Origin and Generation Process of High Mg# Peridotites

高镁的来源及生成过程

• 批准号: 07640630
• 负责人: NIIDA Kiyoaki
• 金额: $ 1.47万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640630/
• 关键词: upper mantle; peridotite; dunite; harzburgite; gabbro; basaltic magma; partial melting; Horoman complex; ハルツパ-ジャイト

Origin of high Mg# peridotites derived from upper mantle has been discussed as residual mantle materials after basaltic magma extraction during partial melting, cumulates crystallized from basaltic magma, and replacive peridotites after interactions between channeling melt and wall peridotites. Here, we focused on high Mg# peridotites in the Horoman and Oku-Niikappu ultramafic complexes, Hidaka metamorphic belts, and in the Iwanai-dake peridotites, Kamuikotan ophiolite belt, Hokkaido. This is to understand (1) modes of occurrence of high Mg# peridotites in upper mantle materials, (2) characteristics of chemical composition for the bulk rocks and the constituent minerals, and (3) reconstruction of the magma channeling systems in cluding the magmatic processes and the magmawall peridotite interactions.The results indicate that the high Mg# peridotites always generate in magma channels within upper mantle peridotites, in close association with reaction zones (replacement bands) at the contact with the channels. In the Horoman peridotite complex, two different modes of magma channeling were observed. One is magma channeling with melt extractions from the wall peridotites, and the other is magma channeling with melt addition from the channeling magma vents. Such a high Mg# peridotite as dunite and chromitite are also formed dominantly in highly depleted harzburgites of the Oku-Niikappu and Iwanai-dake ophiolitic peridotite complexes.

上地幔高镁橄榄岩是部分熔融过程中玄武岩岩浆提取后残留的地幔物质、玄武岩岩浆结晶后的堆积物、通道熔体与壁面橄榄岩相互作用后置换橄榄岩的成因。在这里，我们重点研究了Hidaka变质带Horoman和Oku-Niikappu超镁铁质杂岩以及北海道Kamuikotan蛇绿岩带Iwanai-Dake橄榄岩中的高Mg#橄榄岩。这是为了了解(1)高镁橄榄岩在上地幔物质中的赋存方式，(2)块体岩石和组成矿物的化学成分特征，以及(3)岩浆通道系统的重建，包括岩浆过程和岩浆壁橄榄岩相互作用。结果表明，高镁橄榄岩总是在上地幔橄榄岩内部的岩浆通道中产生，与通道接触处的反应带(交代带)密切相关。在霍罗曼橄榄岩杂岩中，观察到了两种不同的岩浆通道模式。一种是从壁面橄榄岩中提取熔体的岩浆通道作用，另一种是通过通道岩浆喷口的熔体添加作用的岩浆通道作用。在Oku-Niikappu和Iwanai-Dake蛇绿橄榄岩杂岩的高度亏损的方辉橄榄岩中，也主要形成了纯橄榄岩和铬铁矿等高镁橄榄岩。

项目成果

Niida,K.: "Ultramafic crystal mush intrusion into crystallizing magma chamber : field evidence from the Chilas complex, northern Pakistan." Proc. Geoscience Colloquium, GSP,. 15. 157-171 (1996)

Niida,K.：“超镁铁质晶体糊状物侵入结晶岩浆室：来自巴基斯坦北部奇拉斯杂岩体的现场证据。”

新井田清信: "幌満かんらん岩に記録されたマグマチャネリング様式:メルト成分の涸渇や付加で形成された置換性かんらん岩." 地質学論集,. 47(印刷中). (1997)

Kiyonobu Niida：“Horoman 橄榄岩中记录的岩浆通道类型：由熔融成分的消耗和添加形成的置换橄榄岩”，47（出版中）。

前田仁一郎: "大陸地殻形成におけるマントル由来未分化マグマの役割:日高化成活動帯の例" 地質学論集,. 47(印刷中). (1997)

Jinichiro Maeda：“未分化地幔来源的未分化岩浆在大陆地壳形成中的作用：日高化生带的一个例子”《地质评论》，47（出版中）。

Maeda, J.: "Interaction of a spreading ridge and an accretionary prism : Inplications from MORB magmatism in the Hidaka magmatic zone, Hokkaido, Japan." Geology,. 24. 31-34 (1996)

Maeda, J.：“扩张脊和增生棱镜的相互作用：日本北海道日高岩浆带 MORB 岩浆活动的影响。”

Maeda, J.: "Interaction of a spreading ridge and an accretionary prism : Implications from MORB magmatism in the Hidaka magmatic zone, Hokkaido, Japan." Geology,. 24. 31-34 (1996)

Maeda, J.：“扩张脊和增生棱镜的相互作用：日本北海道日高岩浆带 MORB 岩浆活动的影响。”