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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.
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.
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.
The levels and distribution of 9 trace elements in apples from two orchards in north-east (NE) Romania were measured by means of Atomic Absorption Spectroscopy (AAS) on 42 samples of 9 different ...apple varieties, with average content ranges of 0.909-4.458 mg·kg
Zn, 0.055-0.409 mg·kg
Cu, 0.700-2.476 mg·kg
Fe, 0.328-0.695 mg·kg
Mn, 0.054-0.257 mg·kg
Ni, 0.005-0.101 mg·kg
Cr, 0.027-0.420 mg·kg
Co, 0.413-1.149 mg·kg
Pb, and 0.025-0.127 mg·kg
Cd. For some apple varieties, Pb contents are 2 times higher than the maximum contents allowed according to national standards, Cd contents are 6 times higher, and in some cases Zn contents also exceed the national threshold, showing preferential accumulation on specific apple varieties. Whilst some research has been carried out on trace element distribution in apples, this study assessed the areal distribution of toxic trace elements in connection to the adjacent roads. The first apple orchard is located near a county road, with reduced car traffic, while the second orchard shares its southern limit with a high-volume traffic road (E583). The results point towards a proportional increase of Pb and, to some extent, of Cd in the samples close to the E583 road in contrast with the other orchard, where no such observation derived. Along the areal distribution of the selected elements, the preferential accumulation of dietary recommended trace elements in different apple varieties was assessed. In matters of daily nutrients content in trace elements, the best sources of Fe, Cu, and Zn in terms of apple varieties are Golden Delicious, Jonathan, and Kaltherer Böhmer.
The “natural GMS laboratory” (granulometry-morphometry-situmetry) is located within the Variscan Basement in SE Germany (Fichtelgebirge Mts.), which is uplifted relative to its Permo-Mesozoic ...foreland along a deep-seated lineamentary fault zone. This transitional study area is crossed by straight to low drainage systems in the basement, turning meandering channel systems into high sinuosity when entering the foreland. Due to its good geological coverage, the entire region is subjected to an advanced-level terrain analysis and completed with a sedimentological study focusing on the GMS tool. Unlike many applications in the past, the three components of the GMS tool that are of almost equal value ought to be used in combination and not as stand-alone procedures so as to be integrated into other near-surface geoscientific methods, e.g., sediment petrography. The strong points of granulometry of coarse-grained/gravel-sized sediments are its extension into the smaller sand and clay grain size intervals using the sorting, mean and/or median values for an environmental analysis. Morphometry can be linked to the compositional geosciences, e.g., mineralogy and geochemistry. The grain shape is intimately connected with the lithology, providing options from triaxial measuring of the lithoclast to the digital image analysis. It is a favorable tool to supplement the provenance of lithoclasts. Situmetry is the key element of hydrodynamic research and directly builds upon its sister methods. Its applications and numerical approaches are useful for the identification and quantification of physical land-forming processes. It is the fan sharpness and the orientation of lithoclasts relative to the direction of the talweg and in relation cross-sectional valley features that integrate the GMS tool into geological and geomorphological mapping, both of which result in a digital terrain model. Horizontal rose diagrams are useful for the upper reaches of drainage systems, be they of alluvial or non-alluvial types, and vertical ones for alluvial channels in the distal and proximal foreland where stacked patterns of depositional terraces are of widespread occurrence. In general, the GMS tool can be applied to sedimentological, geomorphological, petrographic and tectonic objects in basements and foreland basins; in applied geosciences, it is suitable for the identification of mineral resources and of areas vulnerable to geohazards, and in genetic geosciences for the discrimination of supergene chemical and physical depositional and land-forming processes.
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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.
The quadripartite/ orthogonal and domal Central European Watershed (CEW) at the NW edge of the Bohemian Massif has been studied by a terrain analysis (fluvial, colluvial, cryogenic, aeolian ...landforms) combined with geochronological dating (hydraulic correlation) of landforms and the resultant hydrographic correlation of relief generations. It resulted in a morphostratigraphic review (subdivided into a protostage- creating the terrestrial platform, prestages - controlling the physical and chemical regime of the landform series, and stages- fine-tuning of the modern landscape) of the Late Cretaceous to Quaternary relief generations that lead to the creation of the “3 + 1” model of the CEW. The term “3 + 1” refers to a triple junction supplemented with a fourth branch. The characteristic land-form type of the CEW is called the “intermediate sediment trap”, a wetland caused by structural or impact-related damming processes. The evolution of the CEW is discussed by a set of four different drivers:
The endogenous 1st order drivers are activities along lineamentary fault zones which demarcate the watershed systems.
