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•The link between exposed carbonatites and hidden agpaitic magmatic rocks hosting Nb-F-Zr-Li-Be-bearing REE deposits.•A binary marine hotspot at the continent-ocean transition and its ...volcanic landscapes (Canary Islands Archipelago)•Definition of the NW-African REE province as a Kiruna-Chibina-Type analogue.•First application of a mineralogical terrain analysis in genetic and applied economic geology.•The impact of geodynamics and climate on complex rare element deposits and their marker landform series.
Two geoscientific disciplines (mineralogy, geomorphology) which are placed far apart from each other are selected to forge a genetic tie line between carbonatite- and agpaitic pegmatite-hosted REE deposits, likewise far away from each other. The Canary Islands Archipelago, Spain, (= CIA) is known as a hotspot hosting REE among other rare elements (28 Ma to the Recent) in volcanic landforms. This rare metal metallogenic province is connected to a carbonatite-pegmatite REE province in NNW Africa. It is a binary mineralization with one hub covering SW Tenerife and NE La Gomera that is characterized by an alkali-magmatite-related REE system with pegmatitic syenites at depth and another hub covering Central - and NW Fuerteventura where (meta) carbonatites are exposed and form a bridge to the REE-bearing carbonatites and pegmatites on mainland Africa, Morocco.
The REE concentration took place in four stages which differ from each as with regard to their landscape and mineralogy:
(1) magmatic calcic-carbonatites with REE-bearing apatite (28 to 24 Ma)
(2) calcic-carbonatites, alkali magmatites with REE phosphate and carbonates (contact-metamorphic - metasomatic, epithermal) (19 to 4 Ma)
(3) alkali magmatites with hydroxyl-group-bearing REE phosphates, REE oxides, Fe oxide, Fe-Cu sulfides, kaolinite-halloysite, and REE-APS minerals (epithermal) (5 to 0.3 Ma)
(4) pyroclastic and volcanic rocks with smectite, kaolinite, REE-bearing silicates and oxides (auto-metasomatic) and a variegated series of more than 100 REE-, Nb-, F-, Zr-, Li- and Be minerals which are diagnostic for carbonatite- and/or alkali-magmatites pegmatitic systems at depth (< 0.6 Ma).
This REE mineralization of the CIA extending into on-shore Morocco is akin to the REE mineralization recorded from titanomagnetite–magnetite–apatite-REE- deposits in carbonatite-alkaline complexes in N Europe with the reference catena-deposits Kiruna-Sokli-Chibina (Sweden, Finland, Russia). The NNW African REE metallogenic province shows from E to W four geodynamic zones:
(1) Atlas Mts. REE - Fe Province (thick continental crust of the mainland),
(2) Fuerteventura (thick continental shelf pinching out to the W),
(3) Gran Canaria – Tenerife-La Gomera (thin continental shelf to oceanic crust),
(4) El Hierro – La Palma (barren zone as to REE oceanic crust).
The REE mineralization starts off with syn- to post-kinematic en-echelon strike-slip faulting followed by a clock-wise rotation of its morpho-structural elements and wanes with a reactivation of NE-SW morpho-structural elements as normal faults attesting to a decoupling from the Atlas Mts. deformation and intensification of an individual hotspot mineralization. The land-forming processes and the resultant volcanic landscape are genetically linked to the REE-, Nb-, F-, Zr-, Li-, and Be mineralization: mass wasting (MW) >fluvial drainage (FD) > lacustrine (L), ≥ coastal marine (CM) >> aeolian (A). Each of the land-forming processes provides marker landforms indicative processes relevant for rare element accumulations:
MW: thrusting, exhumation of the level of primary REE mineralization, zones of structural weakness,
FD: morphostratigraphic tracing of fertile bedrocks, demarcation of ring dyke complexes and zones of contact-metamorphic and contact-metasomatism, zones of ground- and surface water stagnancy, zones of strong argillitization and hematitization,
CM: exhumation, providing marker heavy minerals and gravel lithoclasts,
L: rifting structures, zones of volcanic and epithermal activity,
A: pathfinder heavy minerals.
The methodological approach taken throughout this composite study (field- and laboratory-based research work combined with a meticulous review of the mineralogical, chronological and geological regional literature) is that of a mineralogical-geomorphological terrain analysis.
Numerical geomorphological and sedimentological parameters are of assistance during remote sensing and ground follow-up mapping: (1) elevated degree of sinuosity and argillitization, (2) numerical classification of the terrain based on dip of slope plus altitude, (3) gravel analysis based on granulometry, morphology and situmetry (GMS technique) for provenance and environment analysis. The morphodynamic elements have a high preservation potential and are not blurred by morphoclimatic ones so that the mineralogical terrain analysis can be taken as a trusted exploration tool for REE.
