GeoSed - Associazione Italiana per la Geologia del Sedimentario
Dipartimento di Scienze della Terra dell'Università di Siena
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Table of Contents


Vol. 9 - 2010

Vol. 8 - 2009

Vol. 7 - 2008
SP 1 - 2008

Vol. 6 - 2007
Vol. 5 - 2006
Vol. 4 - 2005
Vol. 3 - 2004
Vol. 2 - 2003
Vol. 1 - 2001-2002

Notes for Authors
(PDF - 80 kb)



GeoActa Special Publication 1 2008


Acquisto online

GeoActa
an international Journal of Earth Sciences


Francesca Castorina1,2 and Stefano Claudio Vaiani3

1 Dipartimento di Scienze della Terra, Università “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy. E-mail: francesca.castorina@uniroma1.it
2 IGAG, CNR sezione “La Sapienza” c/o Dipartimento di Scienze della Terra, Università “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy.
3 Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna, Via Zamboni 67, 40126 Bologna, Italy. E-mail: stefano.vaiani@unibo.it


Early Pliocene 87Sr/86Sr isotopic record from DSDP Site 132 (Tyrrhenian Sea)


Volume 8, 2009, pages 25-32

PDF (600 KB)
Abstract

87Sr/ 86Sr measurements were carried out on planktonic foraminiferal shell samples collected in the Early Pliocene succession of DSDP Site 132 (Tyrrhenian Sea, Western Mediterranean). The measured ratios range between 0.708980 and 0.709023, showing moderate fluctuations and a maximum variation of 0.000043 that falls within the uncertainty range of the Sr isotope measurements (± 0.000022) and suggests relatively constant ratios throughout this succession.
The Mediterranean seawater 87Sr/ 86Sr  ratios measured in a sample collected 55 cm above the Miocene / Pliocene Boundary and dated to 5.31 ± 0.01 Ma, are consistent with those measured in coeval oceanic successions, confirming the open marine depositional environment revealed by foraminiferal assemblages.
The measured ratios are consistent with those collected in the Lower Pliocene deep sea sequence at Hole 654A (about 70 km NW from DSDP Site 132) and these are also comparable with other data from coeval oceanic and on land successions, taking into account the uncertainty of the Sr isotope measurements.
The occurrence of relatively constant ratios throughout this succession, as previously shown in other coeval deep sea sequences of the Mediterranean and if verified in other successions, may hamper precise age determinations of the Early Pliocene marine carbonate in this basin.

Keywords: Sr isotope stratigraphy, Early Pliocene; Mediterranean; DSDP Site 132