Abstract

We present paleomagnetic data acquired on 276 samples from 24 Mesoproterozoic (ca 1132 Ma) postkinematic gabbro–dolerite dykes in the Bunger Hills (Queen Mary Land, East Antarctica). In a stereogram, the mean directions of the high-temperature components of natural remanent magnetization from the dyke samples plot in two antipodal clusters; the reversal test is positive. The primary nature of the obtained components is also confirmed by a positive contact test between a dyke and the Paz Cove stock-like metagabbro intrusion (ca 1170 Ma). The obtained paleomagnetic pole (Plat = –21.6° Plong = 268.9° A95 = 5.8° N = 24) coincides with a pole determined earlier for roughly coeval volcanic rocks from Coats Land (ca 1112 Ma) and is quite close to the pole obtained for mafic rocks in the Grunehogna Craton in western Queen Maud Land (ca 1130 Ma). The most probable interpretation of all available paleomagnetic data is the joint movement within a single block of Mawson cratons and the Coats Land block, starting from the turn of 1110 Ma. The opening and closing of the supposed oceanic basins between these blocks at a later time is a much less likely event, it is possible if the paleomagnetic pole and the rotation pole of these blocks coincide. The rigid tectonic connection between the Mawson cratons and the Coates Land from the end of the Mesoproterozoic to the present time contradicts the assumption about the opening and closing of the hypothetical Shackleton paleoocean separating these cratons, and confirms the assumption about the formation of Gondwana as a result of collision processes of the Kuung time (580–520 Ma) during the collision of the paleocontinents Congo–India–Enderby Land and Kalahari–Mawson–Australia. The data obtained make the paleotectonic reconstructions of Rodinia with the participation of East Antarctica more substantiated at the turn of 1110 Ma and at the same time indicate the need to correct the existing models of the collapse of Rodinia and the amalgamation of Gondwana in the Neoproterozoic and Early Paleozoic. The present pole is the third reliable paleomagnetic definition for the Precambrian of East Antarctica.

中文翻译：

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邦格山（南极东部）中元古代辉长岩-辉绿岩脉的古地磁：一个关键的古地磁极和构造意义

摘要

我们展示了从邦格山（南极洲东部玛丽皇后地）的 24 个中元古代（约 1132 Ma）后运动辉长岩-辉绿岩脉脉中获得的 276 个样本的古地磁数据。在立体图中，来自岩脉样品的自然剩磁的高温分量的平均方向绘制在两个对映簇中；反转测试为阳性。岩脉与 Paz Cove 类长长岩侵入体（约 1170 Ma）之间的阳性接触测试也证实了所获得组件的主要性质。获得的古地磁极 (Plat = –21.6° Plong = 268.9° A95 = 5.8° N = 24) 与早先为来自 Coats Land (ca 1112 Ma) 的大致同时期的火山岩确定的极点重合，并且非常接近于获得的极点莫德皇后地西部 Grunehogna Craton 中的镁铁质岩石（约 1130 Ma）。对所有可用古地磁数据最可能的解释是从 1110 Ma 之交开始的单个 Mawson 克拉通块和 Coats Land 块内的联合运动。这些地块之间假定的海洋盆地在稍后时间打开和关闭的可能性要小得多，如果这些地块的古地磁极和旋转极重合，则有可能发生。从中元古代末期到现在，莫森克拉通和科茨地之间的刚性构造联系与关于分隔这些克拉通的假想沙克尔顿古海洋的开闭的假设相矛盾，并证实了冈瓦纳形成的假设是在古大陆刚果-印度-恩德比地和喀拉哈里-莫森-澳大利亚碰撞期间 Kuung 时代（580-520 Ma）的碰撞过程的结果。所获得的数据使得南极东部参与的罗迪尼亚古构造重建在 1110 Ma 之交得到了更充分的证实，同时表明需要纠正新元古代和新元古代罗迪尼亚崩塌和冈瓦纳古陆瓦纳合并的现有模型。早古生代。现在的极地是南极东部前寒武纪的第三个可靠的古地磁定义。所获得的数据使得南极东部参与的罗迪尼亚古构造重建在 1110 Ma 之交得到了更充分的证实，同时表明需要纠正新元古代和新元古代罗迪尼亚崩塌和冈瓦纳古陆瓦纳合并的现有模型。早古生代。现在的极地是南极东部前寒武纪的第三个可靠的古地磁定义。所获得的数据使得南极东部参与的罗迪尼亚古构造重建在 1110 Ma 之交得到了更充分的证实，同时表明需要纠正新元古代和新元古代罗迪尼亚崩塌和冈瓦纳古陆瓦纳合并的现有模型。早古生代。现在的极地是南极东部前寒武纪的第三个可靠的古地磁定义。