Tectonometamorphic evolution of the Schistes Lustres Complex; implications for the exhumation of HP and UHP rocks in the Western Alps
Tectonometamorphic evolution of the Schistes Lustres Complex; implications for the exhumation of HP and UHP rocks in the Western Alps
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DOI：
10.2113/172.5.617
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发表时间：
2001-09
影响因子：
--
通讯作者：
P. Agard;L. Jolivet;B. Goffé
中科院分区：
文献类型：
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作者：
P. Agard;L. Jolivet;B. Goffé
我们提供了关于Schistes Lustres杂岩的新的构造和变质数据，该杂岩占据了西部阿尔卑斯山外部LP和内部UHP域(例如Dora Maira地块)之间的中心位置。变质条件从西向东逐渐增加，从12-13千巴/300-350摄氏度到20-21千巴/450-500摄氏度，接近多拉迈拉地块。识别出两个不同的折返幕：(1)在低蓝片岩相-绿片岩相条件下，发生了一次普遍的东向韧性D2事件，垂直缩短作用较大。该事件发生在50-40 Ma期间，负责了Schistes Lustres杂岩的大部分折返以及其前部的碳磷石产出的保存。(2)发育西向韧性-脆性、高度非同轴伸展的D3事件，变形强度自东向西递减。该事件发生在亚绿片岩相条件下，与Dora Maira地块和其他内部区域发生的约40-35 Ma的西向绿片岩变形同时代(并可能源于)。
We present new structural and metamorphic data on the Schistes Lustres complex which occupies a central position in the western Alps between the external LP and the internal UHP domains (e.g., the Dora Maira massif). Metamorphic conditions are shown to increase progressively from west to east from ca. 12-13 kbar/300-350 degrees C to 20-21 kbar/450-500 degrees C close to the Dora Maira massif. Two distinct exhumation episodes are recognized: (1) A pervasive east-vergent ductile D2 event, with a large component of vertical shortening, took place under low blueschist-facies to greenschist-facies conditions. This event is responsible for most of the exhumation of the Schistes Lustres complex as well as for the preservation of carpholite occurrences at its front, and took place during the period 50-40 Ma. (2) A west-vergent ductile-to-brittle, highly non-coaxial, extensional D3 event subsequently developed, with a deformation intensity decreasing from east to west. This event took place at subgreenschist-facies conditions and is coeval with (and probably derives from) the west-vergent greenschist deformation taking place in the Dora Maira massif and other internal domains by ca. 40-35 Ma.