The development of orientated symplectites during deformation
The development of orientated symplectites during deformation
复制标题
变形过程中定向辛的发展
DOI：
10.1111/j.1525-1314.1995.tb00237.x
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发表时间：
1995
影响因子：
3.4
通讯作者：
K. Brodie
中科院分区：
文献类型：
--
作者：
K. Brodie
在北方意大利Ivrea-Verbano带的变形麻粒岩相变基性岩中观察到定向合晶。该地区经历了下地壳的伸展，容纳了本地化的高T剪切带的运动。在应变相对较低的地区，如剪切带的边缘，形成了斜方辉石、斜长石和尖晶石的合晶岩。合晶蠕虫状，定向平行于主叶理，并在区域拉伸方向。该反应与变形是同运动的，并且仅在岩石中的潜在塑性晶界中发展。它大概是抑制在晶界受到较高的正应力，由于相对较大的体积增加参与反应。
这些观测结果支持了这样的解释，即变形与高温麻粒岩相条件下的区域伸展有关，合晶岩是压力降低的结果。
Orientated symplectites have been observed in deformed granulite facies metabasic rocks from the Ivrea-Verbano zone in northern Italy. The area underwent lower crustal extension, accommodated by movement on localized high-T shear zones. In areas of relatively low strain, such as at the margins of shear zones, symplectites of orthopyroxene, plagioclase and spinel have formed. The symplectites are vermiform and orientated parallel to the main foliation and in the regional stretching direction. The reaction was synkinematic with the deformation, and only developed in potentially dilatant grain boundaries in the rock. It was presumably inhibited in grain boundaries subjected to higher normal stress due to the relatively large volume increase involved in the reaction.
The observations support the interpretation that the deformation was related to regional extension under high-T granulite facies conditions, the symplectites forming as a result of decreasing pressure.