Magnetostratigraphy and fold tests from Ra?i?ka pe?ina and Pe?ina v Bor?tu caves (Classical Karst,Slovenia) |
| |
| Authors: | Petr Pruner Nadja Zupan Hajna Andrej Mihevc Pavel Bosák Otakar Man Petr Schnabl Daniela Venhodová |
| |
| Institution: | (1) Institute of Geology AS CR, v.v.i., Rozvojova 269, 165 00 Praha 6, Czech Republic |
| |
| Abstract: | Clastic and chemogenic cave sediments were sampled and analyzed from Račiška pečina and Pečina v Borštu caves of southwestern
Slovenia. Samples were subjected to both thermal and alternating field demagnetization; specimens belonging to the same sample
of the same layer produce identical results. Unblocking temperatures of 540 to 560°C on average suggests magnetite as the
principal carrier of magnetization. These directions also pass a reversals test indicating the demagnetization results are
free of secondary overprints and have adequately averaged out paleosecular variation. Normally magnetized clays containing
fauna belonging to the MN17 mammal biozone at a depth of ∼ 4 m in Račiška pecina cave indicate these clays were deposited
at the beginning of the Olduvai subchron (1.95 Ma). Correlation with the Geomagnetic Polarity Time Scale (GPTS) indicates
the base of the speleothems in Račiška pečina terminate in the upper part of subchron C2An.3n with numerous breaks in deposition,
lasting up to 250 ka and more. Therefore rates of speleothem growth cannot be calculated. Fold tests on dome-like stalagmites
of differing sizes and ages (Pleistocene, Pliocene) from the two caves indicate the domelike structures are primary. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
