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Paleoseismological studies are related to the analysis of past earthquakes. One of the most common methods in paleoseismological studies is the excavation of trenches across the faults, or parallel to them in the case of strike-slip. Accurate stratigraphic correlation of sedimentary layers cropping out in different trenches is key to detect and quantify fault movements with precision. Very often, this correlation is a difficult task, plagued with uncertainties owing to the homogeneous appearance and composition of the deposits. Laboratory and field reflectance spectroscopy are applied to 11 samples corresponding to two paleochannels in two parallel trenches excavated in the left-lateral Carboneras fault (Tostana site, Almeria, southeastern Iberian Peninsula). Each sample was sieved into four fractions (<4mm, 4-2 mm, 2-1 mm and <1mm) and together with the total sample, the spectral response was measured with an ASD FieldSpec4 Spectroradiometer. The results show: a) the highest similarity values usually appear between samples of the same fraction size; b) the “total fraction” analysis shows the lowest similarity values between samples; c) the results also confirm the previous characterization of the paleochannels based on field characteristics, with the highest similarity values between samples of the same paleochannel in each trench, and the lowest similarity values between samples of different paleochannels; d) a similar mineralogical composition (presence of dolomite) in all the samples suggests the same source area for the alluvial fan sediments. These results allow to assess the plausibility of correlations based on macroscopic observation in the field, and to help reduce uncertainties in the future quantification of the lateral slip rate for this segment of the Carboneras fault.
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