Sea-level variations and sedimentary response

Cenozoic stable isotopes and sea level

[Ken Miller, Jim Wright, Jim 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.

WHAT’S NEXT: We plan to submit a proposal to analyze an early Paleogene (48-66 Ma) record from Site 1209 for Mg/Ca building on the oxygen isotopic record of Westerhold et al. (2019). We will be seeking a student or post-doc for this project.

Influence of Mantle Dynamic Topography on Sequences

[John Schmelz, Ken Miller, Greg Mountain, Jim Browning]

We show that Cenozoic sea-level estimates derived from “backstripping” of Mid-Atlantic margin cores differ by 10-50 m on the 2-10 Myr scale from Global Mean Sea Level (GMSL) estimates using benthic foraminiferal δ18O and accounting for ice-volume variations with Mg/Ca records.  Spatial analysis reveals coherent differences in these discrepancies among backstripping sites located onshore New Jersey (NJ), offshore NJ, and onshore south of NJ.  These spatial differences have a wavelength that fits mantle dynamic topography, which has influenced the Mid-Atlantic margin over the past 66 Myr.  We estimate topographical effects of up to 40 meters in the Eocene onshore NJ, and of up to 25 m in the Miocene offshore NJ.

WHATS NEXT: Schmelz will continue to develop a forward model for evaluating the effects of global mean sea level and tectonics including Mantle Dynamic Topography on the deposition record of the Mid-Atlantic margins as part of his PhD studies (2020) and post-doc studies (2021).  Student opportunities include working on comparing model output to 3-D seismic data for the Miocene or the long-term (Jurassic to Holocene) record of the margin.

Coastal Plain Depositional Models

[Pete Sugarman, Ken Miller, Jim Browning]

Magothy (Coniacian) sequences.  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.

WHAT'S NEXT: Campanian: Maastrichtian sequences.  We are revisiting classic outcrops of Campanian-Maastrichtian at Big Brook, Hop Brook, and other localities. 


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 bottomsets (Hodgson et al., 2018) and 1-D backstripping (Kominz et al., 2016).

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, Pete Sugarman]

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.

What’s Next 2-D backstripping

[Schmelz, Steckler (LDEO), Mountain, Miller, Browning]

We intend to reconstruct New Jersey Miocene stratal geometries using both: 1) a numerical model that only varies in sea level and sediment supply; and 2) a model that incorporates variations in sea level and sediment supply in addition to imposed non-thermal subsidence effects.  One of the experimental configurations should better explain the data, including the constraints provided by a database of onshore and offshore core data coupled with a dense grid of offshore seismic data. Reconstructing of the Miocene stratigraphy of this margin will facilitate a quantitative evaluation of non-thermal subsidence on stratigraphic development and will contribute to reducing uncertainties associated with Miocene global mean sea-level (GMSL) records derived from the New Jersey margin.

Student opportunities include working on comparing model output to 3-D seismic data for the Miocene or the long-term (Jurassic to Holocene) record of the margin.



Cretaceous/Paleogene Boundary

Ir, stable isotopes, and recovery

[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

[Podrecca, Miller, Browning, Wright]

We built a cross-shelf Paleocene-Eocene Thermal Maximum (PETM) depositional model for input of muds from the “Appalachian Amazon” where large amounts of fluid mud creating expanded PETM records. New cores from Medford, NJ preserve the carbon isotope excursion (CIE) onset overlain by the lower portion of the CIE “body/core.” We use δ13Cbulk, percent CaCO3, and percent coarse fraction (>63 µm) to correlate Medford with records along a paleoslope dip transect, showing that updip locations preserve expanded sections of the earliest portion of the CIE (the onset) in contrast with downdip locations where the final section of the CIE (the recovery) is preferentially preserved. This pattern implies that the fluid mud was deposited in prograding clinoform foresets. Our subaqueous-clinoform delta model explains the variability of the CIE records and provides a framework for future PETM studies in the region.

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).

WHAT'S NEXT: we will convene an international workshop at Rutgers in January 2021.  We propose to drill three transects of coreholes in the mid-Atlantic U.S. Coastal Plain targeting thick (>10 m) sections of the Paleocene-Eocene Thermal Maximum (PETM), building on drilling in New Jersey by IODP Leg 174AX and Maryland-Virginia by the USGS. Previous drilling has sampled across the paleoshelf from inner neritic to deep neritic (>100 m) paleodepths and has provided important constraints on this major event, but existing cores are either depleted or contain stratigraphic gaps due to the patchwork distribution of the successions, updip dissolution, diagenesis, and the discontinuous nature of coastal zone sedimentation, which can be addressed with new cores. We plan to triple core the sections of interest at ten sites sampling the PETM, targeting the underlying normal shelf deposit of the Vincentown/Aquia Formations, a transitional interval that is expanded in updip sections and contains the Carbon Isotopic Excursion (CIE) onset, and the rapidly deposited Marlboro Clay that records a very thick CIE “core/body”. Though truncated at the top of the Marlboro Clay, very much expanded PETM sections (>10 m versus 1 m in the thickest deep-sea section) are available in this region. We will also core and sample other Eocene hyperthermals and the Cretaceous/Paleogene (K/Pg) boundary at these sites. This project will be an international collaboration with the cores archived by IODP, publication by IODP within two years, and with local logistical and support-in-kind provided by USGS and U.S. state surveys. Coring of three transects will provide new material needed to evaluate CIE initiation and subsequent CIE core/body that provides the clearest geological example of a massive release of carbon analogous to anthropogenic release.



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.

IODP Western North Atlantic

Mitch Lyle (OSU) Greg Mountain, Ken Miller, have a pending International Ocean Discovery Program (IODP) Expedition 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.  The proposal is up for scheduling by the IODP JOIDES Resolution Facilities Board in Aug. 2020 for drilling in 2022 or 2022.

WHAT'S NEXT: Undergraduate honors theses by Mariya Galochkina and Sophie Benaroya are being prepared for publication.  Ongoing research by L. Bellino at Site 563 is ongoing.  Studies of Site 982 are being completed.  The next step is to do high resolution (10 cm, 10 kyr) sampling of a Miocene time slice for stable isotopes and correlating with XRF core scans. We plan to submit this as a proposal to NSF



Carbon Capture and Sequestration

We completed projects for the Midwest Regional Carbon Sequestration Partnership (MRCSP) and the Mid-Atlantic Offshore Carbon Storage Resource Assessment Project (MAOCSRAP) with Battelle and DOE with publications by Miller et al. (2017, 2018), Schmelz et al. (2020), Baldwin et al. (in prep.), and Adams et al. (in prep.) and PhD theses by master’s theses by Leslie Jordan, Stephen Graham, and Alexandra Adams.  Our renewal project for 2020-2023 “Regional Initiative to Accelerate CCUS Development” will look toward implementation of carbon storage projects in the region