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S. Todaro et al. / Sedimentary Geology 333 (2016) 70–83 77

Fig. 7. A) Detail of the contact between the original burrow infill (not affected by dissolution) and the overlying laminated reddish sediment alternating to the RFC cements that represent
the filling of the zone 2 of the spongy cavities (see Fig. 6). B) RFC cements showing dark zones of reddish sediments. C) RFCs under polarized light. D) The same of C) under
cathodoluminescence. It is important to notice in D that the luminescence bands correspond to dark laminae of sediments trapped during crystal growth. E) Particular of twin lamellae
in RFC. F) Blocky calcite cements occluding the residual cavities. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
salinity, influencing carbonate saturation, under conditions of parts of the mixing zone has been shown to produce H 2 S, which is oxi-
freshwater–seawater mixing and changes in PCO 2 associated with soil dized to form sulphuric acid at the redox boundary, and hence further
processes. Furthermore, bacterial sulfate reduction in the lowermost reduces pH (Smart et al., 1988). The morphological comparison of our

Table 1
18
13
δ Ovs. δ C data for spongy cavities. Blue indicates the value of radiaxial fibrous calcite that filled the spongy cavities; green indicates value of blocky calcite; red is the reddish sediments.
3
3
Sample name Description 10 δ 13 C VPDB 10 δ 18 O VPDB Symbol
CU 80 A RFC 1.8 −1.95
CU 80 B RFC 1.82 −2.02
CU 80 C RFC 2.7 −0.19
CU 80 D RFC 0.72 −2.87
TS 125 B RFC 3.66 −0.09
TS 125C RFC 2.46 −0.88
TS 125D RFC 1.88 −0.51
TS 118 A RFC −1.44 −1.91
TS 118 B RFC 1.06 −1.27
CU 48 A RFC 1.79 −1.77
CU 48 A RFC 1.81 −1.48
TS 118 C Blocky calcite −4.04 −3.65
TS 125 A Reddish sediments 1.87 0.03
TS 118 D Reddish sediments −1.13 −2.26
CU 48 B Reddish sediments 2.29 −0.61