Compositional trends of silicic and mafic magmas formed in the course of the evolution of the Mongolian-Transbaikalian mobile belt

B. A. Litvinovsky, A. N. Zanvilevich

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Numerous data on the mafic- and silicic-magma mixing point to involvement of the mantle-derived matter in the granitoid magma generation. However, it is still unclear whether the influx of the mantle component was significant or the latter played the role of an admixture only when large volume of silicic magma was produced within granitoid belts. We attempted to find an approach to this problem by comparing some important chemical parameters (alkalinity, HFSE content) in the time-ordered sequences of granitoids, synplutonic and pre-granitic mafic rocks which make up six magmatic series. Formation of the series is timed to the consecutive stages of the evolution of the large Mongolian-Transbaikalian mobile belt. A time span of about 250 Ma was studied. It has been established that at each stage of magmatic activity silicic and mafic magmas of the same or similar geochemical types were generated, from sodium-rich calc-alkaline magmas at the early stages to the alkaline and peralkaline at the latest stages. Compositional changes in the time-ordered sequences, both the granitoid and mafic ones, have been revealed to have the same trends. This is exhibited in the conjugated systematic increase in the rock alkalinity and HFSE content. Analysis of the results obtained, along with discussion of available geological, isotopic, and experimental data, suggests that the amount of the material delivered from the basaltic magmatic chambers to zones of silicic-magma generation was so considerable that in some cases it defined the main geochemical features of the produced silicic magmas.

Original languageEnglish
Pages (from-to)157-177
Number of pages21
JournalGeologiya i Geofizika
Volume39
Issue number2
StatePublished - 1 Dec 1998

Keywords

  • Coeval silicic and mafic magmas
  • Mantle-derived component in granitoids
  • Temporal compositional trends
  • Time-ordered sequences

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

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