Nowadays fluid inclusion petrography and microthermometry are widely applied techniques for inves... more Nowadays fluid inclusion petrography and microthermometry are widely applied techniques for investigating various geological processes. The most common minerals in the process of fluid inclusion microthermometry are primarily quartz, calcite and other transparent minerals. However, many minerals in the 400-700 nm wavelength (visible light) range are opaque. The IR radiation has lower energy than the visible light and therefore its energy is not large enough to excite the movement of an electron from the valence band to the conduction band; thus the light is not absorbed by the mineral. Consequently, the mineral is transparent in IR light. Several opaque minerals -such as pyrite, enargite, stibnite, molybdenite, haematite, etc. -have been found to be transparent in IR light. Microthermometric studies on these minerals have indicated that their fluid inclusions acted in such a way as to preserve certain stages of the geological processes; otherwise, these could not have been reconstructed on the basis of conventional studies of fluid inclusions in transparent minerals. The IR microscopy and microthermometry have recently been introduced into routine practice in the fluid inclusion laboratory of the Department of Mineralogy at the Eötvös Loránd University. The calibration measurements indicate that the "green house effect" on fluid inclusions in enargite -which is caused by the thermal energy of the IR radiation -does not reach the extent of that limit which could effect the geological interpretations of microthermometry data. This can be explained by the properties of the analytical system, given that all the instruments have been optimized for the transmission of the IR radiation. IR microscopy and microthermometry represent a powerful new field for fluid inclusion microthermometry and could open up new areas for the study of various geological processes.
Complex kelyphitic rims after garnet were studied in a lower crustal mafic granulite xenolith fro... more Complex kelyphitic rims after garnet were studied in a lower crustal mafic granulite xenolith from the Bakony– Balaton Highland Volcanic Field, W-Hungary. The xenolith is dominated by a garnet granulite mineral assemblage equilibrated at 900 ̊C, 1.4 GPa within the overthickened orogenic root of the Alps. Garnet breakdown was initiated during the extension of the Pannonian Basin and remained continuous until the xenoliths reached the surface. This resulted in the formation of various microstructural domains within the kelyphitic rims which were distinguished to three main types: fine-grained symplectites, recrystallized symplectites and cyrstallized melts. Fine-grained symplectites are the products of isochemical breakdown of garnet to pure anorthite, Al-orthopyroxene and hercynitic spinel. Nanoscale topography built up by curved chains of humps on the garnet surface showing regular spatial distribution is observed at the reaction front in 3D reconstructions. These patterns follow th...
Although gilt silver threads were widely used for decorating historical textiles, their manufactu... more Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed crosssectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano-and microscale textural, chemical and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron back-scattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy. The thickness of the gold coating varied between 70-400 nm. Data reveal nano-and microscale metallurgy-related, gilding-related and corrosion-related inhomogeneities in the silver base. These inhomogeneities account for the limitations of surface analysis when tracking gilding methods of historical metal threads, and explain why chemical information has to be connected to 3D texture on submicrometre scale. The geometry and chemical composition (lack of mercury, copper) of the gold/silver interface prove that the ancient gilding technology was diffusion bonding. The observed differences in the copper content of the silver base of the different thread types suggest intentional technological choice. Among the examined textiles of different ages (13 th-17 th centuries) and provenances narrow technological variation has been found.
