Mineralogická charakteristika granátického skarnu z lokality Trohanka pri Prakovciach (gemerikum, Slovenská republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 230-240
Author(s):  
Pavol Myšľan ◽  
Peter Ružička ◽  
Martin Števko ◽  
Tomáš Mikuš
Keyword(s):  
Oscillatory Zoning ◽  
Lower Content ◽  
Transition Zones ◽  
Gemeric Unit

Garnet skarn mineralization was recently studied at the Trohanka locality near Prakovce (Gemeric Unit, Eastern Slovakia). Ca-skarn forms lenticular bodies in green schist environment. It mainly consists of zonal garnets, pyroxenes, amphiboles and magnetite accumulations. Studied garnets are rich in andradite component (up to 89.95 mol. %) with minor grossular component (6.83 - 39.67 mol. %). Strong oscillatory zoning in andradite is caused by substitution of Fe3+ and Al3+. Most pyroxenes are rich in the hedenbergite component. In some cases, euhedral diopside crystals with marginal transition zones (composed of diopside with lower content of Mg2+ and higher content of Fe2+) were found in hedenbergite matrix. Amphiboles are dominantly represented by ferro-actinolite and ferro-hornblende in association with isolated euhedral crystals of ferro-tschermakite and ferro-pargasite. Indistinct chemical zonality of amphibole euhedral crystals is caused by presence of ferro-pargasite in the central parts and ferro-tschermakite in the peripheral parts of crystals.

scholarly journals Re-Os and U-Th-Pb dating of the Rochovce granite and its mineralization (Western Carpathians, Slovakia)

2013 ◽  
Vol 64 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Milan Kohút ◽  
Holly Stein ◽  
Pavel Uher ◽  
Aaron Aimmerman ◽  
L’ubomír Hraško
Keyword(s):  
Oscillatory Zoning ◽  
Western Carpathians ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Collisional Orogen ◽  
Granite Intrusion ◽  
Metallogenic Belt ◽  
Central Western Carpathians ◽  
Lower Crustal ◽  
Gemeric Unit

Abstract The subsurface Rochovce granite intrusion was emplaced into the contact zone between two principal tectonic units (the Veporic Unit and the Gemeric Unit) of the Central Western Carpathians (CWC), Slovakia. The Cretaceous age of this granite and its Mo-W mineralization is shown using two independent methods: U-Pb on zircon and Re-Os on molybdenite. The studied zircons have a typical homogeneous character with oscillatory zoning and scarce restite cores. SHRIMP U-Pb data provide an age of 81.5 ± 0.7 Ma, whereas restite cores suggest a latest Neoproterozoic-Ediacaran age (~565 Ma) source. Zircon εHf(81) values -5.2 to + 0.2 suggest a lower crustal source, whereas one from the Neoproterozoic core εHf(565)= + 7.4 call for the mantle influenced old precursor. Two molybdenite- bearing samples of very different character affirm a genetic relation between W-Mo mineralization and the Rochovce granite. One sample, a quartz-molybdenite vein from the exocontact (altered quartz-sericite schist of the Ochtiná Formation), provides a Re-Os age of 81.4 ± 0.3 Ma. The second molybdenite occurs as 1-2 mm disseminations in finegrained granite, and provides an age of 81.6 ± 0.3 Ma. Both Re-Os ages are identical within their 2-sigma analytical uncertainty and suggest rapid exhumation as a consequence of post-collisional, orogen-parallel extension and unroofing. The Rochovce granite represents the northernmost occurrence of Cretaceous calc-alkaline magmatism with Mo-W mineralization associated with the Alpine-Balkan-Carpathian-Dinaride metallogenic belt.

Drivers of Small-Scale Diptera Distribution in Aquatic-Terrestrial Transition Zones of Spring Fens

Wetlands ◽  
2019 ◽  
Vol 40 (2) ◽  
pp. 235-247
Author(s):  
Vendula Polášková ◽  
Jana Schenková ◽  
Martina Bílková ◽  
Martina Poláková ◽  
Vanda Šorfová ◽  
...  
Keyword(s):  
Small Scale ◽  
Transition Zones ◽  
Spring Fens

Magnetite texture and trace-element geochemistry fingerprint of pulsed mineralization in the Xinqiao Cu-Fe-Au deposit, Eastern China

2020 ◽  
Vol 105 (11) ◽  
pp. 1712-1723
Author(s):  
Yu Zhang ◽  
Pete Hollings ◽  
Yongjun Shao ◽  
Dengfeng Li ◽  
Huayong Chen ◽  
...  
Keyword(s):  
Trace Element ◽  
Triple Junction ◽  
Eastern China ◽  
Black Shales ◽  
Hydrothermal Fluids ◽  
Oscillatory Zoning ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Rock Interaction ◽  
Multiple Pulses

