New Norian/Rhaetian magnetostratigraphic data have been obtained from the Pignola-Abriola section cropping out in the Southern Apennines (Potenza, Italy), and composed of ~60 m of hemipelagic-pelagic sediments in stratigraphic continuity (Calcari con Selce Fm). More than 160 samples have been analyzed for the NRM but only 45 gave back the primary magnetic component; successively the VGP has been defined from the principal component analysis. Using the VGP latitude was settled a sequence of 3 normal (MPA-1n, -2n, -3n) and 2 reverse (MPA-1r, -2r) polarity magnetozones, well calibrated by using an integrated conodont/radiolarian biostratigraphy, which provide a detailed Norian/Rhaetian age of the studied succession. In order to identify the magnetozones containing the Norian/Rhaetian boundary, here recognized as FAD of the Misikella posthernsteini, these results have been correlated to published magnetobiostratigraphic data from two other Tethyan marine sections that are Oyuklu (Turkey) and Steinbergkogel (Austria) sections. The IRM analyzes (thermal and back-field) provided information about the magnetic minerals present in the samples, recognizing two principal mineral phases that are magnetite and hematite, with a low and high coercitivity respectively. The comparison between the S-Ratio and the magnetization at room temperature (J) curves shows a cyclic increase of hematite phase that seems correlated to an increase of terrigenous input, peculiar of the upper part of the studied section where the hematite is more abundant. The increase of terrigenous input is probably correlated to a climatic change to more humid conditions, here interpreted as the beginning of the activity of CAMP (Central Atlantic Magmatic Province), also coherent with the more negative values of the coeval Os and Sr isotope curves. The Fisher analysis of the VGP data provides a paleopole declination of 11,3° and an inclination of 89,3°, with an a95 of 8,3°.

Indagini magnetostratigrafiche attorno al limite Norico/Retico nella sezione di Pignola-Abriola (Potenza) = Magnetostratigraphical investigations around the Norian/Rhaetian boundary at the Pignola-Abriola section (Potenza, Italy).

Maron, Matteo
2012/2013

Abstract

New Norian/Rhaetian magnetostratigraphic data have been obtained from the Pignola-Abriola section cropping out in the Southern Apennines (Potenza, Italy), and composed of ~60 m of hemipelagic-pelagic sediments in stratigraphic continuity (Calcari con Selce Fm). More than 160 samples have been analyzed for the NRM but only 45 gave back the primary magnetic component; successively the VGP has been defined from the principal component analysis. Using the VGP latitude was settled a sequence of 3 normal (MPA-1n, -2n, -3n) and 2 reverse (MPA-1r, -2r) polarity magnetozones, well calibrated by using an integrated conodont/radiolarian biostratigraphy, which provide a detailed Norian/Rhaetian age of the studied succession. In order to identify the magnetozones containing the Norian/Rhaetian boundary, here recognized as FAD of the Misikella posthernsteini, these results have been correlated to published magnetobiostratigraphic data from two other Tethyan marine sections that are Oyuklu (Turkey) and Steinbergkogel (Austria) sections. The IRM analyzes (thermal and back-field) provided information about the magnetic minerals present in the samples, recognizing two principal mineral phases that are magnetite and hematite, with a low and high coercitivity respectively. The comparison between the S-Ratio and the magnetization at room temperature (J) curves shows a cyclic increase of hematite phase that seems correlated to an increase of terrigenous input, peculiar of the upper part of the studied section where the hematite is more abundant. The increase of terrigenous input is probably correlated to a climatic change to more humid conditions, here interpreted as the beginning of the activity of CAMP (Central Atlantic Magmatic Province), also coherent with the more negative values of the coeval Os and Sr isotope curves. The Fisher analysis of the VGP data provides a paleopole declination of 11,3° and an inclination of 89,3°, with an a95 of 8,3°.
2012-10-12
Paleomagnetismo, Norico/Retico, Lagonegro
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/16220