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The peak "hothouse" interval of the Turonian-Coniacian (93-87 Ma) is represented on the U.S. middle Atlantic Coastal Plain by sequences of the Raritan/Bass River, Magothy, and Cheesequake Formations deposited on a passive continental margin as mixed wave-, tide-, and river dominated deltas. We apply sequence stratigraphy integrated with biostratigraphy to identify and map two major sequence boundaries separating the Raritan/Bass River, Magothy, and Cheesequake Formations and four to five (Mg1, Mg2, Mg3, ?Mg4, Mg5) Magothy sequences using continuous cores, outcrops, and geophysical logs in New Jersey. We extend correlations into New York and Delaware using well logs. The Magothy sequences disconformably overlie the well-dated (>93 Ma) lower Turonian to Cenomanian marine Raritan/Bass River sequences and are disconformably overlain by the marine Cheesequake Formation, which straddles the Coniacian/Santonian boundary. A "mid-Turonian" hiatus (ca. 93-90 Ma) associated with this major disconformity is a global sequence boundary (K-Tu4) reflecting a ~ 25 m sea-level lowering based on published NJ and Russian Platform backstripping records that indicate this was a major lowering of Global Mean Sea Level (GMSL).Higher-order (~1 Myr scale) sequence boundaries bracketing Mg1-Mg5 apparently correlate with global sequences but are only associated with low-amplitude (

We evaluate Cretaceous depositional sequences on approximately 4400 km (∼2700 mi) of newly released multichannel seismic profiles and five wells on the continental shelf in the southern Baltimore Canyon trough and tie the data to three wells drilled onshore in the Maryland coastal plain. Seismic geometries coupled with facies and biostratigraphy from the wells are used to delineate mid-Cretaceous (Aptian–Turonian) depositional sequences and paleogeography. Beneath these sequences, 400–1000 m (1300–3300 ft) of Lower Cretaceous sedimentary rocks underlie the modern shelf. They thicken along strike to the southwest, implying a southern sediment source. Aptian to Cenomanian sediments were deposited in shelf to nearshore settings. A landward movement of the depocenter and a shift toward facies indicative of deeper paleodepths marks a 107-yr mid-Cretaceous transgression, within which we identify five sequences. A composite maximum flooding surface (MFS) within the uppermost of these retrogradational units is associated with the Cenomanian–Turonian boundary and ocean anoxic event 2. Shingled, lower Turonian seismic reflections prograde across the outer shelf, downlapping onto the composite MFS, and are truncated by a mid-Turonian sequence boundary. The Upper Cretaceous section thickens seaward and along strike to the northeast, implying a northern source and little Late Cretaceous accommodation beneath the modern shelf. Mid-Cretaceous strata offshore Maryland are likely sand-prone, considering their proximity to the correlative fluvial facies of the onshore Potomac Group. These potential reservoir sands are capped by regional confining units generated by 107-yr global mean sea-level flooding events and are excellent targets for supercritical carbon storage.

We identified and described Potomac Formation paleosols from three coreholes in New Jersey and Delaware to interpret depositional history and reconstruct regional landscapes during the climatic transition from the Early to the Late Cretaceous. In total, 103 paleosol profiles were described and grouped into five pedotypes (gray, gray-red, purple, red, and brown) ranging in pedogenic maturity from: 1) weakly developed, immature soils formed under poor drainage conditions (gray and gray-red); to 2) moderately developed soils formed under alternating drainage conditions (purple and red); to 3) well-developed, mature soils formed under well-drained conditions (brown). Geochemical and stable-isotope proxies (Ba/Sr and δ18O on sphaerosiderite) are presented to constrain paleoprecipitation and/or fluvial position and drainage conditions. Potomac Formation Unit I (Barremian to lower Albian) generally displays well-drained, stable landscape conditions upsection, with paleoprecipitation being the main control on development of paleosol type. Potomac Formation Units II (lower Albian to lower Cenomanian) and III (lower Cenomanian) have variable drainage and landscape conditions upsection. Paleoprecipitation exerted a controlling role in the development of paleosol type lower in Unit II, while base-level changes exerted greater influence on landscape conditions upsection into Unit III. Geochemical proxies provide evidence that Unit I was subhumid with episodes of saturation and overall better drainage conditions relative to the overlying units. Units II and III were deposited under more waterlogged conditions, experiencing subhumid to humid conditions, with episodes of enhanced drainage from base-level fall. The use of these proxies is consistent with interpretations made using the macro-features and micro-features of the paleosols and sphaerosiderite δ18O, and emphasizes that the main long-term environmental control on landscape development during this period was initially paleoprecipitation, with progressive influence from base-level changes.

Oyster habitat restoration seeks to recover lost ecosystem services including increased provisioning of refuge and foraging habitat for fish and invertebrate communities. The goal of this study was to quantify the ecosystem service benefit of habitat provisioning in Ninigret Pond, RI, following oyster restoration. Four metrics were measured, abundance, biomass, species richness, and diversity, as well as isotopic composition in fish and invertebrates collected seasonally from restored oyster, aquaculture, and bare sediment sites, to examine whether the oyster habitat outperformed the bare sediment habitat. Sampling locations were chosen in Foster's Cove north and south, Grassy Point, South Sanctuary, and an Aquaculture lease; each had two restored oyster sites and one bare sediment site. Each site was sampled using a box trap, seine net, shrimp trap, and minnow trap. Oyster habitats had significantly greater metrics than did bare sediment habitats in some comparisons from the box trap and seine net samples. Restored oyster sites at South Sanctuary had lower metric values than the other oyster sites. Metrics from the Aquaculture sites were comparable to the Foster's Cove and Grassy Point restored oyster sites and often outperformed South Sanctuaryrestored oyster sites. Seasonally, spring and autumn samples tended to have higher abundance and biomass values than summer samples. Isotopic composition of five species occurring at both restored oyster and bare sediment sites demonstrated some differences in the trophic levels between species but not between habitat types. In Ninigret Pond, fish and invertebrate abundance, biomass, species richness, and diversity benefit from the use of oyster and bare sediment habitats. Coastal zone managers interested in restoring the ecological function of oyster reefs to support fish and invertebrate communities should consider strategically locating restoration projects within the mosaic of structured habitats and monitoring them for selected ecosystem services.

Global mean sea level estimated for the Cenozoic using a new astronomically calibrated Pacific benthic foraminiferal δ18O splice., Using Pacific benthic foraminiferal δ18O and Mg/Ca records, we derive a Cenozoic (66 Ma) global mean sea level (GMSL) estimate that records evolution from an ice-free Early Eocene to Quaternary bipolar ice sheets. These GMSL estimates are statistically similar to “backstripped” estimates from continental margins accounting for compaction, loading, and thermal subsidence. Peak warmth, elevated GMSL, high CO2, and ice-free “Hothouse” conditions (56 to 48 Ma) were followed by “Cool Greenhouse” (48 to 34 Ma) ice sheets (10 to 30 m changes). Continental-scale ice sheets (“Icehouse”) began ~34 Ma (>50 m changes), permanent East Antarctic ice sheets at 12.8 Ma, and bipolar glaciation at 2.5 Ma. The largest GMSL fall (27 to 20 ka; ~130 m) was followed by a >40 mm/yr rise (19 to 10 ka), a slowing (10 to 2 ka), and a stillstand until ~1900 CE, when rates began to rise. High long-term CO2 caused warm climates and high sea levels, with sea-level variability dominated by periodic Milankovitch cycles.

