Mineral Chemistry of Late Cenozoic Mcmurdo Volcanic Group Rocks from the Pleiades, Northern Victoria Land

  1. Edmund Stump
  1. Philip R. Kyle

Published Online: 16 MAR 2013

DOI: 10.1002/9781118664957.ch15

Geological Investigations in Northern Victoria Land

Geological Investigations in Northern Victoria Land

How to Cite

Kyle, P. R. (1986) Mineral Chemistry of Late Cenozoic Mcmurdo Volcanic Group Rocks from the Pleiades, Northern Victoria Land, in Geological Investigations in Northern Victoria Land (ed E. Stump), American Geophysical Union, Washington, D. C.. doi: 10.1002/9781118664957.ch15

Author Information

  1. Department of Geoscience, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801

Publication History

  1. Published Online: 16 MAR 2013
  2. Published Print: 1 JAN 1986

ISBN Information

Print ISBN: 9780875901978

Online ISBN: 9781118664957

SEARCH

Keywords:

  • Geology—Antarctic regions—Victoria Land

Summary

Volcanic rocks from Quaternary cones and domes at The Pleiades comprise a mildly potassic, weakly undersaturated evolutionary trend of trachyandesite, tristanite, K-trachyte, and peralkaline K-trachyte. Electron microprobe analyses of the main mineral phases in seven lava samples and a cognate essexite xenolith were used to examine the mineral paragenesis. Olivine is a common constituent, ranging from Fo81 to Fo46. Clinopyroxene occurs in all rock types except the peralkaline K-trachyte and shows a well-defined augite-hedenbergite-aegirine trend. Kaersutite shows no significant chemical variations in five samples examined. Titanobiotite occurs in the essexite and a K-trachyte. Titanomagnetite is common and often shows evidence of deuteric alteration and oxidation exsolution. Other opaque oxides include titanohematite, maghemite, and ilmenite. Feldspars show a continuous range in compositions from bytownite-labradorite in the basic rocks to sanidine in the trachytes. Minor quantities of apatite, baddeleyite, zircon, and pyrrhotite occur. Magnetite-ilmenite, olivine-clinopyroxene, and plagio-clase geothermometers show poor agreement; however, each indicates a progressive decrease in temperature with increasing magma evolution.