Climate Affects Global Basin-Related Metallogeny

Abstract. The basin-related hydrothermal mineral deposits are the products of metal deposition in a relatively small area from metal-rich saline brines that source from basins. Recent studies have confirmed that the metal-rich ore-forming fluids were formed in semi-arid to arid environments, and are the products of a complex system involving precipitation, weathering, groundwater, precipitation-dissolution reactions, and evaporation. The evaporation is the main reason for the buildup of metals in saline brines. The formation of metal-rich saline brines is commonly accompanied by the formation of evaporites.

The statistical results of basin-related mineral deposits worldwide show that there are two metallogenic periods after the great oxidation event: 2.1–1.4 Ga (Period I) and 0.8 Ga to present (Period II), with few scattered between these two periods (metallogenic quiescence period). In addition, Metallogenic Period II has five metallogenic peaks: ~380–340 Ma (II-1), ~300–240 Ma (II-2), ~160–100 Ma (II-3), 60–40 Ma (II-4), and one specific stratiform Cu metallogenic concentration period of ~580–500 Ma (II-5). These two metallogenic periods and five peaks are coupled with the widespread development of saline deposits in time. The basin-related ore deposits are mainly symmetrically occurring in 10°–60° in paleo-latitudes, which is consistent with the occurring latitudes of evaporites.

The metallogenic quiescence period corresponded to the scarcity of saline deposits and was probably caused by the combination of a lack of hydrological closed basins and arid to semi-arid environments during 1.4–0.8 Ga. This quiescence period was coupled with the booming of stromatolites and the extremely thin continents, both of which suggest an Earth with flat continents that were covered by a hot and wet climate, and the widely developed shallow marine environments of the major continents at middle and low altitudes during 1.4–0.8 Ga.