The structure of sheeted dikes and associated rocks in North Arm massif, Bay of Islands ophiolite complex, and the intrusive process at oceanic spreading centers
The structure of sheeted dikes and associated rocks in North Arm massif, Bay of Islands ophiolite complex, and the intrusive process at oceanic spreading centers
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北阿姆地块、岛屿湾蛇绿岩杂岩的片状岩脉和相关岩石的结构以及海洋扩张中心的侵入过程
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发表时间：
1983
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通讯作者：
E. Rosencrantz
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作者：
E. Rosencrantz
北臂山蛇绿玄武岩和辉绿岩的结构表明，它们形成为类似于当今大洋中部扩张系统的底层岩浆房的冰冻盖子。火山岩由枕状熔岩、熔岩流和角砾岩组成。通过增加跨越厚度通常小于 50 米的过渡区的堤坝频率，火山岩向下分级成片状堤坝。片状岩脉几乎平行，远离古扩张轴倾斜，位于目前蛇绿岩位置的西侧，如冷边缘偏差所示，这意味着盖子向下旋转并远离轴。单向激冷统计、堤坝厚度和堤坝侵入序列分析都指向一个相对狭窄但复杂的堤坝侵入区域。测量的平均堤坝厚度为 0.90 m。辉绿岩包含与岩脉趋势近似平行的断裂带，解释为反映了海洋裂隙和断层。这些通常向下终止于叶状辉长岩和（或）线状角闪岩中。迪亚巴斯...
The structures of North Arm Mountain ophiolitic basalt and diabase indicate that these formed as a frozen lid to an underlying magma chamber in a system analogous to present-day mid-ocean spreading systems. Volcanics consist of pillow lavas, flows, and breccias. Volcanics grade downward into sheeted dikes by increase in dike frequency across a transition commonly less than 50 m thick. Sheeted dikes, subparallel throughout, dip away from the paleospreading axis, located to the west of present ophiolite position as indicated by chilled margin bias, implying rotation of the lid down and away from the axis. One-way chilling statistics, dike thickness, and dike intrusion sequence analyses all point toward a relatively narrow but complex zone of dike intrusion. The mean measured dike thickness is 0.90 m. Diabase contains zones of fracturing subparallel to dike trends, interpreted to reflect oceanic fissuring and faulting. These commonly terminate downward in foliated gabbro and (or) lineated amphibolite. Diabas...