Perlite deposits of the Central Slovakia Volcanic Field (Western Carpathians): Geology and properties

Perlites in the Central Slovakia Volcanic Field are associated with with rhyolite dykes, cryptodomes, extrusive domes, coulées and volcanoclastic rocks of the Jastrabá Fm. (12.3–11.4 Ma). From numerous occurrences only the Lehôtka pod Brehmi (LPB) and Jastrabá (JST) represent deposits of economic interest. The LPB deposit exploits a pile of extruded hyaloclastite breccia composed of grey porous and dark dense fragments. The JST deposit exploits glassy rhyolite breccia composed of grey porous fragments associated with an extrusive dome/coulée. The perlites at both deposits are peraluminous, calc-alkaline of the high-K type, poor in phenocrysts (around 5 %) of plagioclase, biotite and minor amphibole (LPB) or sanidine/anorthoclase (JST). Glass at both deposits is silica rich (75.4–79.5 wt. % dry) with Al2O3, K2O and Na2O as other major constituents. It is inhomogeneous showing domains enriched in Na2O or K2O. Glass water content (3.0–6.0 wt. %) shows a weak positive correlation with its silica content and a negative correlation with its Na2O content. Perlites show porosities of 5–16 % (dark dense), 16–30 % (grey porous) and 30–44 % (pale grey pumiceous). Narrow stretched pores represent remnants after outgassing of ascending magma while open undeformed pores grew at a low pressure before quenching. The transformation of volcanic glass into perlite took place owing to the hydration by heated fluids of meteoric origin. The hydration was supported by a significant porosity with interconnected pores and by sustained elevated temperature. Perlites at both deposits show a low content of tightly-bound water and a low Na/K ratio. These properties are responsible for their relatively low degree of expansion. On the other hand, due to the same reason, the perlites have a good mechanical stability.

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Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

10.5194/se-2019-106 ◽

2019 ◽

Cited By ~ 1

Author(s):

Ariadni Georgatou ◽

Massimo Chiaradia

Keyword(s):

Solid Solution ◽

Early Stage ◽

Volcanic Field ◽

Geodynamic Setting ◽

Calc Alkaline ◽

Western Turkey ◽

Epithermal Deposits ◽

High K ◽

Wide Range ◽

Magmatic Sulphides

Abstract. We investigate in both mineralised and barren systems the occurrence and chemistry of magmatic sulphides and their chalcophile metal cargo behaviour during evolution of compositionally different magmas in diverse geodynamic settings. The investigated areas are: (a) the Miocene Konya magmatic province (hosting the Doganbey Cu-Mo and Inlice Au-epithermal deposits) (Post-Subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe and Beydagi volcanoes, the latter associated with the Kisladag Au porphyry) in Western Turkey (Post-Subduction). For comparison we also investigate (c) the barren Plio-Quaternary Kula volcanic field, west of Usak (Intraplate) and finally we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu-Mo and Cascabel Cu-Au porphyry deposits) (Subduction). The volcanism of the studied areas displays a wide range of SiO2 spanning from basalts to andesites/dacites and from high K-calc-alkaline to shoshonitic series. Multiphase magmatic sulphides occur in different amounts in all investigated areas and based on textural and compositional differences, they can be classified in different types, which crystallised at different times (early versus late saturation). A decrease in the sulphide Ni/Cu (proxy for mss-monosulphide solid solution/iss-intermediate solid solution) ratio is noted with magmatic evolution. Starting with an early stage, saturating Ni-richer/Cu-poorer sulphides hosted by early crystallising minerals e.g. olivine/pyroxene, leading up to a later stage, producing Cu-richer sulphides hosted by magnetite. The most common sulphide type resulting from an early saturating stage is composed of a Cu-poor/Ni-rich (pyrrhotite/mss) and one/two Cu-rich (cubanite, chalcopyrite/iss) phases making up 84 and 16 area % of the sulphide, respectively. Our results suggest that independently of the magma composition, geodynamic setting and whether or not the system has generated an ore deposit on the surface, sulphide saturation occurred in variable degrees in all studied areas and magmatic systems and is characterised by a similar initial metal content of the magmas. However not all studied areas present all sulphide types and the sulphide composition is dependent on the nature of the host mineral. In particular sulphides, resulting from the late stage, consisting of Cu-rich phases (chalcopyrite ,bornite, digenite/iss) are hosted exclusively by magnetite and are found only in magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

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Post-collisional high-K calc-alkaline volcanism in Tengchong volcanic field, SE Tibet: constraints on Indian eastward subduction and slab detachment

Journal of the Geological Society ◽

10.1144/jgs2014-078 ◽

2015 ◽

Vol 172 (5) ◽

pp. 624-640 ◽

Cited By ~ 24

Author(s):

Zhengfu Guo ◽

Zhihui Cheng ◽

Maoliang Zhang ◽

Lihong Zhang ◽

Xiaohui Li ◽

...

