Shallow marine response to global climate change during the Paleocene‐Eocene Thermal Maximum, Salisbury Embayment, USA. (17th July 2017) - Self‐Trail, Jean M.
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 12 C‐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. Key Points: We document the response of marine flora and fauna to changing habitats in a nearshore environment during the PETM We show that episodic hyperpycnal flow resulted in an increase in sedimentation rate, input of fresh water, and terrestrial material We propose that authigenic carbonate resulted in a diagenetic isotope pattern that mimics a magnified negative CIE in bulk carbonates