Basalt transitional

Woodhead J, Eggins S, Gamble J (1993) High field strength and transition element systematics in island arc and back-arc basin basalts evidence for multi-phase melt extraction and a depleted mantle wedge. Earth Planet Sci Lett 114 491-504... 

Doe BR (1994) Zinc, copper, and lead in mid-ocean ridge basalts and the source rock control on Zn/Pb in ocean-ridge hydrothermal deposits. Geochim Cosmochim Acta 58 2215-2223 Ehrlich S, Butler I, Halicz L, Rickard D, Oldroyd A, Matthews A (submitted) Experimental study of copper isotope fractionation between aqueous Cu(II) and covellite, CuS. Chem Geol Finney LA, O Halloran TV (2003) Transition metal speciation in the cell insights from the chemistry of metal ion receptors. Science 300 931-936... 

Direction of innovation (from the standpoint of market actors - 6a) A complex assessment situation (classification, criteria for restriction of liability, transitional regulations ) resulted in confusion with regard to the need for substitution for manufacturers and users of basalt rock wools. 

The Boina emission products show a more or less continuous differentiation trend from transitional basalt to pantellerite. In the nonperalkaline field, the transition from basalt to ferro-basalt is dominated first by olivine F > 0.65) and then by plagioclase F > 0.45), with minor clinopyroxene. A second differentiation step with the appearance of Fe-Ti oxide crystals begins at F = 0.45 Fe and Ti decrease abruptly. Less marked discontinuities are also observed at F = 0.3 (silica-oversaturated trachytes) and F = 0.15 (peralkalinity field). 

Barberi F, Ferrara G., Santacroce R., Treuil M., and Varet J. (1975). A transitional basalt-pantellerite sequence of crystallization The Boina Centre (Afar Rift, Ethiopia). J. Petrol, 16 22-56. 

Dal Negro A., Carbonin S., Molin G. M., Cundari A., and Piccirillo E. M. (1982). Intracrystalline cation distribution in natural clinopyroxenes of tholeiitic, transitional and alkaline basaltic rocks. In Advances in Physical Geochemistry, vol. 1, S. K. Saxena (series ed.), New York Springer-Verlag. 

The interpretation of lithogeochemical data from basaltic structural domes is complicated by lithological changes associated with the transition from basalt to overlying siliciclastic rocks, as well as by the polydeformed nature of the host sequence. Ferroan carbonate alteration is well developed, and low-level Au enrichment extends for a considerable distance away from zones of economic interest. Arsenic and Sb/AI anomalies are restricted to within approximately 10 m of mineralized zones. Sericite alteration is indicated by Na depletion and K enrichment in basalt within 20 to 40 m of mineralized zones. A number of other elements, including Mn, P, S, Zn, Mo, Cu, Se and Ba, are variably enriched within the rocks hosting Au mineralization, but it is not clear whether elevated concentrations of these elements are a product of syn-sedimentary exhalative activity or result from later hydrothermal alteration. 

Tuscany shoshonitic basalt Sicily Channel transitional basalt A Tuscany famproite Etna Na-alkaline basalt... 

Magnaghi Seamount 3.0 to 2.7 - N-S elongated, about 1400 m high, cone containing Na-transitional basalts. 

The nature of the rock record from the time of the first sedimentary rocks ( 3.8 billion years ago) to about 1 to 2 billion years ago suggests that the amount of oxygen in the Earth s atmosphere was significantly lower than today, and that there were continuous chemical trends in the sedimentary rocks formed and, more subtly, in hydrosphere composition. Figure 10.6 illustrates how the chemistry of rocks shifted dramatically during this transitional period. The source rocks of sediments during this time may have been more basaltic than later ones ... 

Figure 7.8 Relationship between the octahedral site preference energy and distribution coefficient of divalent transition metal ions partitioned between olivine or pyroxene crystals and the basaltic groundmass (modified from Henderson Dale, 1969 Henderson, 1982, p. 147).

A relationship between octahedral site preference energies (table 6.3) and distribution coefficients has been demonstrated for transition metal ions partitioned between olivine or pyroxene crystals and the groundmass of oceanic basalts, which is assumed to represent the composition of the magma from which the ferromagnesian silicates crystallized (Henderson and Dale, 1969 Dale and Henderson, 1972). Plots of In D against OSPE, such as those illustrated in fig. 7.8, show linear trends between the two parameters. 

Figure 8.1 The uptake of transition metal ions into silicate minerals crystallizing from basaltic magma, (a) Divalent cations (b) trivalent cations. The enrichment factor, R, is the ratio of the concentration of the element in the magma after X per cent solidification to the concentration of the element in the initial liquid (after Williams, 1959).

Crystal field spectral measurements of transition metal ions doped in a variety of silicate glass compositions (e.g., Fox et al., 1982 Nelson et al., 1983 Nelson and White, 1986 Calas and Petiau, 1983 Keppler, 1992) have produced estimates of the crystal field splitting and stabilization energy parameters for several of the transition metal ions, examples of which are summarized in table 8.1. Comparisons with CFSE data for each transition metal ion in octahedral sites in periclase, MgO (divalent cations) and corundum, A1203 (trivalent cations) and hydrated complexes show that CFSE differences between crystal and glass (e.g., basaltic melt) structures,... 

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