Relationship of Mesozoic graben development, stress, shortening magnitude, and structural style in the Eastern Cordillera of the Colombian Andes

Abstract

We use the Eastern Cordillera of Colombia as an example in early stages of inversion orogen showing still modest values of shortening. The style of deformation recorded in this orogenic chain seems to be strongly influenced by two main factors. The first is the pre-compression geometry of the rift basin, conditioning the strong heterogeneity imparted by a trough filled with Jurassic to Neocomian sediments limited by Precambrian and Palaeozoic high-angle walls. The second factor is the orientation of the stress regime with respect to the main normal faults during the inversion. If the stress field is of pure compression, the normal faults are not extensively inverted and the deformation is accommodated mainly in terms of footwall shortcuts. On the other hand, in transpressive regimes the inversion of the former normal faults is more common and the footwall shortcuts are not dominant structures. No significant lateral variations in tectonic shortening are found in the Eastern Cordillera. Finally we emphasize the role of buckle folds in the internal parts of the inversion orogens and give a cautionary note when interpreting these structures in terms of fault-related folding using the well-documented example of the Soapaga fault area.

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

“…Thus it could be argued that they dye out at depth owing to ductile shearing at higher temperatures. However, it has to be noted that some of these faults were originally formed as syn-sedimentary normal faults in Mesozoic times and were subsequently reactivated as thrust faults in the Cenozoic [129]. The Mesozoic activity is well documented in the oppositely dipping faults of the Cobrades Anticline (see Figure 13B), which delimit the occurrence of Jurassic strata.…”

“…A key characteristic of this mountain belt is the reactivation of Mesozoic syn-sedimentary normal faults during Cenozoic contraction, a topic that is discussed in detail in [128]. Figure 13B is a detailed cross-section of the Eastern Cordillera of Columbia between 5.5° and 6.5°N based on [129]. The overall structure is a bivergent thrust belt in the core of which the top basement is uplifted 5 to 10 km relative to the foreland in the east and west.…”

Zonas Transversales en El Dominio Axial De La Cordillera Oriental - Bloque Yacente De La Falla De Soapaga (Sátiva Sur - Sátiva Norte, Boyacá)

“…La Cordillera Oriental contiene exposiciones de basamento metamórfico continental de bajo a alto grado, ubicados en el eje axial y tomando el rumbo de la cordillera, como los macizos de Santander y Floresta (Ramirez-Arias et al, 2012;Tesón et al, 2013). Inconformes a ese basamento, se encuentran rocas sedimentarias en cinturones plegados continentales del Jurásico y depósitos marinos del Cretácico, superpuestas por cuencas foreland presevadas en sinclinales del Paleoceno al Oligoceno (Ramirez-Arias et al, 2012).…”

“…El Sistema de fallas Soapaga-Pesca divide el dominio axial en oriental y occidental (Bayona et al, 2013). Las fallas de Soapaga y Boyacá son fallas inversas que actúan como terminación en cola de caballo al sur de la Falla Bucaramanga (Toro, 1990;Dengo y Covey, 1993;Kammer y Sánchez, 2006;Velandia, 2005;Tesón et al, 2013).…”

“…Estudios previos sugieren una inversión tectónica del orógeno, asociada a fallas normales Mesozoicas, expresado en un estilo estructural de tectónica de piel gruesa (thick-skinned) con cabalgamientos de bajo ángulo a subhorizontales dentro de una tectónica transpresiva (Colletta et al, 1990;Cooper et al, 1995;Toro, 1990;Saylor et al, 2012;Jiménez et al, 2014). Por otro lado, otros autores argumentan que las fallas de Soapaga y Boyacá, en algunos sectores, se comportan como cabalgamientos, pero a su vez están relacionadas regionalmente con estructuras de alto ángulo en profundidad, asociado a fallas que involucran basamento (Kammer, 1999;Taboada et al, 2000;Velandia, 2005;Rodríguez et al, 2009;Tesón et al, 2013).…”