Resumo

CETINA, Lina María; VELANDIA, Francisco  e  PATINO-SANABRIA, Hugo Alonso. Deformation analysis to the west of the Yariguíes Anticlinorium - Eastern Cordillera of Colombia. Bol. geol. [online]. 2019, vol.41, n.3, pp.31-56.  Epub 09-Dez-2019. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v41n3-2019002.

The method to carry out the present analysis of deformation is based on the fold evolution according to the strata dip and the treatment of striated fault planes, especially slickensides. We studied the limb that is shared by the Yariguíes Anticlinorium (eastern) and the Nuevo Mundo Syncline (western), both outstanding structures located northwestward of the Eastern Cordillera of Colombia. Fracture data were analyzed under Anderson and Mohr mechanical criteria, and rotation techniques were applied to the rock layers that contain fault planes out of the initial mechanical parameters. The results of the structural analysis support the progressive deformation processes across the area according to three phases that were deduced as related to different tectonic conditions. The first deformation phase consists of distensiontranstension, with an axis of maximum extension toward 126° (NW-SE), related to accretion onset of the Western Cordillera at the end of the Mesozoic. The second phase is associated with Paleocene compression-transpresion, with a maximum shortening axis to 30° (NNE-SSW). The third phase corresponds to the onset of uplift of the Eastern Cordillera since the late Oligocene-Miocene, with a shortening tensor to 118° (NWW-SEE), perhaps related to the accretion beginning of the Chocó-Panamá block. On the other hand, a structural style was defined with higher angles faults that cut the Jurassic units, and thin-skinned for the Cretaceous sequence. Transverse strike-slip faults are also present in the area, cross-cutting the longitudinal structures with dextral displacements, which partitioned the western limb of the Yariguíes Anticlinorium as evidence of differential deformation.

Palavras-chave : slickensides; strain tensors; Eastern Cordillera; Middle Magdalena Basin; Colombia..

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