Geodynamic and volcanic activity are the driving forces and prevail over the climate impact in shaping the landscape. Therefore, landforms in combination with compositional data from mineralogy can shed some light on the origin of REE-Nb-F-Zr-Li- Be mineral associations on hotspot volcanic islands. This holistic approach can also be taken to different mineral commodities elsewhere in the world given a low maturity of the landscape in the target area. It can also be used for submarine landforms in and around an archipelago simply by minero-stratigraphic correlation from land to sea. The mineralogical terrain analysis as applied in the current study is not a fixed methodological construct but open also for replacements and supplements by e.g. geophysics.
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•Origin of badlands result of geodynamics + climate and lithology + tectonics.•Internal subdivision (Badland trilogy): Gully, wadi and mesa/ hillwash zones.•It is an intermediate ...stage among true badlands.•In is a special facies of the alluvial-fluvial drainage system.•Actual-geological-geomorphological key to the paleogeography of badlands.
The badlands of the “Desierto de la Tatacoa” (DDT) form part of the alluvial-fluvial system and are characterized by a landform trilogy: (1) gully zone, (2) wadi zone, (3) hillwash plain/mesa zone. This facies differentiation is controlled by the fluvial regimes and their degree of sinuosity of channels. The hydraulic and hydrographic systems of the badland trilogy depend on the geodynamic setting and climate (1st order) and on the bedrock lithology and tectonics (2nd order). Allogenic heavy minerals attest to two counteracting palaeogradients which interdigitate where the badlands evolved and authigenic heavy and light minerals furnish evidence of the physical-chemical regime to be governed by alkaline meteoric solutions and oxidizing conditions driven by the climate and the parent rocks. It is the high solubility of sulfates and chlorides and the differential expandability of smectite which impacted on the development of the individual badland zones. Large 1st order synclines plunging to the W and 2nd order fold structures account for the traps and conduits of the subsurface water system. The key to the hydraulic evolution of the badland lies within the hinterland hampering surface alteration and favoring the subsurface hydrogeological system to corrode the gully zone from below. The binary genetic model of the badlands in the DDT reveals, on a local scale, a “fight for dominance” of different fluvial drainage systems at the edge of the badlands as a hydrological consequence of neotectonics while, on a regional scale, badland formation is an upstream expression of a eustatic sea level oscillation in the Caribbean Sea. A review of true, false and pseudo-badlands concludes the study and underscores the reference character of the DDT badlands among the true badland series.
Sphalerite is an abundant mineral in the hydrothermal deposits from the Baia Mare and Oaș areas (northwestern Romania). Sphalerite samples were analyzed with an electron probe microanalyzer and Raman ...spectroscopy. The obtained results indicated different amounts of Fe in the various deposits from the Baia Mare and Oaș areas. The sphalerites from Baia Sprie, Cavnic, Iba, Turț Penigher, and Breiner have a low Fe wt.% content. High Fe wt.% contents are at Herja and partly at Ghezuri and Nistru (copper stage) where sphalerite is associated with pyrrhotite. The correlation between iron and zinc from sphalerites is strongly negative. The negative correlation shows that iron is the main element that replaces zinc in the sphalerite structure. The manganese content of sphalerites in the Baia Mare and Oaș area is up to 0.84 wt.%. The cadmium content is quite uniform in the Baia Mare and Oaș area with contents ranging from 0.01 to 0.72 wt.%. The Fe content of sphalerites is an important indicator of the physico-chemical conditions of deposit formation because it is a function of temperature, pressure, and sulfur fugacity.
The Quaternary volcanogenic landscape and the volcanogenic sediments of the Netherlands Antilles (NA) (Aruba, Bonaire, Curaçao) reflect the most recent stage of the evolution of the Cretaceous to ...early Cenozoic Great Arc of the Caribbean Plate. They provide a “geoscientific keyhole” to look at its geodynamic and lithological evolution at different scales. This sedimentological, micropaleontological, geomorphological/geo-morphometrical, litho-chemical and mineralogical approach, holistic in essence and focused as to the target, can also be taken to better understand other volcanic arcs or facies zones, e.g., in Colombia. It allows for a climatic-geomorphological zonation governed by uplift and erosion of the volcanic arc in time and space. The host rock quality of landforms for volcanogenic sediments abundant in heavy minerals (HM) that are known as the most suitable markers for provenance and geodynamics can be arranged in decreasing order of significance as follows: coastal-marine volcaniclastic > fluvial–marine (deltaic) > aeolian-coastal-marine > mass wasting > residual > coastal-marine calcareous. The coastal sediments facing towards the plate margin contain Cr–Fe–Ti–Nb–Th–U–Zr-bearing HM which derived from off-shore ophiolites, Precambrian shelf sediments of the South-American Plate, volcanic–subvolcanic units, and mantle source rocks. The Quaternary hydrography evolved on different erosion levels and exposes different basement lithologies of volcanic and subvolcanic type. The drainage system is controlled by faulting (tecto-variance) and the volcanic lithologies (litho-variance) both of which indicate different phases of tectonic and magmatic activity during arc emplacement. This in-active volcanic arc of the Netherlands Antilles has been shaped during the Cenozoic by the climate change and modern tectonics on a deeper level of erosion than the active volcanic arc of the Lesser Antilles.
