Very high-resolution seismics as a tool for sequence stratigraphy applied to outcrop scale-examples for Eastern Tyrrhenian margin holocene/pleistocene deposits

Journal Article · Tue Mar 01 00:00:00 EST 1994 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6943913

Chiocci, F L ^[1]

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1. CNR, C.S. Quaternario ed Evoluzione Ambientale, Rome (Italy)

Three Eastern Tyrrhenian continental margin areas with very different depositional and tectonic settings were analyzed using single-channel very high-resolution reflection seismics coupled with sea-floor sampling. Fourth-and fifth-order depositional sequences derived from Quarternary glacio-eustatic processes are now buried at shallow depths within the continental shelf. The sequences have been reconstructed in detail with great lateral continuity. The tectonic setting did not influence the development of high-order sequences, which are probably synchronous at a global scale. Within these sequences, it has been possible to recognize all the systems tracts hypothesized by sequence stratigraphy models, confirming that this method does not depend upon time or scale. The geometry of depositional sequences is strongly dependent on sedimentation rate, i.e., on the distance from sources. Local factors must also be considered because they play an important role in the geometrical development of depositional sequences. In high-order depositional sequences, lowstand systems tracts are volumetrically predominant. High-stand and transgressive systems tracts seem to be linked to point sources because they have a three-dimensional (3-D) geometry. On the contrary, lowstand systems tracts are related to linear sources parallel to the shelf break; they cause the progradation of the whole margin so that they form the margin structure almost entirely. Offshore single channel reflection seismic surveys are generally conducted in prospecting, during planning and construction of civil engineering works and during surveys for oil-drilling sites. However, VHRS profiles also contain a large amount of data on large-scale sedimentary structures, chronostratigraphic surfaces, possible textural variations, and mutual spatial relationships between sedimentary bodies. 60 refs., 12 figs., 1 tab.

• OSTI ID: 6943913
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 78:3; ISSN 0149-1423
• Country of Publication: United States
• Language: English

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