Lowstand Prograding Wedges as Fourth-Order Glacio-Eustatic Cycles in the Pleistocene Continental Shelf of Apulia (Southern Italy)
Published:January 01, 2004
Gemma Aiello, Francisca Budillon, 2004. "Lowstand Prograding Wedges as Fourth-Order Glacio-Eustatic Cycles in the Pleistocene Continental Shelf of Apulia (Southern Italy)", Cyclostratigraphy: Approaches and Case Histories, Bruno D’Argenio, Alfred G. Fischer, Isabella Premoli Silva, Helmut Weissert, Vittoria Ferreri
Download citation file:
The Salento continental shelf of Apulia (southern Adriatic) shows a complex stratigraphic architecture of Pleistocene prograding wedges that records the effects of the interplay of sediment accumulation, glacio-eustatic sea level changes, and regional tectonics. The interpretation of high-resolution seismic reflection profiles reveals three ravinement surfaces, extending landwards from the shelf break and showing low gradients. They have been considered to be stratigraphic markers and tentatively correlated to the oxygen curves of the isotopic stratigraphy. Even if direct dating of seismic sequences and corresponding unconformities is lacking, this correlation is well supported by the lateral extent and continuity of the ravinement surfaces, recognized in the whole investigated area. Similar qualitative correlation of unconformities with the curves of oxygen-isotope stratigraphy has been already used by other authors in different case histories of continental shelves of both active and passive margins. Moreover, in the study area the regional geological framework suggests that during the Middle Pleistocene the rate of tectonic uplift interacted with the rateof glacio-eustatic fluctuations, producing the deposition of forced-regression systems tracts. The forced-regression prograding wedge that enlarged the shelf by about fifteen kilometers is here dated as Middle Pleistocene. Starting fromthe upper part of the Middle Pleistocene, the stratigraphic architecture of the prograding wedges was controlled mainly by glacio-eustatic sea-level changes forced by short-eccentricity cycles. This is suggested by the stratigraphic architecture of the last two prograding wedges, interpreted as incomplete fourth-order depositional sequences and consisting of forced-regression, lowstand, and transgressive systems tracts. The eustatic signal as an expression of the Earth’s orbital cyclicity (short eccentricity) appears over whelming with respect to the tectonic one, and its prominence suggests a decrease in the rate of uplift of the Apulian foreland during the last 250 ky.
Figures & Tables
Cyclostratigraphy: Approaches and Case Histories
This volume is derived from an SEPM international workshop entitled Multidisciplinary Approach to Cyclostratigraphy, organized by the editors in May 2001 and held in Sorrento (Naples, Italy). In the Introduction we offer a brief history of how concepts of orbital cyclicity and its effects on the Earth evolved, an appraisal of the present state of research, and an overview of the papers in this volume. The main body of the volume consists of the contributed studies. These include a paper on conceptual and pragmatic approaches to stratification cycles by one of the pioneers of cyclostratigraphy, Walther Schwarzacher, who, in the 1940s, discovered the hierarchical expression of orbital cycles in rocks. The other contributions are specific studies of cyclic sequences, extending from the Quaternary back to the Triassic, covering the range from continental deposits to the deep sea, and employing a wide variety of techniques for extracting and processing the information.