Gold: From birth in neutron star collisions to human exploitation on Earth’s crust

• Gold formed in neutron star collisions and entered Earth’s core via cosmic dust accretion. • Mantle overturn and plate tectonics transferred gold from Earth’s core to its crust. • Metasomatized mantle lithosphere influenced gold genesis in diverse ore systems. • Supercontinent assembly and dispersion controlled gold deposit temporal distribution. • Tectonic switching controlled gold-rich systems in convergent margins. Gold was born during neutron star collisions, with Earth forming from a cosmic cloud of gas and dust with metals, including gold, concentrated in its core during differentiation of the elements as planetesimals collided. The hot Earth witnessed crust-mantle-core overturns in the Paleoarchean and Mesoarchean that enriched the mantle in metals including gold, as recorded in mantle xenoliths and deep mantle CLIPPIR diamonds. The first small supercontinent Ur was assembled at ca. 3.1 Ga from cratons that included the Kaapvaal Craton with its mantle enriched in metals from the core such as Fe, PGEs, Cr, Ti, and V and including Au. It and the Pilbara and Zimbabwe Cratons, other components of Ur, all contain small, but significant, Mesoarchean orogenic gold systems that formed as a result of primitive subduction-related plate tectonics that predate the assembly of Ur. Breakup of Ur at about 3.0 Ga resulted in the development of the Witwatersrand Basin in a foreland setting. The unique giant concentration of gold and carbon in the Witwatersrand goldfields is interpreted to result from episodic mantle degassing of methane, hydrogen, and gold and other metal hydrides along a basin margin suture that resulted in exhalation of gold and other metals plus hydrocarbons into the basin: a phenomenon that was never repeated in Earth history. Major Neoarchean and Palaeoproterozoic orogenic gold systems, and some gold-rich volcanic massive sulfide (VMS) systems, formed in convergent margins during assembly of the Kenorland and Columbia supercontinents, respectively. There was then a hiatus in orogenic gold and VMS in the Boring Billion with its lack of subduction-related tectonics. However, giant iron-oxide copper–gold (IOCG) and related Cu-Au systems that had formed in an intracratonic setting in the Amazon Craton in the Neoarchean and Paleoproterozoic flourished in central Australia in the Boring Billion with formation of arguably the world’s most valuable mineral system at Olympic Dam. The breakup of Rodinia and assembly and breakup of Gondwana and Pangea witnessed many orogenies with related orogenic gold and gold-rich VMS systems developed in long-lived, complex convergent margins. Mesozoic to Cenozoic convergent margins and collisional zones related to tectonic events involving the paleo-Pacific and Pacific oceans led to an incredible inventory of gold in orogenic gold, porphyry-epithermal-skarn, gold-rich submarine porphyry-epithermal-VMS, intrusion-related, and Carlin systems. The idealized progression of mineralization events from VMS to porphyry, orogenic, epithermal, intrusion-related to Carlin gold-bearing systems in Cenozoic convergent margins relates to tectonic switching events from compression to extension or transpression that allowed structural access to fertile volatile-rich mantle lithosphere as a magma and fluid source. Hence, gold has followed a complex and tortuous pathway from birth more than 4.6 billion years ago to its availability for human conceptual exploration and subsequent exploitation close to the Earth’s surface.