We obtained global sea-level (eustatic) estimates with a peak of similar to 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 delta O-18 values, and Mg/Ca-delta O-18 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 delta O-18 values appear to require that the peak was <20-21 m. Our estimates imply loss of the equivalent of the Greenland and West Antarctic ice sheets, and some volume loss from the East Antarctic Ice Sheet, and address the long-standing controversy concerning the Pliocene stability of the East Antarctic Ice Sheet.

Chief Scientists: Miller, Sugarman Staff Scientist: Browning Operations: Cobbs, Miller, Sugarman Lithostratigraphy: Browning, Kulpecz, McLaughlin, Miller, Mizintseva, Monteverde, Pusz, Rankin, Sugarman, Tomlinson, Uptegrove, Velez Biostratigraphy: Planktonic foraminifers: Olsson Calcareous nannofossils: Aubry (Cenozoic), Bukry (Mesozoic), Mizintseva (Mesozoic) Spores and pollen: Brenner, McLaughlin Logging: McLaughlin Sr isotopic stratigraphy: Browning, Feigenson

The Eyreville and Exmore, Virginia, core holes were drilled in the inner basin and annular trough, respectively, of the Chesapeake Bay impact structure, and they allow us to evaluate sequence deposition in an impact crater. We provide new high-resolution geochronologic (<1 Ma) and sequence-stratigraphic interpretations of the Exmore core, identify 12 definite (and four possible) postimpact depositional sequences, and present comparisons with similar results from Eyreville and other mid-Atlantic core holes. The concurrence of increases in delta O-18 with Chesapeake Bay impact structure sequence boundaries indicates a primary glacioeustatic control on deposition. However, regional comparisons show the differential preservation of sequences across the mid-Atlantic margin. We explain this distribution by the compaction of impactites, regional sediment-supply changes, and the differential movement of basement structures. Upper Eocene strata are thin or missing updip and around the crater, but they thicken into the inner basin (and offshore to the southeast) to rapid crater infilling and concurrent impactite compaction. Oligocene sequences are generally thin and highly dissected throughout the mid-Atlantic region due to sediment starvation and tectonism, except in southeastern New Jersey. Regional tectonic uplift of the Norfolk Arch coupled with a southward decrease in sediment supply resulted in: (1) largely absent Lower Miocene sections around the Chesapeake Bay impact structure compared to thick sections in New Jersey and Delaware; (2) thick Middle Miocene sequences across the Delmarva Peninsula that thin south of the Chesapeake Bay impact structure; and (3) upper Middle Miocene sections that pinch out just north of the Chesapeake Bay impact structure. Conversely, the Upper Miocene-Pliocene section is thick across Virginia, but it is poorly represented in New Jersey because of regional variations in relative subsidence.due

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.

The Chesapeake Bay impact structure is a ca. 35.4 Ma crater located on the eastern seaboard of North America. Deposition returned to normal shortly after impact, resulting in a unique record of both impact-related and subsequent passive margin sedimentation. We use backstripping to show that the impact strongly affected sedimentation for 7 m.y. through impact-derived crustal-scale tectonics, dominated by the effects of sediment compaction and the introduction and subsequent removal of a negative thermal anomaly instead of the expected positive thermal anomaly. After this, the area was dominated by passive margin thermal subsidence overprinted by periods of regional-scale vertical tectonic events, on the order of tens of meters. Loading due to prograding sediment bodies may have generated these events.

Paleogeographic, isopach, and deltaic lithofacies mapping of thirteen depositional sequences establish a 35 myr high resolution (> 1 Myr) record of Late Cretaceous wave- and tide-influenced deltaic sedimentation. We integrate sequences defined on the basis of lithologic, biostratigraphic, and Sr-isotope stratigraphy from cores with geophysical log data from 28 wells to further develop and extend methods and calibrations of well-log recognition of sequences and facies variations. This study reveals the northeastward migration of depocenters from the Cenomanian (ca. 98 Ma) through the earliest Danian (ca. 64 Ma) and documents five primary phases of paleodeltaic evolution in response to long-term eustatic changes, variations in sediment supply, the location of two long-lived fluvial axes, and thermoflexural basement subsidence: (1) Cenomanian-early Turonian deltaic facies exhibit marine and nonmarine facies and are concentrated in the central coastal plain; (2) high sediment rates, low sea level, and high accommodation rates in the northern coastal plain resulted in thick, marginal to nonmarine mixed-influenced deltaic facies during the Turonian-Coniacian; (3) comparatively low sediment rates and high long-term sea level in the Santonian resulted in a sediment-starved margin with low deltaic influence; (4) well-developed Campanian deltaic sequences expand to the north and exhibit wave reworking and longshore transport of sands; and (5) low sedimentation rates and high long-term sea level during the Maastrichtian resulted in the deposition of a sediment-starved glauconitic shelf. Our study illustrates the widely known variability of mixed-influence deltaic systems, but also documents the relative stability of deltaic facies systems on the 10(6)-10(7) yr scale, with long periods of cyclically repeating systems tracts controlled by eustasy. Results from the Late Cretaceous further show that although eustasy provides the template for sequences globally, regional tectonics (rates of subsidence and accommodation), changes in sediment supply, proximity to sediment input, and flexural subsidence from depocenter loading determines the regional to local preservation and facies expression of sequences.