The 2nd order endogenous driver is the alkaline volcanic activity from the Late Cretaceous to the Holocene which contributed to dome-and starlike geomorphological expression.
The 3rd order impact-related driver of the Ries Meteorite impact provoked a deflection and damming of channels thereby leading to one of the intermediate sediment traps.
The 4th exogenous driver is the climate change. It is accountable for the transition from fluvial incision during the Late Cretaceous and Paleogene (humid-tropical climate zone) to a planation during the Neogene (tropical wet and dry paleoclimate zone). The Quaternary humid mid-latitude, dry continental, and (peri)glacial climate zones put the final touch on the CEW's geomorphological outward appearance.
The influence of mining, metallurgy, and mineral processing on the landscape debated in the final stage 8 heralds the onset of the Anthropocene in the CEW.
This review of the evolution of the CEW also lends support to the idea that an advanced terrain analysis can be an efficient tool for mineral exploration.
a) Weathering and hydrological zones of the CEW at the western edge of the Bohemian Massif (Germany) the platform for the chronological constraining of landforms. The physica-chemical regime is based upon thermo-dynamical calculations. White: Uranium mineral zonation, brown: Manganese mineral zonation.
b) The geodynamic structural and geodynamic magmatic controls on the quadripartite watershed system (3 + 1 model) and the geodynamic-geomorphological maturity concept accountable for the clockwise evolution of the quadripartite CEW. Display omitted
•Terrain analysis - geochronological dating of landforms - correlation of relief generations•Morphostratigraphy (Late Cretaceous to Quaternary) in an orthogonal, quadripartite watershed system•Geotectonic, magmatic, extraterrestrial and climatic drivers during evolution•All landscape-forming processes involved: fluvial, mass wasting, cryogenic, aeolian, lacustrine.•Intermediate sediment traps are the characteristic feature of these watershed systems.
Provenance analysis and terrain analysis backed by radiometric age dating have been combined for the first time and conducted as a composite in a foreland-basement transition zone with mutual ...benefits for both disciplines. A meticulous provenance analysis enables a fine-tuning during studies of the landscapes and relief generations, while a detailed terrain analysis is essential for the disentanglement of lithological-geodynamic processes that often are telescoped into each other by sedimentological processes. The basic drivers for the denudation, transport and deposition processes of the various clast communities (gravel, sand, clay) are the climate change from a tropical (Neogene) to a glacial/temperate Earth and the brittle neotectonics along the margin of the study area (Rhine Graben Rift N-S, Eger/Ohře Graben Rift E-W). As a result of this composite approach the landscape formation in the study area is described as follows: (1) (Paleogene)-Neogene peneplanation in the basement, (2) Quaternary straight to low sinuosity drainage in the basement, (3) Late Pleistocene to Holocene high-sinuosity drainage in the proximal foreland and (4) Holocene (to Late Pleistocene) meandering fluvial rivers evolving in the distal foreland. In additions to these geomorphological results progress can be made in the geodynamic evolution of the study/source area. Five Proterozoic to Late Paleozoic lithological units are identified: (1) Para-metamorphic rocks, (2) greenstones, (3) basic volcano-sedimentary rocks, (4) sedimentary units abundant in chert and (5) felsic volcanics. By means of these sedimentological finds a more detailed picture of the Variscan orogeny can be presented.
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•A terrain- and-provenance analysis is backed by U/Pb, K/Ar and radiocarbon dating.•The provenance of gravel, sand (heavy/light) and clay minerals is determined.•Gravel-, sand- and clay-sized rocks and minerals are used as proximity-, extra- and intra-basinal markers.•Climatic and neotectonics control the fluvial, mass wasting and cryogenic sedimentological and land-forming processes.•The characteristic landform of the watershed systems is the “Intermediate sediment trap”.
