Seismic models of a prograding carbonate platform: Vercors, south-east France

Stafleu, Jan; Everts, Arnout J.W.; Kenter, J.A.M.

doi:10.1016/0264-8172(94)90065-5

Cited by 40 publications

(16 citation statements)

References 19 publications

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“…This results in significant subseafloor compaction and sourcing of CaCO 3 to adjacent calciturbidite layers that had lower noncarbonate content-and possibly higher aragonite content. Finally, combined with the documented negative effect of clay (Stafleu et al 1994) the organic matter in the noncarbonate fraction decreases the acoustic velocity of the background sediment layers and enhances that of the calciturbidites. Although most aragonitic grains in the calciturbidites were leached producing moldic porosity, this has only a minor effect on the velocity, because the rigid framework efficiently transmits the elastic waves (Anselmetti and Eberli 1993).…”

Section: Controls On Acoustic Propertiesmentioning

confidence: 94%

“…One possible explanation may be the subtle, but consistent, basinward increase of the average noncarbonate fraction: Clino and Unda are 99% pure carbonate; Site 1005 has more than 98% carbonate; Site 1003 has more than 92% carbonate; and Site 1007 has ϳ 90% carbonate. Minor amounts, ϳ 5 to 10%, of noncarbonate matter, mostly clay and minor amounts of organic material, have a documented negative effect on acoustic velocity (e.g., Tosaya and Nur 1982;Klimentos and McCann 1990;Stafleu et al 1994;Han et al 1986) (Fig. 7).…”

Section: Velocity Transformsmentioning

confidence: 98%

“…Several studies have been made (e.g., Raymer et al 1980;Rafavich et al 1984;Wang et al 1991;Anselmetti and Eberli 1993;Anselmetti 1994;Stafleu et al 1994;Kenter and Ivanov 1995;Han et al 1986;Kenter et al 1997aKenter et al , 1997bWoodside et al 1998) that show the primary factors controlling acoustic velocity in nearly pure carbonates are both the amount and type of porosity, diagenetic properties, and mineralogy. The classic velocity transforms, Wyllie's time-average equation (Wyllie et al 1956), and Gardner's empirical relation (Gardner et al 1974), allow the prediction of P-wave velocity from porosity or bulk density in single data sets but fail to account for the variation in velocity at a given porosity value.…”

Section: Introductionmentioning

confidence: 97%

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Acoustic Properties of "Young" Carbonate Rocks, ODP Leg 166 and Boreholes Clino and Unda, Western Great Bahama Bank

Kenter¹,

Anselmetti²,

Kramer³

et al. 2002

Journal of Sedimentary Research

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Acoustic properties determined from logs and discrete measurements along a borehole transect across the slope of the western Great Bahama Bank margin (ODP Leg 166) show a distinct relationship with primary sediment composition and noncarbonate content.Dominant sediment types are alternating cemented and uncompacted calciturbidites with shallow-water derived grains, and poorly to uncemented and compacted periplatform ooze of globigerinid-dominated wackestone to packstone. Comparison of the velocity-porosity variation from logs and discrete measurements reveals that both tend to follow the trend of generally accepted velocity transforms. Primary control on the acoustic velocity is exerted by total porosity, whereas the remaining variation in velocity is explained by differential diagenesis. The less cemented to uncemented and compacted background sediments have velocities that, at a given porosity, fall below the timeaverage equation for calcite. The cemented turbidites, however, have velocities that are higher than those predicted by the time-average equation. Although it is unclear whether the original volume of aragonite or presence of organic matter controlled this difference, it is suggested that the acoustic properties reflect an input signal. The presence of noncarbonate material, some of which is clay, increases basinward and further reduces the acoustic velocities in the background sediment. In contrast, earlier work on the more proximal slope, and nearly pure carbonate, intervals in Clino and Unda cores documents diagenetic differentiation in compositionally similar sediment, resulting in alternating acoustically fast and slow layers. Marginal and nearly pure limestones have a more complex acoustic behavior and hence are difficult to predict.Though both velocity logs and discrete velocity measurements show comparable general trends, logging data show a considerably larger variation at a given porosity value (up to 3.5 km/s) than discrete data, which ranges between 1.0 and 2.5 km/s. To improve the quality of velocity logs it is suggested to groundtruth these data with other logging data, general velocity transforms, and, ideally, discrete measurements on core plugs.

