHARLES V. GUIDOTTI 1Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1974) 85 (3): 475–490. https://doi.org/10.1130/0016-7606(1974)85<475:TFSTSZ>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 CHARLES V. GUIDOTTI; Transition from Staurolite to Sillimanite Zone, Rangeley Quadrangle, Maine. GSA Bulletin 1974;; 85 (3): 475–490. doi: https://doi.org/10.1130/0016-7606(1974)85<475:TFSTSZ>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 Study of pelitic schists in the Rangeley area, Maine, by means of petrographic, x-ray, and electron-microprobe techniques enables definition of the isogradic reaction relating the Staurolite and lower sillimanite zones. The reaction is a discontinuous one and can be shown on an AFM projection as the tie line change from Staurolite + chlorite to sillimanite + biotite. This topology change, in conjunction with the mineralogical data provides the equation:Staur + Mg-Chte + Na-Musc + (Garn?)→Sill + Bio + K-richer Musc + Ab + Qtz + H2O.This reaction should result in a sharp isograd in the field but in fact is found to be spread out over a zone which is called the transition zone. It is proposed that this zone results from buffering of fH2O by means of the equation above. Buffering of fH2O by continuous reactions also appears to be taking place in the lower sillimanite zone.Metamorphic conditions for the isogradic reaction are believed to be near 4 kb and 600°C. Pfluid was probably equal to Ptotal but somewhat greater than PH2O. 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.