Geochemistry, mineralogy and evolution of the madan ore field – An overview

Vladimir Georgiev*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The ore field is located in a metamorphic core complex. The latest metamorphism is of Paleogene age. The mineralization is lead-zinc, hydrothermal. The ore bodies are mainly of vein type. The following stages and mineral parageneses are distinguished: First stage – early pre-ore alterations (johannsenite-rhodonite skarns); immediate pre-ore alterations (berezites); post-ore alterations (chloritization); quartz-pyrite paragenesis; galena-quartz paragenesis; quartz-galena-sphalerite (main productive) paragenesis; rhodochrosite-dolomite-manganocalcite paragenesis. Second stage – quartz-arsenopyrite-sulphosalt paragenesis; manganocalcite-calcite paragenesis. Isotopic studies of water composition show δ D values in the range of −40 to −80‰. The δ18O content varies between 0 and −12‰. These data suggest a predominantly meteoric origin of the hydrotherms. The isotopic composition of the sulphide sulphur δ34S ranges from +0.3 to +8.2‰. Average δ34S values of sulphides coincide with those of the pre-metamorphic pyrrhotite from the metamorphic basement. These data suggest crustal origin of the sulphur. Isotopic studies of Pb in galena fall entirely within the field of the “upper crust” or the granite layer, suggesting a crustal origin of the ore substance. According to Ar/Ar age determinations of muscovite, the mineralization is dated 30.4±0.5 Ma, which is comparable with or by 0.5–1.0 Ma younger than the rhyolite dykes in the area. These data give reason to assume a paragenetic connection between the late extensional Paleogene magmatism (subvolcanic bodies) and the ore mineralizations. This magmatism is the “initiator” of the ore-forming processes.

Original languageEnglish
Pages (from-to)1021-1026
Number of pages6
JournalComptes Rendus de L'Academie Bulgare des Sciences
Volume68
Issue number8
Publication statusPublished - 2015 Aug 8
Externally publishedYes

Keywords

  • Hydrothermal lead-zinc ore mineralizations
  • Isotopic composition
  • Mineral paragenesis
  • Physico-chemical parameters
  • Rhodopes

ASJC Scopus subject areas

  • General

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