Late Mesoproterozoic magnetostratigraphic results from Siberia: Paleogeographic implications and magnetic field behavior
Late Mesoproterozoic magnetostratigraphic results from Siberia: Paleogeographic implications and magnetic field behavior
复制标题
西伯利亚中元古代晚期磁性地层结果：古地理意义和磁场行为
DOI：
10.1029/1999jb900354
复制
发表时间：
2000
影响因子：
--
通讯作者：
P. Petrov
中科院分区：
文献类型：
--
作者：
Y. Gallet;V. Pavlov;M. A. Semikhatov;P. Petrov
本文对位于西伯利亚克拉通东南部（乌丘尔-玛雅地区）和西北部（图鲁汉斯克地区）边缘的晚中元古代Malgina组和Linok组进行了磁地层学研究。生物地层学、放射学和化学地层学资料表明，这些地层可能是在1050 ~ 1100 Ma之间形成的。古地磁分析揭示了由磁铁矿和/或赤铁矿携带的高温成分。该成分对Malgina组进行了正面的褶皱和反转测试，以及正面的砾岩测试，这表明磁化是在沉积物沉积期间或之后不久获得的。从乌丘尔-玛雅地区获得的平均古地磁方向表明，如果西伯利亚位于南半球，如果我们假设劳伦西亚和西伯利亚沿着它们现在的北部海岸线相连，那么它在当时就不可能是罗迪尼亚的一部分。我们强调，如果像Rainbird等人[1998]最近提出的那样，西伯利亚南部与Laurentia北部相连，那么在中元古代晚期，西伯利亚可能是Rodinia的一部分。如果这是真的，将西伯利亚克拉通置于南半球意味着约1000 Ma劳伦古磁极的磁极性必须被转换。我们的数据还显示了至少15次对称地磁场倒转的发生，这表明中元古代晚期Keweenawan熔岩的古地磁结果并没有反映出元古代期间一个全球性的、持续的不对称地磁场。
We present a magnetostratigraphic study of the late Mesoproterozoic Malgina and Linok Formations, located along the southeastern (Uchur-Maya region) and northwestern (Turukhansk region) margins of the Siberian craton, respectively. Biostratigraphic, radiometric, and chemostratigraphic data indicate that these formations are likely coeval between 1050 and 1100 Ma. Paleomagnetic analyses reveal a high-temperature component carried by magnetite and/or hematite. This component yields positive fold and reversal tests, together with a positive conglomerate test for the Malgina Formation, which indicates that the magnetization was acquired during or soon after sediment deposition. The mean paleomagnetic direction obtained from the Uchur-Maya region, which is unambiguously representative of the Siberian craton, indicates that it could not have been part of Rodinia at that time if Siberia was located in the Southern Hemisphere and if we assume that Laurentia and Siberia were connected along their present northern shorelines. We emphasize that Siberia could have been part of Rodinia during the late Mesoproterozoic if southern Siberia was joined to the northern part of Laurentia as recently proposed by Rainbird et al. [1998]. If true, placing the Siberian craton in the Southern Hemisphere implies that the magnetic polarity of the ∼1000 Ma Laurentian paleomagnetic poles must be switched. Our data also show the occurrence of at least 15 symmetric geomagnetic field reversals, indicating that the paleomagnetic results from the late Mesoproterozoic Keweenawan lavas do not reflect a worldwide and persistent asymmetric field during the Proterozoic.
DOI：
10.1098/rspa.1953.0064
发表时间：
1953-01-01
影响因子：
--
作者：
FISHER, R
通讯作者：
FISHER, R