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| Titel |
Palaeointensity determinations and rock magnetic properties on rocks from
Izu-Bonin-Mariana fore-arc (IODP Exp. 352). |
| VerfasserIn |
Claire Carvallo, Pierre Camps, Will Sager, Thierry Poidras |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143874
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| Publikation (Nr.) |
 EGU/EGU2017-7637.pdf |
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| Zusammenfassung |
| IODP Expedition 352 cored igneous rocks from the Izu-Bonin-Mariana fore-arc crust: Sites
U1440 and U1441 recovered Eocene basalts and related rocks whereas Sites U1439 and
U1442 recovered Eocene boninites and related rocks. We selected samples from
Holes U1439C, U1440B and U1440A for paleointensity measurements. Hysteresis
measurements and high and low-temperature magnetization curves show that samples
from Hole U1440B undergo magnetochemical changes when heated and are mostly
composed of single-domain (SD) or pseudo-single-domain (PSD) titanomaghemite.
In contrast, the same measurements show that most selected samples from Holes
U1439C and U1442A are thermally stable and are composed of either SD or PSD
titanomagnetite with very little titanium content, or SD ferromagnetic grains with a large
paramagnetic contribution. Thellier-Thellier paleointensity experiments carried out on
U1439C and U1442A samples give a good success rate of 25/60 and Virtual Dipole
Moment values between 1.3 and 3.5 ×1022 Am2. Multispecimen paleointensity
experiments carried out on 55 samples from Hole U1440B (divided into 4 groups)
and 20 from Hole U1439C gave poor quality result, but they seem to indicate a
VDM around 4-6 ×1022 Am2 in Hole U1440B fore-arc basalts. These results are
in agreement with the low few VDM values previously measured on rocks from
Eocene. However, they do not support an inverse relationship between intensity of
the field and rate of reversal, since the rate of reversal in Eocene was rather low. |
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