Editorial (Preface)rge_169 313..315

Thematic Issue: Isotopic Geochemistry of MineralDeposits—Implication for Ore Genesis

Mineralization involves several processes, of whichchemical processes are the ones that finally result inprecipitation of metals or formation of minerals. Thus,geochemistry is an important field in the study ofmineral deposits. Geochemical (e.g. elemental, isoto-pic, etc.) characterization of mineral deposits is impor-tant in (i) understanding ore genesis, (ii) mineraldeposit classification, (iii) mineral exploration, (iv)extractive metallurgy or mineral processing, and (v)geoenvironmental research. This thematic issue ofResource Geology is devoted to isotopic geochemistry ofmineral deposits for understanding of ore genesis.

Isotopic geochemical characterization of mineraldeposits makes use of either radiogenic isotopes orstable isotopes. Radioactive decay of certain elementsnot only provides precise ages of geologic events butalso natural tracers of geologic processes and informa-tion on the rates and pathways of geologic evolution.These natural tracers are in the form of the radiogenicisotopes, which are products of natural radioactivity.The elements of usual interest in radiogenic isotopegeochemistry for understanding of ore genesis are Sr,Nd, Hf, Os, and Pb. These elements represent variousradioactive decay systems that are commonly used ingeochronology, namely Rb–Sr, Sm–Nd, Lu–Hf, Re–Os,La–Ce, U–Th–Pb, and decay systems involving iso-topes of He and other rare gases (e.g. Ar). Geochro-nology is, therefore, one of the most importantapplications of radiogenic isotope geochemistry, andthese two knowledge fields are often closely inter-twined. In contrast, the elements of interest in stableisotope geochemistry are H, Li, B, C, N, O, Si, S, and Cl.Most of these elements have the following commoncharacteristics: (i) have low atomic mass; (ii) have largerelative mass difference between their isotopes; (iii)form bonds with a high degree of covalent character;(iv) exist in more than one oxidation state (C, N, and S);(v) form a wide variety of compounds; (vi) are impor-tant constituents of naturally occurring solids andfluids; and (vii) have sufficiently high (generally at leasttenths of a percent) abundance, which facilitates analy-sis. Elements without these characteristics are usuallynot useful for obtaining geological information

relevant to ore genesis. Among the stable isotopes, O,H, C, and S are of the greatest interest in stable isotopegeochemistry for understanding of ore genesis.

A search through Resource Geology papers (i.e. origi-nal articles, review articles, notes, short communica-tions), from volumes 48 through to the present issueof volume 61, which are available in the Wiley On-line Library (http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1751-3928), shows the following results.One hundred sixty-nine papers have used K–Ar data,111 Rb–Sr, 90 U–Pb, 60 Ar–Ar, 52 La–Ce, 36 Sm–Nd, 30Re–Os, and 2 Lu–Hf. Thus, in the 421 papers in theResource Geology volumes mentioned, the most fre-quently used radioactive decay systems are K–Ar (c.40%), Rb–Sr (c. 26%), and U–Pb. This indicates theimportance of geochronology in understanding oregenesis. A further search through the same volumes ofResource Geology papers shows the following results.There are 56 papers dealing with stable isotopegeochemistry. In these papers, O is the mostly fre-quently used (c. 57%), followed by S (c. 52%), then H(c. 34%), and C (c. 30%). These papers have dealt withthe genesis of mostly hydrothermal, epithermal, skarn,porphyry-Cu, volcanogenic massive sulfide, andorogenic-Au deposits. Thus, at least in Resource Geologypapers, stable isotopes seem to be less frequently usedthan radiogenic isotopes in studies of ore genesis.

This thematic issue brings together six papers, whichare examples of how isotopic geochemistry is appliedto understand how certain mineral deposits haveformed. The first five papers were presented at theGoldschmidt 2010 Conference (13–18 June 2010, Knox-ville, Tennessee, U.S.A), and the last paper was pre-sented at the European Geosciences Union GeneralAssembly 2010 (2–7 May 2010, Vienna, Austria). Thefirst two papers use radiogenic isotope geochemicaldata. The next two papers use radiogenic and stableisotope geochemical data. The last two papers usestable isotope geochemical data.

