High Rb Contents Research Articles

The Crystallization History of a Granitic Magma, as Revealed by Trace Element Abundances

The spatial distribution of Ti, Ba, Sr, and Rb in the 2400 m thick sheet-like, acid, plutonic phase (Main Granite) of the Bushveld Complex is examined. Zones of greater concentrations of Ti, Ba, and Sr, and lower Rb, are developed along the roof, and especially along the floor. Ti, Ba, and Sr decrease in abundance, and Rb increases, inwards into the sheet, producing nearly-symmetric concentration profiles through the sheet. Asymmetric patterns are developed across a late-forming, miarolitic portion of the sheet (Bobbejaankop Granite). The uppermost portions of this tin-mineralized granite are characterized by relatively low abundances of Ba, Sr, and Ti, and high Rb contents. Comparisons of the observed spatial Sr distribution in the granites with model calculations indicate that simple ionic diffusion in the magma during crystallization could not have produced the observed pattern, but that convective mixing must have occurred in the parent melt. This is confirmed by the likely range of Peclet numbers of ...

Rubidium as a guide to ore in Chilean porphyry copper deposits

Hypogene mineralization in porphyry copper deposits is characteristically associated with zones of potassic alteration. The mineralization and hydrothermal alteration are thought to be produced by an aqueous phase which has separated from a crystallizing magma. Due to the similarity in geochemical characteristics of K and Rb, Rb can be incorporated in K minerals that crystallize from a magma. The Rb ion is only 0.14 Aa larger than the K ion, but this size difference results in a higher bonding energy between K and O than between Rb and O. Therefore, when K minerals crystallize from a magma, K is preferentially removed with respect to Rb. The Rb tends to concentrate in the residual melt. If an aqueous phase separates from a magma during late stages of crystallization, it should have relatively higher Rb concentrations and low K/Rb ratios. High Rb concentrations and low K/Rb ratios might therefore be expected in rocks that have undergone potassic alteration.Wide zones of potassic alteration are closely associated with the orebodies at the Chilean porphyry copper deposits in the El Teniente (Braden), Rio Blanco, and Los Bronces (Disputada) mines. Therefore, the distribution of Rb and its relationship to ore and alteration at the three deposits is determined. As K replaces Ca in plagioclase, and Sr is geochemically related to Ca, the distribution of Sr is also determined. Background values for Rb and Sr are difficult to determine, as all accessible parts of the intrusions near the deposits are hydrothermally altered. Background values for intrusive rocks were obtained from 17 samples of unaltered intrusive bodies not associated with porphyry copper deposits.The following conclusions, though based on the study at El Teniente, Rio Blanco, and Los Bronces, may also be applicable to other porphyry copper deposits.1. Rocks that have undergone potassic or sericitic alteration have a two- to threefold increase in Rb and low K/Rb ratios. As these types of alteration characteristically accompany mineralization in porphyry copper deposits, Rb distribution may be useful to locate favorable alteration zones for porphyry copper exploration. The highest anomalies are found in mafic host rocks, which have low Rb background values, though anomalies can also be detected in rocks as siliceous as quartz monzonite.2. A twofold increase in Rb in the propylitic zone at El Teniente produces an anomaly which extends more than 400 meters beyond the margin of the orebody. No corresponding increase in K was observed. The Rb anomaly represents an enlarged target enclosing the zones of alteration commonly associated with porphyry copper mineralization.3. Weathering does not affect the distribution of Rb in rocks from the leached capping at El Teniente. Due to this immobility of Rb, weathering of the potassic zone in porphyry copper deposits should not destroy the Rb anomaly. The distribution of Rb could be a useful tool to locate potassic alteration zones in areas of tropical weathering, for example, in the southwest Pacific and in Central America.4. Addition of Rb and removal of Sr during hypogene alteration can produce high Rb/Sr anomalies which extend out through all of the zones of hydrothermal alteration. However, care must be taken in interpreting the significance of Rb/Sr anomalies because they may simply indicate extensive removal of Sr during normal weathering processes.5. Contouring the Rb values may be useful for quantitatively mapping the extent of K metasomatism.6. Anhydrite is readily dissolved and removed by acid meteoric waters. In deposits where anhydrite is an abundant hypogene alteration product, Sr depletion can be used as a quantitative guide to the degree of supergene activity.

Petrology and geochemistry of Easter Island

Easter Island has developed around three volcanoes—Poike, an older (3 m.y.) strato-volcano, Rano Kau, a caldera, and the fissure complex of Terevaka and its associated cones. The lavas show a wide compositional spread from tholeiites and olivine tholeiites to hawaiites, mugearites, benmoreites, trachytes and rhyolites (comendites). Hawaiite is by far the most abundant rock type and trachytes and rhyolites are relatively rare. Intermediate and acid rocks are concentrated in the southwestern part of the island on or around Rano Kau. The basaltic rocks, which are plagioclase-phyric or aphyric, are transitional hypersthenenormative types characterized by high contents of Fe, Ti and Zr but low K and Mg. The Poike basalts are marginally lower in Zr, Nb, Y and Zn compared with those of the younger volcanoes, but the trachytes from this centre show anomalously high concentrations of Rb, Zr and Nb. The island's youngest flow, the Roiho basalt, is an olivine tholeiite with distinctly more alkaline affinities: it is olivine-microphyric with relatively high contents of Mg, Ni and K.

