Hydrodynamic influences on multiproxy-based paleoclimate reconstructions from marine sediments

Blanca Ausin Gonzalez, Clayton Magill, Pascal Wenk, Gerald Haugh, Cameron McIntyre, Negar Haghipour, David A. Hodell, Timothy Eglinton

Research output: Contribution to conferenceAbstract

Abstract

Multiproxy approaches, including those based on the abundance and composition of sedimentary organic matter at both the bulk (total organic carbon; TOC) and molecular (e.g., alkenone-derived Uk'37) level, are increasingly applied in investigations of past climate variability. Constraining of short-term and abrupt climate changes requires the establishment of accurate chronostratigraphies. For the last glacial to the present, a single age-depth model is typically constructed from radiocarbon ages of planktonic foraminifera and then applied to all proxy records derived from the same sediment core. Here, we develop independent, high-resolution 14C chronologies for planktonic foraminifera, TOC, and alkenones for a sediment core retrieved from the so-called "Shackleton sites" in the Northeast Atlantic Ocean. We observe 14C age offsets between these sedimentary components of up to several thousand years within the same sediment layer, with TOC and alkenones exhibiting older ages than corresponding foraminiferal carbonate. This asynchroneity suggests that application of planktic foraminifera-based chronostratigraphies to other proxy carriers (e.g., TOC and alkenones) may lead to spurious interpretation of sedimentary records. In order to further explore the influence of lateral transport processes on organic matter signatures and ages, we performed down-core, grain size-specific OC 14C analyses on selected sediment horizons. Results indicate strong interdependence between 14C age of OC and sediment grain size, underlying strong hydrodynamic controls on OC age. Furthermore, the magnitude of these temporal offsets varies over time in concert with changes in the strength of the Mediterranean Outflow Water (MOW), implying that OC [proxy] signatures are influenced by non-local inputs. Such influences co-vary with ocean and climate changes, such as Heinrinch Event 1, the Younger Dryas, and those corresponding to deposition of Sapropel 1 in the Mediterranean Sea (ca. 8 ka BP). Our findings suggest an interplay between past climate and ocean change, hydrodynamic forcing, and the (a)synchroneity of multiproxy records, and highlight the importance of developing independent, proxy-specific chronostratigraphies to accurately decipher past millennial- and centennial-scale climate variability.
Original languageEnglish
Publication statusPublished - Dec 2017
EventAmerican Geophysical Union Fall Meeting 2017 - New Orleans, United States
Duration: 11 Dec 201715 Dec 2017

Conference

ConferenceAmerican Geophysical Union Fall Meeting 2017
CountryUnited States
CityNew Orleans
Period11/12/1715/12/17

Keywords

  • Biogeosciences
  • Organic geochemistry
  • Paleoceanography
  • Biosignatures

Fingerprint Dive into the research topics of 'Hydrodynamic influences on multiproxy-based paleoclimate reconstructions from marine sediments'. Together they form a unique fingerprint.

  • Cite this

    Ausin Gonzalez, B., Magill, C., Wenk, P., Haugh, G., McIntyre, C., Haghipour, N., Hodell, D. A., & Eglinton, T. (2017). Hydrodynamic influences on multiproxy-based paleoclimate reconstructions from marine sediments. Abstract from American Geophysical Union Fall Meeting 2017, New Orleans, United States.