The phase relations and the chemical variations of Ca-amphibole, MgFe-amphibole and Na-amphibole under low water vapor pressure.

低水蒸气压下Ca-角闪石、MgFe-角闪石和Na-角闪石的相关系和化学变化。

• 批准号: 63540646
• 负责人: OBA Takanobu
• 金额: $ 1.15万
• 依托单位: Joetsu University of Education
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63540646/
• 关键词: Ca-amphibole; Mg-Fe amphibole; Cummingtonite; Na-amphibole; low water vapor pressure; MgFe角閃石

Phase relations in the systems cummingtonite(Mg_<50>)-actinolite(Mg_<50>)- plagioclase (An_0,An_<20>,An_<40>)-quartz-water have been studied within the melting range 675-850ﾟC under water pressures of 1 and 2 kbar and oxygen fugacities of the FMQ buffer. The experiments were performed in standard 'cold seal' pressure vessels (Koatsu-Kagaku MR01-10).In the system cummingtonite-actinolite-plagioclase(An_0)-quartz, cummingtonite (Cum) coexists with Ca-amphibole, liquid and vapor. Cummingtonite is separated from Ca-amphibole by a wide miscability gap. At 725ﾟC cummingtonite is present is present for bulk system compositions with up to 4.1 wt % CaO, and Ca-content in cummingtonite increases systematically with increasing bulk Ca content. The cummingtonite stability field is shifted toward the actinolite-rich end member. As compared to Ca-amphibole and cummingtonite synthesized at 5 kbar, they have the lower Na content at 1 kbar.In the system cummingtonite-actinolite-plagioclase(An_<20> or An_<40>)-quartz, cummingtonite (Cum) is always accompanied by actinolite or actinolitic hornblende. The phase relations are otherwise similar to those in the system with An_0 but Ca-amphiboles stability progressively increases with more calcic plagioclase component, so that the respective stability fields are shifted toward the cummingtonite-rich end member. In these systems(An_<20> or An_<40>) the stability field of cummingtonite at 1 kbar is similar to that at 5 kbar. As compared to cummingtonite synthesized at 5 kbar, it has the lower glaucophane content at 1 kbar.Chemical compositions of amphiboles in the three systems reflect their high temperature of equilibration relative to metamorphic conditions, with either single-phase amphiboles lying within accepted "miscability gaps" or coexisting compositions showing extensive mutual solid solution.

在 1 和 2 kbar 的水压和 FMQ 缓冲液的氧逸度下，在 675-850°C 熔化范围内研究了斜长石 (Mg_<50>)-阳起石 (Mg_<50>)-斜长石 (An_0,An_<20>,An_<40>)-石英-水体系中的相关系。实验在标准“冷密封”压力容器（Koatsu-Kagaku MR01-10）中进行。在方斜石-阳起石-斜长石（An_0）-石英体系中，方斜石（Cum）与Ca-角闪石、液体和蒸气共存。钙明石与钙角闪石之间存在较大的混溶性间隙。在 725°C 时，块状体系组合物中的钙明石含量高达 4.1 wt%，并且块状钙石中的 Ca 含量随着块状 Ca 含量的增加而系统性地增加。角辉石稳定场向富含阳起石的端元移动。与5 kbar下合成的Ca-角闪石和角闪石相比，它们在1 kbar下的Na含量较低。在角闪石-阳起石-斜长石(An_<20>或An_<40>)-石英体系中，角闪石(Cum)总是伴随着阳起石或阳起石角闪石。相位关系在其他方面与 An_0 系统中的相位关系相似，但随着钙质斜长石组分的增加，Ca-角闪石稳定性逐渐增加，因此各自的稳定性场向富含角闪石的端元移动。在这些体系（An_<20> 或 An_<40>）中，1 kbar 下的角闪石稳定场与 5 kbar 下的稳定场相似。与在 5 kbar 下合成的角闪石相比，它在 1 kbar 下具有较低的蓝闪石含量。三个体系中角闪石的化学成分反映了它们相对于变质条件的高温平衡，单相角闪石位于可接受的“混溶性间隙”内，或者共存成分显示出广泛的相互固溶体。

项目成果

Oba,T.& Shiraishi,K.: "Mineralogy of the syenitic rocks from the Yamato and the Sor Rondane mountains,East Antarctica." Proc.NIPR Symp.Antarct.Geosci. 3. 150 (1989)

奥巴，T.

Oba,T.and Shiraishi,K.: "Mineralogy of the syenitic rocks from the Yamato and the Sφr Rondane mountains,East Antarctica." Proc.NIPR Symp.Antarct.Geosci.3. 150 (1989)

Oba, T. 和 Shiraishi, K.：“南极洲东部大和和 Sφr Rondane 山脉正长岩的矿物学”，Proc.NIPR Symp.Antarct.Geosci.3 (1989)。

Oba, T., Yoshikawa, K. & Watanabe, T.: "Notes on rock-forming minerals in the Joetsu district, Niigata Prefecture, Japan. (3) Hedenbergite-ferrosalite from Yoneyama." Bull.Joetsu Univ.Educ. 9, 57-65, 1990.

大场，T.，吉川，K.

Oba, T.: "Phase equilibrium of amphibole, its present problem." Jour.Mineral.Soc. Japan. (in Japanese with English abstract).

Oba, T.：“角闪石的相平衡，它目前的问题。”

Oba, T. & Harada, H.: "Behavior of fluorine in the andesites and their basaltic xenoliths from Sakurajima, Kagoshima Prefecture" Japan. Proc.Kagoshima Intnal. Conf.Volcanos. 280-283.1989.

奥巴，T.