Petrophysical Properties and Microstructural Analysis of Faulted Heterolithic Packages: A Case Study from Miocene Turbidite Successions, Italy

Figure 10

Thin sections cut from samples of fault core. (a) The darker parts are dominated by mica flakes and clay. Mica flakes have a tendency to iso-orientation and evidencing plastic flow within the lighter parts, which are made mainly of quartz and feldspar crystals and/or grains; (b) interstitial limonite between breccia clasts is rust red to dark brown (mottled color changes) and includes rare host rock-derived grains and patches of later calcite crystals in the middle of breccia clast interspaces; (c) cataclasite grains are barely distinguishable, both grains and crystals are fine sand to silt in size, and the interstitial spaces are filled by limonite that also coats/impregnates some grains and crystals; (d) interstitial sandstone is made of relatively loosely packed grains (detrital quartz and minor detrital feldspar, rock fragments, and mica) with more intergranular brownish to rust red limonite (also coating/impregnating some grains) than sandstone clasts; (e) fractured grains found in both clasts and matrix of the cataclasite; (f) grains iso-oriented parallel to the fault and with intergranular limonite are recognizable in the probable cataclasite matrix.

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