J, Mineral Deposits. 78, p. Bucureşti, 1997 ALPINE METALLOGENESIS OF ROMANIAN Şerban VLAD, Mircea Institutul Geologic a.1 României. Str. Ca.rafisebe!j fir.I. R 78344 Bucureliti 32. words: Alpine metallogenesis. Plate tectonÎcs. Romanian Carpathians. Metallo­ models. Abstract: From both metallogenetic and structural of view the Romanian belong to the Alpine realm and represent a part of the subglobal Mediter­ ranean (Tethyian )-Himalayan belt. The IS by a complete se­ quence of spreading-contraction events. Both ahort-lived and more evolved rifta are characteristic of this setling and yielded variou8 types of and Hlt"""UJ~t:u The Alpine ores are the most the national resource estimates out and present r ..",,,nlp," stages are connected with the Laramian and magmatic products. The is related ta Senonian-Paleocene and Late Tertiary subduction events ore deposits of island arc of Andean types. Regional occurrences. tectonic characteristics, alteration and zoning, ore and other elements form the outline of the metallogenetic models in and non-porphyry environments. Laramian (Banatitic) metallogenetic modela in environments are represented in Banat by the Suvorov model with skarn halo and the Bozovici model with pyrite halo. Laramian (Banatitic) metallogenetic modela in non-porphyry environment are de­ nned as Ocna de Fier model and Dognecea model in Banat of commonly calcareous host rock with aud diatal Fe-Cu/Pb-Zn skaen formation and Bă.î~a Bihorului model in the Mts. with extended skarn formation and Mo-Bi- W-CIl mineralisation the whole contact aureole of the metallogenetic models in por- phyry environment are outlined in the Sout,h Le. Valea Morii mode! with veins halo and Rosia Poieni model with halo. The Gurghiu-Harghita- C1I.limani portion of the East Carpathian volcanic arc exhibits aborted porphyry copper systems. metallogenetic models in non- environment are represeuted systems in Baia Mare and Mts as follows: Baia with breccia pipe and veins Cavnic model with Săcărâmb model with Montană Au-Ag aud 1. lntroduction westward by the West V"'ClII'''''''' and southeastward by the Balkans. The main geotectonic units of the Romanian ter- ritory are represented by two mobile the Carpathians and North Dobrogea, and cra- II. .."u .. ,.,,- evolution lons. The Carpathian mountain range (that is the East and South Carpathians and Mts) witb intramontane Transylvanian and Pannonian Basina is The geodynamic evolution the Romanian terri- surrounded by the foreland of main/y . tory is interpreted in connection with successi ve 'cycles From both metallogenetic and structural of of ocean and (Wilson orogenic cycles). view the Romanian t.o the Alpine Geologic- structural and data provide realm and Mediter- evidence for reconstitution of recent aud prior (tbat ranean is Alpine as well as U pper Lower Paleozoic 6 and Precambrian) tectonic The Alpine metallic resources (Au, Ag, Cu, Mn , etc) is by a complete sequence of spreading- have been almost continuously extracted, especially contraction events whereas the the ores. Numerous ore minerals have type are represented by remnants of sequences incorporated localities in occurrences in famous ore such as into Alpine strudures. Baia Mare, the Gold Quadrilater in the South Apuseni The architecture of the Romanian Mts., and Banat. Baia Mare vein sets and the Gold is confined to evolution of the Quadrilateral are known in the literature for Tethyian trench system. Both short-lived and more their gold-silver whereas skarn deposits in Ba­ evolved rifts are characteristic of this setting and nat are type deposits of their kind. yielded various types of magmatic and metallogenetic An is made below ta out line the Alpine produds. The ultimate result is the Tethyside col­ metallogenetic evolution of the Romanian Carpathi­ that formed by interaction of the African plate ans. Metallogenesis related to ali of a Wilson with the and orogenic cyde has been (Plate). Interpretation of ocean nel1tal riftil1g to subduction-, collision- and fioor subduction, collision and post-collision-related settings). The geologic al features events is sometimes difficult due to contradictory as­ that controlled the ore deposition during this sessments when terms such as plate-microplate­ are correlated with the behaviour of sialic block, related subduction or subfluence (in­ the metals tracrusfal movement), ophiolite meaning and signifi­ The Alpine ores are the most important cance (island arc- or ocean floor spreading-products), tively and 80% of the national resource es­ calc- alkaline volcanicity or rift- timates (mined out and present rezerves/resources) of related to and correlation with the the national resource estimates. The main major Tethyian acceptance or denial of back- connected with the Laramian arc