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 a t the margin of the Cretaceous Vercors platform expose prograding to tongues of platform grainstones. Growth and lateral progradation of these platform tongues was frequently interrupted, as by the deposition of wedges of fine-grained deeper water sediments that encroached the clinoform slopes. Petrographic and geochemical analyses have been carried 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 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 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 and 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 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 continuation of the Surface 3 bedding plane exhibits a distinct wedge of dolomitized 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 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 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 on the resulting platform stratal geometries. I n any marine depositional setting where sediment input varies with time, classically defined systems tracts (Van Wagoner al. 1988) represent a dynamic equilibrium between accommodation and sediment supply rather than changes in relative sea-level alone. As a result, the accurate reconstruction of sea-level history from the sedimentary record requires that the effects of eustatic and tectonically controlled sea-level fluctuations be separated from environmental changes (Kendall Schlager 1981; Schlager, 1991, 1993). However, two stratigraphic features a re exempt from the ambiguities associated with distinguishing changes in accommodation versus changes in sediment supply. These include From Howell, A. F. High Resolution Sequence Stratigraphy: Innovations and Applications, 295 Geological Society Special Publication No. 104, pp. B. W. FOUKE ET AL. SUBAER Fig.1. Geographical location of the Cirque at the southern margin of the Vercors carbonate in southeastern France (modified after Arnaud 1981). The perspectives from which outcrop photographs in Figs 2 and 3 are taken are indicated by the dashed lines adjacent to each figure number. Legend: 1. Neocomian;2. Barremian-Aptian fine-grained slope and basinal sediments; 3. Lower Barremian allodapic limestones (Borne Formation);4. Barremian and foreslope sediments (Glandasse 4a. members Bi 1 to Bi 5; 4b. members Bi 6 to Bs 5. Aptian platform sediments (Urgonian Formation). subaerial exposure unconfonnities and abrupt basinward shifts of shallow water facies regressions of Posamentier al. 1992; Schlager 1993; Franseen et al. 1993; Pomar, 1993; Goldstein & Franseen both of which are indicative of relative falls in sea-level. The diagenetic susceptibility and flat-top to flank morphology of carbonate platforms make the preservation, distribution and resulting recognition of subaerial exposure ties in these deposits greater than in siliciclastic systems James Choquette 1984; Weimer 1992). Moreover, several diagenetic criteria have been established with which to recognize subaerial exposure surfaces in carbonate platforms Allen 1982; Meyers mann 1985; Saller Moore 1989; Goldstein et 1991). Diagenetic analyses provide a means to verify the subaerial character of presumed unconformities, which is essential for an accurate reconstruction of sea-level history from depositional sequences. The spectacular outcrops of the Barremian Glandasse Formation limestones comprising the SUBAERIAL EXPOSURE UNCONFORMITIES, VERCORS CARBONATE PLATFORM 297 carbonate outcrop photographs in egend: Neocomian; 2. limestones (Borne . members Bi I to Bi 5; agenetic criteria have to recognize carbonate platfonns Meyers 1989; Goldstein et ses provide a means of presumed vhich is essential for of sea-level history