Resumen

MELENDEZ GRANADOS, Hilda Lucia et al. Orogenic uplift around the Soapaga block, Eastern Cordillera of Colombia: Inferences from thermokinematic modeling, geomorphology and seismicity. Bol. Soc. Geol. Mex [online]. 2021, vol.73, n.2, 00003.  Epub 31-Ene-2022. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2021v73n2a141220.

Studying the exhumation history and surface uplift in mountainous regions are key to understand how inversion orogens are built. In this contribution, we study the exhumation history on the central sector of the Colombian Eastern Cordillera; this region includes the Boyacá and Soapaga thrust faults and other minor faults. To reconstruct the exhumation history of this area, a compilation of existing thermochronological data was carried out. This data was used to perform inverse 3D thermal-kinematic modeling, to compare predicted versus observed ages and to estimate exhumation rates of tectonic blocks. The results suggest an asynchronous exhumation pattern. The area between the Boyacá and Soapaga faults experiences two exhumation pulses at 69.1 and 15.7 Ma with rates of 0.91 and 0.16 km/ Ma, respectively. In contrast, in the footwall block of the Soapaga fault, an exhumation episode of 22.7 Ma was discriminated at a rate of 0.49 km/Ma. This last sector coincided with a significant accumulated seismic uplift during the last 5 Ma, obtaining seismic uplift values between 70 and 100 m/Ma. Analysis of the relation magnitude-frequency of earthquakes allow us obtaining b-values for the hanging block of Soapaga fault of 0.55 ± 0.01, consistent with mechanisms associated to transpressional tectonics. However, the numerical model suggests a surface rejuvenation between 6 to 9 Ma for a sector of the study area. With the purpose of discriminating against other processes that could cause such rejuvenation, other variables were incorporated as precipitation data, normalized steepness index (ksn in rivers), hypsometric integral and relief. Strong correlations were discriminated between seismic relief and deformation, and seismic relief and uplift in the zone of greater exhumation, which suggests the tectonic forces exert a greater control on the relief in the short term as well as in the long term. Additionally, a highly active seismic region was identified for the study zone that had not been discriminated against.

Palabras llave : time-temperature history; thermochronology; thermal-kinematic modeling; exhumation; Eastern Cordillera.

        · resumen en Español     · texto en Español     · Español ( pdf )