Aeromagnetic data from the southern Weddell Sea embayment and adjacent areas: synthesis and interpretation
Aeromagnetic data from the southern Weddell Sea embayment and adjacent areas: synthesis and interpretation
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来自威德尔海南部海湾和邻近地区的航磁数据：综合和解释
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
N. D. Aleshkova
中科院分区：
文献类型：
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作者：
R. J. Hunter;A. C. Johnson;N. D. Aleshkova
摘要结合1973 ~ 1989年俄罗斯和英国的磁异常资料，绘制了覆盖威德尔海南部及周边地区的新区域航磁异常图。根据特征异常波长将地图划分为四个区域：南极半岛、威德尔海海湾、Haag Nunataks和东南极洲西海岸。在南威德尔海和罗纳和费尔奇纳冰架上，磁场相对平滑，表明有厚厚的沉积覆盖，尽管有一些明显的异常。在该区域的北部，可以清楚地看到一个从西到东的广泛的正异常，这被解释为代表了大陆-海洋的边界。最突出的磁特征是细长的Explora异常，它与东南极洲海岸平行，一直延伸到Berkner岛，直到Dufek地块。我们将这一异常的来源解释为裂谷相关的火山岩，可能与Dufek入侵同时就位。裂谷本身被解释为在安第斯悬崖和东南极洲之间向南延伸，并在伯克纳岛以南结束。俄罗斯的重力剖面显示，伯克纳岛没有相应的布格异常，尽管在该岛东部的费尔奇纳冰架上方有一个大的正异常（约80 mGal），表明存在第二个裂谷结构。跨越这些特征的重力模型显示，罗纳和费尔奇纳冰架下方的地壳变薄，表明整个地区经历了显著的延伸。一个横跨伯克纳岛两侧的重力模型被用来估计未拉伸与拉伸的地壳厚度之比。结果值约为2.7，表明已经发生了足够的伸展以诱发熔融，支持了Berkner岛磁异常的来源是与裂谷有关的火山岩的观点。
Abstract A new regional aeromagnetic anomaly map covering the southern Weddell Sea and surrounding areas was produced by combining Russian and British magnetic anomaly data acquired between 1973 and 1989. The map is divided into four zones on the basis of characteristic anomaly wavelength: Antarctic Peninsula, Weddell Sea embayment, Haag Nunataks and the western coast of East Antarctica. Over the southern Weddell Sea and the Ronne and Filchner ice shelves, the magnetic field is relatively smooth indicating a thick sedimentary cover although there are some distinctive anomalies. A broad positive anomaly is clearly visible running W-E across the north of the area, which is interpreted as representing the continent — ocean boundary. The most prominent magnetic feature is the elongate Explora Anomaly which runs parallel to the coast of East Antarctica and continues over Berkner Island terminating at the Dufek Massif. We interpret the source of this anomaly as rift-related volcanic rocks probably emplaced around the same time as the Dufek intrusion. The rift itself is interpreted as running south between the Andenes escarpment and East Antarctica and terminating south of Berkner Island. Russian gravity profiles show that Berkner Island does not have an associated Bouguer anomaly, although a large positive anomaly (approx 80 mGal) is seen to the east of the island over the Filchner Ice Shelf, suggesting the presence of a second rift structure. Gravity modelling across these features shows thinned crust below the Ronne and Filchner ice shelves, indicating that the whole area has undergone significant extension. A gravity model across the flanks of Berkner Island is used to estimate the ratio of unstretched to stretched crustal thickness. The resulting value of approximately 2.7 indicates that enough extension has taken place to induce melting, supporting the idea that the source of the magnetic anomaly over Berkner Island is rift-related volcanic rocks.