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

Abstract

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 12C‐enriched CO2. 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.

Evidence for Shelf Acidification During the Onset of the Paleocene‐Eocene Thermal Maximum

“…Sections from the subsurface of the Atlantic Coastal Plain from New Jersey and Maryland provide a transect from innermost shelf depths of ~50 m (Self‐Trail et al, ) to outer shelf depths of ~150 m (Stassen et al, ). Here we investigate the onset of the PETM in three cores from New Jersey, including Bass River (BR), Millville (MV), and Wilson Lake (WL; (Cramer et al, ; John et al, ; Sluijs et al, ; Wright & Schaller, ) and three cores from Maryland, including Cambridge Dorchester Airport (Cam‐Dor [CD]), Howards Tract (HT Core 2), and South Dover Bridge (SDB; Self‐Trail et al, ; Figure and Table ).…”

“…The study interval includes the transition from upper Paleocene glauconite‐rich quartz sands of the Vincentown and Aquia formations to the silty‐clay and clay of the Marlboro Clay (Cramer et al, ; Gibson et al, , ; Harris et al, ). The sections are highly expanded with sedimentation rates in the early part of the PETM up to 50 cm/kyr (John et al, ; Self‐Trail et al, ; Stassen et al, ). Samples were examined every 5 to 25 cm across the interval just below and within the onset of the CIE and at lower resolution in the upper part of the event.…”

Tracking the Paleocene‐Eocene Thermal Maximum in the North Atlantic: A Shelf‐to‐Basin Analysis With a Regional Ocean Model

“…Precipitation patterns in the Mid‐Atlantic region during the PETM have not been conclusively characterized, but they may have tended toward monsoonal, wet‐ and dry‐season extremes as a consequence of atmospheric warming (Zachos et al, ). Hyperpycnal flow structures, terrigenous plant detritus, and planktic/benthic assemblage changes on inner shelf sections of the Marlboro Clay also lend evidence for high seasonality of precipitation and a monsoonal discharge pattern in the Salisbury Embayment during the PETM (Self‐Trail et al, ). The average discharge of the ancient Susquehanna‐Potomac system may have risen to roughly one fourth of the modern Amazon River discharge or about 5 × 10 4 m 3 /s (0.05 Sv), during the PETM (Kopp et al, ).…”

“…Continental shelves are critical components of Earth's biogeochemical cycles: they sustain 10 to 30% of marine primary production, 30 to 50% of inorganic carbon burial, and 80% of organic carbon burial (Bauer et al, ; Mackenzie et al, ). The Paleocene‐Eocene depositional units of the Mid‐Atlantic and New Jersey Coastal Plains are of particular interest because their record of the PETM composes an inner‐to‐outer shelf transect (Gibson & Bybell, ; Self‐Trail et al, ; Stassen et al, ). Paleogene sediments of the Mid‐Atlantic and New Jersey Coastal Plains were deposited primarily by the ancient Susquehanna and Potomac Rivers into a basin referred to as the Salisbury Embayment (Figure S1; Poag & Sevon, ).…”

Little lasting impact of the Paleocene-Eocene Thermal Maximum on shallow marine molluscan faunas

“…Global marine temperatures rose by 5° to 8°C ( 4 ), and acidification in the mixed layer ( 2 , 5 ) and deep ocean ( 6 ) was severe and often coupled with hypoxia both at depth ( 7 ) and on continental margins ( 8 ). The PETM likely underestimates the expected impact of ongoing combustion of fossil fuels ( 2 , 9 ) but nonetheless remains the closest analog to the present offered by the geological record.…”