Development of Incisions on a Periodically Emergent Carbonate Platform (Natih Formation, Late Cretaceous, Oman)

Abstract

Subaerial exposure of carbonate platforms is generally recorded by karstification and pedogenesis, whereas erosion features such as incisions along emersion surfaces have seldom been observed and studied. However, the recognition of incisions and the characterization of their fill may facilitate definition and hierarchy of sequence boundaries, especially along exposure surfaces that do not otherwise present clear petrographic evidence for emersion. In the Natih Formation (Late Albian-Early Turonian, Oman), two successive incision surfaces are present in the upper part of the first third-order depositional sequence. Seismic interpretation of regional subsurface data has allowed the quantification of progradational geometries within the Natih sequence I carbonate platform and the correlation of incision surfaces with forced regressive prograding wedges on the margins of the intrashelf basin. Detailed geological sections and correlations have been made from three outcrop localities, allowing a precise description of geometries and facies of incision fills. Morphology, orientation, and extent of these incisions have been assessed from detailed seismic interpretation coupled with forward seismic modeling. The integration of outcrop and seismic data sets at the regional and local scales allows the interpretation and discussion of the origin and factors controlling the development of these incisions and a refinement of the stratigraphic model. These two incisions record rapid sea-level variations (500 ky) with a magnitude of approximately 20 and 30 m that occurred during the early Cenomanian. This is probably not a unique case, since for the same time interval, incisions have been observed in siliciclastic systems in western Canada and India and in carbonate systems on the Arabian plate.

High-energy sedimentary events in lagoonal successions of the Upper Silurian of Podolia, Ukraine

“…9g) embracing depressions a few centimetres long (cf. comparison of incisions and channel erosion features presented by Grélaud et al 2006). The depressions are usually Wlled with small lithoclasts that also occur in the marginal parts of the channel inWlling (Fig.…”

New Alveolinoidea (Foraminifera) from the Cenomanian of Oman

“…The upper Albian/Turonian Natih Formation consists of mainly mud-supported and some grain-supported limestone (with local rudist development) alternating with intraplatform basin organic rich calcareous shales. Deposition was interrupted several times by subaerial exposure with emersion and incision (Immenhauser et al, 2000;Droste and Van Steenwinkel, 2004;Gr elaud et al, 2006Gr elaud et al, , 2010Homewood et al, 2008). Outcrop sedimentology of the Natih Fm.…”

Evolution of a Maastrichtian–Paleocene tropical shallow-water carbonate platform (Qalhat, NE Oman)

“…During the Late Cretaceous, the Oman was situated in a paleo-equatorial position (Dercourt et al 1993). Uplift during the onset of ophiolite obduction changed the depositional setting during Turonian time (Grelaud et al 2006). The Aruma Group comprises the sedimentary cover of the ophiolite ( Fig.…”