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Marci M. Robinson

Publications and source records attributed to Marci M. Robinson.

At least 37 records · Page 2Linked to original sources
USGS2022

Surface ocean warming and acidification driven by rapid carbon release precedes Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM) is recognized by a major negative carbon isotope (δ 13 C) excursion (CIE) signifying an injection of isotopically light carbon into exogenic reservoirs, the mass, source, and tempo of which continue to be debated. Evidence of a transient precursor carbon release(s) has been identified in a few localities, although it remains equivocal whether there is a global signal. Here, we present foraminiferal δ 13 C records from a marine continental margin section, which reveal a 1.0 to 1.5‰ negative pre-onset excursion (POE), and concomitant rise in sea surface temperature of at least 2°C and a decline in ocean pH. The recovery of both δ 13 C and pH before the CIE onset and apparent absence of a POE in deep-sea records suggests a rapid (< ocean mixing time scales) carbon release, followed by recovery driven by deep-sea mixing. Carbon released during the POE is therefore likely more similar to ongoing anthropogenic emissions in mass and rate than the main CIE.

Science Advances↗
USGS2022

Ratification of Neogene subseries as formal units in international chronostratigraphy

The International Union of Geological Sciences Executive Committee (IUGS EC) voted on 13 October 2021 to ratify a proposal for the Neogene subseries/subepochs to have formal status. They are now incorporated into a sixtiered chronostratigraphic hierarchy within the International Chronostratigraphic Chart (ICC). The Lower/Early Miocene Subseries/Subepoch comprises the Aquitanian and Burdigalian stages/ages, the Middle Miocene Subseries/Subepoch comprises the Langhian and Serravallian stages/ages, the Upper/Late Miocene Subseries/Subepoch comprises the Tortonian and Messinian stages/ages, the Lower/Early Pliocene Subseries/Subepoch comprises the Zanclean Stage/Age and the Upper/Late Pliocene Subseries/Subepoch comprises the Piacenzian Stage/Age. This ratification is an important move towards both a common language in the wider Earth Sciences community and a step forward in the unification of Cenozoic chronostratigraphy, with Neogene and Quaternary subseries/subepochs now formalized.

Episodes↗
USGS2021

The Yorktown Formation: Improved stratigraphy, chronology and paleoclimate interpretations from the U.S. mid-Atlantic Coastal Plain

The Yorktown Formation records paleoclimate conditions along the mid-Atlantic Coastal Plain during the mid-Piacenzian Warm Period (3.264 to 3.025 Ma), a climate interval of the Pliocene in some ways analogous to near future climate projections. To gain insight into potential near future changes, we investigated Yorktown Formation outcrops and cores in southeastern Virginia, refining the stratigraphic framework. We analyzed 485 samples for alkenone-based sea surface temperature (SST) and productivity estimates from the Holland and Dory cores, an outcrop at Morgarts Beach, Virginia, and the lectostratotype of the Yorktown Formation at Rushmere, Virginia, and analyzed planktonic foraminferal assemblage data from the type section. Using the structure of the SST record, we improved the chronology of the Yorktown Formation by establishing the maximum age ranges of the Rushmere (3.3–3.2 Ma) and Morgarts Beach (3.2–3.15 Ma) Members. SST values for these members average ~26 °C, corroborating existing sclerochronological data. Increasing planktonic foraminifer abundance, productivity, and species diversity parallel increasing SST over the MIS M2/M1 transition. These records constitute the greatest temporal concentration of paleoecological estimates within the Yorktown Formation, aiding our understanding of western North Atlantic temperature patterns, seasonality and ocean circulation during this interval. We provide a chronologic framework for future studies analyzing ecological responses to profound climate change.

