Establishing a first archaeointensity record for the SW Pacific

Stark, Florian; Cassidy, John F.; Hill, Mimi J.; Shaw, John; Sheppard, Peter

doi:10.1016/j.epsl.2010.07.031

Cited by 24 publications

(22 citation statements)

References 43 publications

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“…This has driven recent efforts to obtain archeomagnetic data from Argentina (Goguitchaichvili et al 2010(Goguitchaichvili et al , 2011, Brazil (Hartmann et al 2010(Hartmann et al , 2011, India (Venkatachalapathy et al 2013 Senegal and Mali (Mitra et al 2013), South Africa (Neukirch et al 2012), and the SW Pacific (Stark et al 2010). Furthermore, determining the age of magnetization is a major challenge; however, the quality of the age determination is crucial, e.g., when interpreting temporal variations in regionally compiled archeomagnetic curves (e.g., De Marco et al (2008); Hagstrum and Blinman (2010); Márton (2010); Shaar et al (2011); Tema and Kondopoulou (2011)) or in comparing magnetic field variations in sediment records from different locations (e.g., Nilsson et al (2010Nilsson et al ( , 2014).…”

Section: Introductionmentioning

confidence: 99%

GEOMAGIA50.v3: 1. general structure and modifications to the archeological and volcanic database

et al. 2015

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Background: GEOMAGIA50.v3 is a comprehensive online database providing access to published paleomagnetic, rock magnetic, and chronological data from a variety of materials that record Earth's magnetic field over the past 50 ka.Findings: Since its original release in 2006, the structure and function of the database have been updated and a significant number of data have been added. Notable modifications are the following: (1) the inclusion of additional intensity, directional and metadata from archeological and volcanic materials and an improved documentation of radiocarbon dates; (2) a new data model to accommodate paleomagnetic, rock magnetic, and chronological data from lake and marine sediments; (3) a refinement of the geographic constraints in the archeomagnetic/volcanic query allowing selection of particular locations; (4) more flexible methodological and statistical constraints in the archeomagnetic/volcanic query; (5) the calculation of predictions of the Holocene geomagnetic field from a series of time varying global field models; (6) searchable reference lists; and (7) an updated web interface. This paper describes general modifications to the database and specific aspects of the archeomagnetic and volcanic database. The reader is referred to a companion publication for a description of the sediment database. Conclusions:The archeomagnetic and volcanic part of GEOMAGIA50.v3 currently contains 14,645 data (declination, inclination, and paleointensity) from 461 studies published between 1959 and 2014. We review the paleomagnetic methods used to obtain these data and discuss applications of the data within the database. The database continues to expand as legacy data are added and new studies published. The web-based interface can be found at http:// geomagia.gfz-potsdam.de.

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Section: Introductionmentioning

confidence: 99%

GEOMAGIA50.v3: 1. general structure and modifications to the archeological and volcanic database

et al. 2015

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“…The remaining material was kept for microwave and rock magnetic experiments. Two mini cores per fragment (5 mm diameter and 2-5 mm long) were drilled for use with the 14 GHz microwave and Tristan magnetometer system (Stark et al, 2010) at Liverpool University.…”

Section: Sample Preparationmentioning

confidence: 99%

Improving our knowledge of rapid geomagnetic field intensity changes observed in Europe between 200 and 1400 AD

Gómez‐Paccard

Chauvin

Lanos

et al. 2012

Earth and Planetary Science Letters

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a b s t r a c tAvailable archaeomagnetic data indicate that during the past 2500 yr there have been periods of rapid geomagnetic field intensity fluctuations interspersed with periods of almost constant field strength. Despite Europe being the most widely covered region in terms of archaeomagnetic data the occurrence and the behaviour of these rapid geomagnetic field intensity changes is under discussion and the challenge now is to precisely describe them. The aim of this study is to obtain an improved description of the sharp intensity change that took place in western Europe around 800 AD as well as to investigate if this peak is observed at the continental scale. For this purpose 13 precisely dated early medieval Spanish pottery fragments, four archaeological French kilns and three collections of bricks used for the construction of different French historical buildings with ages ranging between 335 and 1260 AD have been studied. Classical Thellier experiments performed on 164 specimens, and including anisotropy of thermoremanent magnetisation and cooling rate corrections, gave 119 reliable results. The 10 new high-quality mean archaeointensities obtained confirm the existence of an intensity maximum of $ 85 mT (at the latitude of Paris) centred at $ 800 AD and suggest that a previous abrupt intensity change occurred around 600 AD. Together with previously published data from western Europe that we deem to be the most reliable, the new data also suggest the existence of two other abrupt geomagnetic field intensity variations during the 12th century and around the second half of the 13th century AD. High-quality archaeointensities available from eastern Europe indicate that very similar geomagnetic field intensity changes occurred in this region. European data indicate that very rapid intensity changes (of at least 20 mT/century) took place in the recent history of the Earth's magnetic field. The results call for additional high-quality archaeointensities obtained from precisely dated samples and for a selection of the previously published data if a refined description of geomagnetic field intensity changes at regional scales is to be obtained.

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“…Results are shown before (red open symbols) and after (blue scale bars and solid blue symbols) MW cooling‐rate correction for: (Figure a) SW Pacific islands pottery (MW and TT data from Stark et al . []), (Figures b and c) NE Brazilian bricks (TT and TR data from Hartmann et al . []).…”

Section: Resultsmentioning

confidence: 99%

“…[] and improve the estimates presented by Stark et al . []. Several studies have demonstrated that a cooling‐rate correction is needed for the TT method but is not necessary for the TR method.…”

Section: Discussionmentioning

confidence: 99%

The cooling‐rate effect on microwave archeointensity estimates

Poletti

Hartmann

Hill

et al. 2013

Geophysical Research Letters

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[1] New microwave (MW) paleointensity data on historical bricks from Northeast Brazil presented a bias toward higher fields when compared to previous cooling-rate corrected double-heating paleointensity estimates; the same relates to the previously reported values for pottery from Southwestern Pacific islands. A simple theoretical approach suggests that the MW bias in both collections is due to a cooling-rate effect on MW estimates. We then experimentally corrected the MW cooling-rate effect on Brazilian fragments, increasing the degree of consistency between the previous and new results (reducing discrepancies from 25% to 8%). Results indicate similar experimental behavior between microwave and thermal procedures despite the different ways in which the energy is transferred into the spin system. Finally, they allow cooling times of less than 90 s to be empirically estimated in most of these MW experiments highlighting the need for systematic cooling-rate corrections to be applied in similar MW paleointensity studies in the future.

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Establishing a first archaeointensity record for the SW Pacific

Cited by 24 publications

References 43 publications

GEOMAGIA50.v3: 1. general structure and modifications to the archeological and volcanic database

GEOMAGIA50.v3: 1. general structure and modifications to the archeological and volcanic database

Improving our knowledge of rapid geomagnetic field intensity changes observed in Europe between 200 and 1400 AD

The cooling‐rate effect on microwave archeointensity estimates

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