A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

Figure 6

Temperature -δ¹⁸O diagram in which theoretical curves are reported representing δ¹⁸O of calcite (a), dolomite (b), and siderite (c) at equilibrium with a fluid as a function of temperature. Each curve corresponds to a fixed δ¹⁸. δ¹⁸ of 0 SMOW corresponds to seawater, δ¹⁸ ranging from −2 to −8 corresponds to the introduction of meteoric waters in the system. The dotted lines in each diagram indicate the range of the δ¹⁸O of analyzed carbonates. The oxygen isotopic fractionations used for the calculations are calcite-water [22], dolomite-water [23], and siderite-water [24].

(a)

(b)

(c)