那須茶臼岳火山をもたらしたマグマの過去約3万年間の状態変化

过去三万年来岩浆状态的变化导致了那须茶须岳火山的形成

• 批准号: 05740331
• 负责人: 伴 雅雄
• 金额: $ 0.51万
• 依托单位: Yamagata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Encouragement of Young Scientists (A)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05740331/
• 关键词: 那須茶臼岳; 火山; 岩石; 斜長石; 斜方輝石; マグマ; マグマ混合率

那須茶臼岳火山は約3万年前以降,大沢火砕流堆積物,大丸火砕流堆積物群,茶臼岳溶岩流,茶臼岳火砕丘,茶臼岳溶岩円頂丘の順に形成されたと考えられる.本研究では70個の岩石を採取し全岩化学組成と斑晶鉱物の種類,量比,形態,化学組成を測定した.岩石は,石英±かんらん石±斜方斜輝石安山岩である.斜長石斑晶は自形のもとの汚濁帯を有するなどの異常な形態を示すものが混在している.両者の量比は試料毎に異なる.斜方輝石は自形のものと単斜輝石の反応緑を有するものが混在している.後者は前者に比して小量である.単斜輝石は主に自形である.かんらん石は柱状で角が骸晶状に突出しているものが主体である.石英は他形で単斜輝石の反応緑もみられる.自形以外の形態を示す斑晶の含有率は茶臼岳溶岩流,茶臼岳火砕丘,大丸火砕流堆積物群で大きい.また,全ての層準で,径20cm程度以下の球形〜不定型の包有物が認められる.包有物はガラスと針状〜骸晶状の結晶からなる.斑晶鉱物化学組成では,斜長石,輝石で組成逆累帯,波状累帯構造,同種の鉱物で2種の組成の異なる物の共存が認められる.これらの特徴は,噴出前のマグマの状態の急激な変化,最も可能性が高いものとして,2種のマグマの混合を示唆する.全岩化学組成は2成分組成変化図上で直線的な変化傾向を示し,SiO_2含有量は,大沢火砕流堆積物が59-62wt%,大丸火砕流堆積物群と茶臼岳溶岩流が57-60wt%,茶臼岳火砕丘が57-58wt%,茶臼岳溶岩円頂丘が58-60wt%と初期に最も珪長質で,その後苦鉄質に傾き,長後にやや珪長質に回復している.一方包有物は各層準共53-55wt%と一定している.包有物と母岩にK/Y比が異なり,起源が異なると考えられる.2種のマグマの混合を考える場合,上記のような組成変化はマグマ混合率の変化に起因すると考えられる.

Since the fall of the Chajiuyue volcano about 30,000 years ago, the Dabu fire flow has been active, the big pill fire flow has been active, the tea mortar Yue karst rock flow, the tea mortar Yue fire hill, the tea mortar Yue karst mound, the tea mortar Yue karst mound has formed an ancient mountain. In this study, 70 samples of rock samples were collected from whole rock chemical composition to determine the content, quantity ratio, shape and chemical composition of phenocrysts. Rock, quartz ±rhombohedral stone, orthorhombic andesite. Plagioclase phenocrysts show that plagioclase phenocrysts are mixed in plagioclase crystals. The amount of money is much higher than that of the material. The rhombohedral stone is self-shaped, the trapezoid stone is in the opposite direction, and there is a rhombohedral stone mixed in the trapezoid. The latter is better than the former. The oblique stone is mainly self-shaped. The stone, the column, the corners, the crystal, the main body, the main body. The quartz is in his shape, the oblique stone is in the opposite direction, and the quartz is in the opposite shape. The shape outside the shape shows the percentage of phenocrysts, the karst rock flow of tea mortar Yue, the fire mound of tea mortar Yue, and the active material group of large pill fire flow. The diameter below 20cm level is spherical to non-stereotyped, and there are some materials in the package. It contains materials, crystals, etc. Phenocrysts are chemically composed of phenocrysts, plagioclase and plagioclase, and the same kind of phenocrysts are composed of plagioclase, plagioclase and feldspar. Because of the special situation, the situation in front of the market is becoming more and more intense, and the most likely situation is high, and the mixture of two kinds of drugs indicates that they are instigated. The chemical composition 2 of the whole rock shows a straight line of chemical composition, the content of SiO_2 is high, the active material of Dawang fire flow reactor is 59-62wt%, the active material group of Dawu fire flow reactor is Yecha Yue karst flow 57-60wt%, the Chajiu Yue fire mound 57-58wt%, the tea mortar Yue karst hill 58-60wt%, the highest growth rate is 58-60wt% in the early stage. After a long time, the manager will go back to the hospital. A total of 53-55wt% of the goods and materials of one party must be sold. There is a comparison between the parent rock and the parent rock, and the origin of the compound is compared. the mixture of two kinds of materials is combined, and the chemical composition, the mixing rate and the cause of the mixture are tested.