Trace elements in tourmalines from massive sulfides deposits and tourmalinites; geochemical controls and exploration applications

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doi: 10.2113/gsecongeo.91.4.657
Authors:Griffin, William L.; Slack, John F.; Ramsden, Anthony R.; Win, Tin Tin; Ryan, Chris G.
Author Affiliations:Primary:
CSIRO Exploration and Mining, North Ryde, N.S.W., Australia
Other:
Macquarie University, Australia
U. S. Geological Survey, United States
Volume Title:Economic Geology and the Bulletin of the Society of Economic Geologists
Source:Economic Geology and the Bulletin of the Society of Economic Geologists, 91(4), p.657-675. Publisher: Economic Geology Publishing Company, Lancaster, PA, United States. ISSN: 0361-0128
Publication Date:1996
Note:In English. 69 refs.; illus., incl. 5 tables
Summary:Trace element contents of tourmalines from massive sulfide deposits and tourmalinites have been determined in situ by proton microprobe; >390 analyses were acquired from 32 polished thin sections. Concentrations of trace elements in the tourmalines vary widely, from <40 to 3,770 ppm Mn, <4 to 1,800 ppm Ni, <2 to 1,430 ppm CU, <9 to 4,160 ppm Zn, 3 to 305 ppm Ga, <6 to 1,345 ppm Sr, <10 to 745 ppm Sn, <49 to 510 ppm Ba, and <3 to 4,115 ppm Pb. Individual grains and growth zones are relatively homogeneous, suggesting that these trace elements are contained within the crystal structure of the tourmaline, and are not present in inclusions. The highest base metal contents are in ore-related tourmaline samples from Kidd Creek (Ontario), Broken Hill (Australia), and Sazare (Japan). Tourmaline data from these and many other massive sulfide deposits cluster by sample and display broadly linear trends on Zn vs. Fe plots, suggesting chemical control by temperature and hydrothermal and/or metamorphic fluid-mineral equilibria. Significant Ni occurs only in samples from the Kidd Creek Cu-Zn-Pb-Ag deposit, which is associated with a large footwall ultramafic body. An overall antithetic relationship between Zn and Ni probably reflects fluid source controls. Mn is correlated with Fe in tourmalines from barren associations, and possibly in some tourmalines associated with sulfide vein deposits. Sn increases systematically with Fe content irrespective of association; the highest values are found in schorls from granites. Other trace elements are generally uncorrelated with major element concentrations (e.g., Sr-Ca). Base metal proportions in the tourmalines show systematic patterns on ternary Cu-Pb-Zn diagrams that correlate well with the major commodity metals in the associated massive sulfide deposits. For example, data for tourmalines from Cu-Zn deposits (e.g., Ming mine, Newfoundland) fall mainly on the Cu-Zn join, whereas those from Pb-Zn deposits (e.g., Broken Hill, Australia) plot on the Pb-Zn join; no data fall on the Cu-Pb join, consistent with the lack of this metal association in massive sulfide deposits. The systematic relationship between base metal proportions in the tourmalines and the metallogeny of the host massive sulfide deposits indicates that the analyzed tourmalines retain a strong chemical signature of their original hydrothermal formation, in spite of variable metamorphic recrystallization. Such trace element patterns in massive sulfide tourmalines may be useful in mineral exploration, specifically for the evaluation of tourmaline concentrations in rocks, soils, and stream sediments.
Subjects:Base metals; Cations; Chemical composition; Copper ores; Crystal chemistry; Emission spectra; Geochemical controls; Hydrothermal alteration; Inclusions; Lead ores; Massive deposits; Massive sulfide deposits; Metal ores; Metamorphic rocks; Metasomatism; Mineral assemblages; Mineral composition; Mineral deposits, genesis; Mineral exploration; Mineral inclusions; Mines; Patterns; Petrography; Phase equilibria; Recrystallization; Ring silicates; Rocks; Schists; Silicates; Silver ores; Soils; Spectra; Stratabound deposits; Stream sediments; Thin sections; Tourmaline group; Tourmalinite; Trace elements; Zinc ores; Asia; Australasia; Australia; Broken Hill Mine; Canada; Eastern Canada; Far East; Japan; Newfoundland; Ontario; Hydrothermal processes; Kidd Creek Deposit; Ming Mine; Proton probe data; Sazare Deposit
Abstract Numbers:97M/1858
Record ID:1997019769
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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