Abstract The origin of stratabound deposits in the Middle-Lower Yangtze River Valley Metallogenic Belt (MLYRB), Eastern China, is the subject of considerable debate. The Xinqiao Cu-Fe-Au deposit in the Tongling ore district is a typical stratabound ore body characterized by multi-stage magnetite. A total of six generations of magnetite have been identified. Mt1 is commonly replaced by porous Mt2, and both are commonly trapped in the core of Mt3, which is characterized by both core-rim textures and oscillatory zoning. Porous Mt4 commonly truncates the oscillatory zoning of Mt3, and Mt5 is characterized by 120° triple junction texture. Mt1 to Mt5 are commonly replaced by pyrite that coexists with quartz, whereas Mt6, with a fine-grained foliated and needle-like texture, commonly cuts the early pyrite as veins and is replaced by pyrite that coexists with calcite. The geochemistry of the magnetite suggests that they are hydrothermal in origin. The microporosity of Mt2 and Mt4 magnetite, their sharp contacts with Mt1 and Mt3, and lower trace-element contents (e.g., Si, Ca, Mg, and Ti) than Mt1 and Mt3 suggest that they formed via coupled dissolution and reprecipitation of the precursor Mt1 and Mt3 magnetite, respectively. This was likely caused by high-salinity fluids derived from intensive water-rock interaction between the magmatic-hydrothermal fluids associated with the Jitou stock and Late Permian metalliferous black shales. The 120° triple junction texture of Mt5 suggests it is the result of fluid-assisted recrystallization, whereas Mt6 formed by replacement of hematite as a result of fracturing. The geochemistry of the magnetite suggests that the temperature increased from Mt2 to Mt3 and implies that there were multiple pulses of fluids from a magmatic-hydrothermal system. Therefore, we propose that the Xinqiao stratiform mineralization was genetically associated with multiple influxes of magmatic hydrothermal fluids derived from the Early Cretaceous Jitou stock. This study demonstrates that detailed texture examination and in situ trace-elements analysis under robust geological and petrographic frameworks can effectively constrain the mineralization processes and ore genesis.

Phosphate immobilisation dynamics and interaction with arsenic sorption at redox transition zones in floodplain aquifers: Insights from the Red River Delta, Vietnam

2021 ◽  
Vol 411 ◽  
pp. 125128
Author(s):  
Harald Neidhardt ◽  
Sebastian Rudischer ◽  
Elisabeth Eiche ◽  
Magnus Schneider ◽  
Emiliano Stopelli ◽  
...  
Keyword(s):  
River Delta ◽  
Red River ◽  
Red River Delta ◽  
Transition Zones ◽  
Redox Transition

The component composition of planted pine wood cultivated in the boreal zone

2020 ◽  
Vol 35 (4) ◽  
pp. 685-693
Author(s):  
D. A. Danilov ◽  
A. V. Griazkin ◽  
V. A. Sokolova ◽  
I. V. Bacherikov
Keyword(s):  
Component Composition ◽  
Water Soluble ◽  
Boreal Zone ◽  
Lower Content ◽  
Average Yield ◽  
Leningrad Oblast ◽  
Pine Wood ◽  
Natural Stands

AbstractThe present study analyzes the composition of pine wood cultivated on artificial plantations in the Leningrad Oblast (Region). Comparing to pine wood from natural stands, a smaller heartwood zone along the height of the pine trunk and a lower content of resinous substances are noted. The content of cellulose and lignin in the heartwood and sapwood of pine is distributed differently along the trunk. The distribution of pentosans and water-soluble substances in the heartwood and sapwood along the trunk is associated with the lignin complex. The component composition of the studied pine wood from planted stands is quite uniform in its indicators if compared to the wood of older natural stands. Sulphate pulping of planted pine wood showed a higher yield of technical cellulose than the average yield from wood obtained at natural stands of the studied region.

Characterizing Reactive Iron Mineral Coatings in Redox Transition Zones

2020 ◽  
Vol 4 (12) ◽  
pp. 2337-2346
Author(s):  
Han Hua ◽  
Xin Yin ◽  
James A. Dyer ◽  
Richard Landis ◽  
Lisa Axe
Keyword(s):  
Transition Zones ◽  
Redox Transition ◽  
Iron Mineral ◽  
Reactive Iron ◽  
Mineral Coatings

scholarly journals Modeling of relative permeabilities including dynamic wettability transition zones

2021 ◽  
pp. 108556
Author(s):  
Abay Molla Kassa ◽  
Sarah E. Gasda ◽  
Kundan Kumar ◽  
Florin A. Radu
Keyword(s):  
Relative Permeabilities ◽  
Transition Zones

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

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