Foraminifera from salt-marsh environments have been used extensively in quantitative relative sea-level reconstructions due to their strong relationship with tidal level. However, the influence of temporal and spatial variability of salt-marsh foraminifera on quantitative reconstructions remains unconstrained. Here, we conducted a monitoring study of foraminifera from four intertidal monitoring stations in New Jersey from high marsh environments over three years that included several extreme weather (temperature, precipitation, and storm surge) events. We sampled four replicates from each station seasonally (four times per year) for a total of 188 samples. The dead foraminiferal assemblages were separated into four site-specific assemblages. After accounting for systematic trends in changes in foraminifera over time among stations, the distribution of foraminiferal assemblages across monitoring stations explained ~87% of the remaining variation, while ~13% can be explained by temporal and/or spatial variability among the replicate samples. We applied a Bayesian transfer function to estimate the elevation of the four monitoring stations. All samples from each station predicted an elevation estimate within a 95% uncertainty interval consistent with the observed elevation of that station. Combining samples into replicate- and seasonal-aggregate datasets decreased elevation estimate uncertainty, with the greatest decrease in aggregate datasets from Fall and Winter. Information about the temporal and spatial variability of modern foraminiferal distributions was formally incorporated into the Bayesian transfer function through informative foraminifera variability priors and was applied to a Common Era relative sea-level record in New Jersey. The average difference in paleomarsh elevation estimates and uncertainties using an informative vs uninformative prior was minimal (

The Mid-Atlantic U.S. Coastal Plain (New Jersey, Delaware, Maryland, and northern Virginia) contains thick (> 500 m) mid-Cretaceous sand–sandstone reservoirs confined by thick clay–shale confining units and thus has high potential for storage of CO 2 captured from nearby point sources. The predictability of the continuity of the reservoir and confining units can be improved by applying principles of sequence stratigraphy, including integration of lithostratigraphy, biostratigraphy, paleoenvironmental proxies, and a novel application of fluvial aggradation cycles (FACs). We evaluate the storage and confinement potential for the Lower Cretaceous Waste Gate Formation and mid-Cretaceous Potomac Formation/Group in New Jersey and Maryland, which we divide into three major reservoirs (Waste Gate-Potomac Unit I, Potomac Unit II, and Potomac Unit III). We use new core data to ground-truth well-logs and paleoenvironmental changes, sequence stratigraphic stacking patterns (including FACs), and pollen biostratigraphy to update previous well-log correlations in New Jersey and extend these correlations into deep holes in Maryland. While individual sand beds are typically local in extent, zones of sands are broadly correlative over distances of 60 km. These regionally traceable sand-prone zones should be useful for carbon storage. Cenomanian Potomac Unit III sands are relatively thick (∼ 70 m) in New Jersey, but generally thin (average of ∼ 50 m) into Maryland; they are near the updip limit for supercritical storage (800 m) in New Jersey and Maryland and may not be suitable due to updip migration above the supercritical level. Potomac Unit II sands (Albian Pollen Zone II) appear to be discontinuous and less suitable in both states. Potomac Unit I (Aptian Pollen Zone I) and Waste Gate Formation sands (?early Aptian to Berriasian pre-Pollen Zone I) are relatively thick (∼ 88–223 m and ∼ 81–288 m, respectively) and confined in New Jersey and appear to be widespread and continuous; the updip confinement of this reservoir in Maryland is less certain. Volume storage estimates for the Potomac I-Waste Gate in the Mid-Atlantic Coastal Plain are 8.4–33.5 Gt CO 2 , adequate to store CO 2 captured from 24–95 GW of natural gas generation for a century.

We present new δ13C and δ18O records of surface (Morozovella and Acarinina) and thermocline dwelling (Subbotina) planktonic foraminifera and benthic foraminifera (Gavelinella, Cibicidoides, and Anomalinoides) during the Paleocene-Eocene Thermal Maximum (PETM) from Millville, New Jersey and compare them with three other sites located along a paleoshelf transect from the U.S. mid-Atlantic coastal plain. Our analyses show different isotopic responses during the PETM in surface versus thermocline and benthic species. Whereas all taxa record a 3.6-4.0 ‰ δ13C decrease associated with the carbon isotope excursion (CIE), thermocline dwellers and benthic foraminifera show larger δ18O decreases compared to surface dwellers. We consider two scenarios that can explain the observed isotopic records: 1) a change in the water column structure; and 2) a change in habitat or calcification season of the surface dwellers due to environmental stress (e.g., warming, ocean acidification, surface freshening, and/or eutrophication). In the first scenario, persistent warming during the PETM would have propagated heat into deeper layers and created a more homogenous water column with a thicker warm mixed layer and deeper, more gradual thermocline. We attribute the hydrographic change to decreased meridional thermal gradients, consistent with models that predict polar amplification. The second scenario assumes that environmental change was greater in the mixed layer forcing surface dwellers to descend into thermocline waters as a refuge or restrict their calcification to the colder seasons. Though both scenarios are plausible, similar δ13C responses recorded in surface, thermocline, and benthic foraminifera challenge mixed layer taxa migration.

Over the past decade, nitrogen (N) loads to Narragansett Bay have decreased by more than 50%. These reductions were, in large part, the direct result of multiple wastewater treatment facility upgrades to tertiary treatment, a process which employs N removal. Here we document ecosystem response to the N reductions and assess how the distribution of sewage N in Narragansett Bay has changed from before, during, and shortly after the upgrades. While others have observed clear responses when data were considered annually, our seasonal and regional comparisons of pre- and post-tertiary treatment dissolved inorganic nitrogen (DIN) concentrations and Secchi depth data, from bay-wide surveys conducted periodically from the early 1970s through 2016, resulted in only a few subtle differences. Thus we sought to use stable isotope data to assess how sewage N is incorporated into the ecology of the Bay and how its distribution may have changed after the upgrades. The nitrogen (δ(15)N) and carbon (δ(13)C) stable isotope measurements of particulate matter served as a proxy for phytoplankton, while macroalgae served as short-term integrators of water column bio-available N, and hard clams (Mercenaria mercenaria) as integrators of water column production. In contrast to other estuarine stable isotope studies that have observed an increased influence of isotopically lower marine N when sewage N is reduced, the opposite has occurred in Narragansett Bay. The tertiary treatment upgrades have increased the effluent δ(15)N values by at least 2‰. The plants and animals throughout Narragansett Bay have similarly increased by 1–2‰, on average. In contrast, the δ(13)C values measured in particulate matter and hard clams have declined by about the same amount. The δ(15)N results indicated that, even after the N-reductions, sewage N still plays an important role in supporting primary and secondary production throughout the Bay. However, the δ(13)C suggest that overall net production in Narragansett Bay has decreased. In the five years after the major wastewater treatment facilities came on-line for nutrient removal, oligotrophication has begun but sewage remains the dominant source of N to Narragansett Bay.