Virginia↗
USGS2021

Miocene neritic benthic foraminiferal community dynamics, Calvert Cliffs, Maryland, USA: Species pool, patterns and processes

The presence/absence and abundance of benthic foraminifera in successive discrete beds (Shattuck “zones”) of the Miocene Calvert and Choptank formations, exposed at the Calvert Cliffs, Maryland, USA, allows for investigation of community dynamics over space and time. The stratigraphic distribution of benthic foraminifera is documented and interpreted in the context of sea-level change, sequence stratigraphy, and the previously published distribution of mollusks. Neritic benthic foraminiferal communities of four sea-level cycles over ∼4 million years of the middle Miocene, encompassing the Miocene Climatic Optimum and the succeeding middle Miocene Climate Transition, are dominated by the same abundant species. They differ in the varying abundance of common species that occur throughout most of the studied section and in the different rare species that appear and disappear. Transgressive systems tracts (TSTs) have higher species diversity than highstand systems tracts (HSTs) but much lower density of specimens. In contrast to some previous research, all beds in the studied section are interpreted as being from the inner part of a broad, low gradient shelf and were deposited at water depths of less than ∼50 m. It is suggested that species are recruited from a regional species pool of propagules throughout the duration of TSTs. Recruitment is curtailed during highstands leading to lower diversity in the HSTs.

Maryland↗
USGS2021

Estimating Piacenzian sea surface temperature using an alkenone-calibrated transfer function

Stationarity of environmental preferences is a primary assumption required for any paleoenvironmental reconstruction using fossil materials based upon calibration to modern organisms. Confidence in this assumption decreases the further back in time one goes, and the validity of the assumption that species temperature tolerances have not changed over time has been challenged in Pliocene studies. We use paired U K′ 37 (unsaturated ketones with 37 carbon atoms) sea surface temperature (SST) and faunal assemblage data to directly calibrate North Atlantic Piacenzian planktonic foraminifer assemblages to Piacenzian alkenone paleotemperature estimates to provide an alternative paleoceanographic reconstruction approach that does not rely on stationarity. In doing so, we extend Pliocene SST estimates to sites where only quantitative faunal assemblage data were previously available and improve the spatial resolution of the North Atlantic SST reconstruction.

Scientific Investigations Report↗
USGS2021

Shallow marine ecosystem collapse and recovery during the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM), the most well-studied transient hyperthermal event in Earth history, is characterized by prominent and dynamic changes in global marine ecosystems. Understanding such biotic responses provides valuable insights into future scenarios in the face of anthropogenic warming. However, evidence of the PETM biotic responses is largely biased towards deep-sea records, whereas shallow-marine evidence remains scarce and elusive. Here we investigate a shallow-marine microfaunal record from Maryland, eastern United States, to comprehensively document the shallow-marine biotic response to the PETM. We applied birth-death modeling to estimate the local diversity dynamics, combined with evaluation of time-variable preservation artifacts. We discovered strong increase of species disappearance and appearance predating the onset and at the final recovery phase of the PETM, respectively. Our paleoecological analyses indicate that bathymetric habitat compression due to extreme warmth and oxygen minimum zone expansion caused shallow-marine benthic species extirpation and ecosystem perturbation during the PETM; and that rapid recovery and diversification followed the PETM disaster, thus contributing new understanding to the shallow-marine biotic changes in a broad context of global warming.

Maryland↗
USGS2020

Planktic foraminiferal test size and weight response to the late Pliocene environment

Atmospheric carbon dioxide ( p CO 2 atm ) is impacting the ocean and marine organisms directly via changes in carbonate chemistry and indirectly via a range of changes in physical parameters most dominantly temperature. To assess potential impacts of climate change on carbonate production in the open ocean, we measured size and weight of planktic foraminifers during the late Pliocene at p CO 2 atm concentrations comparable to today and global temperatures 2 to 3 °C warmer. Size of all foraminifers was measured at Atlantic Ocean Deep Sea Drilling Project (DSDP) Site 610, Ocean Drilling Program (ODP) Site 999, and Integrated Ocean Drilling Program (IODP) Site U1313. Test size was smaller during the Pliocene than in modern assemblages under the same environmental conditions. During the cold marine isotope stage (MIS) M2, size increased at Site 999, potentially linked to intensified stratification of the surface ocean in response to the closure of the Central American Seaway. At Site U1313, test size tracks the warming throughout the late Pliocene. Size-normalized weight (SNW) of Globigerina bulloides at Site U1313 decreased during warmer temperature intervals. SNW of Globigerinoides ruber (white) at Site 999 displays high-frequency variability not correlated to temperature. Yet during the glacial period within MIS M2, test weight was higher during higher temperatures. Our results support studies in the modern ocean, which challenge the view that carbonate chemistry is the primary driver for calcification. To better understand processes driving changes in SNW, computer tomography was used to quantify calcite to volume ratios. During interglacial periods, lower calcite volume but higher test volume suggests less suitable conditions for calcification. As this signal is not evident in SNW, subtle changes in calcification might not be observed by the weight-based method.