The massive sulfide deposits (VMS) from Mănăilă are associated with the metamorphic formations of the Tulgheș Lithogroup from the Bucovinian Nappes of the Crystalline-Mesozoic Zone in the Eastern ...Carpathians, Romania. The following types of ore were identified: pyrite-polymetallic, pyrite copper, compact and precompact copper, and quartz-precompact copper. The polymetallic mineralization consists of pyrite, chalcopyrite, sphalerite, galena, and subordinately arsenopyrite and tennantite. The copper, especially the quartz-copper mineralizations, have a distinct mineralogical composition compared to the other metamorphosed mineralizations of the Tulgheș Lithogroup. These types of deposits from Mănăilă contain large amounts of bornite and chalcocite along with chalcopyrite. Tennantite is abundant and has up to a 3.57 wt.% of bismuth. Wittichenite was identified for the first time in the metamorphic mineralizations and mawsonite was identified as the first occurrence in Romania. An unnamed mineral with the formula: Cu,Fe11Pb,AgS7 was also identified, belonging to the sulfides group. The compact and precompact pyrite-rich ores, located in sericite ± quartzite schists and covered by rhyolitic metatuffs, are of hydrothermal-sedimentary type metamorphosed in the greenschist facies. The source of the quartz-copper mineralization would be the retromorphic or metasomatic hydrothermal solutions that circulated through major fractures.
The Baia Sprie epithermal ore deposit is one of the best-known deposits in Romania and Europe. It consists mainly of a vein system with two major veins: (1) Principal Vein and (2) Southern Vein, ...along fractures that delimitate an andesitic block and a subvolcanic intrusion. The Principal Vein is one of the longest hydrothermal veins in Europe, with more than 5km in length, a thickness that varies between 0.5 and 22m and it extends vertically on more than 800m. Samples belonging to different levels of Principal Vein have been analyzed using electron microprobe. A new occurrence of bismuth minerals was identified within the deeper part of the deposit: bismuthinite, lillianite–gustavite, disordered intergrowths of lillianite homologues, heyrovskyite and cosalite. The presence of Bi-sulfosalts suggests temperature of ~350°C, while the As content in arsenopyrite indicates formation temperatures between 320 and 360°C. The oscillatory zoning bands of pyrite and tetrahedrite–tennantite members indicate an increased Sb and As concentration in hydrothermal solutions. The zoning textures suggest a high S and low As concentration in the early fluids followed by multiple pulses of As-rich solutions in the late fluids. The high content of As in pyrite and the presence of bismuth minerals at Baia Sprie deposit can represent indicators for significant Au concentrations within the lower level of the mineralization. From the type locality Baia Sprie new analytical data for semseyite were presented and for the first time a new occurrence of geocronite–jordanite series was identified in the intermediate and upper part of the deposit.
•Samples from the all three main levels of Baia Sprie deposit were analyzed using EPMA.•New occurrences of bismuth minerals and Pb sulfosalts are identified and described.•Bismuth minerals suggest temperatures of ~350°C and may represent indicators for Au.•Zoning textures of pyrite and fahlores indicates increased Sb–As activity in fluids.•Arsenopyrite geothermometer shows temperatures of 320–360°C for the lower level.
In the current study, different heavy minerals typical of gold placer deposits were identified by means of micro-Raman spectroscopy, and their chemical composition analyzed and discussed (garnet, ...kyanite, staurolite, zircon, allanite, monazite, xenotime, rutile, anatase, cassiterite, titanite, barite). Even complex solid solution series, such as those of garnets, can be deciphered with the aid of systematic trends observed in Raman line frequencies. The ν1 mode in garnets will shift from high to low frequencies as a function of the ionic radius of the X2+ cation, from Mg2+, to Fe2+ and Mn2+, while the presence of Ca2+ will make the band to be shifted strongly to even lower wavenumbers. This approach has successfully been taken to differentiate between polymorph triplets such as kyanite-sillimanite-andalusite and rutile-anatase-brookite. Minerals under consideration with high contents of REE, U and Th are affected by intensive metamictization, particularly zircon and titanite. Raman peak features, such as shape, symmetry and intensity, respond to this radiation damage of the lattice and enable fine-tuning of these heavy minerals, such as in the case of fluorite (fetid fluorite).
