DYNAMICS and ACTIVE PROCESSES - International Lithosphere ...

Figure 2 – Example of porosity measurements realised on a calciturbiditic sequence and
thin section photographies
The diagenesis of the resedimented carbonates is slight visible owing to the mud-rich
facies which prevents the precipitation of diagenetic cements. This diagenesis is mainly
marked by compactionnal stylolites and recristallisation calcite in laminated intervals of
calciturbidites. Which is interesting is the early setting up of the chert and the calcite
recristallisation before the slumping phase. This significates here that these diagenetic
processes occur in the first decameters of sediment depth.
The petrophysical measurements demonstrate a relatively weak matrix porosity which is
due in great part to the mud-rich facies. Besides, the pores are globally disconnected with
important trapped porosity. This demonstrates that matrix porosity does not act as fluid
pathways. In the contrary, at the outcrop-scale numerous fractures and stylolites could act as
fluid pathways through the calciturbiditic strata as previously described in the northern zone
(Grahams Wall et al. 2006). The fracturation phase shows directions and movements coherent
with the alpine tertiary orogen (Kilias et al., 2001).
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