International audience; Shorelines are ephemeral features, yet many science problems cross this ever-moving boundary and require sampling on both its dry and wet sides. The logistics of working on land and at sea are distinct, such that funding agencies in many countries divide their research programs at the shoreline. Similarly, scientific drilling is split between the International Ocean Discovery Program (IODP) in the ocean and the International Continental Scientific Drilling Program (ICDP) on land. Here, we discuss three examples of drilling projects that effectively coordinated activities between IODP and ICDP and highlight the need for increasing cooperation and coordination across the shoreline. We end by casting an eye toward the future of scientific drilling, where truly amphibious projects are now possible.

Onshore drilling by Ocean Drilling Program (ODP) Legs 150X and 174AX and offshore drilling by Integrated Ocean Drilling Program (IODP) Expedition 313 provides continuous cores and logs of seismically imaged Lower to ­Middle Miocene sequences. We input ages and paleodepths of these sequences into one-dimensional backstripping equations, progressively accounting for the effects of compaction, Airy loading, and thermal subsidence. The resulting difference between observed subsidence and theoretical thermal subsidence provide relative sea-level curves that reflect both global average sea level and non-thermal subsidence. In contrast with expectations, backstripping suggests that the relative sea-level maxima in proximal onshore sites were lower than correlative maxima on the shelf. This requires that the onshore New Jersey coastal plain has subsided relative to the shelf, which is consistent with models of relative epeirogeny due to subduction of the Farallon plate. These models predict subsidence of the coastal plain relative to the shelf. Although onshore and offshore sea-level estimates are offset by epeirogeny, the ampli­tude of million-year–scale Early to Middle Miocene sea-level changes seen at the New Jersey margin is generally 5–20 m and occasionally as great as 50 m. These events are interpreted to represent eustatic variations, because they occur on a shorter time frame than epeirogenic influences. Correction for epeiro­genic effects largely reconciles differences between onshore and offshore rela­tive sea-level estimates and suggests that backstripping provides a testable eustatic model for the Early to Middle Miocene.

A rapid and large injection of isotopically light carbon into the ocean-atmosphere reservoirs is signaled by a negative carbon isotope excursion (CIE) at the Paleocene-Eocene boundary ∼56 m.y. ago. To better understand the extent of ocean warming and acidification associated with the carbon injection we generated elemental and isotopic records of surface and thermocline planktonic foraminifera across the Paleocene-Eocene boundary from an expanded section along the Mid-Atlantic coastal plain, New Jersey (USA). Ocean temperatures (derived from magnesium/calcium paleothermometer) document a lag in thermocline warming relative to surface waters, implying a progressive deepening of the mixed layer in addition to global warming. A similar magnitude of acidification (as recorded by boron/calcium, B/Ca) on the shelf compared with open ocean sites confirms widespread acidification of the surface ocean. An increase in seawater alkalinity after the CIE, as recorded by B/Ca in planktonic foraminifera, likely played an important role in neutralizing the added carbon, possibly minimizing benthic extinction along the shelf.

Vegetation is a key component of salt marsh monitoring programs, but different methods can make comparing datasets difficult. We compared data on vegetation composition and cover collected with 3 methods (point-intercept, Braun-Blanquet visual, and floristic quality assessment [FQA]) in 3 Rhode Island salt marshes. No significant differences in plant community composition were found among the methods, and differences in individual species cover in a marsh never exceeded 6% between methods. All methods were highly repeatable, with no differences in data collected by different people. However, FQA was less effective at identifying temporal changes at the plot scale. If data are collected from many plots in a marsh, any of the methods are appropriate, but if plot-scale patterns are of interest, we recommend point-intercept.

We describe sedimentation on the storm-dominated, microtidal, continental shelf and slope of the eastern US passive continental margin between the Hudson and Wilmington canyons. Sediments here recorded sea-level changes over the past 100 myr and provide a classic example of the interplay among eustasy, tectonism and sedimentation. Long-term margin evolution reflects changes in morphology from a Late Cretaceous–Eocene ramp to Oligocene and younger prograding clinothem geometries, a transition found on several other margins. Deltaic systems influenced Cretaceous and Miocene sedimentation, but, in general, the Maastrichtian–Palaeogene shelf was starved of sediment. Pre-Pleistocene sequences follow a repetitive model, with fining- and coarsening-upward successions associated with transgressions and regressions, respectively. Pleistocene–Holocene sequences are generally quite thin (−1 from 5 to 2 ka. Modern shelf sedimentation primarily reflects palimpsest sand sheets plastered and reworked into geostrophically controlled nearshore and shelf shore-oblique sand ridges, and does not provide a good analogue for pre-Pleistocene deposition. Supplementary material: References used in the comparison of all dates for New Jersey localities in Figure 3.8 are available at http://www.geolsoc.org.uk/SUP18749 .

We evaluate paleo-, historical, and future sea-level rise along the U.S. mid-Atlantic coast. The rate of relative sea-level rise in New Jersey decreased from 3.5 ± 1.0 mm/yr at 7.5–6.5 ka, to 2.2 ± 0.8 mm/yr at 5.5–4.5 ka to a minimum of 0.9 ± 0.4 mm/yr at 3.3–2.3 ka. Relative sea level rose at a rate of 1.6 ± 0.1 mm/yr from 2.2 to 1.2 ka (750 Common Era [CE]) and 1.4 ± 0.1 mm/yr from 800 to 1800 CE. Geological and tide-gauge data show that sea-level rise was more rapid throughout the region since the Industrial Revolution (19th century = 2.7 ± 0.4 mm/yr; 20th century = 3.8 ± 0.2 mm/yr). There is a 95% probability that the 20th century rate of sea-level rise was faster than it was in any century in the last 4.3 kyr. These records reflect global rise (∼1.7 ± 0.2 mm/yr since 1880 CE) and subsidence from glacio-isostatic adjustment (∼1.3 ± 0.4 mm/yr) at bedrock locations (e.g., New York City). At coastal plain locations, the rate of rise is 0.3–1.3 mm/yr higher due to groundwater withdrawal and compaction. We construct 21st century relative sea-level rise scenarios including global, regional, and local processes. We project a 22 cm rise at bedrock locations by 2030 (central scenario; low- and high-end scenarios range of 16–38 cm), 40 cm by 2050 (range 28–65 cm), and 96 cm by 2100 (range 66–168 cm), with coastal plain locations having higher rises (3, 5–6, and 10–12 cm higher, respectively). By 2050 CE in the central scenario, a storm with a 10 year recurrence interval will exceed all historic storms at Atlantic City. Summary An analysis of geological and historical sea-level records shows a significant rate of increase in sea-level rise since the nineteenth century. In New Jersey, it is extremely likely that sea-level rise in the twentieth century was faster than during any other century in the last 4.3 thousand years. Accounting for regional and local factors, the authors project sea-level rise in the mid-Atlantic U.S. most likely about 38–42′′ (96–106 cm) over the twentieth century, but possibly as high as 66–71′′ (168–180 cm).

