233-8 Depositional Regimes: An Intermediate Framework to Local and Basinwide Stratigraphy

Abstract:

Nearshore coastal deposits form across a broad range of spatiotemporal scales, and no current framework relates the local responses a single sedimentary archive preserves to the regional history the basin records. Furthermore, sequence-stratigraphic facies do not extend to the subregional and local dynamics that dominate unconsolidated deposits; per-describer site-stratigraphic units conform to no recognized framework; and soil science does not incorporate process-geomorphology. Therefore, correlating site-specific units between cores demands a justification these established frameworks cannot supply.

To bridge this gap, we have developed a progressively coarsening refinement chain: four tiers and three refinement steps, each relating otherwise unique elements under a broader class of dynamics. Cores are describer-authored sedimentary archives that are often recorded at the finest level through horizons or beds. These units resolve into depositional settings against the national bank of parent-material kinds (Field Book for Describing and Sampling Soils, v4). A small, falsifiable set of stratigraphic rules groups related settings into depositional packages, each derived package admitting one national process group. Adjacent packages conceding the same group coalesce into emergent depositional regimes. Each tier is a coarsening of the one below so that any two blocks are nested or disjoint. At the final tier, preserved depositional regimes across all cores describe the partial orders of a region’s total stratigraphic superposition.

Applied to 713 nearshore cores from the 2022-2024 USDA-NRCS Long Island Sound – Coastal Zone Soil Survey, the chain places four process-defined emergent states, recognizes two recurring but too sparsely to place, and identifies one bearing no superpositional relation to that order. Each core contributes a local partial order to the regional totally ordered superposition; for the Connecticut data, that is glacial, eolian, organic, and waterlaid deposits.

Overall, our approach shows that in the limit of a totally-driven region — one where core recovery consumes every reach — the partial order observed in any real corpus of cores would emerge as a subset of the region’s totally ordered superpositional chain. Applying the order-extension principle (Szpilrajn, 1930) to stratigraphy makes regional correlation of unconsolidated deposits an emergent property of the dataset itself and shows that sediment cores preserve a net-depositional, process-filtered partial of the total stratigraphic superposition of the region from which they were collected.

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