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Section: Controls On Acoustic Propertiesmentioning

confidence: 94%

Section: Velocity Transformsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 97%

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Acoustic Properties of "Young" Carbonate Rocks, ODP Leg 166 and Boreholes Clino and Unda, Western Great Bahama Bank

Kenter¹,

Anselmetti²,

Kramer³

et al. 2002

Journal of Sedimentary Research

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“…The platform-to-basin transition exposed in the Cirque d'Archiane exhibits two prograding grainstone tongues (called Bi 5 and Bi 6 respectively) separated by a basinward wedge of finer-grained sediments (called the Fontaine Colombette Marls; Figs 2a, b and 3a, b; Arnaud 1981). Significant controversy has developed over the extent to which these stratal geometries were created by third-order sea-level cycles (Arnaud 1981;Jacquin et al 1991;Hunt & Tucker 1993;Stafleu et al 1994;Everts et al 1995). However, to date no detailed diagenetic analyses have been completed at the stratigraphic intervals where the major changes in depositional geometries occur.…”

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confidence: 96%

Subaerial exposure unconformities on the Vercors carbonate platform (SE France) and their sequence stratigraphic significance

Fouke

Everts

Zwart

et al. 1996

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The integration of data on diagenesis and stratal geometry at the margin of the Vercors carbonate platform (SE France) shows that the most prominent break in depositional style does not coincide with the platform-top horizon exhibiting the most extensive meteoric alteration. This observation again illustrates the ambiguity of geometrical criteria to define sequence boundaries related to subaerial exposure.Outcrops at the margin of the Cretaceous Vercors platform expose prograding to aggrading tongues of platform grainstones. Growth and lateral progradation of these platform tongues was frequently interrupted, as evidenced by the deposition of wedges of fine-grained deeper water sediments that encroached the clinoform slopes. Petrographic and geochemical analyses have been carded out at strategic bedding surfaces in order to evaluate the extent to which these breaks relate to sea-level falls and subaerial exposure. The analyses reveal evidence for minor meteoric alteration at all four of the bedding surfaces on the platform top that were studied. However, the Surface 3 bedding plane is unique in that it shows the overprinting of several events of meteoric diagenesis. Petrographic and geochemical analyses suggest that the rudist floatstones at this particular surface were diagenetically overprinted at least three times by meteoric groundwaters that dissolved skeletal grains and precipitated bladed and blocky calcite cements that exhibit bladed to blocky morphologies, low Mg, Mn and Fe abundances, depleted 6180 and 8lSC signatures, and freshwater fluid inclusions. Hardground borings then cross-cut the meteoric calcite cements and biomolds, indicating that the subaerial exposure and meteoric overprinting took place prior to deposition of the overlying marine grainstones. This ensuing period of marine inundation was also accompanied by the deposition of red argillaceous internal sediments and dolomitization. The marine grainstones overlying Surface 3 contain lithoclasts with truncated dolomite rhombs at their margins, suggesting that the dolomitization at Surface 3 also relates to early stage diagenesis.The offbank continuation of the Surface 3 bedding plane exhibits a distinct wedge of dolomitized lithoclastic debris. No such debris was found along the slope continuation of the other studied surfaces, confirming that the Surface 3 bedding plane relates to a particularly significant episode of subaerial exposure and erosion. However, within the framework of changing stratal geometries at the margin of the Vercors platform, the exposure Surface 3 represents a rather insignificant event. In contrast, the most prominent break in depositional style at the Vercors platform-margin exhibits only minor meteoric alteration along its platform-top continuation. This 'stratigraphic mismatch' suggests that sea-level falls exposing the platform-top exerted only a minor influence on the resulting platform stratal geometries.In any marine depositional setting where sediment input varies with time, classically defined systems tracts (...

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“…Minor amounts of noncarbonate material, clay, and/or quartz silt/sand can dramatically change acoustic velocities (Stafleu et al, 1994;Kenter et al, 1997;Anselmetti and Eberli, 2001). Magnetic susceptibility values are lower in the last deglacial sequence (Unit I) at Maraa than at Tiarei.…”

Section: Petrophysicsmentioning

confidence: 99%