Integrated Ocean Drilling Program (IODP) Expedition 313 drilled three holes (Sites M27, M28, and M29; 34–36 m present water depth) across a series of prograding clinothems from the inner continental shelf of the New Jersey (USA) margin, a region that is sensitive to sea-level change. We examined 702 late Eocene to Miocene samples for benthic foraminiferal assemblages and planktonic foraminiferal abundances. We integrate our results with lithofacies to reconstruct paleobathymetry. Biofacies at all three sites indicate a long-term shallowing-upward trend as clinothems built seaward and sediment filled accommodation space. Patterns in biofacies and lithofacies indicate shallowing- and deepening-upward successions within individual sequences, providing the basis to recognize systems tracts, and therefore sequence stratigraphic relationships in early to early-middle Miocene sequences (ca. 23–13 Ma). The clinothem bottomsets and the lower portions of the foresets, which contain the thickest parts of clinothems, yield the deepest water biofacies. Shallower bio facies characterize the sequences in the upper portions of the clinothem foresets and on the topsets. Topsets are characterized by transgressive (TST) and highstand systems tracts (HST). Foresets contain lowstand systems tracts (LST), TSTs, and HSTs. Flooding surfaces mark parasequence boundaries within LSTs, TSTs, and HSTs. Superimposed on the long-term trends, short-term variations in paleowater depth are likely linked to global sea-level changes indicated by global oxygen isotopic variations.

Integrated Ocean Drilling Program Expedition 313 continuously cored and logged latest Eocene to early-middle Miocene sequences at three sites (M27, M28, and M29) on the inner-middle continental shelf offshore New Jersey, providing an opportunity to evaluate the ages, global correlations, and significance of sequence boundaries. We provide a chronology for these sequences using integrated strontium isotopic stratigraphy and biostratigraphy (primarily calcareous nannoplankton, diatoms, and dinocysts [dinoflagellate cysts]). Despite challenges posed by shallow-water sediments, age resolution is typically ±0.5 m.y. and in many sequences is as good as ±0.25 m.y. Three Oligocene sequences were sampled at Site M27 on sequence bottomsets. Fifteen early to early-middle Miocene sequences were dated at Sites M27, M28, and M29 across clinothems in topsets, foresets (where the sequences are thickest), and bottomsets. A few sequences have coarse (∼1 m.y.) or little age constraint due to barren zones; we constrain the age estimates of these less well dated sequences by applying the principle of superposition, i.e., sediments above sequence boundaries in any site are younger than the sediments below the sequence boundaries at other sites. Our age control provides constraints on the timing of deposition in the clinothem; sequences on the topsets are generally the youngest in the clinothem, whereas the bottomsets generally are the oldest. The greatest amount of time is represented on foresets, although we have no evidence for a correlative conformity. Our chronology provides a baseline for regional and interregional correlations and sea-level reconstructions: (1) we correlate a major increase in sedimentation rate precisely with the timing of the middle Miocene climate changes associated with the development of a permanent East Antarctic Ice Sheet; and (2) the timing of sequence boundaries matches the deep-sea oxygen isotopic record, implicating glacioeustasy as a major driver for forming sequence boundaries.

We obtained global sea-level (eustatic) estimates with a peak of ∼22 m higher than present for the Pliocene interval 2.7–3.2 Ma from backstripping in Virginia (United States), New Zealand, and Enewetak Atoll (north Pacific Ocean), benthic foraminiferal δ18O values, and Mg/Ca-δ18O estimates. Statistical analysis indicates that it is likely (68% confidence interval) that peak sea level was 22 ± 5 m higher than modern, and extremely likely (95%) that it was 22 ± 10 m higher than modern. Benthic foraminiferal δ18O values appear to require that the peak was

Key-words. - Mosasaurs, Cretaceous-Paleogene boundary, Iridium. Abstract. - New data regarding the placement of the Cretaceous-Paleogene (K/Pg) boundary in New Jersey is presented based on a recent campaign of drill coring boundary sections in the Atlantic coastal plain of southern New Jersey. The occurrence of late Maastrichtian mosasaurs worldwide and in New Jersey is reviewed in light of the continuing contro- versy over the rate and cause of the extinction at the K/Pg boundary. At the Meirs Farm site in Monmouth County, NJ, the biostratigraphic position of mosasaur specimens (Halisaurus platyspondylus, Mosasaurus hoffmann) is related to the occurrence of an iridium excursion of 0.5 ppb (5x background levels) in the basal Hornerstown Formation just above the upper Maastrichtian New Egypt Formation. Other specimens in museum collections obtained during the acme of nine- teenth century marl mining are from this area of the Maastrichtian outcrop belt in New Jersey. It is concluded that late Maastrichtian mosasaurs show no diminution of their biogeographic ranges and are not particularly rare in New Jersey in comparison to older mosasaur faunas. Mosasaurs became extinct in association with the collapse of the marine food web at the K/Pg boundary, and were replaced as apical marine predators in the early Danian by a variety of crocodilians.

The geologic record provides constraints on the rates, amplitudes, and mechanisms controlling globally averaged (eustatic) and relative (eustatic plus subsidence/uplift) changes of sea level on various time scales. On geological time scales, global sea level changes are tied primarily to long-term (107–108-year scale) tectonism and short-term (103–106-year scale) changes in continental ice volume, though recent studies also illustrate the importance of tectonism on 106-year time scales. The history of 106-year scale eustatic changes has been controversial; the most widely used sea level curves agree with independently derived estimates with regard to the ages of sea level falls, but depart significantly from many more recent studies with regard to amplitudes. We present a 180-million-year history of sea level changes. A global sea level rise of 120 m followed the last glacial maximum, with rates that exceeded 10 times the modern rate of rise (> 40 mm yr-1 versus ~ 3 mm yr-1). The “ice ages” of the past 2.6 million years were due to growth/decay of large Northern Hemisphere ice sheets. Those of the past 780,000 years caused sea level changes that were large (> 100 m) and paced primarily by the ~100,000 year eccentricity cycle; smaller changes (typically < 60 m) prior to this time were paced primarily by the 41,000 tilt cycle. The growth and decay of a continental-scale ice sheet in Antarctica caused 50–60-m variations on the 106-year scale beginning ~ 33.5 million years ago. Prior to this time, Earth had been a warm, high-CO2 “greenhouse” world that was largely ice-free back to 260 million years ago, though recent evidence suggests that 15–25-m sea level changes may have been caused by the growth and decay of small, ephemeral continental ice sheets.

