Melting in feldspar-bearing systems to high pressures and the structures of aluminosilicate liquids

Research Article| April 01, 1984 Melting in feldspar-bearing systems to high pressures and the structures of aluminosilicate liquids Art Boettcher; Art Boettcher 1Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences University of California, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar Qiti Guo; Qiti Guo 2Institute of Geochemistry, Academia Sinica, Guiyang, Guizhou Province, People's Republic of China Search for other works by this author on: GSW Google Scholar Steve Bohlen; Steve Bohlen 3Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794 Search for other works by this author on: GSW Google Scholar Brooks Hanson Brooks Hanson 4Department of Earth and Space Sciences, University of California, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar Geology (1984) 12 (4): 202–204. https://doi.org/10.1130/0091-7613(1984)12<202:MIFSTH>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 Art Boettcher, Qiti Guo, Steve Bohlen, Brooks Hanson; Melting in feldspar-bearing systems to high pressures and the structures of aluminosilicate liquids. Geology 1984;; 12 (4): 202–204. doi: https://doi.org/10.1130/0091-7613(1984)12<202:MIFSTH>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 SocietyGeology Search Advanced Search Abstract To test the possibility that aluminosilicate liquids exhibit pressure-induced transformations, particularly involving changes in the coordination of aluminum, we determined melting relationships for the feldspar-bearing systems NaAlSi3O8-SiO2, KAlSi3O8-SiO2, and CaAl2Si2O8-SiO2 from 1 atm to 25 kbar. Albite and anorthite behave similarly in that they, and presumably liquids of these compositions, transform at high pressures to jadeite, kyanite, corundum, and other structures with aluminum in six-fold coordination, releasing SiO2 component. This results in a large increase in the activity of SiO2 component in the liquid (alqz), which is manifested by a significant decrease in the melting-point depression of albite and of anorthite by the addition of quartz at pressures above ∼15 kbar. In contrast, sanidine does not transform to denser phases at pressures below at least 100 kbar, but it melts incongruently to leucite + SiO2-rich liquid up to ∼ 15 kbar. This produces a relatively large alqz and a small freezing-point depression by quartz below this pressure; the opposite holds above ∼15 kbar. These results support the concept that significant structural changes, including coordination changes in aluminum, occur in magmas in the upper mantle. 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.