The pressure estimated by amphibole geobarometer in syenite and granil

角闪石地质气压计估算正长岩和花岗岩中的压力

• 批准号: 09640567
• 负责人: OBA Takanobu
• 金额: $ 1.98万
• 依托单位: Joetsu University of Education
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640567/
• 关键词: Amphibole; Geobarometer; Granite; Syenite; Synthetic Experiment; 閃長岩

We attempt to estimate the pressure of amphibole-bearing syenites and granitic rocks in the range 600ﾟC -930ﾟC under a water pressure from 0.05GPa to 0.34GPa and oxygen fugacitied of the FMQ buffer. The stability limit curve of amphibole changes its P-T slope from positive at low pressure to negative at high pressure, and it intersects with a solidus of syenite and granite at two pressure points. We suggest that amphibole in syenite from the Yamato Mountains could have crystallized at pressres less than 0.3GPa (depth : -10 km), probably in a shallow crustal magma chamber.Hammarstrom and Zen (1986, 1992) proposed an empirical correlation between the estimated pressures of crystallization of calc-alkaline plutons and the total Al content of horublende. However, in the present experiments, the chemical composition of amphibole near solidus does not change. We reported that the pargasite content in amphibole increases with increasing temperature. If we compared with amphiboles synthesized at different temperatures, amphibole geobarometer is considerable uncertainty. We attempt the partitioning of Na, Al, Mg and Fe between amphibole and pyroxene.

在0.05GPa ~ 0.34GPa的水压和FMQ缓冲层的氧逸度条件下，估算了含角闪石的正长岩和花岗质岩石的压力范围为600 ℃ ~ 930 ℃。角闪石的稳定极限曲线在低压时的P-T斜率为正，高压时为负，与正长岩和花岗岩的固相线相交于两个压力点。我们认为，大和山正长岩中的角闪石可能在低于0.3GPa（深度：-10 km）的压力下结晶，可能是在浅层地壳岩浆房中结晶的。Hammarstrom和Zen（1986，1992）提出了钙碱性侵入岩结晶压力估计值与角闪石总Al含量之间的经验相关性。然而，在目前的实验中，角闪石固相线附近的化学成分并没有发生变化。角闪石中的角闪石含量随温度的升高而增加。如果将不同温度下合成的角闪石进行比较，角闪石地质压力计存在相当大的不确定性。本文尝试了钠、铝、镁和铁在角闪石和辉石之间的分配。

项目成果

Oba,T.: "Mineralogy of chondrule in Ouellan(Tanezroulft)meteorite." Bull.Joetsu Univ.Educ.17・2. 891-899 (1998)

Oba, T.：“Ouellan(Tanezroulft) 陨石中球粒的矿物学。”Bull.Joetsu Univ.Educ.17・2 (1998)。

吉川和男(共著): "群馬県中之条町に分布する関東ローム層中の大隈石-(Mg)" 群馬大学研究紀要. 47. 103-112 (1999)

Kazuo Yoshikawa（合著者）：“分布于群马县中之条町的关东壤土层中的奥麦石（Mg）”群马大学通报47. 103-112（1999）。

Oba,T.: "Chemistry of chromian spinel in picrite sillfrom Ogi,Sado island,Niigata Prefecture,Japan." Bull.Joetsu Univ.Educ.Vol.18,No2. 687-695 (1999)

Oba,T.：“来自日本新泻县佐渡岛小木的苦铁矿中铬尖晶石的化学成分。”

Oba, T., Uehara, S.and Shiraishi, K.: "Microstructure of perthites in the syenites from the Yamato Mountains, East Antarctica." Proc.NIPR Symp.Antarct.Geosci.10. 121-130 (1997)

Oba, T.、Uehara, S. 和 Shiraishi, K.：“南极洲东部大和山脉正长岩中长长岩的微观结构。”

Oba,T.: "Mineralogyof chondrulein OUellan(Tanezrouff)meteoite." Bull.Joefsu Univ.Educ.Vol.17,No2. 891-899 (1998)

Oba,T.：“OUellan（Tanezrouff）陨石球粒矿物学。”