Paleoceanography and Paleoclimatology↗
USGS2019

Environmental and geomorphological changes on the eastern North American Continental Shelf across the Paleocene-Eocene Boundary

Foraminiferal evidence from two sites in southern Maryland, eastern United States, reveals a series of rapid ecological changes on the continental shelf during the onset of the Paleocene-Eocene Thermal Maximum (PETM). Benthic and planktic foraminifer assemblages from the South Dover Bridge (SDB) and Mattawoman Creek-Billingsley Road (MCBR) cores in the central Salisbury Embayment record changing latest Paleocene and earliest Eocene ecological conditions that began prior to the carbon isotope excursion (CIE) that marks the beginning of the PETM. The foraminiferal response reflects increases in productivity first in bottom water and then in the mixed layer, a minor dissolution event, and rising sea-surface temperatures in the latest Paleocene. Relative sea level changes, a sudden change in sedimentary regime, a decrease in bottom water oxygenation, and a downward expansion of the mixed layer occurred across the PETM onset. In the earliest Eocene, foraminiferal assemblages document a gradual shallowing of the thermocline and/or cooling of the surface layer. While SDB assemblages support a rise in sea level across the PETM onset, MCBR assemblages record a drop in sea level interpreted as delta progradation. Transitional carbon isotope values characterizing the nature of the CIE are recorded in these delta sediments. We present an initial bathymetric reconstruction of the Salisbury Embayment showing the physical effects of the CIE onset on shelf morphology and highlight the importance of understanding coastal zone processes when examining shelf sediments.

Delaware, Maryland, New Jersey, Pennsylvania, Virg↗
USGS2019

The planktonic foraminiferal response to the Paleocene-Eocene thermal maximum on the Atlantic coastal plain

Planktonic foraminiferal assemblages in two cores from Maryland and New Jersey show evidence for significant changes in surface ocean habitats on the continental shelf during the Paleocene-Eocene Thermal Maximum (PETM). At both sites, significant assemblage shifts occur immediately before the onset of the event. These changes include the appearance of abundant triserial/biserial species as well as rare excursion taxa, which are limited to the interval of the carbon isotope excursion at deep-sea sites. The assemblage shifts signal the development of new habitats immediately prior to the onset of the PETM, likely involving warming, surface ocean acidification, increased stratification and oligotrophy. A sharp increase in diversity at the onset of the event is interpreted as a further increase in stratification and warming, as well as increased water depth and more eutrophic conditions. Finally, we observe variant morphologies of several planktonic foraminifera, which may also signal the response of the assemblage to environmental perturbation.

Atlantic coastal plain↗
USGS2018

Evidence for shelf acidification during the onset of the Paleocene-Eocene Thermal Maximum

A transect of paleoshelf cores from Maryland and New Jersey contains a ~0.19 m to 1.61 m thick interval with reduced percentages of carbonate during the onset of the Paleocene-Eocene Thermal Maximum (PETM). Outer paleoshelf cores are barren of nannofossils and correspond to two minor disconformities. Middle paleoshelf cores contain a mixture of samples devoid of nannofossils and those with rare specimens characterized by significant dissolution (i.e., etching). The magnitude of the decrease in carbonate cannot be explained by dilution by clastic material or dissolution resulting from the oxidation of organic matter during early diagenesis. The observed preservation pattern implies a shoaling of the calcite compensation depth (CCD) and lysocline to the middle shelf. This reduced carbonate interval is observed during the onset of the PETM on other continental margins raising the possibility that extreme shoaling of the CCD and lysocline was a global signal which is more significant than in previous estimates for the PETM. An alternative scenario is that shoaling was restricted to the northwest Atlantic, enhanced by regional and local factors (eutrophication from rivers, microbial activity associated with warming) that exacerbated the impact of acidification on the shelf.