Keyword(s):

Volcanic Field ◽

Calc Alkaline ◽

Alkaline Volcanism ◽

High K ◽

Se Tibet

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Fluid Inclusions at the Plavica Au-Ag-Cu Telescoped Porphyry–Epithermal System, Former Yugoslavian Republic of Macedonia (FYROM)

Geosciences ◽

10.3390/geosciences9020088 ◽

2019 ◽

Vol 9 (2) ◽

pp. 88

Author(s):

Vasilios Melfos ◽

Panagiotis Voudouris ◽

Todor Serafimovski ◽

Goran Tasev

Keyword(s):

Fluid Inclusions ◽

Volcanic Rocks ◽

Volcanic Field ◽

Epithermal Deposit ◽

Calc Alkaline ◽

Epithermal Deposits ◽

Republic Of Macedonia ◽

High K ◽

Propylitic Alteration ◽

Yugoslavian Republic

The Plavica Au-Ag-Cu porphyry and high sulfidation (HS) epithermal deposit is located at the Kratovo–Zlatovo volcanic field in Eastern Former Yugoslavian Republic of Macedonia. In this study, new fluid inclusions data provide additional evidence of the presence of a porphyry style mineralization which is associated with an overlain HS epithermal deposit. The Oligocene–Miocene magmatic rocks have a calc–alkaline to high-K calc–alkaline affinity and consist of sub-volcanic intrusions and volcanic rocks. Previous studies distinguished four alteration types: (a) Sericitic, (b) advanced argillic, (c) silicification, and (d) propylitic alteration. Fluid inclusions showed an early magmatic brine in porphyry style veins with high salinity (33–57 wt% NaCl equiv.), which coexists with a vapor rich fluid with lower salinity (14–20 wt% NaCl equiv.), at temperatures 380–500 °C, under boiling conditions. At shallower depths, the fluid inclusions demonstrate various HS–epithermal deposits which were formed by moderate to low salinity (3–14 wt% NaCl equiv.) hydrothermal fluids at lower temperatures from 200 to 300 °C.

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Middle Triassic high-K calc-alkaline effusive and pyroclastic rocks from the Zagorje-Mid-Transdanubian Zone (Mt. Kuna Gora; NW Croatia): mineralogy, petrology, geochemistry and tectonomagmatic affinity

Geologica Acta ◽

10.1344/geologicaacta2021.19.2 ◽

2021 ◽

Vol 19 ◽

pp. 1-23

Author(s):

Damir Slovenec ◽

Branimir Šegvić

Keyword(s):

Middle Triassic ◽

Crustal Contamination ◽

Volcanic Glass ◽

Alkali Feldspar ◽

Oceanic Lithosphere ◽

White Mica ◽

Calc Alkaline ◽

Rock Types ◽

Active Margins ◽

High K

This study uses mineralogical, petrological, geochemical, and Sr and Nd isotope data along with K-Ar ages to infer the petrogenesis and geodynamic evolution of Middle Triassic high-K calc-alkaline lavas and their associated pyroclastics of Mt. Kuna Gora in NW Croatia. Their analogue mineralogy and bulk-rock geochemistry testify to the coeval origin of both rock types. Sanidine and plagioclase accompanied by inor augite and Ti-bearing magnetite are the major phases found in a matrix of devitrified volcanic glass and plagioclase microlites. Hydrothermal anddiagenetic processes in the pyroclastics originated the formation of chlorite and white mica, and mixed-layer clay minerals, respectively. Petrography reveals the following crystallization order: spinel→clinopyroxene→plagioclase→alkali-feldspar±Fe-Ti oxides. Geochemical and isotopic data suggests that the studied rocks had a complex origin that included the contamination of subduction-generated magmas by lithospheric mantle melts. This presumes an interplay between fertile arc mantle, subducted continental crust, and depleted or ocean island basalts-like mantle. A low degree of crustal contamination stands as a last step in the formation of such “hybrid” magmas. The subducted Paleotethyan oceanic lithosphere went through processes of partial melting at depths of ~45-49km and pressures of ≤1.6GPa and fractionation that produced melts which gave rise to the studied rocks. In the model we are proposing herein such formed partial melts are related to the demise of the northward subduction of the Paleotethys oceanic lithosphere during the Early to Middle Triassic epoch, which is consistent with an active, ensialic mature volcanic arc developing along Laurussian southern active margins.

