GNGTS 2016 - Atti del 35° Convegno Nazionale

134 GNGTS 2016 S essione 1.1 3d) presents common Fe-Mn oxides-hydroxides along planar voids, which at the macroscopic scale correspond to systematic joints. The latter are crosscut by a fault gouge, interested by illuvial clay, and locally deformed in a small-scale kink band anticline, due to a rotational component along the fault gouge. The joints filled by Fe-Mn oxides-hydroxides and illuvial clay helped marking the first stage of the deformation history of this site. Instead, the fault gouge including some fragments of illuvial pedofeatures from the base of the colluvial deposit, implied that during a further step of the tectonic history of the site, the topographic surface was coseismically offset after the deposition of the colluvium. Discussion and conclusion. In both the cases the micromorphological approach highlights: - ��� ���������� �� ��������� �� ������ �� ���������� ���� �� ����������� ��� �������� the usefulness of paleosols in giving an additional data to reconstruct the relative chronological framework of seismic deformations; - ��� ����������� �� �������� �������� ������ ���� ���������������� �������� ������������ �� the recognition of repeated tectonic events that disturbed/formed specific pedofeatures is possible in the case of continuous pedogenetic processes; - � ������ ����������� �� ����������� ��������� ������� ���� �� ����������� ���� ��������� ���� a better possibility of recognizing colluvial wedges, even at microscale, also resulting from the reworking of pre-existing soils, thanks to the individuation of specific pedofeatures (i.e., orthic Fe-Mn nodules and papulae; multi-generation of clay coatings); - ��� ��������� ������������� �� ���� ���� �� ����������� ��� ���������������� �������� the potential applicability of this tool to sedimentary and geomorphological settings characterized by e.g., low or discontinuous sedimentation rates, high erosion activity etc. Therefore, we think that it would be necessary to systematically consider, into the current paleoseismological practice, data from pedostratigraphy and micromorphological analysis. The Fig. 2 – a) Scan of a thin section from the Monte Netto site, sampled along one of the main damage zone; b-c’) photomicrographs of a system of sub-vertical fractures filled by illuvial clay (Fig. 2b-c plain-polarized light; Fig. 2b’-c’ cross-polarized light): note, in the close up Fig. 2d (plain-polarized light) and 2d’ (cross-polarized light), the occurrence of an external coating of red clay (black dashed lines), filled by yellow clay (white dashed lines). Modified after Livio et al. , 2014.