Maryland, New Jersey↗
USGS2018

North Atlantic midlatitude surface-circulation changes through the Plio-Pleistocene intensification of northern hemisphere glaciation

The North Atlantic Current (NAC) transports warm salty water to high northern latitudes, with important repercussions for ocean circulation and global climate. A southward displacement of the NAC and Subarctic Front, which separate subpolar and subtropical water masses, is widely suggested for the Last Glacial Maximum (LGM) and may have acted as a positive feedback in glacial expansion at this time. However, the role of the NAC during the intensification of Northern Hemisphere glaciation (iNHG) at ~3.5 to 2.5 Ma is less clear. Here we present new records from Integrated Ocean Drilling Program Site U1313 (41°N) spanning ~2.8–2.4 Ma to trace the influence of Subarctic Front waters above this mid‐latitude site. We reconstruct surface and permanent pycnocline temperatures and seawater δ 18 O using paired Mg/Ca‐δ 18 O measurements on the planktic foraminifers Globigerinoides ruber and Globorotalia crassaformis and determine abundances of the subpolar foraminifer Neogloboquadrina atlantica . We find that the first significant glacial incursions of Subarctic Front surface waters above Site U1313 did not occur until ~2.6 Ma. At no time during our study interval was (sub)surface reorganization in the midlatitude North Atlantic analogous to the LGM. Our findings suggest that LGM‐like processes sensu stricto cannot be invoked to explain interglacial‐glacial cycle amplification during iNHG. They also imply that increased glacial productivity at Site U1313 during iNHG was not only driven by southward deflections of the Subarctic Front. We suggest that nutrient injection from cold‐core eddies and enhanced glacial dust delivery may have played additional roles in increasing export productivity in the midlatitude North Atlantic from 2.7 Ma.

Paleoceanography and Paleoclimatology↗
USGS2018

PRISM marine sites—The history of PRISM sea surface temperature estimation

For more than three decades, the U.S. Geological Survey (USGS) Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project has compiled paleoenvironmental data with the goal of reconstructing global conditions during the warm interval in the middle of the Piacenzian Age of the Pliocene Epoch (about 3.3 to 3.0 million years ago). Because this is the most recent interval of time in which climatic conditions were similar to those expected in the near future, a global reconstruction of conditions from this interval offers an imperfect yet useful representation of near future conditions. PRISM reconstructions have been used extensively as boundary conditions in general circulation model experiments aimed at better understanding Pliocene climate. They have also served as hindcasting targets when testing the ability of climate models to simulate real climates of the past, an exercise in estimating a model’s ability to accurately predict future climate. As data coverage has grown and model precision has improved, PRISM datasets have become important validation tools for pinpointing discrete areas of data-model disagreement and model-model disagreement. The Pliocene sea surface temperature (SST) dataset is the best developed component of the PRISM reconstructions and is the keystone of Pliocene paleoclimate research. For the first time, we compile all data related to PRISM SST estimation. This discussion chronicles the history of PRISM SST research as it evolved, responding to advances in paleochronology and paleotemperature estimation. Paleoclimatic considerations unique to each location are illustrated, as are any new developments since the initial publication of the data.

Open-File Report↗
USGS2018

Mid-piacenzian of the north Atlantic Ocean

The Piacenzian Age (Pliocene) represents a past climate interval within which frequency and magnitude of environmental changes during a period of past global warmth can be analyzed, climate models can be tested, and results can be placed in a context to better prepare for future change. Here we focus on the North Atlantic region, incorporating new and existing faunal assemblage and alkenone data from Ocean Drilling Program Sites 642, 662, 982, and 999, and International Ocean Discovery Program Sites 1308 and 1313 into our paleoenvironmental reconstruction. Cores and outcrop material containing Piacenzian sediments from the Atlantic Coastal Plain of Virginia, USA, are also included. These data allow us to characterize regional changes in temperature, salinity, upwelling, surface productivity, and diversity, associated with climate transitions, and make nuanced reconstructions of mid-Piacenzian conditions within a high-resolution temporal framework between ~3.40 and ~3.15 Ma, inclusive of Marine Isotope Stages M2 through KM5. We include an initial comparison of estimated sea-surface temperature to coupled climate model simulations, which shows improvement in model adherence to paleoclimate parameters over previous data-model comparisons for the Pliocene.

