Pebbly phosphate and granular phosphorite (Late Cretaceous, southern Israel) and their bearing on phosphatization processes

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Abstract
Phosphate nodules, including common mineralized internal moulds of macrofauna, are found only at certain levels in the chalky, locally bituminous Ghareb Formation (uppermost Campanian-Maastrichtian) of southern Israel. The microstructure of these nodules suggests that they consist of marine sediment cemented by a microbially-mediated apatite, precipitated locally in protected microenvironments, e.g., within partly closed burrows and shells, or within the upper sediment layer. The globular microstructures commonly recognized in the phosphate cements of the pebbly phosphates are regarded as mineralized cells of endobenthic micro-organisms. The global occurrence of pebbly phosphate in diverse lithofacies throughout the geological column indicates the tolerance of these globular micro-organisms to a wide range of ecological conditions.