Analyzing Triassic and Permian Geomagnetic Paleosecular Variation and the Implications for Ancient Field Morphology
Analyzing Triassic and Permian Geomagnetic Paleosecular Variation and the Implications for Ancient Field Morphology
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DOI：
10.1029/2021gc009930
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发表时间：
2021-11
期刊：
影响因子：
3.7
通讯作者：
B. Handford;A. Biggin;M. M. Haldan-M.;C. Langereis
中科院分区：
文献类型：
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作者：
B. Handford;A. Biggin;M. M. Haldan-M.;C. Langereis
研究古长期变化（PSV）可以提供独特的见解的平均形态的地磁场和地球发电机的操作。虽然最近的研究已经扩大了我们对中生代晚期古磁场行为的认识，但对三叠纪（约1000年）的了解相对较少。251.9-201.3 Ma）。本研究编制了第一个三叠纪虚拟地磁极（VGP）数据库，用于分析PSV，作为更长的后石炭-二叠纪逆超时（PCRS）时间间隔（265 - 198 Ma）的一部分。VGP的角色散和依赖于表观古纬度进行了比较，对一个新的PCRS汇编和出版的PSV汇编的时间跨度在过去的1.320亿年。我们发现，后PCRS显示VGP分散的近纬度不变性，而PCRS显示非常强的纬度依赖性。后PCRS期间的PSV行为似乎与之前报道的白垩纪正超时（前CNS; 126-198 Ma）之前的间隔没有区别。具有显著不同的表观平均极性反转频率的时间间隔之间的接近恒定的行为不支持VGP分散和反转频率之间的建议关系。观察到的PCRS的分散与以前的研究结果是一致的，并代表的行为，这是潜在的独特的在过去的320 Ma。最近发表的方法，以获得一个描述的场形态从赤道VGP分散显示PCRS地磁场已更强烈的轴向偶极子为主的比任何间隔以来。这一观察结果可能与PCRS是中生代地磁极性时标中已知最长的超时相有因果关系。
Studying paleosecular variation (PSV) can provide unique insights into the average morphology of the geomagnetic field and the operation of the geodynamo. Although recent studies have expanded our knowledge of paleomagnetic field behavior through the late Mesozoic, relatively little is known regarding the Triassic period (ca. 251.9–201.3 Ma). This study compiles the first Triassic virtual geomagnetic pole (VGP) database for the analysis of PSV, as part of a longer Post‐Permo‐Carboniferous Reversed Superchron (PCRS) time interval (265‐198 Ma). VGP angular dispersion and its dependence on apparent paleolatitude are compared against a new PCRS compilation and published PSV compilations for intervals across the last ∼320 Ma. We find that the Post‐PCRS displays near latitudinal invariance of VGP dispersion while the PCRS displays very strong latitudinal dependence. PSV behavior during the Post‐PCRS appears indistinguishable to that previously reported for the interval preceding the Cretaceous Normal Superchron (Pre‐CNS; 126–198 Ma). The near‐constant behavior between time intervals with significantly different apparent average polarity reversal frequencies does not support a suggested relationship between VGP dispersion and reversal frequency. The dispersion observed for the PCRS is consistent with the results of previous studies and represents behavior that is potentially unique over the last ∼320 Ma. A recently published approach to obtain a description of field morphology from equatorial VGP dispersion shows the PCRS geomagnetic field to have been more strongly axial dipole dominated than any interval since. This observation may be causally linked to the PCRS being the longest known superchron in the Phanerozoic geomagnetic polarity timescale.