Paleointensity determination from Sao Miguel (Azores Archipelago) over the last 3 ka

TitlePaleointensity determination from Sao Miguel (Azores Archipelago) over the last 3 ka
Publication TypeJournal Article
Year of Publication2014
AuthorsDi Chiara A., Tauxe L, Speranza F.
JournalPhysics of the Earth and Planetary Interiors
Volume234
Pagination1-13
Date Published2014/09
ISBN Number0031-9201
Accession NumberWOS:000340987800001
Keywordsatlantic ocean; azores; cretaceous normal superchron; earths magnetic-field; geomagnetic field intensity spike; geomagnetic-field; intensity variations; lava flows; long-term variations; Paleointensity; paleomagnetism; partial thermoremanence; secular variation; submarine basaltic glass; western-europe
Abstract

Paleointensity data from the Atlantic Ocean are rare. We present new paleointensity data from Sao Miguel (Azores Islands, Portugal) based on 20 paleomagnetic sites from 13 lava flows emplaced over the last 3000 years. Ten lava flows are radiocarbon dated, whereas three flows were paleomagnetically dated and one site was dated using stratigraphic relations. All the samples, previously investigated to recover paleo-directions, were subjected to IZZI experiments. Importantly, the new data are internally consistent, agree with Moroccan and European datasets, and offer new constraints for global geomagnetic field models. Some of the ages of the paleomagnetically dated lava flows have been revised based on the intensity data presented here. The inferred Virtual Axial Dipole Moments (VADMs) range from 68.2 to 163.5 ZAm(2). A peak in field strength with an estimated age of around 600 BC is well supported by two sites from the same flow (Furna), and is comparable to the high intensity values found in Portugal for the same age and the earlier field peak at about 1000 BC in the Levant. A gradient in VADM values with latitude from northwestern Africa and across Europe between 100 and 1000 AD is confirmed as well as its absence from between 0 to 100 AD. (C) 2014 Elsevier B.V. All rights reserved.

DOI10.1016/J.Pepi.2014.06.008
Short TitlePhys. Earth Planet. Inter.
Alternate JournalPhys Earth Planet In
Integrated Research Themes: 
Student Publication: 
No