Stratigraphy↗
USGS2018

Sea surface temperature estimates for the mid-Piacenzian Indian Ocean—Ocean Drilling Program sites 709, 716, 722, 754, 757, 758, and 763

Despite the wealth of global paleoclimate data available for the warm period in the middle of the Piacenzian Stage of the Pliocene Epoch (about 3.3 to 3.0 million years ago [Ma]; Dowsett and others, 2013, and references therein), the Indian Ocean has remained a region of sparse geographic coverage in terms of microfossil analysis. In an effort to characterize the surface Indian Ocean during this interval, we examined the planktic foraminifera from Ocean Drilling Program (ODP) sites 709, 716, 722, 754, 757, 758, and 763, encompassing a wide range of oceanographic conditions. We quantitatively analyzed the data for sea surface temperature (SST) estimation using both the modern analog technique (MAT) and a factor analytic transfer function. The data will contribute to the U.S. Geological Survey (USGS) Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project’s global SST reconstruction and climate model SST boundary condition for the mid-Piacenzian and will become part of the PRISM verification dataset designed to ground-truth Pliocene climate model simulations (Dowsett and others, 2013).

Open-File Report↗
USGS2017

Shallow marine response to global climate change during the Paleocene-Eocene Thermal Maximum, Salisbury Embayment, USA

The Paleocene-Eocene Thermal Maximum (PETM) was an interval of extreme warmth that caused disruption of marine and terrestrial ecosystems on a global scale. Here we examine the sediments, flora, and fauna from an expanded section at Mattawoman Creek-Billingsley Road (MCBR) in Maryland and explore the impact of warming at a nearshore shallow marine (30–100 m water depth) site in the Salisbury Embayment. Observations indicate that at the onset of the PETM, the site abruptly shifted from an open marine to prodelta setting with increased terrestrial and fresh water input. Changes in microfossil biota suggest stratification of the water column and low-oxygen bottom water conditions in the earliest Eocene. Formation of authigenic carbonate through microbial diagenesis produced an unusually large bulk carbon isotope shift, while the magnitude of the corresponding signal from benthic foraminifera is similar to that at other marine sites. This proves that the landward increase in the magnitude of the carbon isotope excursion measured in bulk sediment is not due to a near instantaneous release of 12 C-enriched CO 2 . We conclude that the MCBR site records nearshore marine response to global climate change that can be used as an analog for modern coastal response to global warming.

Maryland, New Jersey, Pennsylvania, Virginia↗
USGS2016

The PRISM4 (mid-Piacenzian) paleoenvironmental reconstruction

The mid-Piacenzian is known as a period of relative warmth when compared to the present day. A comprehensive understanding of conditions during the Piacenzian serves as both a conceptual model and a source for boundary conditions as well as means of verification of global climate model experiments. In this paper we present the PRISM4 reconstruction, a paleoenvironmental reconstruction of the mid-Piacenzian (&thinsp;&sim;&thinsp;3 Ma) containing data for paleogeography, land and sea ice, sea-surface temperature, vegetation, soils, and lakes. Our retrodicted paleogeography takes into account glacial isostatic adjustments and changes in dynamic topography. Soils and lakes, both significant as land surface features, are introduced to the PRISM reconstruction for the first time. Sea-surface temperature and vegetation reconstructions are unchanged but now have confidence assessments. The PRISM4 reconstruction is being used as boundary condition data for the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) experiments.

Climate of the Past↗
USGS2016

A simple rubric for Stratigraphic Fidelity (β) of paleoenvironmental time series

The Pliocene, specifically the late Pliocene, has been a focus of paleoclimate research formore than 25 years. Synoptic regional and global reconstructions along with high-resolution time-series have produced nuanced conceptual models of paleoenvironmental conditions and enhanced our understanding of climate variability and climate sensitivity from the Late Pliocene, the most recent interval of global warmth similar to what is projected for the end of the 21st century. These data are used as a source of boundary conditions for climate models as well as ameans of verification of global climate model experiments. In this note, we introduce a measure of stratigraphic fidelity, ß, used to characterize the chronology and achievable resolution of an ever-growing library of Pliocene paleoenvironmental time-series. The ß index serves as an aid to end-users by allowing selection of time-series that meet the stratigraphic requirements of a particular study.

Stratigraphy↗