Saddle dolomite cement

Figure 8.16. A hypothetical trend of changes in the stable isotope composition of carbonate cements in different diagenetic environments. A- marine realm B-meteoric realm C- mixing zone D- successively deeper burial for calcite spar E-successively deeper burial for saddle dolomite. B through E are precipitated in progressively hotter waters. (After Choquette and James, 1987.)...

Analyses of fluid inclusions in saddle dolomite were first reported for the Pine Point lead-zinc deposit in western Canada (Roedder, 1968), but it was not until the late 1980s that fluid-inclusion analysis was widely applied to the study of carbonate cements. 

Spbtl C. and Pitman I. K. (1998) Saddle (baroque) dolomite in carbonates and sandstones a reappraisal of a burial-diagenetic concept. In Carbonate Cementation in Sandstones. Distribution Patterns and Geochemical Evolution (ed. S. Morad). International Association of Sedimento-logists, Oxford, vol. 26, pp. 437-460. 

B) Quartzarenite pervasively cemented by saddle ankerite and minor pyrobitumen (opaque material). Individual dolomite crystal outlines are poorly developed but sweeping extinction is widespread. Same unit as (A). Scale bar = 500 pm. (C) Fracture-fill saddle ankerite composed of crystals with well-developed boundaries and strong curvature. Note authigenic quartz (arrows) intergrown with saddle ankerite. 

---