Geology, geochemistry, and origin of the continental karst-hosted supergene manganese deposits in the western Rhodope Massif, Macedonia, northern Greece

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Authors:Nimfopoulos, M. K.; Pattrick, R. A. D.; Michailidis, K. M.; Polya, D. A.; Esson, J.
Author Affiliations:Primary:
Institute of Geology and Mineral Exploration, Salonika, Greece
Other:
University of Manchester, United Kingdom
Aristotle University, Greece
Volume Title:Exploration and Mining Geology
Source:for the [Exploration and Mining Geology, 6(2), p.171-184. Publisher: Pergamon Press] Geological Society of the Canadian Institute of Mining, Metallurgy and Petroleum, New York - Oxford, International. ISSN: 0964-1823
Publication Date:1997
Note:In English. 39 refs.; illus., incl. 5 tables
Summary:Mn-oxide ore deposits of commerical grade, which occur in the Rhodope massif near Kato Nevrokopi in the Drama region of N Greece, developed by weathering of continental hypogene rhodochrosite-sulphide veins. The latter are confined by tectonic shear zones between marble and metapelites, wich oreshoots (≤ 50 × 20 × 5-10 m) extending into the marble. Supergene oxidation of the mineralization led to the formation of in situ residual Mn oxide deposits and secondary infills of Mn oxide ores in embryonic and well developed karst avities. Whole-rock geochemical profiles across mineralized zones confirm the role of thrusts and faults as solution passageways. Three zones are recongnized in the in situ supergene veins: 1) a stable oxidation zone where immobile elements form stable oxide mineral phases and mobile elements are leached, 2) a transitional zone in which element behaviour is strongly influenced by seasonal movements of the water-table and variations in pH-Eh conditions, 3) a zone of permanent flooding where variations in pH-Eh are minimal. Zone (3) is considered as the source zone for karst cavity mineralization; during weathering, meteoric waters which were CO2-rich (PCO2 ∼ 10-3.8 to 10-1.4) and oxygenated (fO2 ∼ 10-17 for malachite), percolated downwards through the veins causing breakdown and dissolution of sulphides, and marble, and oxidation of rhodochrosite to Mn oxides. The order of mobility of elements in karst settings was Na > K > Mg > Sr > Mn > As > Zn > Ba > Al > Fe > Cu > Cd > Pb. [R.A.H.]
Sections:Geochemistry
Subsections:Minerals and ores
Subjects:Geochemistry; Karst; Lithogeochemistry; Manganese ores; Marbles; Metal ores; Metamorphic rocks; Mineral deposits, genesis; Mineral resources; Oxides; Paleozoic; Paragenesis; Supergene processes; Europe; Greece; Greek Macedonia; Macedonia; Rhodope Mountains; Southern Europe; Karposluk Deposit; Kato Nevrokopi Deposit; Northern Greece; Synthia Mine
Abstract Numbers:98M/3845
Record ID:1998072387
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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