A holistic-modular approach has been taken to study the evolution of three straight to low-sinuosity drainage systems (=SSS) in an uplifted basement block of the Central European Variscides. The ...development of the SSS is described by means of a quadripartite model. (1) The geological framework of the SSS: Forming the lithological and structural features in the bedrock as a result of different temperature, pressure and dynamic-metamorphic processes. (2) Prestage of SSS: Forming the paleo-landscape with a stable fluvial regime as a starting point for the SSS. (3) Proto-SSS: Transition into the metastable fluvial regime of the SSS. (4) Modern SSS: Operation of the metastable fluvial regime Tectonics plays a dual role. Late Paleozoic fold tectonic creates the basis for the studied SSS and has a guiding effect on the development of morphotectonic units during the Neogene and Quaternary. Late Cenozoic fault tectonics triggered the SSS to incise into the Paleozoic basement. The change in the bedrock lithology has an impact on the fluvial and colluvial sediments as well as their landforms. The latter reflects a conspicuous modification: straight drainage system ⇒ higher sinuosity and paired terraces ⇒ hillwash plains. Climate change has an indirect effect controlling via the bedrock the intensity of mechanical and chemical weathering. The impact on the development of the SSS can be assessed as follows: Tectonics >> climate ≅ bedrock lithology. The three parameters cause a facies zonation: (1) wide-and-shallow valley (Miocene), (2) wide-angle V-shaped valley (Plio-Pleistocene), (3) acute-angle V-shaped valley (Pleistocene), (4) V-shaped to U-shaped valleys (Pleistocene-Holocene). Numerical data relevant for the hydrographic studies of the SSS are determined in each reference area: (1) Quantification of fluvial and colluvial deposits along the drainage system, (2) slope angles, (3) degree of sinuosity as a function of river facies, (4) grain size distribution, (5) grain morphological categorization, (6) grain orientation (“situmetry”), (7) channel density, (8) channel/floodplain ratios. Thermodynamic computations (Eh, pH, concentration of solubles) are made to constrain the paleoclimatic regime during formation of the SSS. The current model of the SSS is restricted in its application to the basement of the Variscan-Type orogens, to an intermediate crustal maturity state.
Sediment samples from the Săsar River and its main tributaries were analyzed for their potentially toxic elements at the site of the Romplumb metallurgical company and near the well-known Pb-Zn-Cu ...epithermal deposit of Baia Sprie located in the Neogene volcanic chain of the Eastern Carpathians, Romania. The average metal concentrations arranged in order of decreasing abundance are as follows (mg·kg−1): Mn (4098) > Zn (2093) > Pb (918) > Cu (489) > As (160) > Cr (37.51) > Ni (30.25) > Co (28.13) > Cd (9.72) > Hg (1.81). Several pollution indices were successfully used to assess the degree of contamination and ecological risk. The majority of sampling sites indicate high degrees of pollution, with two major hotspots identified. There are further sources, such as the Șuior (Pb-Zn-Au) and Săsar (Au-Ag) epithermal deposits, Cuprom company, and Bozânta tailing ponds, identified as contaminants. The Baia Mare mining district is causing a serious threat to the aquatic systems in the region, and it can be taken as a reference area for the human impact derived from the mining of mineral deposits of Au-Ag-Cu-Pb-Zn. It is imperative to reduce ecological risks and thereby protect the population living within this abandoned mining area.
Biological invasions in forest ecosystems are recognised as a global scale challenge. However, our current knowledge of invasive alien forest insect species (IAFIS) in Romania is still lacking and ...rather insufficient to support clear policies. The aim of this study is to contribute to a better understanding of the distribution of IAFIS in the Muntenia and Dobrogea provinces of Romania. For this purpose, direct observations and insect collections were made two consecutive years, in 76 locations. Of these, 67 sampling locations forming a long field observation route were visited only once, and nine sampling locations were fixed monitoring points with primed traps used in first year for regular collection of insects at 1-2-week intervals. Seventeen non-native forest insect species from five orders and 11 families were detected: Aproceros leucopoda, Cameraria ohridella, Corythucha arcuata, Cydalima perspectalis, Dasineura gleditchiae, Eopineus strobus, Euura tibialis, Gilletteella cooleyi, Hyphantria cunea, Ips duplicatus, Macrosaccus robiniella, Neoclytus acuminatus, Obolodiplosis robiniae, Parectopa robiniella, Phyllonorycter issikii, Prociphilus fraxinifolii and Xylosandrus germanus. Eleven IAFIS species originate from North America, four from Asia and two from Europe. All detected species were previously reported from Romania, but eight species had not been recorded in these two provinces. Seven species live on native tree species, while 10 thrive on exotic trees or shrubs. The highest number of IAFIS was recorded in urban areas. Except for E. tibialis, all found IAFIS have a significant ecological or economic impact across invaded habitats. The risks posed by biological invasions need more thorough consideration that deserves greater attention and scientific support.
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