GLASS IN MANTLE-DERIVED PERIDOTITE XENOLITHS FROM THE McMURDO VOLCANIC GROUP, ANTARCTICA

• Main Authors: ニイダ キヨアキ, Kiyoaki NIIDA
• Format: Report
• Language: English
• Published: Department of Geology and Mineralogy, Facutly of Science, Hokkaido University 1990
• Subjects: Ross Island; McMurdo Station; Turtle Rock; Antarc*; Antarctica
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2631; http://id.nii.ac.jp/1291/00002631/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2631&item_no=1&attribute_id=18&file_no=1

Glass-bearing, mantle-derived peridotite xenoliths have been found in Late Cenozoic basanites at Turtle Rock and McMurdo Station, Ross Island, Antarctica. Glass in these xenoliths occurs as veinlets, interstitial pools, and thin films surrounding the primary xenolith minerals. The glass analyzed has three different compositions. Low-silica high-alkali glasses (42-48wt% SiO_2,4-6wt% Na_2O+K_2O) are likely to represent volatile-rich melts which were incorporated from the host basanite magma. High-silica low alkali glasses (53.5-56wt% SiO_2,4-5wt% Na_2O+K_2O) are non-alkaline and were possibly generated by decompressional breakdown of pargasitic amphibole. High-silica high-alkali glasses (55.5-57 wt% SiO_2,14-15 wt% Na_2O+K_2O) are unique and resemble the chemical composition of the most evolved nepheline-trachyte.