Podcast INQUA India 2027

Geochemistry is the study of natural archives like sediments, ice cores, soils, and even cave deposits to reconstruct past temperature, rainfall, and atmospheric conditions.

One of the most powerful tools of geochemistry is stable isotope geochemistry.For example, the proportion of oxygen isotopes ¹⁸O and ¹⁶O acts as a paleo-temperature indicator. Lower proportions of 18O generally point to colder climates, while higher values suggest warmer conditions. Similarly, carbon isotopes help us understand vegetation patterns, with different proportions of 13C and 12C indicating whether landscapes were dominated by C₃ plants, C₄ plants or even CAM-type vegetation.

But that’s not all—trace elements can also tell a story.Ratios like the magnesium to calcium ratio in marine shells help estimate ancient sea surface temperatures. And in lakes or caves, proportions of elements such as strontium or barium reflect changes in rainfall and evaporation. Perhaps most strikingly, air bubbles trapped in ice cores preserve ancient atmospheres, giving us direct records of past concentrations of greenhouse gases like carbon dioxide and methane. Together, these geochemical proxies allow us to reconstruct climate with remarkable precision and understand how natural variability compares to today’s changes in the climate.

In simple terms, this means figuring out where sediments come from.

Every rock has a unique chemical fingerprint. By analyzing elemental and isotopic compositions, like strontium, neodymium, or lead isotopes, scientists can trace sediments back to their source regions. This is especially useful in understanding erosion patterns, river systems, and even ancient wind directions. For instance, wind-blown deposits like loess can be traced back to specific desert regions, revealing past aridity and atmospheric circulation. In glacial and river systems, geochemistry helps distinguish between locally sourced material and sediments transported over long distances.

At the Birbal Sahni Institute of Palaeosciences significant contributions have been made since its inception, especially in palynological studies from regions like Rajasthan, Uttarakhand, Himachal Pradesh, Jammu & Kashmir, and northeast India. Geochemical research gained strong momentum after the 1990s, particularly in river, coastal, and lake environments. A major turning point came in 2015 with the establishment of advanced geochemical laboratories at BSIP. These facilities include state-of-the-art instruments like XRD, ICP-OES/MS, IRMS, GC-MS, X-Ray Diffraction, Inductively Coupled Plasma-Optical Emission Spectroscopy / Mass Spectrometry, Isotope Ratio Mass Spectrometry, Gas Chromatography-Mass Spectrometry, and more, making it one of the most comprehensive setups in North India.