Toward a Full-vector Geomagnetic Field Record (~130–550 ka) from the El Golfo Section, El Hierro, Canary Islands, Spain

Marilyn W.L. Monster, Joris van Galen, Lennart V. de Groot, Klaudia F. Kuiper, Mark J. Dekkers
2018 Publications of the Institute of Geophysics Polish Academy of Sciences Geophysical Data Bases Processing and Instrumentation  
The Earth's magnetic field is generated in the liquid outer core. So-called absolute paleointensities, i.e., a field intensity in T for a given location that can be converted to a virtual (axial) dipole moment, are tedious to obtain and therefore remain rather scarce, in particular for periods older than the Holocene. The Holocene field intensity is considered (unusually?) high; it is reasonably well constrained by data from lavas and archaeological artefacts, at least for considerable portions
more » ... of the northern hemisphere. The average intensity of the Brunhes Chron is ~20% higher than most of the underlying Matuyama Chron (Ziegler et al. 2011). 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. Such curves typically lack palaeointensity information. Here, we present new paleointensty data from El Hierro, Canary Islands. The Canary Islands are part of the Canary Island Seamount Province which developed on ancient ocean crust, the oldest Atlantic Ocean crust Jurassic in age, relatively close to a continent, Africa. El Hierro and La Palma represent the youngest islands with ages of < 2 Ma (e.g., Guillou et al. 1996). We sampled 28 lava flows (age range c. 150 to 450 ka) from a section along the Camino de Jinama, about 4.5 km to the south of a section sampled by Széréméta et al. (1999) for an analysis of directional PSV. Individual flows range in thickness between 1 and several meters, and are usually easily distinguished by the presence of scorias, pyroclastic layers, or paleosols. Three groups of flows are recognized, referred to as the upper group (UG), the middle group (MG) and the lower group (LG). In line with earlier results (Széréméta et al. 1999), we observe an easterly declination deviation of c. 14° for the middle and lower part of our section. We relate this to
doi:10.25171/instgeoph_pas_publs-2018-053 fatcat:xjbttjsaobfkdchp5c7trn3b5y