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Alteration of glassy volcanic rocks to Naand Ca-smectites in the Neogene basin of Manisa, western Anatolia, Turkey

Clay Minerals ◽

10.1180/claymin.2013.048.3.08 ◽

2013 ◽

Vol 48 (3) ◽

pp. 513-527 ◽

Cited By ~ 4

Author(s):

M. Çiflikli ◽

E. Çiftçi ◽

H. Bayhan

Keyword(s):

Chemical Weathering ◽

Volcanic Rocks ◽

Experimental Studies ◽

Volcanic Glass ◽

Western Anatolia ◽

Calc Alkaline ◽

Humid Climate ◽

Volcanic Material ◽

Argillic Alteration ◽

High K

AbstractAlkali- and Ca-rich smectites occur in association with Neogene lacustrine sedimentary rocks and high-K calc-alkaline volcanic rocks with compositions ranging from andesite to rhyolite in western Anatolia (Turkey). Major clay occurrences are associated predominantly with the Foça and Akçaköy ignimbrites and with the ignimbrites within the Rahmanlar pyroclastics. Experimental studies indicate that the main clay minerals present are Na- and Ca-smectite and subordinate illite, associated with silica polymorphs, trace clinoptilolite and chlorite. The authigenic minerals formed by weathering and metasomatic reactions between hot volcanic material and lake water. Smectite was produced as a result of argillic alteration of the volcanic glass and feldspars of the ignimbrites, Rahmanlar pyroclastics and reworked volcaniclastic sediments through chemical weathering and dissolution-precipitation processes and formed as authigenic phases both in terrestrial and nearby shallow lacustrine environments under prevalent humid or semi-humid climate during the Neogene.

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Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico

Revista Mexicana de Ciencias Geológicas ◽

10.22201/cgeo.20072902e.2017.1.401 ◽

2017 ◽

Vol 34 (1) ◽

pp. 45 ◽

Cited By ~ 5

Author(s):

Elizard González-Becuar ◽

Efrén Pérez-Segura ◽

Ricardo Vega-Granillo ◽

Luigi Solari ◽

Carlos Manuel González-León ◽

...

Keyword(s):

Metamorphic Core Complex ◽

Primitive Mantle ◽

Isotopic Ratios ◽

Magmatic Evolution ◽

Calc Alkaline ◽

Core Complex ◽

High K ◽

Sierra Madre ◽

Plutonic Rocks ◽

Metamorphic Core

Plutonic rocks of the Puerta del Sol area, in central Sonora, represent the extension to the south of the El Jaralito batholith, and are part of the footwall of the Sierra Mazatán metamorphic core complex, whose low-angle detachment fault bounds the outcrops of plutonic rocks to the west. Plutons in the area record the magmatic evolution of the Laramide arc and the Oligo-Miocene syn-extensional plutonism in Sonora. The basement of the area is composed by the ca. 1.68 Ga El Palofierral orthogneiss that is part of the Caborca block. The Laramide plutons include the El Gato diorite (71.29 ± 0.45 Ma, U-Pb), the El Pajarito granite (67.9 ± 0.43 Ma, U-Pb), and the Puerta del Sol granodiorite (49.1 ± 0.46 Ma, U-Pb). The younger El Oquimonis granite (41.78 ± 0.32 Ma, U-Pb) is considered part of the scarce magmatism that in Sonora records a transition to the Sierra Madre Occidental magmatic event. The syn-extensional plutons are the El Garambullo gabbro (19.83 ± 0.18 Ma, U-Pb) and the Las Mayitas granodiorite (19.2 ± 1.2 Ma, K-Ar). A migmatitic event that affected the El Palofierral orthogneiss, El Gato diorite, and El Pajarito granite between ca. 68 and 59 Ma might be related to the emplacement of the El Pajarito granite. The plutons are metaluminous to slightly peraluminous, with the exception of El Oquimonis granite, which is a peraluminous two-mica, garnet-bearing granite. They are mostly high-K calc-alkaline with nearly uniform chondrite-normalized REE and primitive-mantle normalized multielemental patterns that are characteristic of continental margin arcs and resemble patterns reported for other Laramide granites of Sonora. The Laramide and syn-extensional plutons also have Sr, Nd and Pb isotopic ratios that plot within the fields reported for Laramide granites emplaced in the Caborca terrane in northwestern and central Sonora. Nevertheless, and despite their geochemical affinity to continental magmatic arcs, the El Garambullo gabbro and Las Mayitas granodiorite are syn-extensional plutons that were emplaced at ca. 20 Ma during development of the Sierra Mazatán metamorphic core complex. The 40Ar/39Ar and K-Ar ages obtained for the El Palofierral orthogneiss, the Puerta del Sol granodiorite, the El Oquimonis granite, and the El Garambullo gabbro range from 26.3 ± 0.6 to 17.4 ± 1.0 Ma and are considered cooling ages associated with the exhumation of the metamorphic core complex.

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Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing’an Range, NE China

Geological Magazine ◽

10.1017/s0016756821000170 ◽

2021 ◽

pp. 1-22

Author(s):

Jia-Hao Jing ◽

Hao Yang ◽

Wen-Chun Ge ◽

Yu Dong ◽

Zheng Ji ◽

...

Keyword(s):

Early Cretaceous ◽

Volcanic Rocks ◽

Geochemical Data ◽

Calc Alkaline ◽

Ne China ◽

Asthenospheric Mantle ◽

High K ◽

Wide Range ◽

Great Xing’An Range ◽

Subducting Slab

Abstract Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

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