DOI: 10.1016/j.epsl.2021.116931
论文题名: Extending and refining the paleomagnetic secular variation database for south-eastern Africa (Madagascar) to 2500 cal BP
作者: Haberzettl T. ; Kasper T. ; Stoner J.S. ; Rahobisoa J.J. ; Daut G.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 565 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165489
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Earth and Planetary Science Letters,2021-01-01,565