T3. Palaeoclimatology and palaeoceanography

 

Palaeoclimatology is the science of past climates, which are studied on time scales that vary from a few thousand years to several million years. The deciphering of climate conditions and their natural variability is based on the study of natural archives from the earth’s principal compartment: the hydrosphere, cryosphere, atmosphere, lithosphere and biosphere. Today, the emergence of new analytical techniques allows a better-defined geochemical reading in terms of temporal and spatial resolution, through the use of in situ analysis and new climate proxies respectively.

 

Sub-themes and associated methods:

The four principal research axes developed at the LSCE and GEOPS are as follows:

 

T3.1 - Understanding the processes by which environmental parameters are recorded within the climate archives

Understanding the processes by which environmental parameters (T°, salinity, alkalinity, seawater pH, isotopic composition of precipitation, etc.) are recorded within the climate archives, which are mainly of sedimentary or biogenic origin.

 

T3.2 – Atmospheric water cycle dynamics.

Using water isotopes to trace the current origin of water vapour and the processes involved so as to characterise past climate variations from the archives.

 

T3.3 – Oceanic circulation dynamics

Oceanic circulation dynamics (palaeoceanography) and its role in climate variability and in the linkages between climate, the carbon cycle and acidification.

 

T3.4 – Reconstruction of continental palaeoenvironments

Reconstruction of continental palaeoenvironments using isotopes of hydrogen, oxygen, carbon and nitrogen in calcareous lacustrine organisms, speleothems, tree rings and loess organic matter so as to characterise variations in lake levels, temperature and precipitation.

In order to answer these scientific questions, the following analytical techniques are used:

  • IRMS (Isotope Ratio Mass Spectrometry) of (bio) carbonates for C and O isotopes (A2, A3, A5, A6)), and IRMS of clumped isotopes (D47) (A2, A3, A5, A6)
  • Continuous-flow IRMS for the DIC and O-C of seawater (A2)
  • IRMS (Isotope Ratio Mass Spectrometry) of water isotopes trapped within fluid inclusions (A6).
  • IRMS, 17O and 18O of ice (A1)
  • IRMS, 13C and 18O of tree rings (A4)
  • EA-IRMS for 13C and 15N in sediments and soils (T3.1, T3.2, T3.3)
  • Picarro D/H CRDS (water) (A1)
  • Laser granulometry (A2, A3)
  • Cryogenic magnetometers, Micromag (AGM2900), Curie scale (A2, A3)
  • Magnetic susceptibility (A2, A3, A6)
  • X-ray diffractometry (A2, A3)
  • MC-ICP-MS Actinides Pa/Th, U/Th (A2, A3, A5, A6) ; lanthanides (A2, A3, A5), stable Li and B isotopes (A5); Sr isotopes (A2, A3, A5, A6); Nd isotopes (A2, A3, A5)
  • ICP-AES measurements of Mg/Ca trace elements (A2, A3, A5, A6)
  • ICP-QMS measurements of B/Ca, Li/Mg, Sr/Ca, REE, U and major- and trace elements (A5, A6)
  • ICPMS-HR measurements of B/Ca, Li/Mg, Sr/Ca, REE, U and major- and trace elements (A5, A6)
  • ECHoMICADAS (A2, A3, A5, A6)

 

Climate archives analysed:

  • A1/ Ice

  • A2/ Marine sediments

  • A3/ Continental sediments

  • A4/ Tree rings

  • A5/ Biocarbonates

  • A6/ Speleothems