Grenville-age versus Pan-African magnetic anomaly imprints in western Dronning Maud Land, East Antarctica
Grenville-age versus Pan-African magnetic anomaly imprints in western Dronning Maud Land, East Antarctica
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DOI：
10.1086/317964
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发表时间：
2001-01-01
影响因子：
1.8
通讯作者：
Jacobs, J
中科院分区：
文献类型：
--
作者：
Golynsky, A;Jacobs, J
在本文中，我们研究了泛非东南极造山带西缘部分地区的航磁数据。东南极造山带代表东非造山带的南部延续，该造山带是在新元古代晚期/早古生代时期（约 580-515 Ma）东冈瓦纳大陆和西冈瓦纳大陆碰撞期间共同形成的。东南极造山带的西缘暴露在德龙宁莫德地西部的 Heimefrontfjella 地区，该造山带的西锋在此形成 Heimefront 剪切带。 Heimefront剪切带以西地壳具有典型的中元古代至新元古代早期（格伦维尔时代）K-Ar和Ar-Ar矿物冷却年龄，磁异常范围广、振幅高、细长，与克拉通长波长平行。在 Heimefront 剪切带以东，K-Ar 和 Ar-Ar 矿物冷却年龄范围在约 10-10 之间。 570和470 Ma，磁异常模式完全不同。在这里，存在着一个巨大的磁低压，其上覆盖着小规模的异常，这些异常的方向与区域泛非构造趋势平行，与中元古代异常呈高角度。因此，泛非构造热叠印引起了磁性矿物的根本性重新分布。数据表明，航磁测绘与详细的实地考察相结合是描绘暴露程度较差的南极洲东南极造山带范围的有效方法。
In this article, we examine aeromagnetic data from a part of the western margin of the Pan-African East Antarctic Orogen. The East Antarctic Orogen represents the southern continuation of the East African Orogen that together formed during the collision of East and West Gondwana during late Neoproterozoic/Early Paleozoic times (at ca. 580-515 Ma). The western margin of the East Antarctic Orogen is exposed in Heimefrontfjella, western Dronning Maud Land, where the western front of this orogen crops out as the Heimefront Shear Zone. Crust west of the Heimefront Shear Zone has typical Mesoproterozoic to early Neoproterozoic (Grenville-age) K-Ar and Ar-Ar mineral cooling ages, and magnetic anomalies are broad, of high amplitude, elongate, and craton parallel with long wavelengths. East of the Heimefront Shear Zone, K-Ar and Ar-Ar mineral cooling ages range at between ca. 570 and 470 Ma, and the magnetic anomaly pattern is entirely different. Here, a large magnetic low persists, which is overprinted by small-scale anomalies that are oriented parallel to the regional Pan-African structural trends at a high angle to the Mesoproterozoic anomalies. Thus, the Pan-African tectono-thermal overprint has caused a fundamental redistribution of magnetic minerals. The data show that the combination of aeromagnetic mapping along with detailed fieldwork is a powerful method to delineate the extent of the East Antarctic Orogen in poorly exposed Antarctica.