The complimentary records of ancient differentiation events preserved by Archean-aged crust and modern ocean island basalts

Modern terrestrial mantle-derived rocks display a rich diversity of isotopic compositions that have been key to understanding the assembly of the silicate Earth over the last 2-3 billion years. Parallel to these advancements was an increasing understanding that Archean-aged cratonic rocks provide a window into foundational terrestrial processes that occurred in the first 1-2 billion years of Earth history. The study and application of these distinct records remained mostly independent until statistical and instrumental precision improved enough to measure meaningful heterogeneity in short-lived radiogenic isotopes (especially ¹⁴²Nd and ¹⁸²W) among young mantle-derived rocks. Recent developments in the study of ocean island basalts have revealed that some early domains in Earth’s mantle have never been fully homogenized and may also preserve information about foundational Earth processes.

The ¹⁸²W/¹⁸⁴W records of Archean and modern rocks are especially complimentary and reflect differing perspectives on core formation and subsequent late accretion processes. On the other hand, the ¹⁴²Nd/¹⁴⁴Nd signatures of some ocean island basalts may reflect the same global differentiation event preserved by many less altered cratonic rocks of Archean age. Continuing advancement in analytical precision will increase the potential to integrate the study of Archean-aged and modern rocks as mutually beneficial tools to understand processes such as core and dynamo formation, crustal differentiation, plate tectonics, and impact events. In turn, a detailed understanding of our planet’s early history in these respects is critical to identify which terrestrial exoplanets have the geological propensity to host life.