Gertner et al. (2011) discussed, using mainly radio-genic isotopic geochemical data, a plausible geneticrelationship between mantle plume activity andorogenic-Au mineralization in the Yenisei Ridge in

doi: 10.1111/j.1751-3928.2011.00169.x Resource Geology Vol. 61, No. 4: 313–315

© 2011 The AuthorsResource Geology © 2011 The Society of Resource Geology 313

Central Siberia. In this ridge, alkaline and carbonatitemagmatic complexes, which are associated spatiallywith the Blagodat Au deposit, have Nd and Sr isotopicparameters that are typical of mantle or plume mattersources. In contrast, the Au-bearing sulfurized schistsin the Blagodat deposit are characterized by Nd and Srisotopic parameters typical of crustal rocks. Theseobservations seem to preclude genetic relationshipbetween mantle plume activity and Au mineralizationin the Yenisei Ridge. However, synthesis of the presentgeological, structural and isotopic geochemical data foralkaline magmatic rocks and auriferous metamorphicrocks in the Yenisei Ridge supports a proposition ofgenetic relationship between orogenic-Au mineraliza-tion and mantle plume-related magmatism. The basicrole of mantle plume-related magma was the provisionof local but focused thermal control on reactivation oftectonic processes and activation of metasomatic andhydrothermal processes that were involved in Aumineralization in sedimentary-metamorphic rocks inthe thrust-fold complex of the Yenisei Ridge.

Nie and Jiang (2011) propose that, based on fieldgeological observations and radiogenic isotopicgeochemical data, the Mo–W�Cu deposits in theHonggor-Shamai district (North China) were productsof magmatic hydrothermal events related to Indosinian(235–224 Ma) granitoid igneous processes, althoughone of the deposits was overprinted by the Yanshanian(137–131 Ma) hydrothermal event. They used molyb-denite Re–Os isotopic data from the ores and zirconU–Pb data from their host granitoid rocks. The radio-genic isotopic characteristics of the granitoids hostingthe deposits indicate that they were derived mainlyfrom the melting of juvenile mantle-derived materials,but they may also contain some upper-crust relatedcomponent. The ore-forming fluid, which precipitatedthe deposits, had a predominant magmatic componentat the early (Indosinian) ore-forming period but wascharacterized by magmatic and meteoric componentsat the late (Yanshanian) ore-forming period.

Li et al. (2011) interpreted their He–Ar radiogenicisotope data in conjunction with H and O stable isotopedata from previous works of the Tieshanlong Wdeposit (Jiangxi, China), and they propose that the ore-forming fluids associated with the deposit were domi-nated by crustal fluids with some contributions frommeteoric fluids. The radiogenic and stable isotopegeochemical data indicate that the ore-forming fluidsassociated with the deposit did not result from a simplemixing of the crustal- and mantle-derived end-memberfluids, but that primeval meteoric fluids were also

involved in the generation of the associated graniticmagma by partial melting of crustal metasedimentaryrocks. The data further suggest that boiling and secondmixing with “new” meteoric fluids took place duringmigration of magmatic-hydrothermal fluids intowall-rock fractures, resulting in drastic decrease oftheir metal transport capacity, which triggered theW-polymetallic mineralization.

Jemmali et al. (2011) analyzed and synthesized stableand radiogenic isotope data with published informa-tion about mineralogy, petrography and trace elementgeochemical data to infer that geological processesassociated with the formation of Mississippi valley-type Pb–Zn deposits at Jebel Ressas (Northern Tunisia).The d18O contents of calcite associated with the Pb–Znmineralization suggests that it is likely to have precipi-tated from a fluid that was in equilibrium with theTriassic dolostones. The values of d34S in galenas fromthe Pb–Zn deposits imply mixing of thermochemically-reduced heavy sulfur carried in geothermal- andfault-stress-driven deep-seated source fluid withbacterially-reduced light sulfur carried in topography-driven meteoric fluid. Lead isotope ratios in galenasfrom the Pb–Zn deposits are homogenous and indicatea single upper crustal source of base-metals for thesedeposits. Synthesis of the geochemical data with geo-logical data suggests that the base-metal mineralizationat Jebel Ressas was formed during the Serravallian–Tortonian (or Middle–Late Miocene) Alpine compres-sional tectonics.

