Recrystallization of matrix dolomites is indicated by the uniformly negative d¹⁸O compositions (x = -7.1 d), low Sr contents (x = 230 ppm), low Na contents (x = 364 ppm), contracted unit cells (x: a = 4.812 A, c = 16.058 A), high degree of cation order, high Mg content (x = 46.1 mol% MgCO₃) as compared to most Monterey dolomites, and increasing ⁸⁷Sr/⁸⁶Sr ratios with decreasing Sr content. Vein dolomites have large variation in stoichiometry (41.7-49.0 mol% MgCO₃), Sr content (124-414 ppm), unit-cell dimensions (a: 4.806-4.829 A, c: 16.013-16.178 A), and cation order (Ca site occupancy: 0.73-0.93, g site: 0.68-0.94). Recrystallization of some vein dolomites is indicated by the covariance of mol% MgCO₃ with Sr, d¹⁸O, cation order, and unit-cell parameters. The covariance of d¹⁸O with mol% MgCO₃ is the inverse of the trend expected for the recrystallization of dolomite during burial diagenesis, possibly because of recrystallization during uplift.

Vein dolomites have higher ⁸⁷Sr/⁸⁶Sr values than matrix dolomites. The least radiogenic matrix dolomites (the least recrystallized as inferred from the d¹⁸O composition) have ⁸⁷Sr/⁸⁶Sr apparent ages (13.0 and 15.5 Ma ± 0.3) that agree well with the previously mapped age of the brecciated unit. The more recrystallized matrix dolomites have higher ⁸⁷Sr/⁸⁶Sr ratios (apparent ages too young for the lower Monterey Formation), thus recording the evolution of Sr isotopic composition of the pore fluid. The close chemical similarity of the vein dolomites and the most recrystallized matrix dolomites, the episodic association between hydrocarbons and the ve n dolomites, and the recrystallization trends in the matrix dolomites, all indicate that evolved formation waters were the source of the hydrothermal fluids that precipitated the vein dolomites.