Immune Hemolysis

Abstract Enhancement of immune lysis of HK (MM) and LK (LM) sheep red cells by a high K+ medium did not require that the K+ be present during the action of rabbit hemolysin and complement on the cells. Preliminary exposure of these red cells to a high K+ buffer sufficed, and the K+ effect withstood vigorous washing of the treated cells. Enhancement of immune lysis by a high K+ medium was time, temperature and concentration dependent. It was also 80 to 90% inhibited by 10-4 M ouabain and much less effectively by equimolar G-strophanthidin, the aglycone of ouabain. The transition step from E* to ghost was not demonstrably affected by a high K+ medium. The ability of high concentrations of Rb+ or Li+ to enhance immune lysis was confirmed. Washing experiments suggested that these cations have lesser affinity for relevant sites on the red cell than K+, in the order K+ τ; Rb+ τ; Li+. The Rb+ and Li+ effects on lysis were also antagonized by ouabain. Although these phenomena suggest certain similarities to the stimulation of the traditional red cell Na+-K+ pump, several important differences exist. It is suggested that the K+-induced increment in immune lysis is not directly related to pump activity but possibly to conformational changes in the cell membrane influencing the effectiveness of complement.

Effects of alkali metal and other monovalent ions on the adrenomedullary secretion

The effects of alkali metal ions, ammonium and quaternary ammonium ions on the release of catecholamines were studied in the perfused adrenal glands of rabbits. An immediate secretory response was caused by high concentrations of Rb + or Cs + as well as K +, but not by Na + or Li +. This response was apparently due to their depolarizing effect which is generally observed in excitable tissues. High doses of NH 4 + also evoked catecholamine secretion but in two phases; an early response quite similar to that with alkali metal ions which was followed by a Ca ++-independent discharge which was probably due to a toxic effect on the chromaffin cells. Some of the quaternary ammonium ions, on the other hand, produced an immediate secretory response (the ‘on’ response) and in addition an increase in catecholamine release was observed just after perfusion with high concentrations of these ions had ceased (the ‘off’ response); the mechanism of the latter effect remains to be elucidated although influx of Ca ++ may be responsible.

Sodium and Rubidium as Possible Nutrients for Sugar Beet Plants

This study concerned the degree to which Na or Rb could substitute for K in the growth of sugar beet plants when K in the culture solution was low (1 meq/liter) or high (12 meq/liter).Sodium at high concentrations increased the growth of plants in a basal nutrient medium when either deficient in K or when adequately supplied with K alone. Redistribution of K from petioles to blades could not fully explain these results. Therefore, the essentiality of Na per se for growth of sugar beet plants may be inferred.Rubidium increased the growth of plants significantly when supplied in small doses to a nutrient medium deficient or adequately supplied with K. The amount of K added and the mode of Rb addition to solution cultures should be carefully considered when studying the effect of Rb on growth. High Rb concentrations were toxic, especially to the growth of fibrous roots.Sodium or Rb have been shown to enhance the growth of sugar beet plants under either low or high K conditions. Essentiality of either Na and/or Rb per se for growth of sugar beets may be inferred, but other criteria should be fulfilled also for conclusive proof.

Potassium Ion-dependent Hydrolysis of Adenosine Triphosphate Induced by Nigericin in Mitochondria

K+ is required for the stimulation by the antibiotic nigericin of adenosine triphosphate hydrolysis in rat liver mitochondria. This action does not occur when K+ is replaced by other monovalent cations. It requires slightly hypotonic conditions and is not related to the swelling phenomena linked to the accumulation of K+ in mitochondria. ATPase is inhibited by small anion molecules to which the mitochondrial membrane is impermeable, less so if the anion is translocated inside the mitochondria. High concentrations of Rb+ or Na+ and low concentrations of Ca++ inhibit the ATPase stimulated by nigericin. The ATPase activity of submitochondrial sonic fragments, and of Racker's coupling factor F1, are not stimulated by nigericin. β-Hydroxybutyrate and succinate partially inhibit the hydrolysis of ATP stimulated by nigericin in K+ media. Neither glutamate, malate, pyruvate, nor α-ketoglutarate inhibits this enzymatic activity. The inhibition of ATPase by oxidizable substrates is ascribed to the reincorporation of the liberated inorganic orthophosphate into ADP by way of the phosphorylation linked to the oxidation of succinate and β-hydroxybutyrate. Low concentrations of nigericin partially inhibit the ATPase stimulated by uncoupling agents requiring the presence of alkali metal cations for their mechanism of action; the inhibition depends on the ionic environment of the mitochondria. Nigericin does not affect ATPase activities induced by agents with no alkali metal cation requirement. Dianemycin, an antibiotic with properties similar to nigericin regarding induced ion movement and spectra of respiratory inhibition, does not stimulate the hydrolysis of ATP in any of several media tried. The K+-dependent ATPase stimulated by nigericin appears not to be related to a translocation of alkali metal cations induced by the antibiotic. The possibility that the induction of this activity is related to the participation of a potassium-dependent step in the sequence of reactions leading to the synthesis of ATP in mitochondria is discussed.