The Hagendorf–Pleystein Pegmatite Province, SE Germany, is known for the largest feldspar–quartz pegmatite in Central Europe and renowned for its rare elements, e.g., Li, Nb, and Ta, giving rise to a ...spate of exotic minerals, mainly phosphates. Argillaceous rocks are scarce and eclipsed by the numerous mineralogical investigations on rare phosphates. These phosphate pegmatites are for the first time subjected to a clay mineralogical study, rendered possible by the newly discovered strongly kaolinized aplite near the Kreuzberg Quartz Pegmatite at Pleystein. The supergene kaolin akin to the residual kaolin deposit at Tirschenreuth, SE Germany, was analyzed for its major and minor elements by XRF and micro-chemically by EMPA. Mineralogical investigations involved XRD, IR spectroscopy, thermoanalytical studies, CEC analyses and SEM-EDX. Supergene kaolinization forms a repository for heavy minerals critical for the interpretation of the emplacement of the Late Paleozoic pegmatites as well as a matrix for pegmatite-related trace elements and thereby may be used as an ore guide during exploration of these rare metal pegmatites. The resultant kaolin is also the protagonist in the story of exhumation and destruction of a pegmatite by weathering and erosion. Irrespective of the strength of kaolinization, Nb–Ta–Ti heavy minerals can be identified in the regolith atop the host pegmatite or aplite and used for genetic interpretation of the primary mineralization and the origin of the felsic intrusive. Nb–Ta solid solution series (s.s.s.) have to be treated cautiously because of the disposition of Ta-enriched Nb–Ta oxide s.s.s. to undergo corrosion in their tantalite lamellae more easily than in their niobium-enriched zones. Kaolinization may alter the primary Nb/Ta ratio but not to the extent that Ta is released completely. The most strongly kaolinized new aplite is the youngest member of a series of felsic intrusive rocks in the Pleystein pegmatite–aplite system. The supergene kaolinization extending from the Miocene through the Pliocene can easily be correlated by “minero-stratigraphy” with the larger Tirschenreuth kaolin deposit. The four stages established in the area furnish evidence of gradual alkalinization of the meteoric pore fluids throughout the Neogene and the Quaternary. Youngest stages are found at Tirschenreuth, the oldest regolith stage is present at Pleystein.
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•Tidal-dominated hard-rock coast with a varied HM spectrum forms a natural laboratory.•The tidal range controls the diversity of coastal features and siting of HM.•Neotectonics ...suppresses or accentuates the built-up of coastal-morphological features.•Weathering, erosion and marine processes are conservative with regard to the economic geology.•Granulometry, morphometry and situmetry are efficient quantitative tools to analyze this coastal environment.
The Isles of Jersey and Guernsey, GB, are situated in the Bight of St. Malo which ranks among the upper-macrotidal environments with one of the highest tidal ranges ever measured on the globe. They are built up of metasedimentary and –magmatic basement rocks followed by a suite of gabbro-diorite-granite intrusive rocks. Based on sedimentological, geomorphological and mineralogical investigations focused on heavy minerals (HM) the coastal environment has been subdivided into three principal coastal types headland-, headland-bay and bay types. Chemical and physical weathering, neotectonics, eustatic sea level changes, wave action, land-derived sediment supply and aeolian processes had not only a strong impact on the various coastal landform series (CLFS) established but also on the variegated HM assemblages casting them into the role of markers for the coastal environment and some kind of an ore guide for marine placer deposits. Tidal-dominated coastal environments under study sculptured exclusively out of crystalline bedrocks are conservative with regard to the economic geology and potential of HM placer-type deposits provided while physical weathering predominates over the chemical one. The tidal processes in context with the other land-forming processes are special importance for the diversity of coastal features within the environment hosting HM on a small- and large-scale. Neotectonics may accentuated or suppress tidally-controlled features in that strong uplift and provokes typical tidal features to get suppressed so that vast tidal flats are missing in a great deal of coastal areas and rocky coasts formed instead with consequences for the accumulation of HM. The “GMS tool (granulometry-morphology-situmetry) has methodologically proved to be very effective for the study of the coastal zones hosting HM in two principal ways. Granulometric and the morphological variation of HM can successfully be used for the host rock environment analysis (“ore guide”). Morphometric studies and situmetric measurements of gravel clasts in the coastal sediments bearing HM accompanied by similar measurement of joints and faults cutting through the bedrock can assist in the localization of HM trap sites in shoreline platforms and their rock veneer. The HM associations in upper-macrotidal environments are variegated in terms of morphology, mineralogical composition and their geomorphological trap sites so that they constitute a natural laboratory for environment analysis in terms of hydrodynamic and (paleo) climate along marine terrigenous shorelines and help better understand the way of HM from source to trap site in modern and paleoplacers.
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