Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study

Abstract

Other| December 01, 1998 Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study Douglas M. Yates; Douglas M. Yates Washington State University, Department of Geology, Pullman, WA, United States Search for other works by this author on: GSW Google Scholar Philip E. Rosenberg Philip E. Rosenberg Search for other works by this author on: GSW Google Scholar Author and Article Information Douglas M. Yates Washington State University, Department of Geology, Pullman, WA, United States Philip E. Rosenberg Publisher: Mineralogical Society of America First Online: 02 Mar 2017 Online ISSN: 1945-3027 Print ISSN: 0003-004X GeoRef, Copyright 2004, American Geological Institute. American Mineralogist (1998) 83 (11-12_Part_1): 1199–1208. https://doi.org/10.2138/am-1998-11-1208 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Douglas M. Yates, Philip E. Rosenberg; Characterization of neoformed illite from hydrothermal experiments at 250 degrees C and P (sub v,soln) ; an HRTEM/ATEM study. American Mineralogist 1998;; 83 (11-12_Part_1): 1199–1208. doi: https://doi.org/10.2138/am-1998-11-1208 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 SocietyAmerican Mineralogist Search Advanced Search Abstract Solid products from hydrothermal experiments conducted at 250 degrees C and P (sub v.soln) were characterized by powder X-ray diffraction (XRD) and ATEM/HRTEM. Experiments were conducted with muscovite, kaolinite, and quartz or amorphous silica in 2M KCl solutions for 43 to 176 d. Post-experiment solution compositions lie either within the illite (0.88 K) stability field or on the illite(0.88 K)-kaolinite or illite(0.88 K)-diaspore univariant boundaries in log (a K (super -) /a H (super -) ) vs. log aH 4 SiO 4 activity space. Transmission electron microscopy (TEM) observations of muscovite grain edges reveal the neoformation of illite crystals with a range of compositions (ATEM) from 0.31 to 0.89 K/O 10 (OH) 2 . The range of K-contents appears to narrow toward 0.88 K/O 10 (OH) 2 with increased experiment duration. HRTEM suggests the presence of 2 to 11 layer fundamental particles composed of illitic layers with 10 A periodicity. Fundamental particle thicknesses increase toward an average of 8 layers/particle with increased experiment duration. In the longer duration experiments, fundamental particle thicknesses were normally distributed about thicknesses of 4 and 8 layers, whereas fundamental particles with thicknesses <4 layers were common in a shorter duration experiment. The compositions and structure of the illites are consistent with the multiphase model, which states that the smectite-to-illite transition occurs through the step-wise formation of solubility-controlling phases consisting of fundamental particles with thicknesses of 1, 2, 4. and > or =8 layers. The increase in K-content and fundamental particle thickness with the extent of reaction suggests that the illite crystals underwent a prograde reaction culminating in the formation of end-member illite [0.88 K/O 10 (OH) 2 ]. This reaction, in conjunction with the previously observed, retrograde reaction from muscovite to end-member illite, demonstrates the stability of end-member illite in the system K 2 O-Al 2 O 3 -SiO 2 -H 2 O at 250 degrees C. 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.