The petrology of a complex sodic and sodic-calcic amphibole association and its implications for the metasomatic processes in the jadeitite area in northwestern Myanmar, formerly Burma
文献类型：期刊论文
| 作者 | Shi, GH; Cui, WY; Tropper, P; Wang, CQ; Shu, GM; Yu, HX |
| 刊名 | CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
 |
| 出版日期 | 2003-06-01 |
| 卷号 | 145期号:3页码:355-376 |
| ISSN号 | 0010-7999 |
| DOI | 10.1007/s00410-003-0457-y |
| 文献子类 | Article |
| 英文摘要 | In the Myanmar jadeitite area of Pharkan, amphibole felses occur between jadeitites and serpentinized dunites. These so-called amphibole fels boundary zones were studied optically and by electron microprobe, and found to include the six amphibole species magnesiokatophorite (Mg-kat), nyboite (Nyb), eckermannite (Eck), glaucophane (Gln), richterite (Rich) and winchite (Win). In most samples, the two main amphibole species Mg-kat and Eck coexist with amphiboles containing variable amounts of components of the remaining four species, as well as with the clinopyroxenes jadeite (M), omphacite (Omp) and kosmochlor (Ko). However, Mg-kat, Nyb and Eck are also present as separate phases as well as in zoned porphyroblasts with Mg-kat in the core, Nyb in the inner rims, and Eck in the outer rims. The analytical data on such zoned amphiboles reveal that the chemistry changes from core to inner rim by virtue of the substitution NaAlCa(-1)Mg(-1) (glaucophane vector), and from the inner to the outer rim along MgSiAl(-1)Al(-1) (tschermak vector). The overall substitution from core to outer rim is, therefore, along NaSiCa(-1)Al(-1) (plagioclase vector). Based on the Si content, three groups can be distinguished within Eck: Eck coexisting with Nyb has low Si contents of < 7.6 a.p.f.u., Eck rimming Nyb has higher Si contents of 7.6-8.0 a.p.f.u., and fine-grained Eck in the matrix has Si contents of 7.9-8.0 a.p.f.u. Plotting the amphibole analyses in a compositional volume with the axes (Na + K) in A, Na in M(4), and tetrahedral Si shows that three groups of amphibole compositions can be distinguished, one being subdivided into three subsets. Group A contains Rich and Mg-kat, B comprises of Win and. Gln, whereas the subsets C can be defined as follows: Cl: high-Na amphiboles with low tetrahedral Si; these are mainly amphiboles from the Eck field but overlap with the two fields of Gln and Win; C2: high-Na and low-Si Ecks overlapping to high-Si Nybs; this group is midway between Eck and Nyb end members; C3: high-Na Mg-kats. Textural observations indicate three stages of sodic and sodic-calcic amphibole growth: stage I are amphiboles of group A (Mg-kat + Rich), stage 2 are amphiboles of group C2 (Nyb + Eck with Si < 7.6 a.p.f.u.), and stage 3 are amphiboles of groups Cl and B (Eck with Si > 7.6 a.p.f.u., + Gln + Win). Based on the subdivision into the compositional groups A-C, the only hint to a miscibility gap is provided by the large gap in the (Na + K) content on the A site which may point to a possible solvus in the system Eck-Win. Overall, the amphiboles investigated here show discontinuities in their growth compositions, rather than miscibility gaps. Textural observations suggest amphibole formation during fluid infiltration in the contact zone between the jadeitite bodies and the surrounding peridotite under high-pressure conditions (> 1.0 GPa) and rather low temperatures of about 250-370 degreesC. Based on compositional trends within the amphiboles as well as phase-equilibrium constraints between amphibole and coexisting pyroxene solid solutions, the chemical composition of zoned amphibole porphyroblasts indicates two growth episodes-increasing pressures from stage I to stage 2 lead to the formation of Nyb from Mg-kat, and subsequently decreasing pressures lead to the formation of stage 3 Eck from Rich. |
| WOS关键词 | EURASIA COLLISION CHRONOLOGY ; COMPOSITIONAL VARIATION ; SUBDUCTION ZONE ; MISCIBILITY GAP ; WESTERN ALPS ; GLAUCOPHANE ; ECLOGITE ; MINERALS ; NYBOITE ; ROCKS |
| WOS研究方向 | Geochemistry & Geophysics ; Mineralogy |
| 语种 | 英语 |
| WOS记录号 | WOS:000184055400006 |
| 出版者 | SPRINGER |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/78203]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Tropper, P |
| 作者单位 | 1.Univ Innsbruck, Inst Mineral & Petrog, A-6020 Innsbruck, Austria 2.Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China 3.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100101, Peoples R China |
| 推荐引用方式 GB/T 7714 | Shi, GH,Cui, WY,Tropper, P,et al. The petrology of a complex sodic and sodic-calcic amphibole association and its implications for the metasomatic processes in the jadeitite area in northwestern Myanmar, formerly Burma[J]. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,2003,145(3):355-376. |
| APA | Shi, GH,Cui, WY,Tropper, P,Wang, CQ,Shu, GM,&Yu, HX.(2003).The petrology of a complex sodic and sodic-calcic amphibole association and its implications for the metasomatic processes in the jadeitite area in northwestern Myanmar, formerly Burma.CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,145(3),355-376. |
| MLA | Shi, GH,et al."The petrology of a complex sodic and sodic-calcic amphibole association and its implications for the metasomatic processes in the jadeitite area in northwestern Myanmar, formerly Burma".CONTRIBUTIONS TO MINERALOGY AND PETROLOGY 145.3(2003):355-376. |
入库方式： OAI收割
来源：地质与地球物理研究所
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