Unravelling the widening of the earliest Andean northern orogen: Maastrichtian to early Eocene intra‐basinal deformation in the northern Eastern Cordillera of Colombia

Abstract

The onset of deformation in the northern Andes is overprinted by subsequent stages of basin deformation, complicating the examination of competing models illustrating potential location of earliest synorogenic basins and uplifts. To establish the width of the earliest northern Andean orogen, we carried out field mapping, palynological dating, sedimentary, stratigraphic and provenance analyses in Campanian to lower Eocene units exposed in the northern Eastern Cordillera of Colombia (Cocuy region) and compare the results with coeval succession in adjacent basins. The onset of deformation is recorded in earliest Maastrichtian time, as terrigenous detritus arrived into the basin marking the end of chemical precipitation and the onset of clastic deposition produced by the uplift of a western source area dominated by shaly Cretaceous rocks. Disconformable contacts within the upper Maastrichtian to middle Palaeocene succession document increasing supply of quartzose sandy detritus from Cretaceous quartzose rocks exposed in eastern source areas. The continued unroofing of both source areas produced a rapid shift in depositional environments from shallow marine in Maastrichtian to fluvial‐lacustrine systems during the Palaeocene‐early Eocene. Supply of immature Jurassic sandstones from nearby western uplifts, together with localized plutonic and volcanic Cretaceous rocks, caused a shift in Palaeocene sandstones composition from quartzarenites to litharenites. Supply of detrital sandy fragments, unstable heavy minerals and Cretaceous to Ordovician detrital zircons, were derived from nearby uplifted blocks and from SW fluvial systems within the synorogenic basin, instead of distal basement rocks. The presence of volcanic rock fragments and 51–59 Ma volcanic zircons constrain magmatism within the basin. The Maastrichtian–Palaeocene sequence studied here documents crustal deformation that correlates with coeval deformation farther south in Ecuador and Peru. Slab flattening of the subducting Caribbean plate produced a wider orogen (>400 km) with a continental magmatic arc and intra‐basinal deformation and magmatism.

A Middle to Late Miocene Trans-Andean Portal: Geologic Record in the Tatacoa Desert

“…Collision of oceanic terranes against the Cretaceous passive margin of northwestern South America marked the start of a regional marine regression, and gradual installation of swampy environments where locally thick coal beds were deposited (Bayona et al, 2011). These swamps were bound to the west by a primordial, probably discontinuous, eastwardly-tilted Central/Real Cordillera (Figure 2A), and to the east by isolated intra-plate uplifts (Villamil, 1999;Gomez et al, 2003;Gomez et al, 2005b;Bayona et al, 2011;Bayona et al, 2020). This tectonically-forced marine regression may have started as early as latest Cretaceous to the south in the Oriente Basin, reaching the northern end of the orogen in the Guajira region in middle Paleocene times, taking ∼10 million years to propagate from south to north (Jaimes and de Freitas, 2006;Martin-Gombojav and Winkler, 2008; FIGURE 3 | Updated stratigraphic scheme for the Honda Group in the Tatacoa Desert.…”

How Much Did the Colombian Andes Rise by the Collision of the Caribbean Oceanic Plateau?

“…On the other hand, several lines of evidence suggest that the modern elevations of the Eastern Cordillera, were only reached during the late Miocene -Pliocene as a consequence of increased crustal shortening (review in Mora et al, 2020). However, sedimentological and thermochronological constraints allowed documenting the presence of isolated uplift events related to an unquantified growing topography since the Paleocene -Eocene, which were likely related to the widening of the northern Andes in response to the shallow subduction of the Caribbean oceanic plateau (Bayona et al, 2020;Parra et al, 2012;and references therein). Recent geodetic studies have estimated modern shortening rates of ca.…”

Reconocimiento geológico de la Formación La Luna en el sector de Matanza (Oeste del Macizo de Santander, Colombia)

“…A finales del Triásico y durante el Jurásico, la región que rodea al macizo se caracterizó por una tectónica extensiva y formación de estructuras tipos graben (Mojica y Kammer, 1995;Mojica et al, 1996;Bayona et al, 2020) las cuales estuvieron acompañadas con una sedimentación continental sintectónica (Kammer y Sánchez, 2006;Alarcón y Rodríguez, 2019) evidenciada en el registro estratigráfico de las formaciones Bocas, Jordán y Girón.…”

“…Estas capas se pueden seguir de manera regional en el VMM y se han reportado sobre el margen SW del Macizo de Santander (Villamil y Arango, 1998;Vásquez et al, 2010;Terraza-Melo, 2012;Ballesteros et al, 2013;Sarmiento et al, 2015). Finalmente, a partir del Campaniano la aparición de altos intraplaca al oriente de la Cordillera Central, y el retroceso del nivel del mar llevaron a la progradación de la sucesión sedimentaria hacia finales del Maastrichtiano y el Paleoceno (formaciones Umir, Lisama; Sarmiento et al, 2015;Sarmiento, 2018;Bayona, 2018;Bayona et al, 2020).…”