Abstract The Allchar Au-As-Sb-Tl deposit is situated in the western part of the Vardar zone, the main suture zone along the contact between the Adriatic and the Eurasian tectonic plates. It is spatially and temporally associated with a Pliocene (~5 Ma) postcollisional high-K calc-alkaline to shoshonitic volcano-plutonic center. The Allchar deposit shares many distinctive features with Carlin-type gold deposits in Nevada, including its location near a terrain-bounding fault in an area of low-magnitude extension and intense magmatism. The mineralization is mostly hosted in calcareous sedimentary rocks at intersections of high-angle faults in permeable stratigraphy. The alteration types (carbonate dissolution, silicification, and argillization), ore mineralogy (auriferous arsenian pyrite and marcasite, stibnite, realgar, orpiment, and lorandite), high Au/Ag ratios, and low base metal contents are also typical of Carlin-type gold deposits in Nevada. However, the Allchar deposit differs from Nevada Carlin-type gold deposits as follows: it is an isolated Au prospect with a close spatial and temporal relationship to a shoshonitic volcano-plutonic center in a mineral belt dominated by intrusion-related Cu-Au porphyry, skarn, and hydrothermal polymetallic deposits. The deposit is clearly zoned (proximal Au-Sb to distal As-Tl), it has a significantly higher Tl content, trace elements in pyrite and marcasite are homogeneously distributed, and synore dolomitization is a widespread alteration type. Gold mineralization is most abundant in the southern part of the deposit. It occurs mostly as invisible Au in disseminated pyrite or marcasite and as rare native Au grains. Gold mineralization is accompanied by intense decarbonatization and silicification. Fluid inclusions and the hydrothermal alteration mineral assemblage indicate that Au was deposited from hot (>200°C), saline (up to ~21 wt % NaCl equiv), moderately acidic (pH <5) fluids that carried traces of magmatic H 2 S and CO 2 . In the calcareous host rocks, mixing of such fluids with cool, dilute, near-neutral groundwater triggered deposition of Au and Fe sulfides. In Tertiary tuff, isocon analysis shows that sulfidation of preexisting Fe minerals was a critical factor for deposition of Au and Fe sulfides. Antimony mineralization prevails in the central part of the deposit, and it is mostly associated with dark-gray to black jasperoid. Stibnite, the most common Sb mineral in the Allchar deposit, occurs as fine-grained disseminations in jasperoid and as fine- to coarsely crystalline masses that fill vugs and fracture zones lined with drusy quartz. Fluid inclusions entrapped by stibnite-bearing jasperoid, quartz, and calcite crystals suggest that stibnite was deposited from more dilute and cooled fluids (aqueous-carbonic fluid inclusions: 6.0–3.5 wt % NaCl equiv, T h = 102°−125°C; aqueous fluid inclusions: 14.5 and 17.1 wt % NaCl equiv, T h = 120°−165°C). In contrast to stibnite, As sulfides (orpiment and realgar) and Tl mineralization are associated with argillic alteration. Fluid inclusions hosted by realgar, orpiment, dolomite, and lorandite record deposition from more dilute (2.6–6.9 wt % NaCl equiv) and relatively cold fluids (T H = 120°−152°C) enriched in K. Isocon diagrams show a tight link between Tl and the low-temperature argillic alteration as well as a significant correlation between Tl and K. The spatial relationship of Tl mineralization with dolomite suggests that Tl deposition was also promoted by neutralization of acidic fluids. The δ D and δ 18 O data obtained from gangue minerals and fluid inclusions indicate that magmatic fluid mixed with exchanged meteoric water at deep levels and with unexchanged meteoric water at shallow levels in the system. The δ 13 C and δ 18 O values of carbonate minerals and extracted fluid inclusions suggest mixing of carbonate rock buffered fluids with magmatic and atmospheric CO 2 . The sulfur isotope values of early disseminated pyrite and marcasite show that H 2 S was initially derived from diagenetic pyrite in sedimentary rocks. In contrast, Sb and As mineralization indicate a strong input of magmatic H 2 S during the main mineralization stage. Late-stage botryoidal pyrite and marcasite are depleted in 34 S, which indicates a diminishing magmatic influence and predominance of sulfur from sedimentary sources during the late-mineralization stage. Fractionation of isotopically light sulfide species from isotopically heavy sulfates due to oxidation under increased oxygen fugacity cannot be excluded.

