TEXTURAL AND SPECTROCHEMICAL STUDIES OF THE WHITE TANK QUARTZ MONZONITE, CALIFORNIA

Abstract

Research Article| April 01, 1958 TEXTURAL AND SPECTROCHEMICAL STUDIES OF THE WHITE TANK QUARTZ MONZONITE, CALIFORNIA JOHN J. W ROGERS JOHN J. W ROGERS DEPARTMENT OF GEOLOGY, THE RICE INSTITUTE, HOUSTON, TEXAS Search for other works by this author on: GSW Google Scholar GSA Bulletin (1958) 69 (4): 449–464. https://doi.org/10.1130/0016-7606(1958)69[449:TASSOT]2.0.CO;2 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 JOHN J. W ROGERS; TEXTURAL AND SPECTROCHEMICAL STUDIES OF THE WHITE TANK QUARTZ MONZONITE, CALIFORNIA. GSA Bulletin 1958;; 69 (4): 449–464. doi: https://doi.org/10.1130/0016-7606(1958)69[449:TASSOT]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 Magmatic crystallization of the White Tank quartz monzonite, California, has produced two sequences of differentiation. One sequence is marked by an increase in the size of potassium feldspar crystals and an increase in the Ab/An ratio of the plagioclase from the older toward the younger rocks. The second sequence is marked by an increase in the Ab/An ratio of the plagioclase from the older toward the younger rocks and by the presence of primary muscovite and garnet in the younger rocks.Textures vary with position in the intrusions. Quartz forms aggregates of several grains except near the margins of the intrusions, where it occurs as individual grains. Large potassium feldspar crystals that formed late in the first differentiation sequence are gray, grid-twinned, and commonly intergrown with sodic plagioclase; the earlier-crystallizing grains are pink, poorly twinned, and exhibit no such intergrowth. The more calcic plagioclase grains are zoned and imperfectly twinned, whereas the more sodic grains are twinned and poorly zoned. Biotite and most accessory minerals occur in aggregates, but sphene is scattered through the rock.In the first differentiation sequence the amounts of lead and possibly strontium in the potassium feldspar decrease from older to younger rocks, and the amounts of barium and rubidium remain constant. In the second sequence, the amounts of barium, lead, and strontium in the potassium feldspar decrease during differentiation, and the amount of rubidium is constant. 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.