Palaeomagnetic Studies of Icelandic Lava Flows
This paper describes a palaeomagnetic investigation of 107 igneous bodies, mostly basaltic lavas, of Pliocene and Pleistocene age in Iceland. A variety of conclusions has resulted from the study. Palaeomagnetic directions in lavas erupted in 1729, 1783 and 1875 do not support the postulated ‘cycloid...
| Published in: | Geophysical Journal International |
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| Main Author: | |
| Format: | Text |
| Language: | English |
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Oxford University Press
1972
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| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/26/5/459 https://doi.org/10.1111/j.1365-246X.1972.tb05763.x |
| Summary: | This paper describes a palaeomagnetic investigation of 107 igneous bodies, mostly basaltic lavas, of Pliocene and Pleistocene age in Iceland. A variety of conclusions has resulted from the study. Palaeomagnetic directions in lavas erupted in 1729, 1783 and 1875 do not support the postulated ‘cycloid’ path for the Icelandic geomagnetic pole. Data are given for an application of geomagnetic reversal stratigraphy showing that Bering Strait opened more than 3 My ago, allowing Pacific boreal mollusks to enter Icelandic waters; these data also suggest that there were at least nine extensive glaciations since a time over 2 My ago. Lava flows erupted on Snaefellsnes Peninsula, western Iceland, contain large amounts of viscous remanent magnetization; partial demagnetization studies reveal a predominant reversed polarity for most of these lavas with one pronounced ‘excursion’ of virtual geomagnetic poles to very low latitudes. Detailed studies of a dike cutting a lava flow show that the lava's remanence is unaffected beyond one dike width from the dike contacts. Brunhes epoch paleosecular variation is consistent with a model combining a changing nondipole field like the present one with a dipole wobble of about 11°. |
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