Thrust tectonics in the Scandes - upper crustal extension during Scandian compression
Thrust tectonics in the Scandes - upper crustal extension during Scandian compression
复制标题
斯堪德山脉的逆冲构造——斯堪的纳挤压期间的上地壳伸展
作者：
D. Gee
到19世纪70年代初，Tornebohm清楚地认识到，在Jamtland的Are地区，麻粒岩相片麻岩覆盖着志留纪的化石灰岩。然而，这一发现的区域意义，需要西弗推覆构造至少100公里的逆冲位移，在世界其他地方是未知的，直到1888年，斯堪的纳维亚加里东尼德斯的逆冲假说才被明确地制定出来。Tornebohm认为，发生在Jamtland的逆冲层起源于Trandelag。但是，在挪威确定根区的问题使霍格博姆在1910年推测，加里东晚期推覆体是从挪威海岸的基底以西衍生出来的，这种解释后来得到了阿斯克伦德、霍尔特达尔和库林的支持，此后又得到了许多其他人的支持。在上个世纪的过程中提出了不同的假设；没有人成功地解释了各种外来生物的基本几何形状，因为它们现在暴露在这个深受侵蚀的造山带中。目前普遍认为，在碰撞造山运动期间，波罗的海对Laurentia的逆冲造成了数百公里的舷外地形向波罗的海平台的位移。早期变形和变质作用（芬马克式）已与主大陆碰撞作用（加拿大式）区分开来。
By the early 1870's it was clear to Tornebohm that granulite facies gneisses overlay fossilifer-ous Silurian limestones in the Are area in Jamtland. However, the regional implications of this discovery, requiring at least 100 km of thrust displacement of the Seve Nappes, were of a dimension unknown elsewhere in the world and it was not until 1888 that the thrust hypothesis was clearly formulated for the Scandinavian Caledonides. Tornebohm considered that the thrust sheets occurring in Jamtland were rooted in Trandelag. But the problems of identifying a root-zone in Norway led Hogbom, in 1910, to speculate on the derivation of the higher Caledonian nappes from west of the basement along the Norwegian coast, an interpretation subsequently favoured by Asklund, Holtedahl and Kulling and thereafter, by many others. Alternative hypotheses have been presented during the course of the last century; none have succeeded in explaining the essential geometry of the vari-ous allochthons as they are now exposed in this deeply eroded orogen. Hundreds of kilometres of displacement of outboard terranes onto the Baltoscandian platform are now generally accepted and considered to result from underthrusting of Laurentia by Baltica during collisional orogeny. Early deformation and metamorphism (Finnmarkian) has been distinguished from the main continental collision (Scandian).