We present a mid to late Holocene sea-level record derived from drilling the New Jersey coast that shows a relatively constant rise of 1.8 mm/yr from ~ 5000 to 500 calibrated calendar years before present (yrBP). This contrasts with previous New Jersey estimates that showed only 0.5 mm/yr rise since 2000 yrBP. Comparison with other Mid-Atlantic sea-level records (Delaware to southern New England) indicates surprising uniformity considering different proximities to the peripheral bulge of the Laurentide ice sheet, with a relative rise throughout the region of ~ 1.7–1.9 mm/yr since ~ 5000 yrBP. This regional sea-level rise includes both: 1) global sea-level (eustatic) rise; and 2) far-field geoidal subsidence (estimated as ~ 0.8–1.4 mm/yr today) due to removal of the Laurentide ice sheet and water loading. Correcting for geoidal subsidence, the U.S. east coast records suggest a global sea-level (eustatic) rise of ~ 0.4–1.0 mm/yr (with a best estimate of 0.7 ± 0.3 mm/yr) since 5000 yrBP. Comparison with other records provides a best estimate of pre-anthropogenic global sea-level rise of

article i nfo We assembled and dated a late Pleistocene sea-level record based on sequence stratigraphy from the New Jersey margin and compared it with published records from fossil uplifted coral reefs in New Guinea, Barbados, and Araki Island, as well as a composite sea-level estimate from scaling of Red Sea isotopic values. Radiocarbon dates, amino acid racemization data, and superposition constrain the ages of large (20-80 m) sea-level falls from New Jersey that correlate with Marine Isotope Chrons (MIC) 2, 3b, 4, 5b, and 6 (the past 130 kyr). The sea-level records for MIC 1, 2, 4, 5e, and 6 are similar to those reported from New Guinea, Barbados, Araki, and the Red Sea; some differences exist among records for MIC 3. Our record consistently provides the shallowest sea level estimates for MIC3 (∼25-60 m below present); it agrees most closely with the New Guinea record of Chappell (2002; ∼35-70 m), but contrasts with deeper estimates provided by Araki (∼85-95 m) and the Red Sea (50-90 m). Comparison of eustatic estimates with benthic foraminiferal δ 18

Sea level has been estimated for the last 108 million years through backstripping of corehole data from the New Jersey and Delaware Coastal Plains. Inherent errors due to thismethod of calculating sea level are discussed, including uncertainties in ages, depth of deposition and the model used for tectonic subsidence. Problems arising from the two-dimensional aspects of subsidence and response to sediment loads are also addressed. The rates and magnitudes of sea-level change are consistent with at least ephemeral ice sheets throughout the studied interval.Million-year sea-level cycles are, for the most part, consistent within the study area suggesting that they may be eustatic in origin. This conclusion is corroborated by correlation between sequence boundaries and unconformities in New Zealand. The resulting long-term curve suggests that sea level ranged fromabout 75-110 min the Late Cretaceous, reached a maximum of about 150m in the Early Eocene and fell to zero in the Miocene. The Late Cretaceous long-term (107 years) magnitude is about 100-150mless than sea level predicted from ocean volume. This discrepancy can be reconciled by assuming that dynamic topography in New Jersey was driven by North America overriding the subducted Farallon plate. However, geodynamic models of this effect do not resolve the problemin that they require Eocene sea level to be significantly higher in the New Jersey region than the global average.

We analyzed the latest Early Cretaceous to Miocene sections (∼110–7 Ma) in 11 New Jersey and Delaware onshore coreholes (Ocean Drilling Program Legs 150X and 174AX). Fifteen to seventeen Late Cretaceous and 39–40 Cenozoic sequence boundaries were identified on the basis of physical and temporal breaks. Within‐sequence changes follow predictable patterns with thin transgressive and thick regressive highstand systems tracts. The few lowstands encountered provide critical constraints on the range of sea‐level fall. We estimated paleowater depths by integrating lithofacies and biofacies analyses and determined ages using integrated biostratigraphy and strontium isotopic stratigraphy. These datasets were backstripped to provide a sea‐level estimate for the past ∼100 Myr. Large river systems affected New Jersey during the Cretaceous and latest Oligocene–Miocene. Facies evolved through eight depositional phases controlled by changes in accommodation, long‐term sea level, and sediment supply: (1) the Barremian–earliest Cenomanian consisted of anastomosing riverine environments associated with warm climates, high sediment supply, and high accommodation; (2) the Cenomanian–early Turonian was dominated by marine sediments with minor deltaic influence associated with long‐term (107 year) sea‐level rise; (3) the late Turonian through Coniacian was dominated by alluvial and delta plain systems associated with long‐term sea‐level fall; (4) the Santonian–Campanian consisted of marine deposition under the influence of a wave‐dominated delta associated with a long‐term sea‐level rise and increased sediment supply; (5) Maastrichtian–Eocene deposition consisted primarily of starved siliciclastic, carbonate ramp shelf environments associated with very high long‐term sea level and low sediment supply; (6) the late Eocene–Oligocene was a starved siliciclastic shelf associated with moderately high sea‐level and low sediment supply; (7) late early–middle Miocene consisted of a prograding shelf under a strong wave‐dominated deltaic influence associated with major increase in sediment supply and accommodation due to local sediment loading; and (8) over the past 10 Myr, low accommodation and eroded coastal systems were associated with low long‐term sea level and low rates of sediment supply due to bypassing.

The Eocene–Oligocene transition is the largest global cooling in the Cenozoic period. A comparison of three independent proxies from the continental shelf and deep ocean reveals a three-step transition to cold glacial conditions, with ice sheets 25% larger than their present size.

