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| Titel |
Magnetostratigraphic data from the Pignola-Abriola section (Southern Apennines, Italy): new constraints for the Norian/Rhaetian boundary |
| VerfasserIn |
Matteo Maron, Giovanni Muttoni, Miriam Katz, Linda Godfrey, Mariachiara Zaffani, Angela Bertinelli, Manuel Rigo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090994
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| Publikation (Nr.) |
 EGU/EGU2014-5259.pdf |
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| Zusammenfassung |
| New magnetostratigraphic data have been obtained from the Norian/Rhaetian boundary
section of Pignola-Abriola (Southern Apennines, Italy), which consists in 60 m of basinal
cherty limestones. A total of 10 magnetozones have been identified and calibrated with
conodont and radiolarian biostratigraphy. The Pignola-Abriola section was correlated to the
Newark APTS with a statistical method under the assumption that stratigraphic depth is a
linear proxy of time. The section was slid aside the Newark APTS producing a total of 19
possible correlation options that were evaluated by linear regression of the age-depth tie
points. Then, a student t-test was applied to the linear regression coefficients to isolate
the most reliable correlation options. According to our best correlation option, the
Pignola-Abriola section covers the interval from E13r (~217 Ma) to E20r (~205 Ma) in the
Newark APTS. The Norian/Rhaetian boundary based on the FAD of conodont Misikella
posthernsteini and the base of the Proparvicingula moniliformis radiolarian Zone 1 at
Pignola-Abriola (Giordano et al., 2010: Lethaia 43, 573–586) falls on the Newark APTS at
~205.4 Ma within magnetozone E20r. The magnetostratigraphy of the Pignola-Abriola
section has been successfully correlated to other Late Triassic magnetostratigraphic
sections from the literature spanning the Norian/Rhaetian boundary (Steinbergkogel,
Oyuklu, Brumano and Pizzo Mondello) . Our magnetostratigraphic correlation
reveals an apparent discrepancy in the first appearance of conodont M. posthernsteini
between Pignola-Abriola and Steinbergkogel/Oyuklu. However, we infer that the
forms attributed to M. posthernsteini at Steinbergkogel/Oyuklu are more similar
to what we refer to as M. hernsteini/posthernsteini transition at Pignola-Abriola,
a solution that virtually eliminates the discrepancy. Considering the taxonomic
complexity of the M. hernsteini/posthernsteini lineage, we propose to place the
Norian/Rhaetian boundary in correspondence of a marked negative shift of d13Corgobserved
at Pignola-Abriola at ~41.5 m (close to the FAD of M. posthernsteini),which, according to
the correlation with the Newark APTS, would have an age of ~205.6 Ma. According to this
new definition of the Norian/Rhaetian boundary, the Rhaetian is ~4.5 Myr-long. |
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