Organic Isotope Geochemistry

Group of Dr. Alfredo Martínez-García

Example of organic molecules used in paleoclimatic studies and the organisms that produce them. Credits: upper 2 pictures courtesy of R. Schiebel (MPIC), third picture starting from top is from Könneke et al. 2005 (Reprinted by permission from Nature), bottom picture and molecular structures A. Martínez-García (MPIC).
Example of organic molecules used in paleoclimatic studies and the organisms that produce them. Credits: upper 2 pictures courtesy of R. Schiebel (MPIC), third picture starting from top is from Könneke et al. 2005 (Reprinted by permission from Nature), bottom picture and molecular structures A. Martínez-García (MPIC).

Organic mater preserved through the geological record represents a vast repository of information about past changes in Earth’s biogeochemical cycles and climate.

The distribution and concentration of key organic molecules synthetized by aquatic and terrestrial organisms (biomarkers) provide insights on a wide variety of environmental parameters, such as changes in ocean temperatures, phytoplankton productivity or dust deposition. Furthermore, the stable isotope composition of these molecules (δD, δ13C and δ15N) can be used to reconstruct changes in regional rainfall, vegetation, salinity or atmospheric CO2 levels.

The isotopic composition of organic N bound within microfossils (e.g. foraminifera, diatoms, etc) contains key information about past changes in the nitrogen cycle. For example, in the polar oceans, it can be used to trace the history of nitrate consumption, a process that is directly involved in the modulation of atmospheric carbon dioxide concentrations during ice ages.

Our research focuses on the application and refinement of these techniques to reconstruct the evolution of climate during key intervals of Earth’s history. A particular interest of this group is the study of a series of key biogeochemical processes occurring in high latitude oceans, and its role in controlling atmospheric CO2 levels through time.