Orbital Chronostratigraphy of the Valanginian-Hauterivian Boundary: A Cyclostratigraphic Approach
Published:January 01, 2004
Vittoria Ferreri, Sabrina Amodio, Rosaria Sandulli, Bruno D’ Argenio, 2004. "Orbital Chronostratigraphy of the Valanginian-Hauterivian Boundary: A Cyclostratigraphic Approach", Cyclostratigraphy: Approaches and Case Histories, Bruno D’Argenio, Alfred G. Fischer, Isabella Premoli Silva, Helmut Weissert, Vittoria Ferreri
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On the basis of cyclostratigraphy and sequence stratigraphy criteria, an orbital chronostratigraphy is hereproposed for the Upper Valanginian-Lower Hauterivian (Lower Cretaceous) stratigraphic interval. For such a purpose two biostratigraphically constrainedcarbonate platform section were measured and sampled at centimeter scale in southern Italy: (1) San Lorenzello, Matese Mountains in theCampania Apennines, and (2) Sferracavallo, Palermo Mountains in northwestern Sicily. The former has a thickness of about 87 m,and thelatter totals about 40 m. Analysis of depositional and early diagenetic features has shown that both the successions are characterized byinternal cyclicity, consistent with orbital (Milankovitch) forcing. This high-frequency cyclicity, in which the elementary cycles areorganized in bundles and in groups of bundles (superbundles), appears to be superimposed on three longer (from ~ 800 ky to ~ 1200 km transgressive-regressive facies trends (T∕RFTs). Whereas the elementary cycles record the precession and∕or the obliquity signal (or a combination of them), the bundles and the superbundles correspond to the short- and long - eccentricity signals (~ 100 ky and 400 ky cycles), respectively. Sequencestratigraphic criteria, used to interpret the superbundles and the T∕RFTs in terms of depositional-sequence equivalents, allowed us to propose chronostratigraphic diagrams of the studied intervals and to attempt regional- to global-scale physical correlations.
At regional scale, the Sferracavallo section was correlated, bundle by bundle, with the time-correspondent segment of the San Lorenzello section. The chronostrat igraphic correlation shows that only one main gap, calculated as about 200 ky, occurs in the studied intervals. This allows us to assume that the sedimentary record can be considered quasi-continuous, at least at the superbundle scale (~ 400 ky).The assembled orbital chronostratigraphy suggests that the time recorded in the San Lorenzello and in the Sferracavallo sections is 2.9 and 1.9 My, respectively. At global scale, a physical correlation is proposed with the time-equivalent third-order sequences of Haq et al. 1987 and Jacquin et al. (1998), taking into account the stratigraphic position of the Valanginian-Hauterivian (Early Cretaceous) boundary in the standard time scales, as well as in our orbital chronostratigraphy. This correlation shows that there is a good agreement between the 2.6 My time duration of the stratigraphic interval spanning from the Valanginian 4 to the Hauterivian 1 sequence boundaries (Jacquin et al., 1998) and the 2.8 My interval estimated on the basis of our orbital chronostratigraphy.
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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.