论文部分内容阅读
从华北克拉通的中西部和东部发育的基性岩墙群获得三个精确定年的实际古地磁极位置(VGPs)。华北克拉通中西部恒山GU岩墙的斜锆石U-Pb年龄为1769±3Ma,该岩墙的古地磁给出古地磁极位置在北纬36°,东经247°(dp=2,dm=4);华北克拉通东部DY岩墙的斜锆石U-Pb年龄为1620.8±6.9Ma,获得的古地磁极位置为北纬6.9°东经81.9°(dp=4.31,dm=6.09);东部另一条岩墙LW4的SHRIMP U-Pb年龄为1157±18Ma,获得的古地磁极位置为北纬27.1°东经162°(dp=15.8,dm=18.7)。通过将这三个从基性岩墙获得的华北克拉通古地磁极位置与加拿大地盾的中元古代视极移曲线对比,在中元古代早期(1800～1600Ma),华北克拉通与加拿大地盾一起同属哥伦比亚超大陆,而在中元古代晚期(1600～1200Ma),华北克拉通与加拿大地盾分离,响应哥伦比亚超大陆的最终裂解事件。
Three precise dating of ancient paleomagnetic polar positions (VGPs) were obtained from the basic dyke swarms developed in the central, western and eastern parts of North China Craton. The Palaeozoic U-Pb zircon ages of the Hengshan GU rock wall in the central and western part of North China Craton are 1769 ± 3Ma. The paleomagnetic data from this wall indicate that the paleomagnetic pole is located at 36 ° N and 247 ° E (dp = 2, dm = 4 ). The U-Pb zircon ages of DY dikes in the eastern part of North China craton are 1620.8 ± 6.9Ma, and the paleomagnetic poles obtained are located at a latitude of 6.9 ° E (81.9 ° d d = 4.31, dm = 6.09) The SHRIMP U-Pb age of wall LW4 is 1157 ± 18Ma, and the paleomagnetic pole position obtained is 27.1 ° N and 162 ° E (dp = 15.8, dm = 18.7). By comparing the paleomagnetic pole positions of North China Craton and those of the Canadian Shield obtained from these three basic dykes, we found that in the early Proterozoic (1800 ~ 1600 Ma), North China Craton and Canada Shield together belong to the Columbia supercontinent, and in the late Mesoproterozoic (1600 ~ 1200Ma), North China craton separated from the Canadian Shield, in response to the final cracking of the Columbia supercontinent.