Lava, volcanic

Koshimoda Andesite andesite lava volcanic breccia +500tn... 

Koshimoda Volcano (andesite lava, volcanic breccia)... 

Stem cells, haploid germ cells, somatic cells, transformed cells. The ancient unicellular life forms survived under the most adverse conditions in a chemically hostile, overheated (boiling water pouring lava volcanic fumes), chemically imbalanced as to excessive acidity or alkalinity, and heavily radioactive environment. The y-rays-irradiated but radiation-resistant Deinococcus radiodurans (Figure 4) suffers genomic damage it is its chaperone proteins in its proteome that perform the rescue of the genome (Mediterranean Instimte for Life Sciences, Split, Croatia). 

Fig. 16.44 Mt. Early (2,720 m) is a large volcanic mountain of Miocene age located at the head of the Scott Glacier in Fig. 16.43. It is composed of pillow lavas, volcanic breccia, and palagonite (hydrated volcanic glass of subglacial or subaqueous...

Gas Solid Solid foam Pumice, lava, volcanic ash... 

Most copper deposits are (/) porphyry deposits and vein replacement deposits, (2) strata-bound deposits in sedimentary rocks, (J) massive sulfide deposits in volcanic rocks, (4) magmatic segregates associated with nickel in mafic intmsives, or (5) native copper, typified by the lava-associated deposits of the Keweenaw Peninsula, Michigan. 

Pressure aerators employ a vertical, volcanic lava media-filled PV and receive water at pump pressure. The water is mixed with blown air and fed to the bottom of the bed. Excess air is discharged through an air valve to atmosphere, and the aerated water is collected at the top of the column and then fed to a sand filter for removal of insoluble ferric hydroxide. 

Improved results may be obtained by substituting the volcanic lava for BIRM at a bed depth of 30 to 36 inches (76-91 cm) and a flow rate of 4 to 5 gpm/sq ft of media bed surface area. BIRM acts as a catalyst and normally requires only a periodic backwash to remove surface debris (backwash rate in pressure filter tank is 10 gpm/sq ft). 

Aeration towers are often simply constructed wooden towers with or without the benefit of a forced-air draft, over which the well water is distributed. Typically, the tower holds 8 to 10 trays, each with a 3- to 4-inch (7.6-10.2 cm) bed depth of volcanic lava or coke media to provide the total 30 to 36" (76-91 cm) depth required. The lava or coke acts as a catalyst for the further precipitation of iron and manganese salts. These salts can be readily oxidized provided there is sufficient alkalinity present. If in doubt, ensure a minimum of 120 to 150 ppm total alkalinity (T Aik or M Aik) as CaC03. 

In practice, aeration towers using coke or volcanic lava tend not to be as efficient as spray ponds in facilitating the precipitation of ferrous hydroxide consequently, there is usually a requirement for a cationic flocculant to aid the precipitation of the insoluble materials into a larger floe or denser sludge that can be removed by clarification or sand filtration. 

As already noted, most epithermal Au-Ag vein-type deposits are hosted by young (late Miocene-Pliocene) volcanic rocks and by sedimentary rocks, but dominant host and country rocks for base-metal vein-type deposits are submarine sedimentary and volcanic rocks. Submarine felsic tuff, tuff breccia, dacite lava, intrusive rocks and mudstone are dominant host and country rocks of Kuroko deposits. 

Tertiary rocks are distributed widely. They are composed of alternations of sandstone, mudstone, andesitic and dacitic tuff, tuff breccia and lava. These rocks are intensively and extensively altered and are called as Green tuff. Tertiary volcanic rocks are variable in composition. Andesite, dacite and basalt are found. Quaternary volcanic rocks are dominantly andesite lava and are abundantly distributed in the northern part of the province (Fig. 1.148). 

Hydrothermal alteration in the Osorezan area is extensive. At the foot of the lava dome, highly silicified alteration occurs. From this zone towards marginal parts, kaolinite zone and montmorillonite zone exist. This type of alteration was caused by the acid hydrothermal solution. But at present such acid hot solutions are not present in the Osorezan area. The acid solution is considered to be of volcanic origin. It is therefore thought that the water chemistry evolved from extremely acid at the early stage to neutral pH at present (Aoki, 1992a). 

The age of Green tuff volcanic activity ranges widely from ca. 25 Ma to 2 Ma. Volcanic activity during the early to middle Miocene (25-15 Ma) was intensive, whereas it was weak during the late Miocene to early Quaternary (Sugimura et al., 1963) (Fig. 3.1). The production of lavas and other effusives per unit time reached five or six time more... 

Data on mineral s arates in present day volcanic rocks. Since every dating method (including the K-Ar or C systems) can be affected by several geochemical perturbations which may lead to erroneous ages, the best test for the °Th- U mineral isochrons consists in the analysis of presently erupted lavas or historic lavas of well known eruption dates. Rather surprisingly the data obtained on such samples are not so numerous (some examples are illustrated in Fig. 10). Early data showed that, in some cases, there were interlaboratory analytical discrepancies, especially in Th isotope ratios measured on mineral separates extracted from the same lava flows (this was the case for the 1971 lava from Mt. Etna and 1944 lava from Mt. Vesuvius Capaldi and Pece 1981 Hemond and Condomines 1985 Capaldi et al. 1985). This emphasizes the fact that °Th- U mineral analyses... 

Th- U dating of samples from subaerial volcanoes. When several volcanic rocks covering a significant period of the eruptive activity of a volcano can be dated (either by mineral isochrons or by other dating methods), the evolution through time of the ( °Th/ Th)o or ( °Th/ U)o initial ratios will be revealed (see section 3.4). If these ratios remain nearly constant, then they may be used to calculate the ages of other lavas... 

Gauthier PJ, Le Cloarec MF, Condomines M (2000) Degassing processes at Stromboli Volcano inferred from short-lived disequilibria ( °Pb- °Bi- °Po) in volcanic gases. J Volcanol Geotherm Res 102 1-19 Gill J, Williams R, Braland K (1985) Emption of basalt and andesite lava degasses Rn and °Po. Geophys Res Lett 12 17-20... 

The most important observations about U-series isotopes in arc lavas for this chapter are (1) the widespread excess of over °Th but deficit of with respect to Pa and (2) the extreme Ra enrichments in some arc lavas. We will explore the profound implications of these for magma genesis and transport at subduction zones. The conclusions apply most convincingly to the oceanic arcs where the observations are most extreme (the volcanic fronts of Tonga, Marianas, and eastern Sunda, and one or two volcanoes in some other arcs). Whether the conclusions apply elsewhere is harder to verify but there is no convincing reason with respect to U-series data to believe that they do not. 

One of the seemingly inescapable conclusions from the Ra- °Th disequilibrium data, at least for Tonga and the Mariana volcanic fronts, is that significantly less than 8000 years and arguably only a few half lives (ca. 1000-3000 yrs) can have elapsed since the generation of the Ra-excesses observed in the arc lavas plotted on Figure 10. 

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