in the Carpathians and so ono products skarn deposits and porphyry de­ Pre-Alpine geodynamic or paleotectonic models of posits) volcanic ( especially the Carpathians are difficult to reconstruct. The vein deposits and porphyry Alpine evolution, to recent interpretations 1994, Rădulescu et al, 1993;Balin- Metallogenesis related to intracontinental 1996, M.Lupu, 1996), is related to the rifting main that Îs the Vardar zone. The The Danubian units of tbe South Carpathians con­ Transylvanian Tethys area and the rift of the tain Ma-W mineralization in the Mraconia The and SouthCarpathians occurred during the environment consists ofbimodal magmatic products period. Contractions gave rise la the by north-south curved configuration and the complex granodiorite and lamprophyre dikes that nappe strudure. Anyway, the problem of trated mylonitised metamorphic rocks of the Neamţll and torsion referred ta the orocline versus spurious Series (Metallogenetic unit lA in Plate). A major orocline theme of the belt in general and the monzogranite dike underwent and phyllic al­ Carpathian7Balkan branch in particular still represents teration; molybdenite and common sulfides veinlets a topic of discussions. and impregnations occur in the phyllic zone. Carbon­ Three associations ate int.ercalations of the cryst.alline schists the groups of nappes or nappes basins of the skarns with scheel­ Romanian Carpathians (Plate): the J urassic-Early ite, magnetite, and hematite. Ab­ Cretaceous of tholeiitic ta calc­ solute age data (209-145 m.y., K-Ar) and bimodal mag­ a1kaline charader in the South Apuseni Mountains, matic produds with associated porphyry Mo mineral­ the Laramian magmatic belt (Banatites) of calc­ ization are characteristic of an aborted ensialic rift. It alkaline character in the Apuseni Mountains and South however, difficult to ascertaÎn if this rifting repre­ and the Late magmatic sents back-arc extension of Late PaleozoÎc collisional of calc-alkaline to shoshonitic character in the East or incipient intracontinental rup- a,~lIU"'ll" and South Apuseni Mountains. Mesozoic (Vlad et 1984). The basement nappes of the South and East Carpathians contain amall Pb-Zn-Ba ore The III. Metallogenesis Group (South Carpathians) is cut by Jurassic bimodal (alkali- rhyoIite and lamprophyre) dikes aud The Romanian contains numerous ore de- Pb-Zn ore veins contro\led by ENE-WSW lin- known and mined sin ce times. The eation. sulphides occur in quartz ALPINE METALLOGENESIS OF THE ROMANIAN CARPATHIANS 7 or }}arite gangue (Barsa and Şinca- Holbav metallo­ geochemical evidence that the ophiolite assoclatlOn genetic districts). Aborted rifts found in the Bu­ formed as tholeiitic ocean-floor basalts in a small ocean covinian Nappe (E~t Carpathians) contain Ba-Pb-Zn, baSini the related ore deposits were ascribed to the Fe and Mo occurrences related to Mesozoic sedimen­ Joma type sensu Pearce and Gale (1977). They occur tary and igneous rock!>, as explained below (Ianovici in basalts as small stratiform pods of massive chalcopy­ and Borco§,1982).!' . ri"te;with subordinate pyrite and sphalerite in quartz Triassic dolomitic limestones at Delnita \~~in gangue. The massive ·ore is commonly underlain by strata?ound Fe ores associated with minor barlţf~~d pyrite + chalcopyrite + sphalerite stockworks (Metal­ Pb-Zn ores. The lens-like bodies are mainlY~!3i(Jer~tic­ logenetic Unit 2 in Plate). ankeritic in theeast and hematitic in the w~.: ' Metallogenesis in subduction-related settings Along the Ostra-Gemenea-SIătioara alignrri~ ba­ rite and witherite accumulations are associated with Three successive Alpine subduction events in the base-metal ores. At Ostra north-south striking veins Romanian Carpathians formed the vast majority of cut the metamorphic basement and the Mesozoic sedi­ metallic ore deposits in Romania. mentary cover. At least two barite generations as well Jurassic-Lower Cretaceous, Upper Cretaceous­ as witherite, pyrite, sphalerite, galena, tetrahedrite Paleocene and Late Tertiary events in turn yielded ore have been recognized; at depth the penetrated gneisses deposits of island arc or Andean types (Plate, Fig.l). are impregnated with barite. It seems likely that The Jurassic-Lower Cretaceous event yielded three early barite occurrences were remobilised duringpost­ stages ofmagmatism in the South Apuseni Mts. These Jurassic rifting, before major Middle Cretaceous de­ are.a tholeiite series and subsequent calc-alkaline se­ formation. The mineralization is found discontinu­ ries;".both of island arc type, and a final spilitic com­ ously as far south as Gemenea and SJătioara where plex associated wit.h an active marginal basin (Nicolae base-metal and barite veins cut the crystaHine schists et al., 1992). (Metallogenetic Unit lB in Plate). The