Abstract: High-resolution, time-significant correlations are integral to meaningful stratigraphic frameworks in depositional systems but may be difficult to achieve using traditional sequence stratigraphic or biostratigraphic approaches alone, particularly in geologically complex settings. In steep, reefal carbonate margin-to-slope systems, such correlations are essential to unravel shelf-to-basin transitions, characterize strike variability, and develop predictive sequence stratigraphic models—concepts that are currently poorly understood in these heterogeneous settings. The Canning Basin Chronostratigraphy Project integrates multiple independent data sets (including biostratigraphy, magnetostratigraphy, stable isotope chemostratigraphy, and sequence stratigraphy) extracted from Upper Devonian (Frasnian and Famennian) reefal platform exposures along the Lennard Shelf, Canning Basin, Western Australia. These were used to generate a well-constrained stratigraphic framework and shelf-to-basin composite reconstruction of the carbonate system. The resultant integrated framework allows for unprecedented analysis of carbonate margin-to-slope heterogeneity, depositional architecture, and sequence stratigraphy along the Lennard Shelf. Systems tract architecture, facies partitioning, and stacking patterns of margin to lower-slope environments were assessed for six composite-scale sequences that form part of a transgressive-to-regressive supersequence and span the Frasnian–Famennian (F–F) biotic crisis. Variations are apparent in margin styles, foreslope facies proportions, dominant resedimentation processes, downslope contributing sediment factories, and vertical rock successions, related to hierarchical accommodation signals and ecological changes associated with the F–F boundary. We present these results in the form of carbonate margin-to-basin sequence stratigraphic models and associations that link seismic-scale architecture to fine-scale facies heterogeneity. These models provide a predictive foundation for characterization of steep-sided flanks of reefal carbonate platform systems that is useful for both industry and academia. This study emphasizes the utility of an integrated stratigraphic approach and the insights gained from better-constrained facies and stratal architecture analysis, insights that were not achievable with traditional sequence stratigraphic or biostratigraphic techniques alone.

ABSTRACT Making reliable correlations and sequence stratigraphic interpretations can be challenging in depositionally complex settings due to depositional heterogeneity and data-set limitations. To address these issues, the Canning Basin Chronostratigraphy Project documented the development of a high-resolution, chronostratigraphic correlation framework across different depositional environments in the Upper Devonian (Frasnian–Famennian) of the Lennard Shelf, Canning Basin, by integrating stable isotope chemostratigraphy, biostratigraphy, magnetostratigraphy, and sequence stratigraphy. This integrated data set allows for a rare, detailed look at the carbon isotope record, and specifically its potential as a sequence stratigraphic interpretation tool and its application to improve correlation capabilities, both of which have implications for better understanding of the depositional history of the Lennard Shelf. For platform-top settings, a sequence stratigraphic framework was constructed using stacking pattern analysis constrained by the paleomagnetic reversal record. In slope settings, where depositional variability and a lack of platform-top control have historically hindered our ability to recognize and correlate systems tracts, carbon isotope chemostratigraphy (in conjunction with conodont biostratigraphy and magnetostratigraphy) proved to be a useful chronostratigraphic tool because primary marine δ 13 C values were well preserved. Using the paleomagnetic reversal record, with additional age control from walkout correlations to key outcrop sections, we were able to confidently correlate from the platform-top into the slope. Evaluation of the slope isotope record, within the projected sequence stratigraphic framework from the platform-top, revealed that variations in δ 13 C values corresponded to changes in sea level. Using this relationship, isotopic trends were used as a proxy for delineating systems tracts in slope sections without direct platform-top control. In turn, this improved correlations through heterogeneous slope facies and also allowed for a refined sequence stratigraphic interpretation of Famennian strata in the Canning Basin. Results from this work also allowed us to develop a model that attempts to explain the observed relationships among global carbon cycling, sea-level fluctuations, and paleoceanographic conditions during the Late Devonian.