The Structural Foundations of the Northern Carnarvon Basin
The Structural Foundations of the Northern Carnarvon Basin
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发表时间：
1994
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通讯作者：
H. Stagg;J. Colwell
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作者：
H. Stagg;J. Colwell
1991- 1992年，澳大利亚地质调查组织（AGSO）在西北大陆架的北方卡纳冯盆地获得了大约4500 km的深地震数据。这些数据可以对10-12秒（15-30公里）深处的盆地形成事件进行成像，并可以解释承载大量碳氢化合物积聚的结构的基础。北方卡纳冯盆地是一个主要的凹陷盆地，自其形成以来积累了至少12-15 km的沉积物充填，可能是在石炭纪。古生代和中生代沉积充填物具有“层饼”外观，并经历了多期断层、褶皱和反转，特别是在晚三叠世、侏罗纪和白垩纪。在中生代，几乎没有伸展的证据;压扭和张扭运动似乎占主导地位。唯一的重大中断的“层饼”的外观发生在盆地的内部，其中一个主要的向陆soling断层系统分裂盆地从上三叠统水平，通过至少地壳的基础。该断裂系统（“兰金断裂系统”）沿盆地东南侧延伸沿着500多km，其反向断裂系统集中了侏罗纪和白垩纪主要碎屑岩序列的沉积。综合来自埃克斯茅斯高原的有限速度信息和皮尔巴拉盆地已知的速度结构的深地震数据表明，该盆地是从石炭纪到侏罗纪下地壳减薄的主要阶段的产物。在这一减薄阶段，中地壳间断面以下的几乎整个地壳都被移走。相应的上地壳减薄可能发生在裂解时被移除的共轭边缘上。
In 1991-92, the Australian Geological Survey Organisation (AGSO) acquired approximately 4500 km of deep-seismic data over the northern Carnarvon Basin on the North West Shelf. These data image basin-forming events down to depths of 10-12 seconds (15-30 km) and allow an interpretation of the foundations of structures that host numerous hydrocarbon accumulations. The northern Carnarvon Basin is a major sag basin that has accumulated at least 12-15 km of sediment fill since its initiation, probably in the Carboniferous. The Palaeozoic and Mesozoic sedimentary fill has a 'layer(cid:8226) cake' appearance and has been subjected to multiple episodes of faulting, folding, and inversion, especially in the Late Triassic, Jurassic, and Cretaceous. There is little evidence of extension during the Mesozoic; transpressional and transtensional movements appear to be predominant. The only significant disruption to the 'layer-cake' appearance occurs beneath the inner part of the basin, where a major landwards-soling fault system cleaves the basin from Upper Triassic level through to at least the base of the crust. This fault system (the 'Rankin Fault System') extends for more than 500 km along the southeast flank of the basin and, with its antithetic fault system, has served to focus the deposition of major clastic sequences during the Jurassic and Cretaceous. Integration of the deep-seismic data with limited velocity information from the Exmouth Plateau and the known velocity structure of the Pilbara Craton indicates that the basin is the product of a major episode of lower crustal thinning that lasted from the Carboniferous to the Jurassic. During this thinning phase, almost the entire crust below a mid-crustal discontinuity was removed. Commensurate upper crustal thinning probably took place on the conjugate margin which was removed at breakup.