Plagioclase preferred orientation, Foreshore Group metasediments, Bluff, New Zealand
Plagioclase preferred orientation, Foreshore Group metasediments, Bluff, New Zealand
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斜长石择优取向，Foreshore Group 变质沉积物，布拉夫，新西兰
DOI：
10.1016/0040-1951(79)90313-5
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发表时间：
1979
期刊：
影响因子：
2.9
通讯作者：
D. Shelley
中科院分区：
文献类型：
--
作者：
D. Shelley
前滨群火山变沉积岩（角闪石-角岩相）中的重结晶斜长石具有很强的择优取向，晶体轴 [100] 平行于层理，最大平行于线理（= 最大主应变轴或最大伸长轴）；从寡长石到钙长石，各层的组成差异很大。首选方向被解释为由于邻近布拉夫火成岩复合体侵入引起的应变期间，原始松散凝灰岩中细长斜长石喷射物的机械旋转所致。这种定向机制的证据可以在大的未重结晶斜长石喷射物的优选定向中找到。基质斜长石通常会再结晶形成花岗质马赛克；这种纹理代表了一种模拟重结晶，它在紧随变形之后的热事件期间降低了细晶基体中的晶界能。
Recrystallised plagioclase in volcanic metasediments of the Foreshore Group (hornblende-hornfels facies) has a strong preferred orientation with crystala-axes [100] lying parallel to bedding and with a maximum parallel to a lineation (= maximum principal strain axis or axis of greatest elongation); composition varies widely from bed to bed from oligoclase to anorthite. The preferred orientation is interpreted to result from the mechanical rotation of elongate plagioclase ejecta in the original unconsolidated tuff during strain caused by intrusion of the adjacent Bluff igneous complex. Evidence for such an orienting mechanism is found in the preferred orientation of large unrecrystallised plagioclase ejecta. Matrix plagioclase is generally recrystallised to form granoblastic mosaics; this texture represents a mimetic recrystallisation which reduced grainboundary energy in the fine-grained matrix during the thermal event immediately succeeding deformation.