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

• Main Authors: 加納 隆, Takashi Kano
• Format: Report
• Language: English
• Published: 山口大学理学部地質学鉱物科学教室 1982
• Subjects: 551.1/.4:552; East Antarctica; Antarc*; Antarctica
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=8285; http://id.nii.ac.jp/1291/00008285/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=8285&item_no=1&attribute_id=18&file_no=1

リュツォ・ホルム湾周辺に散在する露岩地域相互の対比を行い, 東南極基盤岩の地質学的総合の基礎資料を与えることを目的として, 変成岩類・深成岩類の分類・命名規準の標準化を試みた.主に日本隊の地質関係者の報文中に使用されている用語に関し, 用語法とその岩石学的意味について考察を加えた.岩石学的用語は, 岩質・岩相・構造・地質体区分(層序区分)・テクトジェネシス, の5つのカテゴリーに分類できる.元来岩石はこれら諸側面を内包しており, 命名に際しては, 野外における産状や特徴をなるべく直感できるような, 岩相名+構造名を用いることが望ましい.またあわせて各用語の使用規準の概要を示した.分類・命名に関しては, なお多くの議論があり, 記載の不備や混乱もあるが, 本論では主として岩質に基づいて, 当地域の変成岩・深成岩類を13種類に大別し, 各岩石の産状や岩石学的性質を総括的に述べた. 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 . . (3) Ultrabasic to basic rocks consisting mainly of amphiboles. . (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. . (7) Pelitic to psammitic rocks including biotite as major mafic mineral. . (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.