Pre-Andean orogenesis in the Coast Ranges of central Chile
Pre-Andean orogenesis in the Coast Ranges of central Chile
复制标题
智利中部海岸山脉的前安第斯造山作用
DOI：
--
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Terence T. Kato
中科院分区：
文献类型：
--
作者：
Terence T. Kato
根据对智利中部南纬38°和43°之间海岸山脉低品位片岩的岩石学和野外观察，推断可能在二叠纪-三叠纪发生了强烈的构造变质事件。镁铁质片岩中残留的富铁榴石的石榴石、黑云母和铝质角闪石被普遍存在的组合所取代，该组合由钠长石+镁铝榴石+绿帘石+阳起石+辉石±石英：±硬钾长石±白色云母±氧化铁组成。电子探针分析的基础上相兼容性的化学分析表明，区域退变质早期上绿片岩和/或绿帘石角闪岩下绿片岩相。一个区域性的西北-东南走向的结构内的火山岩是在较低的绿片岩变质作用，其中涉及广泛的流体重新引入系统。这一主要造山事件被认为是沿南美洲晚古生代边缘沿着俯冲相关增生过程的高潮。辐合带可能明显斜向于现今南北走向的大陆边缘。
An intense structural-metamorphic event of probable Permian-Triassic age is inferred from petrologic and field observations of low-grade schists from the Coast Ranges of central Chile between latitudes 38°S and 43°S. Relict almandine-rich garnet, biotite, and aluminous amphibole in mafic schists are replaced by a pervasive assemblage consisting of albite + chlorite + epidote + actinolite + sphene ± quartz: ± stilpnomelane ± white mica ± iron oxide. Chemographic analysis of phase compatibilities based on electron microprobe analyses suggests a regional retrogradation from earlier upper greenschist and/or epidote amphibolite to lower greenschist facies. A regional northwest-southeast-trending fabric within the terrane was imposed during the lower greenschist metamorphism which involved widespread reintroduction of fluids into the system. This major orogenic event is thought to be the culminating episode in a subduction-related accretionary process along the late Paleozoic margin of South America. Convergence may have been markedly oblique to the present north-south-trending continental margin.