Crustal structure of Fiordland, New Zealand
Crustal structure of Fiordland, New Zealand
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DOI：
10.1016/0040-1951(79)90371-8
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发表时间：
1979-05
期刊：
影响因子：
2.9
通讯作者：
G. Oliver;J. Coggon
中科院分区：
文献类型：
--
作者：
G. Oliver;J. Coggon
对峡湾西部部分地区进行的详细测绘使我们认识到，基底麻粒岩相下地壳物质（可能是前寒武纪）被一个区域性逆冲带与盖层序列（角闪岩相片麻岩，下古生代）隔开。随着对基底-盖层关系的认识和航磁异常的辅助，峡湾被划分为四个大致呈北-东北走向的区域。峡湾西部地区主要由基底岩石组成。峡湾中部和峡湾西南部地区主要由角闪岩和绿片岩相变质沉积物和盖层序列的片麻状花岗闪长岩组成，峡湾中部地区向东倾斜，远离基底。东部峡湾地区的特点是一系列的基本，中间和酸性侵入岩。在峡湾东部、峡湾西南部较突出的磁异常，以及峡湾西部海岸附近的一个大的磁异常，都被认为是由侵入体引起的。在峡湾西部存在正重力异常，加上近海重力低，与该地区的下地壳隆起和暴露是一致的。峡湾下持续的浅层和中深层地震活动，以及大规模的重力异常，表明构造力量目前正在发挥作用，以维持峡湾西部在其异常高的水平。峡湾因此显示了大陆地壳的横截面：前寒武纪（？）下地壳中的变火成麻粒岩;中地壳中的下古生代变沉积角闪岩相片麻岩和熔融等价物;上地壳中的中生代侵入岩以及上覆的白垩纪和第三纪沉积物。
A generalised crustal structure of Fiordland is proposed.Detailed mapping in part of Western Fiordland has led to the recognition of a basement granulite facies lower crustal material, probably Precambrian in age) separated by a regional thrust zone from a cover sequence (amphibolite facies gneisses, of Lower Paleozoic age). With the recognition of the basement—cover relationship and the aid of aeromagnetic anomalies Fiordland has been divided into four, generally north-northeast trending, regions. The Western Fiordland region is composed chiefly of basement rocks. The Central Fiordland and Southwestern Fiordland regions are made up predominantly of amphibolite and greenschist-facies metasediments and gneissic granodiorites of the cover sequence, which in Central Fiordland have a regional dip to the east, off the basement. The Eastern Fiordland region is characterised by a series of basic, intermediate and acid intrusive rocks. The more prominent magnetic anomalies in Eastern Fiordland, Southwestern Fiordland, and a large anomaly off the coast of Western Fiordland, are all considered to be caused by intrusive bodies. The presence of a positive gravity anomaly over Western Fiordland, coupled with a gravity low offshore, is consistent with the lower crust being uplifted and exposed in this area. Continuing shallow and intermediate-depth seismic activity beneath Fiordland, as well as the large size of the gravity anomaly, suggest that tectonic forces are currently acting to maintain Western Fiordland at its unusually high level.Fiordland thus displays a cross-section of continental crust: Precambrian(?) metaigneous granulites in the lower crust; Lower Paleozoic metasedimentary amphibolitefacies gneisses and melted equivalents in the middle crust; Mesozoic intrusives, and overlying Cretaceous and Tertiary sediments in the upper crust.