※一部利用できない機能があります
| 1.
論文 |
論文
|
Python, Marie ; Ishida, Yoshito ; Ceuleneer, Georges ; Arai, Shoji
概要:
金沢大学大学院自然科学研究科自然計測<br />We discovered a new kind of dyke in the mantle section of the Oman ophiolite composed mainly of
…
diopside that we called diopsidite, although traces of forsterite, anorthite, titanite or andradite may be also observed. The texture and chemical composition, and the relationship between antigorite and diopside or rare forsterite, suggest that they formed by high-T metamorphism of serpentine (antigorite) and are the result of interaction between hydrothermal fluid and percolating magma in the shallow mantle. Chemical data, obtained by electron microprobe and in situ laser ablation coupled to ICP-MS, show large heterogeneities from one sample to another and between diopside crystals in each sample. The trace element patterns are characterised by strong positive anomalies in Sr and Eu and a negative anomaly in Ti. Small-scale heterogeneities reflect the disequilibrium conditions in the dyke formation and show that a relatively Ti-rich- and Al-Eu-Sr-LREE-poor phase may be included in the diopside. The exact nature of this phase is difficult to determine but the Eu negative anomaly, and the low Sr and LREE concentration suggest that it is probably some partially altered, relict protolith mineral.
続きを見る
|
||||
| 2.
論文 |
論文
|
Zaki Khedr, Mohamed ; Arai, Shoji ; Python, Marie
概要:
We studied basal lherzolites that are exposed along the metamorphic sole at the base of the central Oman ophiolite (Wadi Sarami). We recognized two types of lherzolites (Types I and II) based on field occurrences, textures, and mineral
…
compositions. Type I lherzolites are massive and transition into harzburgites, whereas Type II lherzolites are strongly foliated with mylonitic to porphyroclastic textures. Type II lherzolites only crop out within a direct contact with the amphibolitic sole to few meters above this sole and are overlain and/or surrounded by Type I. The clinopyroxenes [Mg# = Mg/(Mg + Fe) = 0.89-0.94] of Type II lherzolites show higher contents of Al2O3 (4.5-7.3 wt%), Na2O (0.5-1.2 wt%), Cr2O3 (0.6-1.4 wt%), and TiO2 (0.2-0.4 wt%) than those of Type I lherzolites. Positive correlations among the Al2O3, Na2O, and TiO2 contents of clinopyroxenes show a pronounced residual trend from Type I lherzolites to depleted harzburgite, giving rise to chemical heterogeneities at the base of the mantle section. Clinopyroxenes in lherzolites and harzburgites show compositional trends that are similar to those in abyssal peridotites from normal ridge segments. Olivines (Fo89.4-Fo91.5) show a residual character of the Sarami peridotites. Primary spinels show a wide range of Cr# [= Cr/(Cr + Al) from 0.04 to 0.53] and low YFe [Fe3+/(Cr + Al + Fe3+), <0.046], similar to spinels in abyssal peridotites. The wide range of spinel Cr# is a result of a wide range of partial-melting degrees, which are up to 10% for lherzolites and ~ 10-25% for harzburgites. The Type II lherzolites, which occur near the paleo-fracture zone located to the east of Wadi Sarami, represent a remnant of asthenospheric materials trapped at the base of oceanic lithosphere mantle (Type I) during detachment and obduction. The Type I lherzolites experienced high-degree partial melting, resulting in the formation of harzburgites at the refractory end. The modal and compositional variations of Sarami pyroxenes and spinels indicate intrinsic mantle heterogeneity of Oman ophiolite formed as residues at an oceanic spreading center.
続きを見る
|
||||
| 3.
論文 |
論文
|
Python, Marie ; Ceuleneer, Georges
概要:
金沢大学大学院自然科学研究科<br />Observatoire Midi-Pyrenees<br />Promoting Environmental Pesearch in Pan-Japan Sea Area : Young Resea
…
rchers' Network, Schedule: March 8-10,2006,Kanazawa Excel Hotel Tokyu, Japan, Organized by: Kanazawa University 21st-Century COE Program, Environmental Monitoring and Prediction of Long- & Short- Term Dynamics of Pan-Japan Sea Area ; IICRC(Ishikawa International Cooperation Research Centre), Sponsors : Japan Sea Research ; UNU-IAS(United Nations University Institute of Advanced Studies)+Ishikawa Prefecture Government ; City of Kanazawa
続きを見る
|
