A huge gypsum miarolitic cavity has been found locatedin an antimony mineralized layer. It is an interformational bleb. Four crystallization steps are recognized for mineral crystals in the miarolitic cavity. Gypsum c...A huge gypsum miarolitic cavity has been found locatedin an antimony mineralized layer. It is an interformational bleb. Four crystallization steps are recognized for mineral crystals in the miarolitic cavity. Gypsum crystals seem to have been formed through two forms of crystallization. The data on fluid inclusions and hydrogen isotopes.show that this cavity is the product of hypergenic process, the orebeariug solution is derived from meteorie water, and the compositional material comes from the oxidized ore zone. During the formation of the miarolitic cayity, the pH-value was within the range of 4--5, i.e., weakly acidic solution, and the formation temperature less than 50℃. It can be clearly seen from the crystallization behaviour of gypsum cyrstals and mineral association that there have taken place significant changes in the pH-value of mineralization solution.展开更多
Recent eruption of Unzen Volcano in 1991-1995 caught attention of scientists all over the world because of disastrous character of previous one in 1792. Intrusion of andesitic magma to the chamber with rhyolitic magma...Recent eruption of Unzen Volcano in 1991-1995 caught attention of scientists all over the world because of disastrous character of previous one in 1792. Intrusion of andesitic magma to the chamber with rhyolitic magma is proposed to be a trigger for these eruptions. T-P-X parameters of two end-member magmas have been estimated several times, but usually estimations are based on phenocrysts assemblages. New results of this research are based on mafic enclaves and groundmass. These results are significant for magma mixing and mingling theory.展开更多
To characterize the magma that gave rise to explosive eruptions of Merapi volcano in October-November 2010, melt inclusions and juvenile components fiom the eruption deposits have been analyzed. Major-element composit...To characterize the magma that gave rise to explosive eruptions of Merapi volcano in October-November 2010, melt inclusions and juvenile components fiom the eruption deposits have been analyzed. Major-element compositions of whole-rocks were analyzed by X-ray fluorescence and trace elements, including the Rare Earth Elements by inductively coupled plasma mass spectrometry. Melt inclusions and the host minerals were analyzed using energy-dispersive X-ray spectroscopy and CO2 and H20 in melt inclusions, and their associated bubbles, were analyzed using laser Raman spectrometry. The compositions of the whole-rock eruption products are basaltic and esite that slightly sifting of SiO2 and K20 composition to previous eruption products, whereas the melt inclusions in pyroxene, plagioclase and hornblende are dacite to rhyolite, likely trapped mainly during late stages of crystallization of the magma. The most high volatile content in the melt inclusion are CO2 and H2O which appear strong Raman peaks for CO2 in the gas bubbles indicate abundances on high levels of CO2. Interpretation of result from a long-term flux of CO2 into the reservoir, either derived from more mafic magmas at depth or from reaction of magma in the reservoir with limestone and it may indicate that volcanic outgassing rates far exceed the amounts that can be supplied magmas.展开更多
This review work explains some of the most important techniques to detect the occurrence of magma mixing phenomena in the volcanic rocks by using SEM （scanning electron microscope）. In particular, the most useful me...This review work explains some of the most important techniques to detect the occurrence of magma mixing phenomena in the volcanic rocks by using SEM （scanning electron microscope）. In particular, the most useful methods related to the different types of mixing are reviewed： complete mixing （blending） or incomplete mixing （mingling）. For blending, backscattered electron images and EDS （energy dispersive spectroscopy） are the most accurate methods： an example taken from a sample of ash of the 2007 Stromboli volcano eruption was used. For mingling, the best method is given by X-ray elemental mapping （in particular of Ca and Si）, as explained through the example taken from a sample of the 2003 explosive eruption of Soufriere Hills volcano. The aim of this work was to establish whereas would be useful to use backscattered eletron images, EDS, or X-ray elemental mapping techniques, according to the different types of mixing that occur very often in magmatic systems.展开更多
文摘A huge gypsum miarolitic cavity has been found locatedin an antimony mineralized layer. It is an interformational bleb. Four crystallization steps are recognized for mineral crystals in the miarolitic cavity. Gypsum crystals seem to have been formed through two forms of crystallization. The data on fluid inclusions and hydrogen isotopes.show that this cavity is the product of hypergenic process, the orebeariug solution is derived from meteorie water, and the compositional material comes from the oxidized ore zone. During the formation of the miarolitic cayity, the pH-value was within the range of 4--5, i.e., weakly acidic solution, and the formation temperature less than 50℃. It can be clearly seen from the crystallization behaviour of gypsum cyrstals and mineral association that there have taken place significant changes in the pH-value of mineralization solution.
文摘Recent eruption of Unzen Volcano in 1991-1995 caught attention of scientists all over the world because of disastrous character of previous one in 1792. Intrusion of andesitic magma to the chamber with rhyolitic magma is proposed to be a trigger for these eruptions. T-P-X parameters of two end-member magmas have been estimated several times, but usually estimations are based on phenocrysts assemblages. New results of this research are based on mafic enclaves and groundmass. These results are significant for magma mixing and mingling theory.
文摘To characterize the magma that gave rise to explosive eruptions of Merapi volcano in October-November 2010, melt inclusions and juvenile components fiom the eruption deposits have been analyzed. Major-element compositions of whole-rocks were analyzed by X-ray fluorescence and trace elements, including the Rare Earth Elements by inductively coupled plasma mass spectrometry. Melt inclusions and the host minerals were analyzed using energy-dispersive X-ray spectroscopy and CO2 and H20 in melt inclusions, and their associated bubbles, were analyzed using laser Raman spectrometry. The compositions of the whole-rock eruption products are basaltic and esite that slightly sifting of SiO2 and K20 composition to previous eruption products, whereas the melt inclusions in pyroxene, plagioclase and hornblende are dacite to rhyolite, likely trapped mainly during late stages of crystallization of the magma. The most high volatile content in the melt inclusion are CO2 and H2O which appear strong Raman peaks for CO2 in the gas bubbles indicate abundances on high levels of CO2. Interpretation of result from a long-term flux of CO2 into the reservoir, either derived from more mafic magmas at depth or from reaction of magma in the reservoir with limestone and it may indicate that volcanic outgassing rates far exceed the amounts that can be supplied magmas.
文摘This review work explains some of the most important techniques to detect the occurrence of magma mixing phenomena in the volcanic rocks by using SEM （scanning electron microscope）. In particular, the most useful methods related to the different types of mixing are reviewed： complete mixing （blending） or incomplete mixing （mingling）. For blending, backscattered electron images and EDS （energy dispersive spectroscopy） are the most accurate methods： an example taken from a sample of ash of the 2007 Stromboli volcano eruption was used. For mingling, the best method is given by X-ray elemental mapping （in particular of Ca and Si）, as explained through the example taken from a sample of the 2003 explosive eruption of Soufriere Hills volcano. The aim of this work was to establish whereas would be useful to use backscattered eletron images, EDS, or X-ray elemental mapping techniques, according to the different types of mixing that occur very often in magmatic systems.
