Komatiites: issues of geodynamics and metallogeny

4th International Scientific Conference "Arctic: History and Modernity"

生态环境科学;历史学

Sorokhtin, N.O.^1 ; Kozlov, N.E.^2

Shirshov Institute of Oceanology RAS, Moscow, Russia^1

Geological Institute, Kola Science Centre, RAS, Apatity, Russia^2

关键词: Chalcophile elements;    Equatorial belts;    Genetic diversity;    Greenstone belts;    Platinum group minerals;    Possible mechanisms;    Tidal effects;    Tidal interactions;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/302/1/012052/pdf
DOI  :  10.1088/1755-1315/302/1/012052

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

In the current paper the authors make an attempt to provide a theoretical basis for regular features of enrichment of komatiites in the present-day subequatorial part of the Earth with gold, nickel and platinum group minerals. The authors suggest that Archaean komatiitic greenstone belts formed mostly in the subequatorial area under significant overheating of the mantle at that time. The paper suggests and describes in detail a possible mechanism of these processes. According to it, komatiitic magmas were enriched with siderophile and chalcophile elements during a gradual melt of the "cold" substance of the primary Earth. It melted along the equator due to the tidal effect of the Moon on it. In the Archaean the Moon was much closer to the Earth than nowadays, and its orbit was near the Roche limit. It considerably increased the tidal interaction of the two planets and provided overheating of the Earth's equatorial belt. Therefore, more heated areas must have had melts with high clarkes of protocrystallization elements and lower clarkes of concentration. It inevitably affected specific metallogenic features of produced komatiitic magmas and genetic diversity of deposit types in these areas. This paper corroborates the idea that the drift of the continents did not provide their chaotic movement along the mantle surface in the Earth's history. Continental domains that formed in the subequatorial area in the Archaean are still near it and compose an ancient greenstone belt composed of komatiites.