A review of Paleogene–early Miocene igneous rocks of the Alpine-Carpathian-Pannonian-Dinaric region is presented in this paper. We attempt to reveal the geo-dynamic link between Paleogene–early Miocene igneous rocks of the Mid-Hungarian zone and those of the Alps and Dinarides. Our summary suggests that Paleogene–early Miocene igneous rocks of all these areas were formed along a single, subduction-related magmatic arc. The study also highlights orthopyroxene-rich websterite mantle xenoliths from west Hungary and east Serbia that were formed in the vicinity of a subducted slab. We discuss the location and polarity of all potential subduction zones of the area that may account for the igneous rocks and orthopyroxene-rich mantle rocks. However, results of seismic tomography on subducted slabs beneath the studied area combined with geological data demonstrate that igneous rocks and mantle rocks cannot be explained by the same subduction process. We propose that the Paleogene–early Miocene arc was mainly generated by the Budva-Pindos subduction zone, subordinately by Penninic subduction, whereas mantle rocks were possibly formed in the vicinity of the older Vardar subduction zone. Continental blocks possibly moved together with their mantle lithosphere. The present diverging shape of the proposed arc has been achieved by considerable shear and rotations of those lithospheric blocks.

In the Mediterranean area, four major lamproitic provinces with uniform geological, geochemical, and petrographic characteristics are recognized: Spain, Italy, Balkans, and Turkey. Mediterranean lamproites are SiO 2 -rich lamproites, characterized low CaO, Al 2 O 3 , and Na 2 O, and high K 2 O/Al 2 O 3 and Mg-number. They are enriched by in large ion lithophile elements relative to high field strength elements and in Pb, and show depletion in Ti, Nb, and Ta. The Mediterranean lamproites are characterized by a wide range of 87 Sr/ 86 and 143 Nd/ 144 Sr i Nd i . Both intra- and interprovince variations are significant. In contrast, the Pb isotope compositions of all Mediterranean lamproite provinces are almost identical, falling within the pelagic sediment field and resembling local upper-crustal sediments and Mesozoic flysch sediments from the Tethyan Ocean. Using the Serbian lamproites as an example, we develop constraints on the mantle melting processes and geodynamic environment of the whole Mediterranean lamproitic province. Partial melting of refractory mantle material previously enriched in incompatible elements is considered to be the most likely explanation for Mediterranean lamproites. The depleted-mantle component is probably multiply depleted peridotite from above the subducting plate during Mesozoic subduction processes, which preceded collision and orogenesis. The considerable variations of Sr-Nd isotopes are explained as having been produced by vein + wall-rock melting involving metasomatic veins that were out of isotopic equilibrium with the peridotite wall rock during melting. The uniformity of the Pb isotope compositions of all Mediterranean provinces is a result of the presence of a common crustal isotopic end member in their mantle source similar to flysch sediments from the Vardar Tethyan Ocean. No generic geodynamic scenario can explain lamproites, but neither mantle plume nor subduction is essential for the initiation of the volcanism. Most of the evidence implies postcollisional tectonics, including delamination of lithospheric mantle and/or orogenic collapse, as the major causes for the volcanism.

The Hellenides constitute an integral part of the Alpine orogenic system in southeast Europe. Despite the recognition of several subparallel zones, which are interpreted as terranes separated by ophiolitic sutures (e.g., Pindos and Vardar sutures), the classical view of an orogen with a foreland fold-and-thrust belt, a central crystalline zone, and a rather undeformed hinterland is still under discussion. This paper concentrates on basement terranes of exotic provenance in two of the internal zones of the Hellenides that support the interpretation of the Hellenides as an accretionary orogen formed by amalgamation of crustal segments during the subduction of Tethyan oceanic basins. The oldest of these terranes, the Florina terrane in the Pelagonian zone, is composed of Neoproterozoic arc-related orthogneisses. Two other exotic terranes occur east of the Vardar zone within the Serbo-Macedonian Massif. The Pirgadikia terrane is a microterrane in the southern Chalkidiki Peninsula that consists of Pan-African mylonitic orthogneisses with volcanic arc–related trace-element geochemistry and Sr isotopic composition. The Vertiskos terrane occupies the northwestern part of the Serbo-Macedonian Massif and is primarily composed of coarse-grained, volcanic arc–related peraluminous orthogneisses of Silurian age. These terranes are exotic in relation to the other parts of the Hellenides. The provenance of the late Proterozoic Pan-African Florina and Pirgadikia terranes is assumed to be Gondwanan, whereas the Silurian Vertiskos terrane may have been part of the so-called Hun ter-rane, which formed at the northern active continental margin of Gondwana in the early Paleozoic.