Full-vector geomagnetic field records from the East Eifel, Germany

Abstract

A B S T R A C TTo create meaningful models of the geomagnetic field, high-quality directional and intensity input data are needed. However, while it is fairly straightforward to obtain directional data, intensity data are much scarcer, especially for periods before the Holocene. Here, we present data from twelve flows (age range ∼ 200 to ∼ 470 ka) in the East Eifel volcanic field (Germany). These sites had been previously studied and are resampled to further test the recently proposed multi-method palaeointensity approach. Samples are first subjected to classic palaeomagnetic and rock magnetic analyses to optimise the subsequent palaeointensity experiments. Four different palaeointensity methods -IZZI-Thellier, the multispecimen method, calibrated pseudo-Thellier, and microwave-Thellier -are being used in the present study. The latter should be considered as supportive because only one or two specimens per site could be processed. Palaeointensities obtained for ten sites pass our selection criteria: two sites are successful with a single approach, four sites with two approaches, three more sites work with three approaches, and one site with all four approaches. Site-averaged intensity values typically range between 30 and 35 μT. No typically low palaeointensity values are found, in line with paleodirectional results which are compatible with regular palaeosecular variation of the Earth's magnetic field. Results from different methods are remarkably consistent and generally agree well with the values previously reported. They appear to be below the average for the Brunhes chron; there are no indications for relatively higher palaeointensities for units younger than 300 ka. However, our young sites could be close in age, and therefore may not represent the average intensity of the paleofield. Three of our sites are even considered coeval; encouragingly, these do yield the same palaeointensity within uncertainty bounds.

A Late-Quaternary full-vector geomagnetic record from El Golfo section, El Hierro, Canary Islands

“…This is in line with observations from e.g. the East Eifel (Schnepp 1995(Schnepp , 1996Monster et al 2018) which are broadly coeval. Due to the lack of precise age constraints, it is impossible to compare our data to geomagnetic field models such as PADM2M (Ziegler et al 2011) or palaeointensity stacks such as PISO-1500 (Channell et al 2009) and SINT-800/SINT-2000 (Guyodo & Valet 1999;Valet et al 2005).…”

“…Tauxe & Love 2003) but data paucity precludes firm inferences. To contribute to this issue we recently revisited sites in the Eifel (Germany) and provided multimethod palaeointensity data for a set of lava flows (Monster et al 2018) validating earlier estimates of Schnepp et al (1995Schnepp et al ( , 1996. It should be realized that ages of the lavas may come with a fairly large uncertainty, therefore improving on age determinations is also a prerequisite to progress.…”

The Frequency of Geomagnetic Polarity Reversals in the Carboniferous: Insight into Earth’s Deep Interior

“…Longer term trends within the Brunhes Chron, however, are surprisingly poorly characterised. It seems that the period between ~200 and ~400 ka featured a lower field intensity as determined for Hawaii (Pacific Ocean, USA; Tauxe and Love (2003)) and the Eifel (Germany; Monster et al 2018) but data paucity precludes firm inferences. Regional full-vector PSV curves are essential to further our understanding of geodynamo operation.…”

Paleointensity.org: An Online, Open Source, Application for the Interpretation of Paleointensity Data

“…There is also a trend toward applying different paleointensity methods to the same set of samples in a single study (e.g., de Groot et al, 2013, 2015, 2016; Ertepinar et al, 2016; Greve et al, 2017; Hawkins et al, 2019; Hervé et al, 2017; Monster et al, 2015a, 2018). Such a “multimethod approach” dramatically increases the amount of reliable paleointensities produced for a set of sampled cooling units or sites (de Groot et al, 2013) and has been assigned its own paleointensity quality criterion (Biggin & Paterson, 2014).…”