Colloquium: Dustin Trail

Dustin Trail

Postdoctoral Research Associate, Department of Earth & Environmental Sciences, Rensselaer Polytechnic Institute

Abstract: Geologists investigate the evolution of the atmosphere, crust, and mantle through time by direct study of preserved rocks. However, rocks from the first 700 million years of Earth history (the Hadean Eon) are either sparse or altogether absent. The discovery of >4 billion-year-old detrital zircons (ZrSiO₄) and the development of new micro-analytical capabilities made possible new avenues of early Earth research. While the existence of this mineral is not unique to any particular rock type or environment (e.g., zircons have been discovered in meteorites and lunar rocks), the geochemistry of zircon can in fact be used to understand the crystallization environment. In this regard, laboratory experiments are a key source of information, because experiments allow the trace element and isotope chemistry of (synthetic) zircon to be investigated with respect to a controlled growth environment. Thus, these experiments play a fundamental role in the quest to link chemical signatures preserved in ancient zircons with Hadean processes. The prevailing view that emerged is that the early Earth may have contained a stable hydrosphere, water-saturated or (near water-saturated) granitic magmas, and volcanic emanations dominated by neutral gas species (e.g., CO₂, H₂O, and SO₂). The Hadean Earth may also have been capable of supporting life ~200 million years after accretion and perhaps earlier.