Sea-level variations and sedimentary response

Cenozoic stable isotopes and sea level

[Ken Miller, Jim Wright, JV Browning]

We compiled a splice of benthic foraminiferal δ18O records over the past 66 Myr and scaled to sea level using a smoothed record (>2 Myr) of Cenozoic Mg/Ca variations to account for long-term effects of temperature changes. We assume that shorter term (Milankovitch scale, 104-105 year) temperature changes comprise ~20% of the benthic foraminiferal δ18O changes, as in the Quaternary, and a calibration of 0.13±0.02‰ δ18Oseawater/10m. Our record provides an estimate of ice-volume and attendant Global Mean Sea Level changes due to ice (GMSL-I) with errors of approximately ±10 m, but is not a complete estimate of GMSL because it does not account for changes in the volume of the ocean basin, other tectonic effects, or changes due to sediment input. We compare our GMSL-I records with independent estimates of Myr-scale sea-level changes derived from passive margin (New Jersey, USA, and Marion Plateau, Australia) by backstripping, progressively accounting for the effects of compaction, loading, and thermal subsidence. Both GMSL-I and backstripped records show synchronous 20-60 m variations on the Myr scale during the Icehouse World of the Oligocene-Miocene, suggesting that we have constrained changes in ice volume on this scale.

Sandy Hook Drilling project

Quaternary subsidence history

[Chris Johnson, Ken Miller, Jim Browning]

To understand why Sandy Hook, NJ is sinking faster (1-2 mm/yr) than nearby bedrock sites, three coreholes were drilled on a N-S transect at Sandy Hook in 2014 sampling Quaternary and Cretaceous strata. At the North Maintenance Yard (NMY) adjacent to the tide gauge, thick (84+ m) Quaternary strata consist of uppermost Pleistocene thin (3+ m) basal gravels (?18 ka), thick (29 m) estuarine organic-rich sandy clayey silts to silty clays dated as 13.2-12.1 ka, 13 m of lower Holocene mid-estuarine muddy sands (10.3-9.3 ka), 42 m of Holocene sands (7-0.3 ka). The uppermost Pleistocene muds thin and pinchout to the south. We are conducting sedimentological analyses (grain size, organic carbon, and porosity) of the coreholes, providing datasets needed to remove the effects of compaction. Preliminary results indicate as much as 0.5 mm/yr of subsidence due to natural compaction. Nevertheless, comparison of tide gauges shows a distinctly anthropogenic signal at Sandy Hook, implicating groundwater withdrawal and resultant compaction as a contributor to excess subsidence. 

Magothy Formation (Turonian-Coniaican) depositional models

[Pete Sugarman, Ken Miller, Jim Browning]

Recent drilling at Sandy Hook and Sea Girt in Monmouth County, New Jersey has provided continuously cored, thick delta-plain and delta-front facies of the Magothy Formation (upper Turonian-Coniacian) that comprise important aquifers in this region. The Magothy Formation is informally divided into 5 members and 4 to 5 sequences in NJ. Pollen is critical in correlating these units. These members/sequences can be mapped along strike and downdip throughout the NJ coastal plain, but are best expressed at Sandy Hook, where the Old Bridge and Sayreville Sand Members are thick and show evidence of high rates of deposition. We are evaluating the facies and environmental significance of the members that include a complex mix of fluvial, estuarine, tidally influenced interdistributary bays and swamps, delta front, and prodelta environments. The widespread distribution of Magothy sequences hints at the stability of deltaic depositional systems despite known variations in eustasy during the Turonian-Coniacian.

Potomac Formation (Berriasian to Cenomanian) depositional models

[Jesse Thornburg, Pete McLaughlin (Delaware Survey), Ken Miller, Jim Browning, Pete Sugarman]

Potomac Formation sediments provide a mid-Cretaceous record of the coastal plain along the eastern margin of North America. We described paleosol profiles from the Potomac units I-III and grouped into five pedotypes ranging in pedogenic maturity: 1) weakly developed, poorly drained, immature soils; 2) moderately developed soils forming under wet/dry conditions; and 3) well-developed, well-drained mature soils. A morphology index and two geochemical proxies (Nb and Ba/Sr) provide further information on paleoprecipitation, lessivage, and drainage conditions. We develop a conceptual model linking the Nb paleoprecipitation proxy and Ba/Sr drainage proxy to determine landscape changes as a result of paleoclimate versus base level. Paleosol, proxy and stable isotope data show the change from climate to base level as the major influence on landscape conditions from Unit I (?Berrisian-Aptian), to Unit II (middle to late Albian), to Unit III (early Cenomanian). Paleosol morphology was used in conjunction with assigned fluvial aggradation cycles (FACs) to place candidate sequence boundaries within all three units. The use of FACs to place a sequence stratigraphic framework on these sites offers an additional correlatable surface between corehole sites within the units.

