Ankerite cement phase

The intergranular carbonate cement is always iron-rich dolomite (or ankerite). Electron probe microanalysis gives between 7 and 18 mol% FeCOj (and 0.2-0.8 mol% MnCOj) (Fig. 11). The calcium content of the dolomites is relatively stoichiometric, with an average of 51 mol% CaCOj (range 50.0-53.3 mol%). The cement is generally dull to very dull red-brown in CL, with subtle concentric zonation. It is relatively homogeneous when examined in BSEM, suggesting that intracrystalline chemistry is reasonably consistent within and between individual fractures. The dolomite crystals have a variable fluid inclusion density, with a vast preponderance of monophase aqueous inclusions. Any two-phase inclusions identified in thin section... 

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