The Ljubija ore deposits are the loci typici of siderite-barite-polysulphide deposits within the Inner Dinarides, Gemerides and Eastern Alps. Numerous sites of ore outcrops, smaller or larger ore ...bodies of mineralization, consisting of Fe carbonates, sulphides, barite and fluorite are scattered over an area of 150 square km. The half billion tons of iron ore resources occur as replacement in dolostones and limestones, and as open-space fillings in phyllites and sandstones. The genesis of the Ljubija ore deposits has been explained as (i) syngenetic sedimentary-exalative, (ii) hydrothermal-metasomatic in Middle Triassic time or (iii) hydrothermal replacement of sedimentary carbonates in Permian time. Basically two alternatives Variscan or Alpine metallogeny, frame the time of genesis from the Middle Carboniferous to the Middle Triassic. Genetic interpretation of the Ljubija ore deposits required convincing arguments based on recent achievements of plate tectonics. It adopts argumentatively all the estimated research parameters that constrain a justified genetic model.
The Boqueirão granitic pegmatite, alias Alto da Cabeça pegmatite, is situated in Borborema Pegmatitic Province (BPP) in Northeast Brazil. This pegmatitic province hosts globally important reserves of ...tantalum and beryllium, as well as significant quantities of gemstones, including aquamarine, morganite, and the high-quality turquoise-blue “Paraíba Elbaite”. The studied lithium-cesium-tantalum Boqueirão granitic pegmatite intruded meta-conglomerates of the Equador Formation during the late Cambrian (502.1 ± 5.8 Ma; 40Ar/39Ar plateau age of muscovite). The pegmatite exhibits a typical zonal mineral pattern with four defined zones (Zone I: muscovite, tourmaline, albite, and quartz; Zone II: K-feldspar (microcline), quartz, and albite; Zone III: perthite crystals (blocky feldspar zone); Zone IV: massive quartz). Huge individual beryl, spodumene, tantalite, and cassiterite crystals are common as well. Microscopic examinations revealed that melt inclusions were entrapped simultaneously with fluid inclusions, suggesting the magmatic–hydrothermal transition. The magmatic–hydrothermal transition affected the evolution of the pegmatite, segregating volatile compounds (H2O, CO2, N2) and elements that preferentially partition into a fluid phase from the viscous silicate melt. Fluid inclusion studies on microcline and associated quartz combined with microthermometry and Raman spectroscopy gave an insight into the P-T-X characteristics of entrapped fluids. The presence of spodumene without other LiAl(SiO3)2 polymorphs and constructed fluid inclusion isochores limited the magmatic–hydrothermal transition at the gem-bearing Boqueirão granitic pegmatite to the temperature range between 300 and 415 °C at a pressure from 1.8 to 3 kbar.
Comparative studies on hydrothermal alteration of submarine peperitic basalt occurrences related to the Triassic early rifting of the Neotethys were carried out in various parts of the Dinarides and ...Hellenides. The study areas included the displaced fragments of the Dinarides in the Darnó Unit, NE Hungary, the Kalnik Mts in Croatia and the Vares-Šmreka area in Bosnia and Herzegovina. In the Hellenides, similar environments were studied in the Stragopetra Mts., Greece. Jurassic pillow basalts formed in a back-arc-basin of the Neotethys were also studied (in the Szarvaskő Unit, NE Hungary, which also represents a displaced unit of Dinaridic origin). Within the submarine basaltic lava flows, six volcanic facies were distinguished. The hydrothermal alteration was characterized according to those facies. The first process was the albitization of the rock-forming plagioclase at ~300°C temperature in all localities. During the higher temperature stage of the subsequent cooling, chloritization in the ground mass is typical for all types of basalts, however chlorite and rarely quartz formed in the fractures and amygdales of the Triassic basalts, while chlorite, quartz and prehnite precipitated in the fractures of the Jurassic rocks. At lower temperatures of this cooling-related process, calcite is a common mineral filling up the larger amygdales, jig-saw type fractures and other open spaces, but some epidote, pumpellyite, prehnite and laumontite also occur in the Triassic basalts. The late stage alteration (happened at the lowest temperature) is characterized by argillitization at every locality. The observed hydrothermal alteration patterns also show slight differences according to the volcanic facies as a function of the distal/proximal setting in relation to the eruptive centers and the presence/absence of water-saturated and unconsolidated carbonate or siliciclastic sediments at the time of the emplacement of lava flows. The study revealed that the most important factors influencing mineralogy and zoning of hydrothermal alteration in these short living local hydrothermal systems are the rapid cooling of the hydrothermal fluid, the dominance of the not much evolved seawater as the source of hydrothermal fluid and the local, i.e. effective water/rock ratio, determined by the degree of fracturing in the rock. The mineralogical-textural peculiarities of the highly localized hydrothermal fluid/rock interaction in the studied submarine sea-mount type volcanoes are clearly different from the products of the large-scaled hydrothermal processes occurring at mid-oceanic ridges. Recognition of these differences is important in the evaluation of ore potential of Neotethyan realm or other areas with occurrences of submarine basaltic units
