Infiltration of Intercumulus Liquid as a Process for the Sulfide Relocation—An Example from Low-Sulfide Mineralization of the Burakovo–Aganozero Intrusion
| Autor: | G. S. Nikolaev |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Mineralization (geology) Sulfide Chemistry 020209 energy Pluton Geochemistry Compaction 02 engineering and technology Liquidus 010502 geochemistry & geophysics 01 natural sciences Infiltration (hydrology) Geophysics Geochemistry and Petrology Phase (matter) 0202 electrical engineering electronic engineering information engineering Dissolution 0105 earth and related environmental sciences |
| Zdroj: | Geochemistry International. 59:491-500 |
| ISSN: | 1556-1968 0016-7029 |
| DOI: | 10.1134/s0016702921050050 |
| Popis: | A mechanism is suggested to explain the transport of sulfide material by means of its dissolution and subsequent redeposition under the effect of an ascending infiltrating flow of intercumulus melt during the compaction of cumulates in layered plutons. Evidences of this process are observable in the Burakovo–Aganozero intrusion. Analysis of data on Cu concentrations in rocks of the pluton (more than 10 000 samples of core material from 160 boreholes) reveals two distribution types of the low-sulfide mineralization. The vertical sections of the first type are characterized by mineralization distributed throughout the whole thickness of the lower unit of clinopyroxene–orthopyroxene (Cpx–Opx) cumulates and the almost absolute absence of sulfides in all overlying rocks. In the second type, Cu mineralization is constrained to the top part of this unit of clinopyroxene–orthopyroxene (Cpx–Opx) cumulates, and the overlying rock sequence of the zone of clinopyroxene–orthopyroxene–plagioclase (Cpx–Opx–Pl) cumulates includes intensely mineralized rocks. Physicochemical analysis within the scope of D.S. Korzhinskii’s theory of acid–basic interaction and numerical simulations of the effects of major components of the melt on the solubility of the sulfide phase indicate that Ca and Mg play an important role in the liquid immiscibility/dissolution of the sulfides. A model is proposed for the origin of the low-sulfide mineralization of this pluton: clinopyroxene emergence on the liquidus resulted in the onset of liquid immiscibility of sulfide and produced Cu distribution of the first type. The infiltration of the intercumulus melt during the compaction of the cumulus material led to the dissolution and upward transport of the sulfide material for hundreds of meters and thus produced Cu distribution of the second type. |
| Databáze: | OpenAIRE |
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