• 责任者：Dong Chongzhi (Key Laboratory of Marine Sciences ; SOA ; Hangzhou 310012 ; China) ; Ding Weiwei
• 刊名：Chinese Journal of Geophysics
• 出版年：2013
• 卷期：56(10)
• 关键词：磁异常 ; magnetic anomaly ; 重力异常 ; gravity anomaly ; 地壳结构 ; crustal structure ; 南极洲 ; Antarctica
• 页码：p.3346-3360
• 图表：10 illus., 35 refs.
• 分类号：1400
• issnNo：ISSN0001-5733
• isbnNo：CN11-2074/P

     Prydz Bay is located in the continental margin of East Antarctica and its deep crustal structure is of great significance for understanding the Cretaceous Gondwana rifting and Cenozoic continental margin formation. In this paper, the gravity and magnetic, multi-channel seismic reflection,sonobuoy refraction seismic and ODP drilling data are used to study the deep crustal structure of Prydz Bay. The results show that the Prydz depression is manifested as the typical basin characteristics of negative gravity anomalies and deep sedimentary basement, while gravityanomalies are high in the Four Ladies Bank whose deep sedimentary basement is shallow. There is a SW-NE banding basement uplift in the middle of the continental shelf. The isostatic residual gravity anomalies in the outside part of middle continental shelf present as V-shaped banding characteristics, whose wings are adjacent to the continental slopes of the Four Ladies Bank and Fram Bank. The anomaly zone deviates toward the land in the middle continental shelf due to the impact of the terrain of the ancient edge of the continental shelf. We speculate that both of this zone and Prydz trough mouth fan belong to the landward part of continent-ocean transition zone （COT）, as the crust is gradually thinning from land to ocean as showed in the gravity modelling profile. There is a thinner crust below Prydz alluvial fan, with an average thickness and thinnest thickness are 6 km and 4.6 km, respectively. According to the location of the continent-ocean boundary （COB）, we speculate that it belong to the transitional crust close to the thickness of the oceanic crust. The trend of gravity anomaly division is basically in accordance with the trend of the Lambert graben at the Prydz Bay. It mainly reflects the rifting of Prydz Bay which is caused by the Permian-Triassic super plume. Both of free air gravity anomaly and isostatic residual gravity in this area are greater than 100 X 10.2 m/s2. This is perhaps a result of the regional flexural isostasy effect of the thick sedimentary body at the edge of the continental shelf loading on the top of the high strength lithosphere, which may be related to the evolution of sedimentary hiatus and fast progradation thickening after the second rift stage. The strike of magnetic anomaly is significantly different from gravity anomaly in Prydz Bay. The magnetic anomaly can be divided into two parts which is high and positive in the northeast, hut is low in the southwest. It suggests that the high magnetic anomaly may be mainly derived from mafic igneous rocks, and the era of magmatism is different from the era of the basement uplifting. It may be formed in Precambrian or in Cretaceous when Antarctica and Indian Plate is rifting.