Liu et al. (2011) discussed, based on detailed geology,fluid inclusion and C–H–O stable isotope data, thesource and genesis of ore-forming fluids associatedwith the Dongmozhazhua Pb–Zn deposit in the Tibetanplateau (China). The C–H–O stable isotope data of orefluids, cation compositions of fluid inclusions, and geo-logical information suggest two main possible fluidsources, namely basinal brines and condensed seawa-ter. The fluid inclusion data and regional geologysuggest that basinal brines derived from Tertiary basinslocated southeast of the Dongmozhazhua depositmigrated along deep detachment zones of the regionalthrust system, leached substantial base metals fromcountry rocks, and finally ascended along thrust faultsat Dongmozhazhua. There, the base-metal-rich basinalbrines mixed with bacterially-reduced H2S-bearingfluids derived from evaporated seawater preserved inthe Permo–Triassic carbonate strata. The mixing of thetwo fluids resulted in Pb-Zn mineralization.

Sushchevskaya et al. (2011) presented new stableisotope (H, O) data of fluids in tourmalines from the

E. J. M. Carranza

314© 2011 The Authors

Resource Geology © 2011 The Society of Resource Geology

large Sn deposit at Solnechnoye (Far East of Russia),and proposed that isotopic (H, O) data of fluids intourmaline, rather than those in quartz, muscovite, orchlorite, support robust interpretation on the nature ofmineralizing fluids associated with Sn deposits. Thesedata indicate that the Solnechnoye Sn deposit formedby fluid-rock interactions in a hydrothermal systemwhere the mineralizing fluid was mainly magmatic andto a lesser extent meteoric.

These papers demonstrate collectively that radio-genic isotope geochemical data and/or stable isotopegeochemical data, in conjunction with geological dataand other types of geochemical data, are useful forunderstanding ore genesis. Hopefully, the examplespresented in this thematic issue will inspire otherresearchers to use isotope geochemistry for under-standing mineral deposit formation and/or stimulatefurther mineral deposit studies in each of the areasdescribed in the papers in this thematic issue.

I thank Yasushi Watanabe for accepting to publishthis collection of papers in a thematic issue of ResourceGeology. I am grateful to all the authors for their con-tributions. I deeply appreciate the support of the fol-lowing individuals for reviewing the quality of thesubmitted manuscripts: Regina Baumgartner, MariaBoni, Ana Neiva, Sophie Decrée, Phillip Blevin, AlanGalley, Fidel Grandia, Zengqian Hou, Franco Pirajno,German Ripp, Hidehiko Shimazaki, Fernando Tornos,Bo Wan, and Wenjiao Xiao.

Emmanuel John M. Carranza

Department of Earth Systems AnalysisFaculty of Geo-Information Science and Earth Observation

(ITC)University of Twente

Enschede, the Netherlands

References

Gertner, I., Tishin, P., Vrublevskii, V., Sazonov, A., Zvygina, E.and Kolmakov, Y. (2011) Neoproterozoic alkaline igneousrocks, carbonatites and gold deposits of the Yenisei ridge,central Siberia: evidence of mantle plume activity and latecollision shear tectonics associated with orogenic gold miner-alization. Resour. Geol., 61, 316–343.

Jemmali, N., Souissi, F., Vennemann, T. W. and Carranza, E. J. M.(2011) Genesis of the Jurassic carbonate-hosted Pb-Zn depos-its of Jebel Ressas (North-Eastern Tunisia): evidence frommineralogy, petrography and trace metal contents andisotope (O, C, S, Pb) geochemistry. Resour. Geol., 61, 367–383.

Li, G., Hua, R., Zhang, W., Hu, D., Wei, X., Huang, X., Xie, L., Yao,J. and Wang, X. (2011) He-Ar isotope composition of pyriteand wolframite in the Tieshanlong tungsten deposit, Jiangxi,China: implications for fluid evolution. Resour. Geol., 61, 356–366.

Liu, Y. C., Hou, Z. Q., Tian, S. H., Yang, T. N., Song, Y. C., Zhang,H. R. and Carranza, E. J. M. (2011) Formation of the Dong-mozhazhua Pb-Zn deposit in the thrust-fold setting of theTibetan plateau, China: evidence from fluid inclusion andstable isotope data. Resour. Geol., 61, 384–406.

Nie, F. J. and Jiang, S. H. (2011) Geological setting and origin ofMo-W-Cu deposits in the Honggor-Shamai District, InnerMongolia, North China. Resour. Geol., 61, 344–355.

Sushchevskaya, T., Ignatiev, A. and Velivetskaya, T. (2011) Mag-matic nature of mineralizing fluids in the Solnechnoye Sndeposit (Russia) deduced from isotopic (H, O) compositionsof tourmaline. Resour. Geol., 61, 407–413.

Preface

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