ABSTRACT 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 (10 7 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.

Operations: Cobbs, Miller, Sugarman Lithostratigraphy: Browning, Harris, Katz, Kulpecz, McLaughlin, Miller, Misintseva, Monteverde, Patrick, Pekar, Sugarman, Uptegrove Biostratigraphy: Spores, pollen and dinocysts: Brenner Planktonic foraminifers: Olsson, Browning Benthic foraminifers: Browning, Harris, Misintseva, Olsson Calcareous nannofossils: Aubry (Cenozoic), de Romero (Mesozoic) Logging: McLaughlin Sr isotopic Stratigraphy: Browning, Feigenson, Monteverde

The regional extent and connectivity of Cretaceous to Miocene aquifer sands in the New Jersey Coastal Plain are evaluated using detailed facies analysis within a sequence stratigraphic framework.We correlate sequences from continuous coreholes using well logs to trace strike and dip sections throughout this region, allowing us to predict the continuity of confining units and aquifer sands. Marine sequences follow a predictable shallowing upward pattern: fine-grained shelf and prodelta sediments grade upward into delta front and shallow-marine sands, corresponding to confining unit-aquifer couplets. Aquifer sands deposited inmarine shelf environments tend to be continuous on the 10+ km (6.2 mi) scale and are traceable for >60 km (37.3 mi) along strike and >25 km (15.5 mi) along dip. Confining units for these marine sequences are typically shelf or prodelta silty clays that are even more laterally continuous than their associated aquifer sands.Marginalmarine to non-marine sequences aremore difficult to predict due to a lack of continuous marine marker beds, difficulty in interpreting paleoenvironments of thick sand beds, and lack of fossil material except pollen for biostratigraphy. Marginal to non-marine sequences are generally less continuous, though some show surprising lateral continuity along strike (>60 km [37.3 mi]), reflecting the widespread extent of delta front environments.We conclude that sequence stratigraphy provides a predictive framework for aquifers and confining units, but that regional and local differences in sediment supply and tectonics affect the development of the hydrostratigraphic framework.

The regional extent and connectivity of Cretaceous to Miocene aquifer sands in the New Jersey Coastal Plain are evalu- ated using detailed facies analysis within a sequence stratigraphic framework. We correlate sequences from continuous coreholes using well logs to trace strike and dip sections throughout this region, allowing us to predict the continuity of confining units and aquifer sands. Marine sequences follow a predictable shallowing upward pattern: fine-grained shelf and prodelta sediments grade upward into delta front and shallow-marine sands, corresponding to confining unit-aquifer couplets. Aquifer sands deposited in marine shelf environments tend to be continuous on the 10+ km (6.2 mi) scale and are traceable for >60 km (37.3 mi) along strike and >25 km (15.5 mi) along dip. Confining units for these marine sequences are typically shelf or prodelta silty clays that are even more laterally continuous than their as- sociated aquifer sands. Marginal marine to non-marine sequences are more difficult to predict due to a lack of continuous marine marker beds, difficulty in interpreting paleoenvironments of thick sand beds, and lack of fossil material except pollen for biostratigraphy. Mar- ginal to non-marine sequences are generally less continuous, though some show surprising lateral continuity along strike (>60 km (37.3 mi)), reflecting the widespread extent of delta front environments. We conclude that sequence stratigraphy provides a predictive frame- work for aquifers and confining units, but that regional and local differences in sediment supply and tectonics affect the development of the hydrostratigraphic framework.