Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: application to Middle Jurassic carbonate reservoirs in the Paris basin
Résumé
In recent years stylolites, which are rough dissolution surfaces commonly found in carbonates, have been used for paleopiezometry estimates. The Stylolite Roughness Inversion Technique (SRIT) applied on sedimentary bedding-parallel stylolites (BPS) grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo-depth. This study reports the results of SRIT applied to a BPS population hosted in carbonate platform reservoirs of the Paris basin sub-surface (France). Middle Jurassic carbonates from two well cores from the depocenter and margin of the basin, for which the burial and thermal history are known, based on a thermally calibrated 3-D basin model, were analyzed. By defining a consistency criterion and using two signal treatment methods, we propose a new approach to select which BPS can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates, which then can be converted into maximum burial depth. The study of a BPS population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded. Especially suture and sharp peak BPS are better suited to estimate the real maximum depth, whereas seismogram pinning BPS record preferentially intermediate depths. Median values of maximum depth derived from our data set (1300 and 1650 m for the margin and depocenter cores, respectively) are in line with maximum burial estimates provided by conventional basin modeling (1450 and 1800 m, respectively), thus showing that SRIT is a standalone robust depth gauge in sedimentary basins, provided sample selection and data treatment are carried out in a rigorous and thoughtful manner
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