We integrate upper Eocene–lower Oligocene lithostratigraphic, magnetostratigraphic, biostratigraphic, stable isotopic, benthic foraminiferal faunal, downhole log, and sequence stratigraphic studies from the Alabama St. Stephens Quarry (SSQ) core hole, linking global ice volume, sea level, and temperature changes through the greenhouse to icehouse transition of the Cenozoic. We show that the SSQ succession is dissected by hiatuses associated with sequence boundaries. Three previously reported sequence boundaries are well dated here: North Twistwood Creek–Cocoa (35.4–35.9 Ma), Mint Spring– Red Bluff (33.0 Ma), and Bucatunna-Chickasawhay (the mid-Oligocene fall, ca. 30.2 Ma). In addition, we document three previously undetected or controversial sequences: midPachuta (33.9–35.0 Ma), Shubuta-Bumpnose (lowermost Oligocene, ca. 33.6 Ma), and Byram-Glendon (30.5–31.7 Ma). An ~0.9‰ δ 18 O increase in the SSQ core hole is correlated to the global earliest Oligocene (Oi1) event using magnetobiostratigraphy; this increase is associated with the ShubutaBumpnose contact, an erosional surface, and a biofacies shift in the core hole, providing a fi rst-order correlation between ice growth and a sequence boundary that indicates a sea-level fall. The δ 18 O increase is associated with a eustatic fall of ~55 m, indicating that ~0.4‰ of the increase at Oi1 time was due to temperature. Maximum δ 18 O values of Oi1 occur above the sequence boundary, requiring that deposition resumed during the lowest eustatic lowstand. A precursor δ 18 O increase of 0.5‰ (33.8 Ma, mid-chron C13r) at SSQ correlates with a 0.5‰ increase in the deep Pacifi c Ocean; the lack of evidence for a sea-level change with the precursor suggests that this was primarily a cooling event, not an ice-volume event. Eocene–Oligocene shelf water temperatures of ~17–19 °C at SSQ are similar to modern values for 100 m water depth in this region. Our study establishes the relationships among ice volume, δ 18 O, and sequences: a latest Eocene cooling event was followed by an earliest Oligocene ice volume and cooling event that lowered sea level and formed a sequence boundary during the early stages of eustatic fall.

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 ± 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10 4 - to 10 6 -year scale, but a link between oxygen isotope and sea level on the 10 7 -year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).

Backstripped eustatic estimates from New Jersey and the Russian platform show large (> 25 m) and rapid ( δ 18 O record highlights the enigma. This was the warmest interval of the past 200 my, yet it was bracketed by two inferred eustatic falls of ∼ 25 m that were associated with two large (> 0.75‰) deep-sea δ 18 O increases (92–93 Ma, mid-Turonian and 96 Ma, mid-Cenomanian). We reconcile records of warm high latitudes with glacioeustasy by proposing that Late Cretaceous–early Eocene ice sheets generally reached maximum volumes of 8–12 × 10 6 km 3 (20–30 m glacioeustatic equivalent), but did not reach the Antarctic coast; hence, coastal Antarctica (hence deep water) remained relatively warm even though there were significant changes in sea level as the result of glaciation. Unlike the Oligocene and younger icehouse world, these ice sheets only existed during short intervals of peak Milankovitch insolation, leaving Antarctica ice-free during much of the greenhouse Late Cretaceous to middle Eocene. These results highlight the need to re-evaluate the paradigm that polar ice sheets did not exist during times of warm high-latitude climates.

The oxidation of Earth’s atmosphere is coupled to the net sequestration of organic matter, which is related to the relative fractions of organic carbon (forg) and carbonate (fcarb) buried in marine sediments. These fractions can be inferred from carbon isotope data. We present bulk sediment d 13 C records of carbonate (d 13 Ccarb) and organic carbon (d 13 Corg) with a compilation of evolutionary trajectories of major eucaryotic phytoplankton for the past 205 million years. Our analysis indicates that changes in phytoplankton community structure, coupled with the opening of the Atlantic Ocean basin and global sea-level rise, increased the efficiency of organic carbon burial beginning in the Early Jurassic; in turn, this organic carbon burial increased the oxidation state of Earth’s surface while drawing down atmospheric CO2 levels (assuming no substantial negative feedbacks). The net oxidation and CO2 drawdown appear to be related to the opening phase of the current Wilson cycle, where the newly formed passive plate margins store organic matter for hundreds of millions of years. This process should reverse during the closing phase of the Wilson cycle, when the continents reassemble and the Atlantic Ocean basin closes. The associated oxidation and storage of organic matter have contributed to the long-term depletion of CO2, which was a key factor that selected C4 photosynthetic pathways in marine and terrestrial ecosystems in the latter part of the Cenozoic; these pathways increasingly influenced d 13 Corg, and ultimately contributed to the reversal of the long-term trend in d 13 Ccarb.

The Paleocene/Eocene thermal maximum (PETM) was a time of rapid global warming in both marine and continental realms that has been attributed to a massive methane (CH 4 ) release from marine gas hydrate reservoirs. Previously proposed mechanisms for this methane release rely on a change in deepwater source region(s) to increase water temperatures rapidly enough to trigger the massive thermal dissociation of gas hydrate reservoirs beneath the seafloor. To establish constraints on thermal dissociation, we model heat flow through the sediment column and show the effect of the temperature change on the gas hydrate stability zone through time. In addition, we provide seismic evidence tied to borehole data for methane release along portions of the U.S. continental slope; the release sites are proximal to a buried Mesozoic reef front. Our model results, release site locations, published isotopic records, and ocean circulation models neither confirm nor refute thermal dissociation as the trigger for the PETM methane release. In the absence of definitive evidence to confirm thermal dissociation, we investigate an alternative hypothesis in which continental slope failure resulted in a catastrophic methane release. Seismic and isotopic evidence indicates that Antarctic source deepwater circulation and seafloor erosion caused slope retreat along the western margins of the North Atlantic in the late Paleocene. Continued erosion or seismic activity along the oversteepened continental margin may have allowed methane to escape from gas reservoirs trapped between the frozen hydrate-bearing sediments and the underlying buried Mesozoic reef front, precipitating the Paleocene/Eocene boundary methane release. An important implication of this scenario is that the methane release caused (rather than resulted from) the transient temperature increase of the PETM. Neither thermal dissociation nor mechanical disruption of sediments can be identified unequivocally as the triggering mechanism for methane release with existing data. Further documentation with high-resolution benthic foraminiferal isotopic records and with seismic profiles tied to borehole data is needed to clarify whether erosion, thermal dissociation, or a combination of these two was the triggering mechanism for the PETM methane release.

High-resolution seismic reflection profiles (,1‐5 m resolution), including Geopulsee, Uniboome, minisparker, small air gun, and water gun sources, are used to trace the d 18 O stage 5 portion of the outcropping Cape May Formation across the shelf to the continental slope. The d 18 O stage 5/6 boundary identified at Ocean Drilling Project (ODP) Site 903 on the continental slope anchors the onshore-offshore seismic correlations. Above the d 18 O stage 5 sequence, there are distinguishable lowstand systems tracts (LST), transgressive systems tracts (TST) and highstand systems tracts (HST) that correlate with d 18 O stages 4 through 1. Atlantic Margin Coring Project (AMCOR) holes 6009, 6010, 6011, 6020, and 6021C provide age and paleoenvironmental indicators that agree with these correlations. The sub-arctic paleoenvironmental indicators in sequences of d 18 O stage 3 agree with the cooler temperatures and lower sea-level highstands of that time. Thicker d 18 O stage 3 and 4 sequences are preserved in the Paleo-Hudson River incised valley across the shelf. The expanded ice sheets during stage d 18 O 3 compared to d 18 O stages 1 and 5 probably increased sediment discharge in the Hudson River drainage system. q 2000 Elsevier Science B.V.

