气候变化领域集成服务门户(CCPortal): Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP

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DOI	10.1016/j.epsl.2021.116931
	Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP
	Haberzettl T.; Kasper T.; Stoner J.S.; Rahobisoa J.J.; Daut G.
发表日期	2021
ISSN	0012821X
卷号	565
英文摘要	Today's knowledge about paleomagnetic secular variations in (southern) Africa is extremely limited. Here, we derive paleomagnetic records from independently radiocarbon dated sediment records from three maars in Madagascar: Andraikiba and Amparihibe are terrestrial maars located on the main island of Madagascar and on a small island in the Northwest, whereas Crater Lake is a maar which has an open connection to the Indian Ocean. Studied through alternating field demagnetization of u-channel samples, characteristic remanent magnetization (ChRM) directions document similar inclination and declination patterns in two of the archives for the past 2,500 years (except for the last 400 cal BP). These new data are the first allowing to test the reliability of previous records which often suffer from low resolution and other obstacles. This will further allow to start to distinguish between robustly confirmed paleomagnetic secular variation data for this region from potentially problematic data. Considering a much lower resolution and a shorter covered time interval of archaeomagnetic data from La Réunion, South Africa, Botswana and Zimbabwe the temporal successions of maxima and minima reveal a coherent picture. Although slightly shifted in time, similarities also exist to the global geomagnetic field reconstruction model SHAWQ2k (Campuzano et al., 2019) which includes the above mentioned data. Surprisingly also similarities, though only in declination, are observed to the CALS3K.4 model (Korte and Constable, 2011) which is used as Northern Hemisphere biased model example. In contrast to this, no declination similarities but remarkable inclination similarities are observed to a lake record from Lake Malawi. An analog inclination pattern is also observed in a record from the Makran Accretionary Wedge which is ∼5,000 km to the north of the investigated sites. Interestingly the spatial distribution of archives showing these inclination similarities resembles the spatial distribution of inclination anomalies detected in model predictions. PSV similarities over such a large area are suggestive of a large-scale core dynamic origin independent of westward drift of non-dipole field components often associated with PSV records. This study emphasizes the potential of maar lakes in Madagascar for paleo reconstructions but also suggests that shallow marine and marine-brackish systems should be avoided if possible when trying to expand the (South) African paleomagnetic database. © 2021 Elsevier B.V.
关键词	declination inclination lacustrine sediments maar paleomagnetism
英文关键词	Lakes; Sediments; Spatial distribution; Declination; Eastern Africa; Inclination; Lacustrine sediments; Lower resolution; Maar; Madagascar; Paleomagnetic record; Paleomagnetic secular variations; Sediment records; Geomagnetism; lacustrine environment; maar; magnetic declination; magnetic inclination; paleomagnetism; remanent magnetization; secular variation; Madagascar
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203111
作者单位	Physical Geography, Institute for Geography and Geology, University of Greifswald, Friedrich-Ludwig-Jahn-Str. 16, Greifswald, 17489, Germany; Physical Geography, Institute of Geography, Friedrich Schiller University Jena, Löbdergraben 32, Jena, 07743, Germany; College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Admin Building, Corvallis, OR 97331, United States; University of Antananarivo, Department of Earth Sciences, Faculty of Sciences, University of Antananarivo, Post Box 906, Antananarivo, Madagascar
推荐引用方式 GB/T 7714	Haberzettl T.,Kasper T.,Stoner J.S.,et al. Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP[J],2021,565.
APA	Haberzettl T.,Kasper T.,Stoner J.S.,Rahobisoa J.J.,&Daut G..(2021).Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP.Earth and Planetary Science Letters,565.
MLA	Haberzettl T.,et al."Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP".Earth and Planetary Science Letters 565(2021).