The Hruškovec quarry of basaltoid rocks is situated on the northwestern slopes of Mt. Kalnik, within the Zagorje–Mid-Transdanubian zone, a part of the North-western Dinarides. The basaltoids are ...inter-bedded with radiolarites of the Middle and Upper Triassic age (Langobardian, Carnian–Norian). Spilites, altered diabases and meta-basalts form part of Triassic volcanic-sedimentary sequence, made of sandstones, shales, micritic limestone, altered vitric tuffs and radiolarian cherts, incorporated tectonically into the Jurassic–Cretaceous mélange.
The architecture of the 2 km long and 100 m high pile of the extrusive basaltoid rocks is interpreted as a subaqueous basaltic lava flow. The presented research deals with a variety of volcanic facies of the subaqueous basaltic lava flow, which consists of several facial units: 1. Coherent pillow lavas, with massive core; the bending rims around the massive core, 30–50 cm thick, are dissected by polygonal columnar joints radiating from the pillow centres; 2. Closely packed pillows; densely packed and contorted pillows due to emplacement accommodation, clearly younging upward; 3. Pillow fragment breccia; clast supported, matrix poor, monomict breccia, formed proximal to the axis of the extrusion; 4. Isolated pillow breccia; matrix supported, clast poor breccia, made of lava pipes and tubes, within a matrix of fine-grained sideromelan granules and shards; 5. Pyjama-style pillows; spherical, decimetre to meter size pillow lava balls, grown and chilled in isostatic state (i.e. in a state of diminished density contrast) within water-soaked sediments, named after peculiar alternating basaltic shelves inside the sphere, which are encrusted with white secondary minerals; 6. Peperite and peperitic hyaloclastites; blocky and globular peperites developed at the contact of soft, wet sediment and hot intruding magma.
Discovery of peperite and peperitic hyaloclastites within the Triassic radiolarian cherts, shales, and micritic limestone, with registration of conodonts (index microfossils), links their origin to magmatism during advanced rifting in a progressively subsiding basin during the Triassic. It precludes an affiliation of the subaqueous basaltic lava flow with the dismembered ophiolite formation, a product of oceanization created in Jurassic–Cretaceous times, which is a commonly stated alternative explanation.
The basaltic rocks and their sedimentary hosts may be correlated with advanced Triassic rifting, and related volcanic-sedimentary successions in the Dinarides, Albanides, Helenides and further along the Tethyan orogenic belt.
The paper presents data about the geology, geochemistry, structure, genesis and specific features of the Bucim porphyry Cu deposit which is actively mined in Macedonia. The porphyry mineralization ...(0.3 % Cu, 0.3-0.5 ppm Au) is spatially and temporarily associated with Tertiary subvolcanic intrusions of latitic and latitic-andesitic composition. The intrusions occurred during Oligo-Miocene time (24 to 27 Ma), a period of intensive tectono-magmatic and ore-forming processes.. The latest results of this study identify an array of major ore (hypogen) minerals such chalcopyrite, pyrite, magnetite, haematite, cubanite, valleriite, native Au and bornite and secondary enrichment zone minerals (within Cukar ore body) including chalcocite, covellite, tenorite, native Cu, malachite, azurite etc. Added minerals such as calaverite, krennerite, electrum, petzite and bismuth±selenium minerals (bismuthinite, galenobismutite, krupkaite, friedrichite, emplectite, cosalite, laitakarite and native bismuth) are also present. Variations of the δ^sup 34^S values for the whole Bucim ore deposit ranged from +0.2 per thousand to +2.5 per thousand while δ^sup 13^Cper thousand and δ^sup 18^Oper thousand isotope values ranged from -10.8 to -3.8per thousand and from +14.0 to +22.7 per thousand, respectively. With regard to fluid inclusions, it was confirmed that beside the pre-dominant gas-liquid, two-phase inclusions, there are also three-phase fluid inclusions (gas + liquid + solid phase). Also, recent Sr and Nd isotope ratios (^sup 87^Sr/^sup 86^Sr 0.70666-0.70741 and ^sup 143^Nd/^sup 144^Nd 0.512487-0.512489) indicate slight contamination of the magmatic products by continental crust material, due to partial melting of the deep parts of continental crust underthrust by collision of continental blocks. The REE data show results that are comparable with high contents of large ion lithophile elements (LILE), high Ba/Nb ratio (116.72-190.72) and depletion in high field strength elements (HFSE) and Europium negative anomaly (0.68893-0.91251).