The New Jersey passive continental margin records the interaction of sequences and sea-level, although previous studies linking seismically defined sequences, borehole control, and global δ18O records were hindered by a seismic data gap on the inner-shelf. We describe new seismic data from the innermost New Jersey shelf that tie offshore seismic stratigraphy directly to onshore boreholes. These data link the onshore boreholes to existing seismic grids across the outer margin and to boreholes on the continental slope. Surfaces defined by age; facies, and log signature in the onshore boreholes at the base of sequences Kw2b, Kw2a, Kw1c, and Kw0 are now tied to seismic sequence boundaries m5s, m5.2s, m5.4s, and m6s, respectively, defined beneath the inner shelf. Sequence boundaries recognized in onshore boreholes and inner shelf seismic profiles apparently correlate with reflections m5, m5.2, m5.4, and m6, respectively, that were dated at slope boreholes during ODP Leg 150. We now recognize an additional sequence boundary beneath the shelf that we name m5.5s and correlate to the base of the onshore sequence Kw1b. The new seismic data image prograding Oligocene clinoforms beneath the inner shelf, consistent with the results from onshore boreholes. A land-based seismic profile crossing the Island Beach borehole reveals reflector geometries that we tie to Lower Miocene litho- and bio-facies in this borehole. These land-based seismic profiles image well-defined sequence boundaries, onlap and downlap truncations that correlate to Transgressive Systems Tracts (TST) and Highstand Systems Tracts (HST) identified in boreholes. Preliminary analysis of CH0698 data continues these system tract delineations across the inner shelf. The CH0698 seismic profiles tie seismically defined sequence boundaries with sequences identified by lithiologic and paleontologic criteria. Both can now be related to global δ18O increases and attendant glacioeustatic lowerings. This integration of core, log, and seismic character of mid-Tertiary sediments across the width of the New Jersey margin is a major step in the long-standing effort to evaluate the impact of glacioeustasy on siliciclastic sediments of a passive continental margin.

Nine latest Eocene to Oligocene (34.2‐23.9 Ma) sequences were identified and dated from eight sites situated on the onshore New Jersey Coastal Plain and nearshore region. These sequences show a patchy distribution, with more complete lower Oligocene sections updip and more complete upper Oligocene sections downdip. We projected these sequences onto a dip profile and reconstructed their original thicknesses and distributions by 2-D flexural backstripping. This demonstrated that depocenters migrated offshore during the Oligocene, indicating that the patchy distribution can be best explained by progradation of generally thin and spacially limited clinoforms over an Eocene carbonate ramp. During the late Eocene to Oligocene, the New Jersey passive margin underwent a major morphologic change. Reconstructions indicate that the margin was a relatively steeply dipping carbonate ramp (1:500 paleoslope gradient) during the Eocene and was transformed into a siliciclastic margin characterized by a gentler gradient of 1:1000 and prograding clinoforms by the Miocene. Clinoform progradation probably began during the latest Eocene. Increased sediment supply during the Oligocene resulted in the further progradation of sediments across the antecedent carbonate ramp. The heights of the clinoforms ranged from ,20 m during the latest Eocene and earliest Oligocene to nearly 50 m during the late Oligocene. Most sediment accumulated within clinoform wedges, with little or no sediment being preserved behind the clinoform inflection point. q 2000 Elsevier Science B.V. All rights reserved.

We have reconstructed the Oligocene to Middle Miocene paleobathymetry and stratigraphy of the New Jersey margin using a modified backstripping technique. By analyzing the geometry of the margin through time, we investigate its response to fluctuating sea level, changing climate, and variable sediment supply during the Tertiary. The reconstructions reveal a change in the margin morphology from a more steeply dipping (1 : 300 to 1 : 500) carbonate ramp in the Eocene to a flatter shelf with a sharp shelf edge at present. This was accomplished by an increase in the terrigenous sediment supply that filled available accommodation and caused progradation across the margin. We link the increase in sediment flux with climatic cooling rather than tectonic processes. The progradation is evidenced by a series of clinoforms whose formation was modulated by sea level and which extend over 100 km across the shelf. The height and dip of the clinoforms increased as they extended onto the deeper parts of the earlier ramp. The Miocene clinoform rollovers at the New Jersey margin had water depths of60‐130 m and are interpreted as the edge of a new continental shelf built over the older ramp. Sea-level fall was probably insufficient to drive the Miocene shorelines past the shelf breaks. Thus, measurements of sea-level amplitude based upon ‘coastal’ onlap over the clinoforms are not reliable. © 1999 Elsevier Science B.V. All rights reserved.

The New Jersey Sea Level Transect was designed to evaluate the relationships among global sea level (eustatic) change, unconformity-bounded sequences, and variations in subsidence, sediment supply, and climate on a passive continental margin. By sampling and dating Cenozoic strata from coastal plain and continental slope locations, we show that sequence boundaries correlate (within ±0.5 myr) regionally (onshore-offshore) and interregionally (New Jersey-Alabama-Bahamas), implicating a global cause. Sequence boundaries correlate with δ18O increases for at least the past 42 myr, consistent with an ice volume (glacioeustatic) control, although a causal relationship is not required because of uncertainties in ages and correlations. Evidence for a causal connection is provided by preliminary Miocene data from slope Site 904 that directly link δ18O increases with sequence boundaries. We conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since ∼42 Ma. We speculate that prior to this, the growth and decay of small ice sheets caused small-amplitude sea level changes (less than 20 m) in this supposedly ice-free world because Eocene sequence boundaries also appear to correlate with minor δ18O increases. Subsidence estimates (backstripping) indicate amplitudes of short-term (million-year scale) lowerings that are consistent with estimates derived from δ18O studies (25–50 m in the Oligocene-middle Miocene and 10–20 m in the Eocene) and a long-term lowering of 150–200 m over the past 65 myr, consistent with estimates derived from volume changes on mid-ocean ridges. Although our results are consistent with the general number and timing of Paleocene to middle Miocene sequences published by workers at Exxon Production Research Company, our estimates of sea level amplitudes are substantially lower than theirs. Lithofacies patterns within sequences follow repetitive, predictable patterns: (1) coastal plain sequences consist of basal transgressive sands overlain by regressive highstand silts and quartz sands; and (2) although slope lithofacies variations are subdued, reworked sediments constitute lowstand deposits, causing the strongest, most extensive seismic reflections. Despite a primary eustatic control on sequence boundaries, New Jersey sequences were also influenced by changes in tectonics, sediment supply, and climate. During the early to middle Eocene, low siliciclastic and high pelagic input associated with warm climates resulted in widespread carbonate deposition and thin sequences. Late middle Eocene and earliest Oligocene cooling events curtailed carbonate deposition in the coastal plain and slope, respectively, resulting in a switch to siliciclastic sedimentation. In onshore areas, Oligocene sequences are thin owing to low siliciclastic and pelagic input, and their distribution is patchy, reflecting migration or progradation of depocenters; in contrast, Miocene onshore sequences are thicker, reflecting increased sediment supply, and they are more complete downdip owing to simple tectonics. We conclude that the New Jersey margin provides a natural laboratory for unraveling complex interactions of eustasy, tectonics, changes in sediment supply, and climate change.

