Palaeomagnetism of the Upper Miocene- Lower Pliocene lavas from the East Carpathians: contribution to the paleosecular variation of geomagnetic field

Abstract

Investigations of the paleosecular variation of the geomagnetic field on geological timescales depend on globally distributed data sets from lava flows. We report new paleomagnetic results from lava flows of the East Carpathian Mountains (23.6°E, 46.4°N) erupted between 4 and 6 Ma. The average virtual geomagnetic pole position (76 sites) includes the North Geographic Pole and the dispersion of virtual geomagnetic poles is in general agreement with the data of the Time Averaged geomagnetic Field Initiative. Based on this study and previous results from the East Carpathians obtained from 0.04–4 Ma old lava flows, we show that high value of dispersion are characteristic only for 1.5–2.8 Ma old lava flows. High values of dispersion during the Matuyama chron are also reported around 50°N, in the global paleosecular variation data set. More data are needed at a global level to determine if these high dispersions reflect the behaviour of the geomagnetic field or an artefact of inadequate number of sites. This study of the East Carpathians volcanic rocks brings new data from southeastern Europe and which can contribute to the databases for time averaged field and paleosecular variation from lavas in the last 6 Ma.

Paleosecular Variation and the Time‐Averaged Geomagnetic Field Since 10 Ma

“…Our data collection increases the number of sites (2,543 records; Table ), although the number of paleomagnetic studies (80) is a little lower compared to the PSV10 compilation because of the stricter criteria employed here. An improved spatial data distribution is achieved by inclusion of new records from the East Carpathians (Vişan et al., 2016), Israel (Behar et al., 2019), and Saint Helena Island (Engbers et al., 2020). In terms of temporal distribution, there was a 5% increase in data coverage for the age interval older than 5 Ma.…”

“…Our data collection increases the number of sites (2,543 records; Table S1), although the number of paleomagnetic studies (80) is a little lower compared to the PSV10 compilation because of the stricter criteria employed here. An improved spatial data distribution is achieved by inclusion of new records from the East Carpathians (Vişan et al, 2016), PSV and TAF estimates N fd S3-S5). u Upper 95% confidence limit.…”

Testing paleomagnetic directional distributions against field models for the averaging of secular variation and correcting for inclination shallowing using an updated elongation/inclination approach (SVEI)

“…The data sets from the Golan Heights (Behar et al, 2019) and from Northern Patagonia (Moncinhatto et al, 2023) were also incorporated. There were 13 studies in the compilation of de Oliveira et al ( 2021) that were not included in PSV10 (Camps et al, 2001;Monster et al, 2018;Pinton et al, 2018;Visan et al, 2016); they are now included in our updated compilation, referred to here as PSV10-24. For the purposes of comparing a given GGP model to the PSV database, we follow the suggestion of Behar et al (2019) and filter the PSV10-24 database (N ≥ 6 samples per lava flow with a κ of at least 100; the complete set is available in the MagIC database (Section 6).…”

Late Miocene to late Pleistocene geomagnetic secular variation at high northern latitudes

“…A key objective of GAD studies is to estimate TAF and PSV for well-dated time intervals using modern-standard high-quality data (Johnson et al 2008;Cromwell et al 2018). It is also of particular interest to compare normal and reverse polarity intervals, such as the Brunhes and Matuyama chrons, which have repeatedly been shown to record significantly different overall geomagnetic field behaviours (Merrill & McElhinny 1977;Johnson et al 2008;Ziegler et al 2011;Vişan et al 2016;Cromwell et al 2018). However, global palaeomagnetic databases are dominated by results from Brunhes as well as low-to mid-latitudes, whereas data from the older chrons, including the Matuyama, Gauss and Gilbert chrons, as well as from high latitudes, are relatively scarce (Johnson et al 2008;Cromwell et al 2018).…”

“…We calculate and compare the dispersion S B specifically for the Matuyama (S B(Mat) ), Gauss (S B(Gauss) ) and Gilbert (S B(Gil) ) chrons in order to map any differences in PSV between these geomagnetic intervals such as has been suggested for the Brunhes normal and Matuyama reverse intervals (Johnson et al 2008;Vişan et al 2016; Downloaded from https://academic.oup.com/gji/article-abstract/222/1/86/5813917 by Imperial College London Library, Adrian.muxworthy@imperial.ac.uk on 05 May 2020…”