Ore Mineralogy and Fluid Inclusion Constraints on the Temporal and Spatial Evolution of a High-Sulfidation Epithermal Cu-Au-Ag Deposit in the Recsk Ore Complex, Hungary*
The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and vo... more The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and volcaniclastics, carbonate rocks, black shales, mica schists and greywackes which were deposited from ca. 2.44 to~1.91 Ga, during the rifting of the Archaean basement in the eastern part of the Fennoscandian shield. Metamorphism and multiple folding of the basin fill took place during the Svecofennian orogeny (1.9-1.8 Ga) followed by intrusions of late-orogenic (1.84-1.80 Ga) and post-orogenic granitoids (1.79-1.76 Ga). The Rompas Au-U mineralisation is hosted by deformed calcsilicate veins in mafic volcanic rocks and locally contains very high grade (>10,000 g/t Au) gold pockets with strict spatial association of gold minerals to uraninite and pyrobitumen. Chemical ages from the unaltered domains in the structure of uraninite indicate a 1.95-1.90 Ga age for the
Nowadays fluid inclusion petrography and microthermometry are widely applied techniques for inves... more Nowadays fluid inclusion petrography and microthermometry are widely applied techniques for investigating various geological processes. The most common minerals in the process of fluid inclusion microthermometry are primarily quartz, calcite and other transparent minerals. However, many minerals in the 400-700 nm wavelength (visible light) range are opaque. The IR radiation has lower energy than the visible light and therefore its energy is not large enough to excite the movement of an electron from the valence band to the conduction band; thus the light is not absorbed by the mineral. Consequently, the mineral is transparent in IR light. Several opaque minerals -such as pyrite, enargite, stibnite, molybdenite, haematite, etc. -have been found to be transparent in IR light. Microthermometric studies on these minerals have indicated that their fluid inclusions acted in such a way as to preserve certain stages of the geological processes; otherwise, these could not have been reconstructed on the basis of conventional studies of fluid inclusions in transparent minerals. The IR microscopy and microthermometry have recently been introduced into routine practice in the fluid inclusion laboratory of the Department of Mineralogy at the Eötvös Loránd University. The calibration measurements indicate that the "green house effect" on fluid inclusions in enargite -which is caused by the thermal energy of the IR radiation -does not reach the extent of that limit which could effect the geological interpretations of microthermometry data. This can be explained by the properties of the analytical system, given that all the instruments have been optimized for the transmission of the IR radiation. IR microscopy and microthermometry represent a powerful new field for fluid inclusion microthermometry and could open up new areas for the study of various geological processes.
Complex kelyphitic rims after garnet were studied in a lower crustal mafic granulite xenolith fro... more Complex kelyphitic rims after garnet were studied in a lower crustal mafic granulite xenolith from the Bakony– Balaton Highland Volcanic Field, W-Hungary. The xenolith is dominated by a garnet granulite mineral assemblage equilibrated at 900 ̊C, 1.4 GPa within the overthickened orogenic root of the Alps. Garnet breakdown was initiated during the extension of the Pannonian Basin and remained continuous until the xenoliths reached the surface. This resulted in the formation of various microstructural domains within the kelyphitic rims which were distinguished to three main types: fine-grained symplectites, recrystallized symplectites and cyrstallized melts. Fine-grained symplectites are the products of isochemical breakdown of garnet to pure anorthite, Al-orthopyroxene and hercynitic spinel. Nanoscale topography built up by curved chains of humps on the garnet surface showing regular spatial distribution is observed at the reaction front in 3D reconstructions. These patterns follow th...
Although gilt silver threads were widely used for decorating historical textiles, their manufactu... more Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed crosssectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano-and microscale textural, chemical and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron back-scattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy. The thickness of the gold coating varied between 70-400 nm. Data reveal nano-and microscale metallurgy-related, gilding-related and corrosion-related inhomogeneities in the silver base. These inhomogeneities account for the limitations of surface analysis when tracking gilding methods of historical metal threads, and explain why chemical information has to be connected to 3D texture on submicrometre scale. The geometry and chemical composition (lack of mercury, copper) of the gold/silver interface prove that the ancient gilding technology was diffusion bonding. The observed differences in the copper content of the silver base of the different thread types suggest intentional technological choice. Among the examined textiles of different ages (13 th-17 th centuries) and provenances narrow technological variation has been found.
Ore Mineralogy and Fluid Inclusion Constraints on the Temporal and Spatial Evolution of a High-Sulfidation Epithermal Cu-Au-Ag Deposit in the Recsk Ore Complex, Hungary*
The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and vo... more The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and volcaniclastics, carbonate rocks, black shales, mica schists and greywackes which were deposited from ca. 2.44 to~1.91 Ga, during the rifting of the Archaean basement in the eastern part of the Fennoscandian shield. Metamorphism and multiple folding of the basin fill took place during the Svecofennian orogeny (1.9-1.8 Ga) followed by intrusions of late-orogenic (1.84-1.80 Ga) and post-orogenic granitoids (1.79-1.76 Ga). The Rompas Au-U mineralisation is hosted by deformed calcsilicate veins in mafic volcanic rocks and locally contains very high grade (>10,000 g/t Au) gold pockets with strict spatial association of gold minerals to uraninite and pyrobitumen. Chemical ages from the unaltered domains in the structure of uraninite indicate a 1.95-1.90 Ga age for the
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Papers by Ágnes Takács