Nomenclature and classification of the basement metamorphic and plutonic rocks around the Lutzow-Holm Bay region, East Antarctica

• Main Author: Takashi Kano
• Format: Article
• Language: English
• Published: National Institute of Polar Research 1982-02-01
• Series: Antarctic Record
• Online Access: https://doi.org/10.15094/00008285

The report discusses the usages and terminology of petrological terms used in the previous papers concerning the basement metamorphic and plutonic rocks around the Lutzow-Holm Bay region, East Antarctica. The terms are classified into the following categories : (1) Lithology (mainly based on chemical composition of rocks), (2) Lithofacies, (3) Structure, (4) Megascopic litho-stratigraphic classification and (5) Tectogenesis. The report points out the general views on terminology in practical use for standardizing the nomenclature and classification of basement rocks. The metamorphic and plutonic rocks in the region will be classified into the following 13 types, although several problems still remain, and petrological properties of each rock-type are described. (1) Ultrabasic to basic rocks consisting mainly of olivines. (2) Ultrabasic to basic rocks consisting mainly of pyroxenes ...<Pyroxenite>. (3) Ultrabasic to basic rocks consisting mainly of amphiboles..................<Amphibolite>. (4) Other ultrabasic to basic rocks. (5) Basic to intermediate rocks including amphiboles as major mafic minerals....<Hornblende gneiss>. (6) Intermediate rocks including orthopyroxene and clinopyroxene as major mafic minerals....<Two-pyroxene gneiss>. (7) Pelitic to psammitic rocks including biotite as major mafic mineral........<Biotite gneiss, etc.>. (8) Leucocratic or acidic rocks associated with other metamorphic rocks. (9) Calcareous rocks. (10) Quartzite. (11) Plutonic or metamorphic rocks with syenitic or charnockitic compositions. (12) Plutonic or metamorphic rocks with granitic or migmatitic appearances. (13) Plutonic rocks with granitic or granodioritic compositions.