IODP Expedition 313

[Greg Mountain, Ken Miller, Jim Browning, Don Monteverde, Pete Sugarman]

Expedition 313 (Mountain et al., 2010) drilled and logged three sites on the New Jersey shallow shelf (~30 m present depth) to investigate the history of sea-level change and the response of continental margin sedimentation to such changes. Numerous papers have being published on the chronology (Browning et al., 2013), paleobathymetric changes (Katz et al., 2013; McCarthy et al., 2013), seismic-core-log correlations (Miller et al., 2013a), testing sequence stratigraphic models on foresets (Miller et al., 2013), and 1-D backstripping (Kominz et al., in review). Ongoing studies include:

Bottomset facies

[Jim Browning, Dave Hodgson (Leeds University), Ken Miller, Greg Mountain]

The onshore New Jersey Coastal Plain Drilling Project sampled sedimentary sequences in topset locations establishing they are dominated by fining upward transgressive and coarsening upward highstand systems tracts bracketed by sequence boundaries (Miller et al., 2013a, 2013b). Sediments on the basin floor at the bases of foresets had not been drilled on the coastal plain and their sedimentary facies and relationships were not known. IODP Exp. 313 recovered thick sections (Mountain et al., 2010) of base of slope sediments that are the subject of ongoing research to determine the relationship between sediments deposited and the timing of sea level change.

Synthetic seismograms

[Greg Mountain, Don Monteverde]

2-D backstripping

[Mike Steckler (LDEO), Greg Mountain, Ken Miller, Jim Browning]

3-D seismic survey of NJ continental shelf

[Greg Mountain]

The New Jersey margin is among the best continental margins for learning the timing and amplitude of global mean sea level change over millions of years, for establishing quantitative links between sea-level change and the stratigraphic record, and for assessing the impact of sea-level rise on the world's coastlines. Although IODP Exp313 continuously cored/logged boreholes within shallow-water facies where prior studies revealed Miocene clinothem morphologies, ultra-high resolution 3D seismic images were collected aboard the R/V Marcus G. Langseth in July, 2015 that will put that sampled record into a spatially accurate, stratigraphically meaningful context. 3D images will yield maps of sequences surrounding the Exp313 sites showing shoreline positions, fluvial incisions, estuary complexes, point bars and other nearshore features. The long-term objectives of this research are to: 1) determine the amplitude and timing of global sea-level changes during the “Ice House” 2) establish the impact of base-level changes on the preserved stratigraphic record; and 3) improve understand­ing of the response of shorelines/nearshore environments to changes in global sea level, a societally relevant topic today.

Onshore-offshore correlations

[Ken Miller, Jim Browning, Gabe Gallegos, Pete Sugarman, Turan Işçimen]

We correlated onshore New Jersey coastal plain sequences Kw2 and Kw1 with offshore shallow shelf sequences m5.4 (ca. 18.0-17.7 Ma) and m5.8 (20.1-19.6 Ma), respectively, using multichannel seismic profiles (MCS), stratal stacking patterns in cores, well logs, and chronostratigraphy. Seismic-core-log correlations at offshore Expedition 313 Sites M27 and M28 allow extension of lithologic and chronostratigraphic data into the time domain of seismically well imaged sequence. Sequences were traced shoreward using R/V Cape Hatteras 0698 MCS data to onshore Atlantic City, Cape May, Ocean View, Cape May Zoo, and adjoining boreholes. Depositional environments of the sequences were evaluated by analyzing lithology, well logs, and benthic foraminifera-derived paleobathymetric estimates to constrain environmental changes in the sequences. Age resolution of the sequences was determined by Sr analyses onshore and Sr and biostratigraphy at offshore locations. The onshore sequences Kw2 (ca. 17.5-15.1 Ma) and Kw1 (ca. 20.4-19 Ma) are thick (>50 m) and contain an upper (Kw2b and Kw1b) and lower (Kw2a and Kw1a) Myr-scale sequence. Both onshore upper sequences Kw2b and Kw1b were found to be single sequences. However, the Kw2a sequence was determined to be a composite sequence containing 3 higher order (100/400 kyr) sequences (Kw2a1, Kw2a2, and Kw2a3) thatcorrespond to 3 sequences within offshore composite sequence m5.4 (m5.4-1, m5.34, and m5.33). We note that the lower Kw1 sequence (Kw1a) also contains three higher order sequences (Kw1a1, Kw1a2, and Kw1a3), prompting us to reexamine offshore sequence m5.8. We conclude that as resolution increases, the nearshore stratigraphic record can be shown to be a stacking together of sequences on various scales that is remarkably incomplete.



Cretaceous/Paleogene Boundary

Ir, stable isotopes, and recovery

[Selen Esmeray-Senlet, Ken Miller, Rob Sherrell]

Recent studies have focused on the Iridium anomaly in several New Jersey coastal plain outcrops and coreholes (Miller et al., 2010; Esmeray-Senlet, Ph.D. thesis) and the recovery of planktonic foraminifera and carbon cycle from mass extinction (Esmeray-Senlet et al., 2015). Our data from New Jersey and the deep sea indicate reduced export productivity consistent with the Living Oceans hypothesis, though other studies indicate zones of continued export productivity, prompting us to coin the term Heterogeneous Oceans (Esmeray-Senlet et al., 2015). Ir is associated with the mass extinction event in most sections, though it appears to have migrated downsection at Bass River, and Tighe Park. We continue to explore the relationship between Deccan Trap volcanism, impact, and the mass extinction. 



Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene thermal maximum (PETM) was an abrupt warming event characterized by a 5-8°C temperature increase. It is globally recognized by a negative carbon isotope excursion (CIE) across the Paleocene/Eocene boundary in both marine and terrestrial sections. Despite numerous records of this major Cenozoic hyperthermal, there is still considerable debate on timing, triggers, and impacts of the PETM on the Earth’s system. The New Jersey coastal plain is a unique place to study this event because it provides one the most stratigraphically complete marine records (~ 15 m thick).

Depositional models

[Chris Lombardi, Jim Browning, Jim Wright]

Integration of stable isotopes, TEX86, and Mg/Ca proxies

[Masha Makarova, Ken Miller, Jim Wright, Yair Rosenthal]

We have studied paleoenvironmental changes across the Paleocene/Eocene boundary in the Millville New Jersey coastal plain core (ODP Leg 174AX). Using two independent temperature proxies (the organic paleothermometer TEX86 and Mg/Ca ratio of planktonic foraminifera) and δ18O of planktonic foraminifera, we evaluated temperature and salinity changes at Millville (Makarova et al., in prep.). Paleotemperature estimates show warming of 5-7°C across the PETM, though different temperature calibrations provide a broad range of absolute temperatures. The TEXL86 temperature calibration (Kim et al., 2010) is the only one that yields realistic salinities and thus arguably provides the best temperature estimate (warming from 23°C to 30°C). We are currently integrating isotopic records of planktonic (surface and deep dwelling) and benthic foraminifera at Millville and other New Jersey coastal plain cores to reconstruct the water column structure along the New Jersey paleoshelf during the PETM (i.e. changes in surface to deep water temperature gradient, carbon cycle, and oceanic productivity).



Miocene paleoceanography

Evaluation of stable isotopes, TEX86, and Mg/Ca proxies of western North Atlantic

[Masha Makarova, Ken Miller, Jim Wright, Yair Rosenthal]

The North Atlantic plays a critical role in heat transport in the ocean-atmosphere system because it is an area of deep water formation where surface waters sink to produce the North Atlantic Deep Water (NADW). Surface water temperature and salinity define the strength of the NADW in the conveyor circulation and consequently the strength of the Atlantic meridional overturning circulation (AMOC). For this project, we are studying thermal history of the western North Atlantic during the critical climate transition of 17-12.8 Ma and the role of the North Atlantic in the global climate change during the middle Miocene. Previous work in the North Atlantic has focused on benthic foraminiferal δ18O and δ13C tracers to study deep water and isolate temperature vs. ice volume signal for the Oligocene-upper Miocene (e.g., Miller et al., 1985; Wright et al., 1992). We are enhancing existing records of benthic foraminifera by performing stable isotopes and trace metals (Mg/Ca) analyses on planktonic foraminifera and obtaining sea surface temperatures from organic paleothermometers TEX86 and UK'37. Integration of these multiple proxies is essential in deciphering paleotemperature signals from those of ice volume and salinity.

Seismic and coring cruise of western North Atlantic

[funding pending; Ken Miller, Jim Wright]

Greg Mountain, Ken Miller, and Mitch Lyle (OSU) will submit a site survey cruise proposal in Aug 2016 in support of an IODP drilling in the Western North Atlantic. Proposal 851-Pre is designed to drill to monitor the evolution of northern deep waters (Northern Component Water, NCW), changes in sea surface temperature (SST), thermocline structure, and meridional thermal gradients in the North Atlantic subtropical and subarctic gyres, and changes in biogeochemical cycling and biogenic production through the Miocene and into the Paleogene.



Carbon Capture and Sequestration

Northern Baltimore Canyon Trough

[Chris Lombardi]

The Baltimore Canyon Trough (BCT) offshore New Jersey provides the thickest record of Jurassic to Holocene strata along the U.S. Atlantic Continental Margin. Investigations of this region paved the way for understanding the evolution of passive continental margins and more recently sequence architecture for the Late Cretaceous to Holocene based on cores. However, previous studies of the mid Cretaceous of this region were relegated to 1970’s seismic profiles and industry exploration wells. Based on original and reprocessed 2D-seismic lines and well log data, we find the interval of the mid-Cretaceous (Barremian-Cenomanian) in the Northern BCT largely overlooked, yet records sequences similar to younger records. Previous well log correlations from 31 industry wells situated in the Northern BCT identify 3 sandstones units arranged in a retrogradational succession between confining shales. Here, we apply sequence methods to seismic profiles and well logs, allowing a first-order reconstruction of relative sea-level variations.

George's Bank Basin

[Stephen Graham]

Correlating multi-channel seismic and well log data to analyze underlying geologic structure to evaluate the regionally correlatable sequences and their relationships to sea level change and evaluate the suitability of mid Cretaceous sands for sequestration of CO2.