CUMULATE INCLUSIONS FROM TURTLE ROCK, ROSS ISLAND, ANTARCTICA

• Main Authors: ニイダ キヨアキ, カミヌマ カツタダ, シブヤ カズオ, Kiyoaki NIIDA, Katsutada KAMINUMA, Kazuo SHIBUYA
• Format: Report
• Language: English
• Published: Department of Geology and Mineralogy, Faculty of Science, Hokkaido University 1991
• Subjects: Ross Island; Turtle Rock; Antarc*; Antarctica
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2695; http://id.nii.ac.jp/1291/00002695/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2695&item_no=1&attribute_id=18&file_no=1

Ultramafic to mafic cumulate inclusions in Late Cenozoic basanite at Turtle Rock off Ross Island, Antarctica, were used to propose a well-defined compositional variation of the constituent minerals. The Turtle Rock cumulate suite (dunite-wehrlite-clinopyroxenite-gabbro), composed of Fe-rich olivine, clinopyroxene, kaersutitic amphibole, plagioclase and Ti-Fe oxide minerals, has undeformed and unmetasomatized igneous cumulate textures. All the ferromagnesian minerals are Fe-rich (100Mg/(Mg+Fe)=87-60). Clinopyroxenes are dominant in the cumulates and are always Fe-, Ti-, and Al-rich fassaitic augites, of which compositional range is separated from that of the upper mantle clinopyroxenes. Kaersutitic amphibole, varying continuously from Ti-pargasite to kaersutite, has a chemical composition typical of amphibole found in subcontinental cumulate xenoliths.