Generation and reorganization of Oman oceanic crust-mantle

阿曼大洋壳幔的生成与重组

基本信息

批准号：
11691121
负责人：
ARAI Shoji
金额：
$ 12.8万
依托单位：
kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11691121/
关键词：
OPHIOLITE OMAN OCEANIC RIDGE UPPER MANTLE CRUST HYDROTHEMAL ALTERATION METAMOR PHIC SOLE 島弧

项目摘要

1. We recognized a wide petrographical variation of peridotite, its deformational history, cystallographical change of minerals and origin of mylonites within the upper mantle section of the northern Oman ophiolite. High-PGE chromitite was also discovered.2. We classified the late-intrusive rocks into three types in terms of petrography. Komatititic extrusives were found associated with picrite basalt, a quench phase of the late intrusives.3. The segmetation structure of a mid-ocean ridge was estimated by the strutural change of gabbroic layers. Noritic gabbro intruding around the derivative magma chmabers around the segment center impose contact metamorphism of up to granulite facies on surrounding sheeted dike complex. The structure and evolutional history of the roof zone of magma chambers were clarified.4. The upper lavas can be classified into three groups by high-accuracy chemical analysis of their Cpx phenocrysts, and the genesis was estimated for individual groups. Boninite was newly found. Preliminary data on the Salahi volcanics that erupted at the obuduction stage were presented.5. Hysrothermal metal mineralization was geologically and geochemically examined to understand its genesis. Reaction between aqueous fluid and chlorite in meta-basalts is of vital importance for their characteristics of Zn and Ni contents. The water/rock ratio in the hydrothermal fluid formation is around 20, that is far higher than the calculated values, 2 to 4.6. The thermal structure of the ocean-floor metamorphism was examined in basalt to dolerite to confirm a temprature increase downward.7. The shear sense on the metamorphic sole is NE-SW and the hanging side was confirmed to have moved toward SW.The basic amphibolite of the sole demonstrates variable flow textures within several tens of meters from the contact with overlying ultramafic rocks.

1。我们认识到橄榄岩的广泛岩石岩变化，其变形史，矿物质和肌lon虫的起源的膀胱图变化，在阿曼蛇形北部的上地幔段内。还发现了高细铬铁矿2。在岩石学方面，我们将后期侵入的岩石分为三种类型。发现了与picrite玄武岩相关的高质分流，这是后期入侵的淬灭阶段。3。通过gabbroic层的形式变化估计了中山脊的segmetration结构。在片段中心围绕衍生物岩浆Chmabers侵入的Noritic Gabbro将接触变质施加到周围的薄堤板络合物上的颗粒状相。阐明了岩浆室屋顶区的结构和进化历史。4。可以通过对其CPX表晶的高临界化学分析将上部熔岩分为三组，并估算了单个组的起源。新发现。提供了有关在陈述阶段爆发的萨拉希火山的初步数据。5。在地质和地球化学上检查了Hysrothermal金属矿化，以了解其起源。荟萃分析中水性流体和氯酸盐之间的反应对于它们的Zn和Ni含量的特征至关重要。水热流体形成中的水/岩比约为20，远高于计算值2至4.6。在玄武岩中检查了海底变质的热结构，以确认降温向下增加。7。变质鞋底上的剪切感是NE-SW，并且确认悬挂侧已移动到SW。鞋底的基本闪石表现出可变的流动纹理，距离与上覆盖的超镁铁质岩石接触几十米。