![]() Where weathering has caused changes in abundance patterns these may be recognised by careful comparisons of appropriate elemental ratios (e.g., Ba/Rb) throughout a particular analysed sample suite. Electronic coatings based on barium titanate are essential to cell phones and. The study illustrates that relatively slight alteration at the earliest stages of weathering can produce drastic changes in the concentrations of REE, Y and Ba and petrographic assessment of the freshness of samples is not precise enough to eliminate, prior to analysis, cases where these effects may be manifested. it is frequently used as a contrast medium for imaging the gastrointestinal tract. Sr isotopic compositions are not strongly affected by incipient weathering and do not show significant changes until alteration has progressed to the point where plagioclase begins to break down. Because of its high chemical reactivity, barium is never found in nature as a free element. Barium is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Ba anomalies are not necessarily accompanied by “abnormal” Y and REE behaviour and this is probably because the mobility of each trace element is a function of: (a) the ionic radius and charge of the ionic species it forms in solution (b) local groundwater parameters (such as Eh, pH, groundwater flux, and concentrations in the groundwater of species such as SO 4 2−) and (c) the secondary mineral assemblages developed in a particular situation. Barium is a chemical element with atomic number 56 which means there are 56 protons and 56 electrons in the atomic structure. This is reflected in the broad patterns of trace-element behaviour manifested by an extensive analysed sample suite from the Victorian Newer Volcanic Province where there is no correlation between anomalous enrichments in Ba, Y, or REE and the level of incipient alteration. Samples taken sequentially across a weathering profile in a tholeiitic basalt flow, from fresh to intensively altered rock, illustrate that, in the very earliest stages of alteration, extreme variations in the abundances of Ba, Y and REE can occur. Leaching experiments suggest that glassy or fine-grained rocks are more likely to release REE, Y and Ba while more extensively altered rocks are likely to hold these elements, probably because they substitute in, or are adsorbed on, clay minerals or because secondary BaSO 4 and REE phosphates are resistant to acid leaching. ![]() ![]() REE and Y released during weathering of basalts are retained either in secondary phosphate or clay minerals and, in rocks showing very high Ba concentrations, the Ba is present as BaSO 4. Tholeiitic basalts showing anomalously high Ba, Y and rare-earth element (REE) concentrations occur within the Tertiary Newer Volcanic Province of Victoria and these geochemical characteristics are related to incipient alteration accompanying weathering.
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