We have developed a Miocene sequence stratigraphic framework using data from recently drilled boreholes in the New Jersey Coastal Plain. Sequences are shallowing upward, unconformity-bounded units; fine-grained shelf and prodelta sediments grade upward to delta front and shallow-marine sands, corresponding to confining bed—aquifer couplets. By dating Miocene sequences using Sr-isotope stratigraphy, and mapping with borehole data and geophysical logs, we can predict the continuity and effectiveness of the confining beds and aquifers. The following are illustrated on a 90-km basinward dip section: (1) the composite confining bed is comprised of the Kw0 and lower Kw1a (ca. 23.8−20.5 Ma) sequences downdip at Atlantic City, and the Kw1b, Kw1a and older sequences updip (ca. 69.3−20.6 Ma), and is continuous throughout most of the coastal plain; (2) the major confined aquifer, the Atlantic City 800-foot sand, is comprised of the upper Kw1a and Kw1b sequences (ca. 20.5−20.2 Ma) and is an areally continuous sand that is interconnected with the Kirkwood-Cohansey aquifer system updip of Mays Landing; (3) the confining bed above the Atlantic City 800-foot sand is comprised of the Kw2a, Kw2b, and Kw3 sequences (18.1−13.3 Ma) and is an extensive confining bed that pinches out updip. These sequences and aquifer-confining bed couplets are linked to global sea-level changes evinced by the δ18O record. We conclude that sequence stratigraphy is a powerful tool when applied to regional hydrogeologic problems, although basinal tectonic differences and localized variations in sediment supply can affect aquifer thickness and permeability.

Coherent bathymetric features along the Reykjanes Ridge indicate that there were significant changes in the flux of buoyant material within the Icelandic Hot Spot during the Neogene. The radial extent of the topographic swell associated with this hot spot is of the order of 1000 to 2000 km, and therefore these changes affected the Greenland-Scotland Ridge (GSR). At present, sill depths along the GSR are generally less than 500 m with the deepest passage being less than 1000 m, making the overflow water sensitive to even small changes in the ridge depths. Reconstructions of Neogene mantle plume activity correlate with the deepwater circulation patterns in the North Atlantic. Times of high mantle plume activity caused Northern Component Water (NCW) production to cease. NCW fluxes resumed once this phase of high mantle plume activity slowed. The long-term climate change during the Neogene must be controlled by factors other than NCW production. However, climatic optima during the late early Miocene and early Pliocene appear to have been augmented by high NCW fluxes, while subsequent middle Miocene and “middle” Pliocene coolings correlate with uplifts on the GSR and reduced NCW flux. We suggest that reductions in NCW may have contributed to both of these cooling events.

The sedimentary fill of the Canterbury Basin, New Zealand, is the product of a long-term (80 Ma), tectonically controlled relative sea-level cycle with a megasequence geometry analogous to the sequence stratigraphic model of Vail (Am. Assoc. Petrol. Geol. Stud. Geol No. 27, 1, 1–10, 1987). The condensed section of the megasequence, resolvable in detail in outcrop and on seismic profiles, comprises a basin-wide pelagic to hemipelagic limestone interval. A regional mid-Oligocene unconformity, the Marshall Paraconformity, lies within the limestone interval onshore and correlates with hiatuses in at least two, and possibly three, offshore exploration wells and with a temporary lithological change from limestone to quartz sand at a fourth. Strontium isotopic age estimates confirm that a 2–4 Ma hiatus is associated with onshore outcrops of the Marshall Paraconformity (between ∼32 and 29 Ma), which correlates with the opening of the Pacific sector of the Southern Ocean and the postulated mid-Oligocene sea-level fall of Haq et al. (Science235, 1156–1167, 1987; Spec. Publ. Soc. Econ. Paleonotol. Mineral. No. 42, 71–108, 1988). Lowering of base level, coupled with cooling and enhancement of current activity, may have caused the temporary cessation of limestone deposition and a regional hiatus. This hypothesis reconciles the apparently contradictory palaeogeographical evidence for a regional highstand. The Marshall Paraconformity may exemplify the signature by which similar glacio-eustatic events can be recognized in offshore platform facies.

The Eocene-Oligocene transition (EOT; ca. 33–34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (~15–34 k.y. resolution) from St. Stephens Quarry, Alabama, USA, derived from foraminiferal Mg/Ca, d18O, and TEX86. We constrain sea-surface temperatures (SSTs) in the latest Eocene and early Oligocene and address the issue of climatic cooling during the EOT. Paleotemperatures derived from planktic foraminifera Mg/Ca and TEX86 are remarkably consistent and indicate late Eocene subtropical SSTs of >28 °C. There was substantial and accelerated cooling of SSTs (3–4 °C) through the latest Eocene “precursor” d18O shift (EOT-1), prior to Oligocene Isotope-1 (Oi-1). Our multispecies planktic foraminiferal d18O records diverge at the E/O boundary (33.7 Ma), signifying enhanced seasonality in the earliest Oligocene in the Gulf of Mexico.

[1] We reconstruct trends in ice volume and deep ocean temperature for the past 108 Myr, resolving variations on timescales of ∼2 Myr and longer. We use a sea level record as a proxy for ice volume, a benthic foraminiferal Mg/Cabf record as a proxy for temperature, and a benthic foraminiferal δ18Obf record as a proxy for both. This allows us to construct dual estimates of temperature and ice volume variations for the interval 10–60 Ma: extracting temperature from δ18Obf by using sea level as a proxy for ice volume to constrain the δ18Osw component, and extracting seawater δ18Osw (which reflects ice volume) from δ18Obf by using Mg/Cabf to constrain the temperature component. Each of these approaches requires numerous assumptions, but the range of plausible solutions are concordant on timescales >2 Myr and within an uncertainty of ±2°C temperature and ±0.4‰ δ18Osw. The agreement between the two approaches for the last 50 Myr provides empirical justification for the use of δ18Obf, Mg/Cabf, and sea level records as robust climate proxies. Our reconstructions indicate differences between deep ocean cooling and continental ice growth in the late Cenozoic: cooling occurred gradually in the middle–late Eocene and late Miocene–Pliocene while ice growth occurred rapidly in the earliest Oligocene, middle Miocene, and Plio-Pleistocene. These differences are consistent with climate models that imply that temperatures, set by the long-term CO2 equilibrium, should change only gradually on timescales >2 Myr, but growth of continental ice sheets may be rapid in response to climate thresholds due to feedbacks that are not yet fully understood.