Facies indicator

Triarylphosphines were prepared by the reaction between lithium diphenylphosphide in THF and m-and p-iodotoluene (or the corresponding bromo compounds), 4-bromobiphenyl and p-dibromobenzene in yields of 70-80% (isolated after oxidation, as the phosphine oxides).143 The absence of cine substitution products is a synthetic advantage and would have been taken as a prima facie indication that the displacements are examples of the 5rn1 reaction, had the mechanism been recognized at the time. Operation of the radical ion mechanism in DMSO, or liquid ammonia, in which marginally improved yields are obtained, was confirmed by Swartz and Bunnett,48 but no extension to the scope of the reaction was made. Rossi and coworkers have developed a procedure for one-pot preparation of triarylphosphines starting from elemental phosphorus (Scheme 6).146 As an example of the synthesis of a symmetrical tri-arylphosphine, triphenylphosphine (isolated as its oxide) was obtained in 75% yield, with iodobenzene as the aryl halide (ArX in Scheme 6, steps i-iii only). Unsymmetrical phosphines result from the full sequence of reactions in Scheme 6, and p-anisyldiphenylphosphine (isolated as its oxide) was produced in 55% yield, based on the phosphorus used, when chlorobenzene (ArX) and p-methoxyanisole (AiOC) were used. 

Comet, P.A., and Eglinton, G (1987) The use of lipids as facies indicators. In Marine Petroleum Source Rocks. Geological Society Special Publication 26, 99-117. 

The eclogite facies indicates high-grade metamorphism produced when oceanic crust containing magnesium and iron is subducted to extreme depths. The very high temperatures and pressures produce garnet and pyroxene. 

The temperatures shown are estimated maxima for the facies indicated whenever PH2o is less than Pt0tai, or whenever the chemical potential of water is lowered by the presence of solutes, the boundaries will be displaced, perhaps drastically, towards lower temperatures. 

If the prehminary stage of the investigation discloses prima facie indications that a State Party may have been responsible for a breach, or may have otherwise been involved, the Director-General shall consider and may propose immediate action for decision of... 

Graham et al. (1988) established 8 facies from the exterior to interior for the midoceanic ridge chimneys 1, anhydrite-rich 2, marcasite - - wurtzite 3, pyrite 4, bornite-rich 5, chalcopyrite 6, pyrite 7, marcasite 8, wurtzite. This study also indicated... 

The coordination of transition metal ions in acidic chloroaluminate melts has not been firmly established. However, in the case of AICb-EtMelmCI. the E0 values of simple redox systems that are electrochemically accessible in both acidic and basic melt, e.g., Hg(II)/Hg [51], Sb(III)/Sb [52], and Sn(II)/Sn [53] exhibit a large positive potential shift on going from basic melt, where metal ions are known to exist as discrete anionic chloride complexes, to acidic melt. Similar results were observed for Cu(I) in AlCh-NaCl [48]. This dramatic decrease in electrochemical stability isprima facie evidence that metal ions in acidic melt are probably only weakly solvated by anionic species such as AICI4 and AECI-. Additional evidence for this is derived from the results of EXAFS measurements of simple metal ions such Co(II), Mn(II), and Ni(II) in acidic AlCh-EtMelmCl, which indicate that each of these ions is coordinated by three bidentate AICI4 ions to give octahedrally-coordinated species such as [ M (AIC14) 2 ] [54]. Most transition metal chloride compounds are virtually... 

Summary of the various evaporitic textures indicative of particuiar physicai environments. Source-. From Kendaii, A. C. (1984). Facies Modeis, 2nd ed., Geoscience Canada Reprint Series, Walter, R. G., ed. pp. 259-296. 

Figure 31b indicates the compositional spread of chlorites from six rocks in the illite-montmorillonite mixed layered mineral facies and from the illite-chlorite zone in the French Alps (Velde, unpublished). The grains analyzed with the microprobe are chlorites replacing isolated grains of detrital mica or were newly formed grains. They are usually 15 microns in the smallest dimension. 

Because the compositions are basic, the expanding minerals are trioctahedral and they are apparently associated in all facies with chlorite. The occurrence of a regularly interstratified montmorillonite (saponite) -chlorite mineral, corrensite, is typified by an association with calcic zeolites and albite. Temperature measurement in the "hydrothermal" sequences at several hundred meters depth indicate that the ordered, mixed layered mineral succeeds a fully expandable phase between 150-200 C and this ordered phase remains present to about 280°C. In this interval calcium zeolites disappear, being apparently replaced by prehnite. The higher temperature assemblage above corrensite stability typically contains chlorite and epidote. 

The second division of the zeolite facies is based upon the appearance of albite as a diagenetic mineral, usually coexisting with analcite in the initial stages of its development, and also with the widespread development of montmorillonite-illite mixed layered mineral (30 to 90% expandable layers) coexisting with illite. The phase relations of this facies are indicated by Figure 35b. Assemblages can contain natrolite as above. They are ... 

Zone two can be defined by the absence of montmorillonite and by the tie-line mica-opal (Figure 37). Zone one, which contains montmorillonite shows the coexistence of feldspar and montmorillonite (Figure 37a). Trona and halite found in the sediments are considered to indicate higher alkalinity and alkali content of the pore fluids that effected the crystallization of the feldspar "facies" in zone two at the lake center. Here the evaporated fluids became more concentrated. 

Donald R. Baker. It seems to me that your results on the distribution of boron and gallium have important implications for the work of others who have concluded that these elements are depositional environmental indications. I wonder if the enrichment of these elements in nonmarine rocks of Pennsylvanian age in the eastern U.S. may simply reflect their proximity to the source area and not have any real bearing on the depositional environment. And conversely, the lower content of these elements reported for marine shales may be caused by deposition of these facies in areas far removed from the source areas. What is your opinion ... 

In summary, it can be stated that there is nothing markedly unusual about the Isua supracrustal facies and their organic contents. They can be compared closely with younger Precambrian, and in some cases Phanerozoic lithologies and successions. Depositional mechanisms and hydrosphere — atmosphere chemical equilibria appear to have been within the range of more recent times (Nutman et al., 1984)119). It seems from all indication that the advent of photoautrophy preceeded Isua times. It was probably the most crucial single event to make an impact on the evolution of the terrestrial atmosphere. 

Gas chromatograms of three saturated hydrocarbon fractions, roughly representing the different facies (Figure 2), show that some relative and absolute variations exist between the three facies. n-Alkanes, pristane, phytane and the extended hop-17(21)-enes are indicated. The most prominent changes within different compound classes in the saturated hydrocarbon fraction are highlighted below. 

Figure 2. Gas chromatograms (CP Sil-5) of the saturated hydrocarbon fractions of the indicated samples from Facies A, B and C of the Jurf ed Darawish oil shale.

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