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Studies on budget of organic matter in mantle and crust of arc during subduction and magmatism

俯冲和岩浆作用期间弧地幔和地壳有机质收支研究

基本信息

批准号：
13440148
负责人：
SAWADA Yoshihiro
金额：
$ 9.66万
依托单位：
Shimane University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440148/
关键词：
arc magma subducted slab pelitic rocks organic matter fluid components polymerization wedge mantle high P-T experiment 堆積岩高温高圧変成岩炭素化合物島弧マントル火山ガス

项目摘要

The purpose and targets of the project are the understanding of the behavior and budget of volatile components an the crust and wedge mantle during subduction, accretion and magmatism in arc systems based on EPMA, CNS, FT-JR, Py-GC, Py-GC/MS and stable carbon isotopes analyses for natural rocks, and experiments using natural glass + H_2O + hydrocarbon under high P-T conditions.The results of researches are summarized as follows ;1)Carbonaceous matter in S-type granitoids was derived from interaction between granitoid magmas and surrounding pelitic rocks. Particulate carbonaceous materials in minerals in the granodiorite contain long-aliphatic hydrocarbon bonds, oxygen-bearing organic compounds, and aromatic fragments. The distribution of these organic groups differs between feldspar, quartz and biotite. We conclud that (a) most organic matter is released from the system during partial melting of pelitic rocks, however, (b) a small amount is trapped in highly viscous felsic melt and pol … More ymerized during cooling and crystallization of granitoid magma under differing oxidation conditions.2) Carbonaceous matter including B, N and Cl was found in olivine and pyroxene from the Horoman Peridotite Mass and high-Mg andesite. Aromatic compounds with Cl and N, n-C_8 alkane and n-C_<8-12> alkane were detected from pyrolyzed bulk rocks of spinel and plagioclase lherzolite, and harzburgite in the Horoman Peridotite Mass. Aromatic compounds such as toluene and naphthalene were found from pyrolyzed bulk rocks of high-Mg andesite. δ ^<13>C values of non-carbonate carbon are lherzolite : -25.5‰ vs PDB, harzburgite : -23.4‰, and dunite : -21.9‰ and -28.0‰. These results indicate that the Horoman Peridotite Mass and HMA magma were influenced by fluid, which was probably derived from subducted slab, in wedge mantle.3)Preliminary experiments were carried out to examine transformation of sediment -derived hydrocarbons in felsic magma and during its solidification at middle crustal condition. Starting materials and conditions were : granitic glass + hydrocarbon [n-hexane and n-tetracosane] + H_2O ; 5kb, 900℃. Results showed that remnant carbonaceous materials remained in all experimental products, not only as carbonate and graphite but also as solid state hydrocarbon, indicating that polymerization occurred. Less

该项目的目的和目标是通过对天然岩石的EPMA、CNS、FT-JR、Py-GC、Py-GC/MS和稳定碳同位素分析，以及利用天然玻璃+H_2O+烃在高P-T条件下的实验，了解弧系俯冲、吸积和岩浆作用过程中地壳和楔形地幔中挥发性组分的行为和收支。研究结果如下：1)S型花岗岩中的碳质物质来自花岗岩类岩浆与周围泥质岩石的相互作用。花岗闪长岩矿物中的颗粒状碳质物质含有长脂肪族碳氢键、含氧有机化合物和芳香族碎片。这些有机基团在长石、石英和黑云母中的分布有所不同。我们的结论是：(A)大部分有机质在泥质岩的部分熔融过程中被释放出来，但(B)少量被困在高粘长英质熔体和Poll…中。在不同的氧化条件下，花岗岩类岩浆在冷却和结晶过程中更容易发生硫化。2)在霍罗曼橄榄岩和高镁安山岩中的橄榄石和辉石中发现了含B、N和Cl的碳质物质。在霍罗曼橄榄岩体内的尖晶石、斜长二辉橄榄岩和方辉橄榄岩的热解岩石中发现了含有氯和N，n-C_8烷烃和n-C_&lt；8-12&gt；烷烃的芳香族化合物。在高镁安山岩的热解岩石中发现了甲苯和萘等芳香族化合物。非碳酸盐碳的δ^&lt；13&gt；C值分别为二辉橄榄岩：-25.5‰vs PdB，方辉橄榄岩：-23.4‰，纯橄榄岩：-21.9‰和-28.0‰。这些结果表明，霍罗曼橄榄岩和HMA岩浆在楔形地幔中受到流体的影响，这种流体可能来自俯冲板片。3)初步实验研究了长英质岩浆中沉积物来源的烃类的转化及其在中地壳条件下的固化过程。起始原料和条件为：花岗岩玻璃+碳氢化合物[正己烷和正四烷]+H_2O，5kb，900℃。结果表明，所有实验产物中残留的碳质物质不仅以碳酸盐和石墨的形式存在，而且还以固态烃的形式存在，表明发生了聚合反应。较少