New observations on the Quaternary stratigraphy and tectonics around Bucaramanga

Abstract

The Quaternary deposits in the Bucaramanga area are in chronological order the following: the Bucaramanga terrace, a red complex and some little terraces and peat deposits. The Bucaramanga terrace is formed by three members; a lower detrital member, 200-250 m thick, formed chiefly by pebbles; a middle member, 15 m  thick, of lacustrine character, formed by silt, clay and very fine sand; and an upper member, with an average thickness of about 10 m, formed by pebbles. The red complex is formed by silt, pebbles and boulders in a silty matrix, and big isolated blocks; this complex is stringly oxidized; from the different materials that form this complex, the silt is the most important by far. Between the deposition of the terrace and the deposition of the red complex was an erosion period. Latter in time, little terraces and some peat deposits, probably of local meaning, were formed. The red complex is the most important Quaternary deposit in the area, because it can be found in the whole Eastern Cordillera, What permits to be used for correlation purposes. The Bucaramanga terrace occupies a graben limited by the Bucaramanga and the Suarez-Río de Oro faults. The last one has moved during Quaternary time; the Quaternary deposits constituting the terrace of Bucaramanga have been disturbed along the fault and carried on to the vertical in a stripe of about 100 m wide along the fault