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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


Daniele Scarponi1 and Lorenzo Angeletti2
1Dipartimento di Scienze della Terra e Geologico-Ambientali, University of Bologna, Via Zamboni 67, 40127 Bologna, Italy. E-mail: daniele.scarponi@unibo.it
2ISMAR–CNR, Istituto di Scienze Marine, Bologna, Via Gobetti 101, 40129 Bologna. E-mail: lorenzo.angeletti@bo.ismar.cnr.it


Integration of palaeontological patterns in the sequence stratigraphy paradigm: a case study from Holocene deposits of the Po Plain (Italy)


Volume 7, 2008, pages 1-13

PDF (2,0 MB)
Abstract

The influence of sequence-stratigraphic (base-level driven) processes on patterns derived from the fossil record has received an increasing attention. In particular, multiple recent studies, which focused on quantitative integration of palaeontological and sequence-stratigraphic patterns (Stratigraphic Palaeobiology), showed that multivariate paleoecological data, derived from rigorously collected bulk samples, can yield quantitative or semi-quantitative insights into environmental, stratigraphic, and taphonomic patterns. In this study, mollusk associations found in Holocene Po Plain deposits (Northern Italy), were used to test the informative power of quantitative palaeoecological patterns derived from well-understood marine sedimentary successions. A densely sampled core dominated by extant mollusk taxa with known environmental distribution was analyzed at a genus level using Detrended Correspondence Analysis. The raw database consists of 51 samples, including a total of 78 genera, more than 120 species, and ~2000 specimens.
A comparison of ordinations outputs derived using various filtering parameters allowed the separation of analytically robust patterns, which persist regardless of the data filters applied, from the analytically volatile (and thus suspect) outcomes, which vary depending on data filters applied. The robust-performing ordination retaining the largest subset of the entire dataset has been integrated with an ecological (bathymetric) dataset compiled for extant genera from the Italian Mollusk Census Database (IMCD). A putative bathymetric interpretation of the first DCA axis is suggested by a depth-related ordination of mollusk associations aligned along that axis. This is confirmed directly by a strong and statistically significant linear correlation between DC1 genus scores and the preferred bathymetry of extant mollusk genera recorded in IMCD. The approach also offers us an independent test of sequence-stratigraphic interpretations, enhancing sedimentary basin analysis with numerical bathymetric estimates.
The resulting outputs confirm that Late Quaternary mollusk associations can be used to calibrate quantitatively bathymetric gradients in the shallow-marine sedimentary successions. Furthermore, fossils marine association clearly track 4th-order cyclicity. Moreover, our incipient data (that require more extensive testing), suggest that the approach may be applicable to even higher frequency cycles (103 yr).

Keywords: Sequence stratigraphy, Mollusk associations, Po Plain, Holocene