North China craton: The conjugate margin for northwestern Laurentia in Rodinia
North China craton: The conjugate margin for northwestern Laurentia in Rodinia
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华北克拉通：罗迪尼亚西北劳伦大陆的共轭边缘
DOI：
10.1130/g48483.1
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发表时间：
2021-07-01
期刊：
影响因子：
5.8
通讯作者：
Chen, Jianping
中科院分区：
文献类型：
--
作者：
Ding, Jikai;Zhang, Shihong;Chen, Jianping
在罗迪尼亚超大陆，劳伦蒂亚处于中心位置，因为它的两侧是新元古代晚期的裂谷边缘；然而，西部劳伦蒂亚的共轭边缘仍然是个谜。本文对冀东中国克拉通北部15个约775 Ma的镁铁质岩脉进行了新的古地磁研究。阶梯式热退磁显示了一个东北向或西南向的浅倾角高温成分，解堵温度高达580℃。岩石磁性表明，该成分由单磁区和拟单磁区磁铁矿颗粒携带。其原始起源得到了正反转试验和区域剩磁方向对比试验的支持，古地磁极(S 29.0度，东经64.7度，A95=5.4度)与已发表的北冰洋年轻磁极不同。中元古代晚期和新元古代早期(约1110-775 Ma)NCC和Laurania的视极移轨迹的匹配表明，NCC可能是罗迪尼亚劳伦蒂亚西北部的共轭边缘，而不是位于罗迪尼亚主要陆块东北海岸之外。地质资料表明，NCC和Laurania的解体发生在约775 Ma至720 Ma之间。
In the Rodinia supercontinent, Laurentia is placed at the center because it was flanked by late Neoproterozoic rifted margins; however, the conjugate margin for western Laurentia is still enigmatic. In this study, new paleomagnetic results have been obtained from 15 ca. 775 Ma mafic dikes in eastern Hebei Province, North China craton (NCC). Stepwise thermal demagnetization revealed a high-temperature component, directed northeast or southwest with shallow inclinations, with unblocking temperatures of as high as 580 degrees C. Rock magnetism suggests the component is carried by single-domain and pseudo-single-domain magnetite grains. Its primary origin is supported by a positive reversal test and regional remanence direction correlation test, and the paleomagnetic pole (29.0 degrees S, 64.7 degrees E, A95 = 5.4 degrees) is not similar to any published younger poles of the NCC. Matching the late Mesoproterozoic to early Neoproterozoic (ca. 1110-775 Ma) apparent polar wander paths of the NCC and Laurentia suggests that the NCC could have been the conjugate margin for northwestern Laurentia in Rodinia, rather than sitting off the northeast coast of the main Rodinian landmass. Geological data indicate that breakup of the NCC and Laurentia occurred between ca. 775 and 720 Ma.