S2S Sequence Stratigraphy: Applying Concepts and Methods of Environmental Signal Propagation in S2S Sedimentary Systems to Improve Sequence Stratigraphic Interpretation
Abstract
A fundamental tenet of sequence stratigraphy theory is that shoreline trajectories are governed by both space available for sedimentation (accommodation A, controlled by absolute sea-level changes and subsidence) and the amount of sediment delivered to this space (sediment supply S). In practice however, and at most timescales, shoreline trajectories have been typically associated with sea-level changes rather than with sediment supply whose difficult-to-measure variations have generally been considered of negligible effect compared to those of absolute sea-level. This view may well hold under icehouse planetary conditions during which glacio-eustatic sea-level variations could have overprinted any sediment supply variations, particularly in large and buffered sedimentary systems. Such view could also be misleading in other, warmer, periods of Earth's history with smaller amplitude global sea-level variations, such as the Early Eocene which was not only >8° globally warmer but also typically punctuated by short (50ky-200ky) yet significant (>1°) episodes of global warming called "hyperthermals" (e.g., PETM, ETM2, ETM3). We test this hypothesis by using stable isotopic proxy records to confront climatic signals with the sedimentary record of the back-and-forth of a small, reactive, early Eocene deltaic system. The Roda Sandstone is a shallow marine succession of mixed siliciclastic and carbonate sediments situated in the Tremp-Graus Basin, South-Pyrenees, Spain. The sequence stratigraphic architecture of this formation shows several episodes of deltaic progradation followed by carbonate accumulation that have been classically ascribed to sea-level changes or hinterland tectonic pulses. We generated carbon stable isotope profiles that can be correlated with target curves from ODP site 1258 and permit the identification of hyperthermals I1, I2, J, ETM 3 and L, systematically associated with deltaic progradation. Thus, in contrast with classical sequence stratigraphy, these results suggest that deltaic progradation of the Roda formation is primarily driven by climate-controlled sediment supply in a background of rising and high sea-level, while carbonate deposition occurs at times of maximum flooding due to a lack of available clastic material in generally lower sea-level stands.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP34B..03C
- Keywords:
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- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 1807 Climate impacts;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1861 Sedimentation;
- HYDROLOGY