The mineralogy and chemistry of some coals and associated sediments from the South Wales coalfield

Baqri, Syed Rafiqul Hassan (1976) The mineralogy and chemistry of some coals and associated sediments from the South Wales coalfield. University of Southampton, Doctoral Thesis.

Abstract

The carbonates consist dominantly of two end members, carbonate cad and bioclastic, mainly crinoid, debris. Most are bioclastic micrites, sparse biomiomicrites, packed biomicrites or packed biomicrites though biosparites and biosparrudites are seen occasionally. They contain a fauna including crinoids, brachiopods, corals, molluscs, algae and foraminifera and accuuulated in a marine sublittoral environment of normal salinity. In places coral, brachiopod and algal bmes are developed and bioherms, consisting of mounds of unbedded bryozoan calcilutite or crinoid-stem celciradites both capped and flanked by bedded crinoid-stem calcarenites and calcirudites, occur locally. The bioherms swell the limestone thickness considerably and mark sites of exceptionally abundant carbonate production. Most of the carbonate is biogenic, the finer carbonate tilt and mud resulting from post-mortem mechanical or biological breakdown of organic skeletons. Since accumulation a complicated senquence of chemical, mineralogical and textural changes has occurred durmg lithification, diagenesis and epigenesis including carbonate cementation, dissolution, neomorphism, dolomitisation and silicification.

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