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Elements for the Origin of Life on Land — A Deep-Time Perspective from the Pilbara Cratonof Western Australia

Key Points

Overview

Water is one of the prerequisites for life to appear on a planet, and deep-sea hydrothermal vents have been a preferred setting for the origin of life. However, its propensity to dilute critical prebiotic elements and to retard polymerization of organic molecules suggests that a terrestrial hot spring field with the capacity for wet-dry cycling and element concentration represents a more likely candidate.

At a 3.5 billion-year-old, anoxic hot spring setting from the Pilbara Craton, Western Australia, its hydrothermal veins and compositionally varied pools and springs have concentrated all of the essential elements required for prebiotic chemistry, including not only the organic elements, C, H, N, O, P, and S, but also the critical trace elements, B, Mo, Zn, Ti, Mn, and K (Fig.1).

Figure 1: Schematic representation of a 3.5 billion-year-old hot spring system, the Pilbara Craton, Western Australia. The elements are concentrated in hot spring pools and in the altered footwall.

Temporal variability, together with the known propensity of hot springs for wet-dry cycling and information exchange, would lead to innovation pools with peaks of fitness for developing molecules (Fig.2).

An inference from the chemical complexity of the Pilbara analogue is that life could perhaps get started on planets with volcanoes, silicate rocks, an exposed land surface, and water, and the ingredients should form the backbone in the search for life in the Universe.

Figure 2: Schematic representation of the ability of thermally and chemically varied hot spring pools to drive molecular and structural innovation that led to peaks of fitness through random mixing of components via geyser splashing, pool recharge, and overspill.

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