New insights on the evolution of the US Mid-Atlantic continental margin from sequence stratigraphy, statistics, and forward modeling: implications for carbon sequestration and sea-level studies
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Schmelz, William John. New insights on the evolution of the US Mid-Atlantic continental margin from sequence stratigraphy, statistics, and forward modeling: implications for carbon sequestration and sea-level studies. Retrieved from https://doi.org/doi:10.7282/t3-cc0r-6243
TitleNew insights on the evolution of the US Mid-Atlantic continental margin from sequence stratigraphy, statistics, and forward modeling: implications for carbon sequestration and sea-level studies
DescriptionI have used the strata of the US mid-Atlantic margin, sequence stratigraphy, and numerical modeling to assess: 1) the geologic and economic feasibility of carbon capture and sequestration in Cretaceous strata offshore New Jersey and Maryland; and 2) the effects of mantle dynamic topography (MDT) on Cenozoic stratigraphy of the US mid-Atlantic margin. Early to mid-Cretaceous shifts in sedimentation attributable to base-level variations generated subsurface reservoir units and overlying seals in the offshore New Jersey and Maryland that I have identified using integrated sequence stratigraphic methods. In particular, the strata just offshore Maryland can likely be used to store large volumes of supercritical carbon dioxide. Applying a sink-source matching model that matches carbon captured from electricity-generating power plants in the region with a geological storage reservoir indicates that storage in these offshore reservoirs would be marginally (~$10 per ton) more expensive than storing the emissions geologically onshore. Statistically modeling the discrepancies in estimates of global mean geocentric sea-level change (GMGSL) derived from US mid-Atlantic margin core data and independent estimates indicates that MDT likely generated up to 60 m of Cenozoic relative vertical land motion in given locations on the US mid-Atlantic margin. The modeled effect can be characterized as a pulse of relative uplift onshore New Jersey from 50 to 20 Ma that is also observed offshore from ~35-3 Ma, but net subsidence likely occurred since 55 Ma. These observations suggest that the subducted Farallon slab generated both a long-term subsidence effect and shorter-wavelength mantle anomalies associated with the more recent relative uplift of the Mid-Atlantic margin. Applying a forward stratigraphic model to reconstruct the sedimentation of the US mid-Atlantic margin for the past 23 Myr supports the assessment that a phase of relative MDT-driven uplift occurred offshore New Jersey during this time. The forward model parameterizes thermal subsidence, lithospheric flexure, compaction, sediment transport, sea-level, and sediment-supply variations. We optimize the parameters to produce the greatest probability that they are the true values considering the fit of the model output to stratigraphic data and parameter priors. Invoking between 0 and ~105 m of MDT-driven uplift produces the greatest posterior probabilities. This result is compatible with the statistical modeling that suggests estimates of GMGSL from core data collected offshore New Jersey is ~30 m too high.