冲绳海槽火山岩中岩浆包裹体用气体同位素组成研究

IOCAS-IR > 海洋环流与波动重点实验室

	冲绳海槽火山岩中岩浆包裹体用气体同位素组成研究
	于增慧
学位类型	博士
	2000
学位授予单位	中国科学院海洋研究所
学位授予地点	中国科学院海洋研究所
学位专业	海洋地质学
关键词	包裹体挥发性组分同位素组成岩浆作用与热液活动冲绳海槽inclusion
摘要	本文首次对冲绳海槽的浮岩和玄武岩中矿物的包裹体进行了系统的分析研究。工作主要包括：包裹体的均一与爆裂温度测量，化学成分与气相组分分析，热解释放气体分析，碳、氢、氦、氖同位素分析等。据此探讨了岩浆的起源及演化过程、不同火山岩之间的成因联系、岩浆作用与热液活动的关系等。（1）斜长石中的包裹体至少有两个捕获期，斜长石的两个结晶阶段。斜长石是贯穿岩浆作用始终的结晶相，其包裹体记录了岩浆物源与结晶演化的过程。（2）玄武岩与浮岩中包裹体的化学成分与气相组分具有同系列岩浆演化的相关性与继承性，二者同时具有N_2、CO等幔源组分，碳、氢同位纯素组成具幔源特征，说明玄武岩和滠岩具有共同的地幔来源，分别代表岩浆作用早期和结晶分异作用晚期产物。（3）岩浆中富气富水，气相组分的碳、氢、氦同位素组成具有俯冲板块脱失流体的特征。俯冲板块脱失流体的混入可能发生在岩浆作用早期，或者说俯冲板块脱失流体对地幔熔融产生岩浆起了重要作用。（4）岩浆中的挥发性组分不仅是导致地幔熔融产生岩浆的“催化剂”，而且是岩浆结晶演化及形成分层岩浆房的主要控制因素之一。（5）冲绳的海槽的岩浆作用不仅为现代海底热液活动提供了热源，而且有气液相的物质供应。
其他摘要	The inclusions hosted in the phenocrysts of basalt and pumice in the Okinawa Trough was systematically studied in this thesis for the first time. The homogeneous temperature, decrepitation temperature, major element compositions and volatile components of the inclusions were determined. Meanwhile, the content of volatile components in whole-rock and their carbon, hydrogen, helium and neon isotopic compositions of the same samples were also analyzed. Based on the obtained data, the magma genesis, magma evolution process, relations in the petrogenesis of different kinds of volcanic rocks, and effects of magmatism on the hydrothermal activity were discussed. (1) The inclusions hosted in plagioclase were trapped at two periods at least, which respectively corresponded to the two stages of crystallization of plagioclase. Plagioclase was the mineral crystallized throughout the whole magmatic process. So, the inclusions hosted in plagioclase have recorded the information of magma source and magma evolution. (2) The major element compositions of inclusions hosted in basalt and pumice samples were correlated and inheritance in the same evolution series. The presents of the components N_2 and CO generally originated from the mantle and the mantle-sourced characteristics of carbon, hydrogen isotopic compositions suggest that basalt and pumice were cognate and respectively represented the products at early stage of magmatism and at the late stage of crystal fractionation. (3) The magma in the trough was rich in H_2O and other volatile components. The carbon, hydrogen and helium isotopic compositions of volatile components displayed the characteristics of the fluid dehydrated from subducting slab. Therefore, the fluid dehydrated from subducting slab should have been added to magma at its forming stage or play an important role in the melting of mantle. (4) The volatile component was not only the "catalyzer" of melting of the mantle to form initial magma but also one of the main factors to control the trend of magma evolution and the formation of zoned magma chamber under the trough. (5) The magmatism in the Okinawa Trough contributed a lot to the hydrothermal activity not only as heat source but also as material source.
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1001
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	于增慧. 冲绳海槽火山岩中岩浆包裹体用气体同位素组成研究[D]. 中国科学院海洋研究所. 中国科学院海洋研究所,2000.

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