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Geomagnetic Field Reversals in the Palaeozoic and Cenozoic: Palaeomagnetic Evidence from Russia and Turkmenia

古生代和新生代的地磁场反转：来自俄罗斯和土库曼尼亚的古地磁证据

基本信息

批准号：
5249916
负责人：
Professor Dr. Valerian Bachtadse, since 4/2006
金额：
--
依托单位：
Sektion Geophysik
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2000
资助国家：
德国
起止时间：
1999-12-31 至 2009-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/5249916?language=en
关键词：
Geomagnetic Field Reversals Palaeozoic Cenozoic

项目摘要

The aim of this project is the investigation of Palaeozoic and Ceonozoic geomagnetic reversals. Using palaeomagnetism, the morphology of these reversals and main features, e.g. duration of the process, mode of the geomagnetic component changes, symmetry (or asymmetry) of the process with respect to polarity and time, will be studied. Late Permian reversals recorded in sedimentary sequences of the Volga-Viatka region (eastern part of the Russian platform) will be studied. These reversals are of particular significance as they mark the transition from a long-lasting reversed polarity superchron (PCRS or Kiaman superchron) to the rapidly changing field of Permo-Triassic times. Furthermore, few data are as yet available for field reversals of pre-Cenozoic age. Polarity transitions will also be studied in Plio-Pleistocene marine sediments of the Lopet-Dagh foothills, western Turkmenistan. These sequences span the entire Matuyama polarity chron and the transiton to the present day Bruhnes normal polarity chron. All the proposed sections are known to carry primary directions of magnetisa- tion. From palaeomagnetic studies it will be possible to determine the variations in magnetic direction recorded by the sediments during a number of different reversals from different geological time-periods. This will allow characterisation of the dipolar versus non-dipolar field features of the Earth`s magnetic field and whether or not there are systematic patterns in the VGP longitudes during magnetic reversals. Relative palaeo-intensity measurements will enable characterise the total transition time for polarity transitions as recorded in oscillations of the palaeofield intensity prior, during and after the polarity transitions. This will yield vital information with regards to the stability of the geodynamo, and provide a test for the various models which have been proposed.

该项目的目的是调查古生代和新生代地磁反转。利用古地磁学，将研究这些逆转的形态和主要特征，例如过程的持续时间、地磁分量变化的模式、过程相对于极性和时间的对称性（或不对称性）。将研究伏尔加-维亚特卡地区（俄罗斯地台东部）沉积序列中记录的晚二叠世反转。这些反转具有特殊的意义，因为它们标志着从长期的极性反转超时（PCRS或Kiaman超时）到二叠纪-三叠纪时期快速变化的领域的过渡。此外，很少有数据可用于前新生代年龄的场反转。还将研究土库曼斯坦西部Lopet-Dagh山麓的上新世-更新世海洋沉积物中的极性转换。这些序列跨越了整个松山极性年代和过渡到今天的布鲁内正常极性年代。所有建议的部分是已知的进行磁化的主要方向。通过古地磁研究，将有可能确定在不同地质时期的多次不同反转期间沉积物记录的磁方向变化。这将允许表征地球磁场的偶极与非偶极场特征，以及在磁反转期间VGP磁迹中是否存在系统模式。相对古强度测量将能够确定极性转换的总转换时间，如记录在极性转换之前、期间和之后的古场强度振荡中。这将产生关于地球发电机稳定性的重要信息，并为已提出的各种模型提供测试。