Metasediments of the Paleozoic Bashibos-Bajrambos unit, comprising the western perimeter of the Serbo-Macedonian Massif in SE Republic of North Macedonia, were investigated by employing whole-rock ...geochemistry and detrital zircon geochronology to put constraints of age, provenance and depositional tectonic setting. The metasedimentary unit consists of polymetamorphic and highly altered pelitic mica-schists and phyllites and metamafic rocks. The first limited data from the whole-rock composition of the metapelites and zircon Th/U ratios suggest derivation of detrital material from felsic and recycled older upper crustal sources. At the same time, mafic samples indicate an origin from a volcanic source without a significant contribution from ultramafic rocks. Whole-rock data and the detrital zircon record suggest that deposition of the sequence took place in collision-related, foreland basin, formed by the merging of Pelagonian and the Serbo-Macedonian Massifs. The population of the youngest recorded zircons indicates Early Permian sedimentation. The detrital zircon record speaks for significant sedimentary input of old crustal material from the Serbo-Macednonian Massif, while younger Carboniferous-Permian magmatic zircon populations support the significant influence of the Pelagonian Massif.
Comparative studies on hydrothermal alteration of submarine peperitic basalt occurrences related to the Triassic early rifting of the Neotethys were carried out in various parts of the Dinarides and ...Hellenides. The study areas included the displaced fragments of the Dinarides in the Darno Unit, NE Hungary, the Kalnik Mts. in Croatia and the Vares-Smreka area in Bosnia and Herzegovina. Within the submarine basaltic lava flows, six volcanic facies were distinguished. The hydrothermal alteration was characterised according to those facies. The first process was the albitisation of the rock-forming plagioclase at ~300 degreesC in all localities. The study revealed that the most important factors influencing mineralogy and zoning of hydrothermal alteration in these short lived local hydrothermal systems are the rapid cooling of the hydrothermal fluid, the dominance of the poorly evolved seawater as the source of hydrothermal fluid and the local, i.e. effective water/rock ratio, determined by the degree of fracturing in the rock.
Comparative volcanological, mineralogical, petrological, and geochemical studies of blocks of Triassic submarine basalt occurrences hosted by the Jurassic mélange have been carried out. The studied ...localities are located in displaced parts of the Dinarides in NE-Hungary (Darnó Unit), in the Dinarides (Kalnik Mts., Croatia and Vareš-Smreka, Bosnia and Herzegovina), and in the Hellenides (Stragopetra, Greece). The common characteristic of the studied occurrences is the well observable result of the lava–water-saturated sediment mingling, i.e., the presence of the so-called carbonate peperitic facies. Mixing of the basaltic lava with pelagic lime mud (representing the unconsolidated stage of the red, micritic limestone), as well as fluid inclusion and chlorite thermometry data support that the carbonate peperite was formed above CCD and at the Bosnian locality, a shallower water, about 1.4 km depth is proven. The igneous rocks show mainly within-plate basalt geochemical characteristics; MORB signatures are not common. Low temperature (<200°C) hydrothermal alteration is characteristic to the pillow basalt blocks with peperitic facies. The similarities in the volcanological, geochemical, and textural characteristics observed at the different localities support a strong genetic connection among them. The results of this study suggest to the advanced rifting stage origin of the Triassic basaltic suits and their distinction from the true oceanic basalt pillow units of the Dinarides can be based on the occurrences of the peperite facies.
PDF
