The Long‐Term Stratigraphic Record on Continental Margins

Abstract

LONG-TERM GOALS My goal within the EuroSTRATAFORM program is to understand the creation of the preserved stratigraphic record on continental shelves and slopes as the product of physical processes acting with spatial and temporal heterogeneities. I have been using numerical models to provide insight into the formation and preservation of stratigraphic sequences at margins. My goal has been to obtain a quantitative understanding of the interactions of environmental parameters and their influence on stratal architecture and facies distribution. I wish to be able decipher the stratigraphy on margins to read the geologic record of the past and predict future stratigraphy. OBJECTIVES EuroSTRATAFORM is an opportunity to extend stratigraphic model applicability to new margins and to expand the capabilities of our products. The Rhône and Adriatic margins are similar to the earlier field areas in that they are mid-latitude clastic margins, but the stratigraphy is highly affected by the 3D geometry of the basins. The forcing provided by these boundary conditions provide a challenge, but are also necessary for modeling realistic systems. My aim is to quantitatively determine the system response of margins to different forcing functions sufficiently to be able to both predict stratigraphy and invert observed sequence architecture for geologic history. APPROACH I have used numerical models as a tool to provide insight into the formation and preservation of stratigraphic sequences at continental margins. To study these margins I will apply a multi-pronged approach. Together with Italian and French colleagues, I have been modifying and apply our existing 2D stratigraphic models to serial sections of the two EuroSTRATAFORM margins. This will test the portability of the models. It will also aid in evaluating the relative along-and across-strike transport and tectonics, and their influences on sequence architecture. John Swenson, with assistance from Chris Paola, Juan Fedele, I and others are jointly developing a 3-D sequence stratigraphic model. Together, we will extend our time-averaged, moving-boundary model for continental-margin sedimentation with its coupling of multiple transport regimes from 2-D to 3-D. The advantage of this modeling approach is that it allows for a systematic exploration of the margin's response to variations in sea level, sediment supply, tectonic subsidence, and wave climate over longer timescales. I am providing flexural component and parameterizations for the field areas. I will also make use of 3D flexural modeling and backstripping being done for a separate project on the Gulf of Lion to recover 1

Seabed fluid expulsion along the upper slope and outer shelf of the U.S. Atlantic continental margin

“…Using the geometry of shelf edge strata and results from previous studies [ McHugh et al ., ; Mountain et al ., ], each of the four Pleistocene sequence boundaries identified at Site 1073 (Figure a) were extended to profiles located to the north of Hudson Canyon (e.g., Profile‐04; Figures b and supporting information Figure S1). Beneath the shelf edge, each sequence boundary is associated with erosional truncation and/or toplap.…”

“…In contrast, the shelf edge and upper slope of the Hudson Apron and southern New England sections are smooth (i.e., widely spaced canyons), broad, and gently inclined. During the Pleistocene, up to 18 km of shelf edge progradation [ Mountain et al ., ] produced thick sequences that can be continuously traced from the shelf edge to the uppermost rise in some places [ Brothers et al ., ]. These sequences provide a rare opportunity to examine variations in stratigraphic character across regionally conformable depositional surfaces.…”

The New Jersey Margin Scientific Drilling Project (IODP Expedition 313): Untangling the Record of Global and Local Sea-Level Changes

“…Nonetheless, calculations that removed the imprint of processes affecting the accumulation of Oligocene-Miocene sediments left 30-50 m sea-level changes that were assumed to be eustatic (Van Sickel et al, 2004). Offshore high-resolution profiles collected in 1995 and 1998 (Mountain et al, 2007;Monteverde et al, 2008) (Fig. 2).…”

Assessment of tsunami hazard to the U.S. Atlantic margin

“…3 and 5). Here the paleo-Hudson River and pro-glacial drainage systems supplied a mixture of fluvial and glacially derived sediment to a broad and gently inclined shelf edge/upper slope (Mountain et al, 2007). Widely spaced canyons, low mean gradients and abundant sediment supply have allowed parallel-bedded stratigraphy to prograde across the margin; in places Pleistocene sequences can be traced from the shelf edge to the uppermost rise (Brothers et al, 2013b, Fig.…”