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| Titel |
Paleomagnetism and paleosecular variation from the late Miocene to recent
lavas of Mauritius |
| VerfasserIn |
Pavel V. Doubrovine, Trond H. Torsvik  , Mathew Domeier |
| 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 |
250144016
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| Publikation (Nr.) |
 EGU/EGU2017-7794.pdf |
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| Zusammenfassung |
| We present new paleomagnetic data from the late Miocene to recent lavas of the island of
Mauritius in the southwestern Indian Ocean (20.3˚ S, 57.6˚ E). The island is a shield volcano
that has formed over the Reunion hotspot and is composed of three temporally-distinct series
of basaltic lavas: the Older Series (4.7-8.9 Ma), the Intermediate Series (1.7-3.5 Ma) and the
Younger Series (0-1 Ma). Oriented core specimens were collected from 36 sampling sites
covering all three lava series. Rock magnetic analyses indicate that the remanence carriers in
these basalts are pseudo-single-domain titanomagnetites with variable degrees of
high-temperature oxidation. Nearly half of the sites showed pervasive magnetic
overprints imparted by lightning strikes. Nonetheless, in almost all cases (35 sites),
we were able to isolate the characteristic (primary) remanence directions through
detailed thermal and alternating field demagnetization experiments, using the principal
component analysis of demagnetization data and the analysis of remagnetization
circles. Both normal and reverse polarity directions were observed, with the mean
direction of the reversely-magnetized lavas (15 sites, D = 189.2˚ , I = 44˚ ,
α95 = 5.3˚ ) being steeper than and ca. 9˚ of antiparallel from the mean direction of the
normal-polarity flows (20 sites, D = 1.1˚ , I = -37.3˚ , α95 = 6.9˚ ). The mean normal
and reverse directions yield a negative reversal test that is just significant at the
5% probability level (P = 4.5%). However, when our new data set is combined
with previously published paleomagnetic results from Mauritius, the difference
between the normal mean direction and the antipode of the reverse mean is not
significant at the 5% level, yielding a positive reversal test. The paleomagnetic pole
corresponding to the combined polarity data set excluding transitional directions
(86.7˚ N, 186.2˚ E, A95 = 3.5˚ , n = 32) is slightly far-sided, but the difference
between its position and the geographic pole is not statistically significant. The
estimates of paleosecular variation (PSV) and inclination anomaly (Sb = 11˚ ,
ΔI = -2˚ ) are in good agreement with the results of PSV studies of recent lavas
erupted at low latitudes. The implications of our new results for the structure of
time-averaged geomagnetic field and the latitude dependence of PSV will be discussed. |
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