摘要:
本文根据西罗斯海北端阿黛尔盆地及周缘地球物理资料,对地震数据进行二维F-K频率与波数滤波处理,获得噪音被压制,同相轴更连续以及深部信号被明显揭露的数据资料.基于此分析了该区新生代构造特征和岩浆活动,并结合该区冰川作用,总结了与冰川有关的沉积相.研究发现,16 Ma时受到残余岩浆加热造成的阿黛尔海槽隆升作用以及阿黛尔盆地最开始不对称扩张的双重影响,在阿黛尔海槽两翼外分别形成隆起褶皱区和掀斜隆升区.隆起褶皱区以高角度断层和褶皱为特征,分布在阿黛尔海槽东翼南部,覆盖范围较小.掀斜隆升区则以雁行断层和掀斜断块为特征,分布在阿黛尔海槽西翼南部,向南一直伸到陆地边缘.利用火成岩体与围岩间的接触关系,将本区火成岩形成时代大体分为两期:早期和晚新生代火山.早期火山形成时间不易确定,只零星散落在掀斜隆升区内,推测其形成可能与残余岩浆活动有关.晚新生代火山形成时间至少晚于5.5 Ma,分布范围广且分散,基本覆盖整个研究区.这期岩浆活动无论从时间还是空间上可能都与裂谷作用无关,而是受到上新世以来大规模冰川消退造成的地幔减压熔融作用的影响.
Abstract:
Based on the geophysical data obtained from the Adare Basin and its adjacent areas, West Ross Sea, the authors employed the frequency wave-number filtering technique to recover the newly processed dataset with high signal noise ratio and complete seismic event which highly contributes to reveal more detailed deep-seated geological structures than previously thought. The structural features and magmatism of the study area in Cenozoic were classified and analyzed. Combined with glaciation, the associated sedimentary facies were summarized systematically. The authors' analysis revealed that, at 16 Ma, under the influence of the thermal effect caused by residual magmatism and asymmetric spreading of Adare Basin in the initial period, surrounding areas of two flanks of the Adare trough were characterized by uplift folds and tilted uplift zone, respectively. The small-scale uplift fold zone was characterized by nearly upright faults and folds and was located in the southern part of the eastern flank, whereas the tilted uplift zone dominated in the corresponding district of western flank that reached the continental margin. By utilizing the contact relationship between igneous rocks and surrounding rocks, igneous rocks can be divided into two periods: early-stage and late Cenozoic igneous rocks. The early-stage rocks are generally located dispersedly in the tilted uplift zone and the age is poorly known. It is suggested that they were related to the residual magmatism. On the other hand, the spatial distribution of Late Cenozoic igneous rocks, formed not earlier 5.5 Ma, was extensive and scattered, almost covering the whole study area, which indicates that they might be unrelated to the rifting in space and time, instead they were affected by decompression melting of the mantle because of the large-scale deglaciation since Pliocene.
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