A Tertiary non-marine stratigraphic sequence composed of carbonates (limestone),siliceous carbonates, coaly layers overlain by pyroclastic rocks and lavas, outcrops in the Ga-vatha area of northwestern Lesvos Island. ...A Tertiary non-marine stratigraphic sequence composed of carbonates (limestone),siliceous carbonates, coaly layers overlain by pyroclastic rocks and lavas, outcrops in the Ga-vatha area of northwestern Lesvos Island. Pure carbonates consist almoot completely of calcite,the siliceous carbonate sediments of quartz, opal-CT and calcite, the shales of quartz, opal-CT,K-feldspar, smectite-illite and calcite, and the coaly layers of organic matter, quartz, opal-CT,feldspars and pyrite. Geochemical data indicate that smectite-illite, feldspars and associated ele-ments (La, Zr, Y, Ba, Ce) are the preducts of alteration of volcanic rocks in a subtropicalarea.A combination of sources is suggested for the formation of silica polymorphs: (a) biogenicor non-biogenic silica (opal-A) that was originally present in the form of diatom frustules or inthe form of inorganically precipitated silica; (b) transformation of opal-A to opal-CT and quartzopal-C from alteration of volcanic glass of intercalated tuffites and overlying volcanics; and (c)opal-CT deposited primarily from hydrothermal solutions.展开更多
High purity silica bricks have stable physical properties,except for the RUL （0.2 MPa） exhibiting extreme two different levels of high-level RUL T0.6 of 1 683-1 686 ℃ and low-level RUL T0.6 of1 174-1 184 ℃.The low...High purity silica bricks have stable physical properties,except for the RUL （0.2 MPa） exhibiting extreme two different levels of high-level RUL T0.6 of 1 683-1 686 ℃ and low-level RUL T0.6 of1 174-1 184 ℃.The low RUL phenomenon was researched,the formation reasons and solutions were analyzed in this paper.The low-level RUL T0.6 of 1 174-1 184 ℃ of the un-burnt high purity silica bricks is a pseudo RUL T0.6 phenomenon for the transformation of crystalline morphology.The real RUL T0.6 of the specimen hot treated at 1 093 ℃ is ＞ 1 680 ℃.Therefore,the un-burnt high purity silica bricks shall be hot treated at about 1 100 ℃ firstly before testing RUL.For the heating up of the lining of glass tank arch,baking curves with long holding time at 1 100 ℃ shall be strictly obeyed to avoid the obvious shrinkage negatively influencing the lining stability.展开更多
文摘A Tertiary non-marine stratigraphic sequence composed of carbonates (limestone),siliceous carbonates, coaly layers overlain by pyroclastic rocks and lavas, outcrops in the Ga-vatha area of northwestern Lesvos Island. Pure carbonates consist almoot completely of calcite,the siliceous carbonate sediments of quartz, opal-CT and calcite, the shales of quartz, opal-CT,K-feldspar, smectite-illite and calcite, and the coaly layers of organic matter, quartz, opal-CT,feldspars and pyrite. Geochemical data indicate that smectite-illite, feldspars and associated ele-ments (La, Zr, Y, Ba, Ce) are the preducts of alteration of volcanic rocks in a subtropicalarea.A combination of sources is suggested for the formation of silica polymorphs: (a) biogenicor non-biogenic silica (opal-A) that was originally present in the form of diatom frustules or inthe form of inorganically precipitated silica; (b) transformation of opal-A to opal-CT and quartzopal-C from alteration of volcanic glass of intercalated tuffites and overlying volcanics; and (c)opal-CT deposited primarily from hydrothermal solutions.
文摘High purity silica bricks have stable physical properties,except for the RUL （0.2 MPa） exhibiting extreme two different levels of high-level RUL T0.6 of 1 683-1 686 ℃ and low-level RUL T0.6 of1 174-1 184 ℃.The low RUL phenomenon was researched,the formation reasons and solutions were analyzed in this paper.The low-level RUL T0.6 of 1 174-1 184 ℃ of the un-burnt high purity silica bricks is a pseudo RUL T0.6 phenomenon for the transformation of crystalline morphology.The real RUL T0.6 of the specimen hot treated at 1 093 ℃ is ＞ 1 680 ℃.Therefore,the un-burnt high purity silica bricks shall be hot treated at about 1 100 ℃ firstly before testing RUL.For the heating up of the lining of glass tank arch,baking curves with long holding time at 1 100 ℃ shall be strictly obeyed to avoid the obvious shrinkage negatively influencing the lining stability.
