Chapter 5

Abstract

This chapter summarizes knowledge (published up to February 2019) of metamorphic, plutonic, volcanic, carbonate, and clastic sedimentary Jurassic rocks that are exposed from northern Perú to Venezuela. This compilation allows an evaluation of three tectonic models that have been proposed for the evolution of the northwestern corner of Gondwana: an extensional model, a subduction-dominated model, and the along-marginal migration of blocks model, that last of which considers the interaction of western subduction and the north-south separation of continental blocks. We conclude that (1) the Jurassic evolution of this orthogonal margin cannot be represented in a single paleogeographic map that represents a dominant geodynamic process; (2) future analyses must consider the superposition of both Pacific subduction and proto-Caribbean extensional processes; (3) extensional basins in La Guajira, the serranía de Perijá, and the Mérida Andes include the sedimentary record of predominantly proto-Caribbean extension, whereas western-subduction processes are recorded by a batholith chain that extends from southern Ecuador to the Santa Marta Massif in northern Colombia; and (4) a Middle Jurassic unconformity separates Lower to Middle Jurassic sedimentary and volcanic successions, which are related to subduction magmatism and the separation of the North and South American Plates, from Upper Jurassic continental and marine deposits in extensional basins along the northern margin, which record the opening of the proto-Caribbean Sea. Future geochemical studies in Jurassic intrusive bodies should be able to evaluate the contamination from Triassic versus Grenvillian and older continental crust. Metamorphic studies should concentrate on the petrology and the pressure-temperature-time (P-T-t) paths. The chronostratigraphic framework of sedimentary basins should be improved by resuming paleontological investigations and geochronological analysis at the base and top of volcanoclastic rocks. Sedimentological analysis should focus on establishing the geometry of sedimentary basins, the relationship of basin generation with magmatic centers, and documenting the record of paleo-climate indicators in order to establish possible paleo-latitudinal variations of tectonic blocks. Paleomagnetic studies should be conducted at different localities in Lower -Middle Jurassic rocks to test whether tectonic blocks have been static or record northward translations. The strong decrease in magmatic activity during the Late Jurassic time should be explained within a regional tectono-magmatic framework.

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

“…The Eastern Cordillera of Colombia is a doubly vergent orogen that resulted from the Cenozoic inversion of a Cretaceous continental rift system (Colleta, Hébrard, Letouzey, Werner, & Rudkiewikz, 1990;Cooper et al, 1995;Mora, Casallas, et al, 2015;Sarmiento-Rojas, Van Wess, & Cloetingh, 2006;Siravo et al, 2018; Figure 1), which, in turn, had overprinted other phases of Jurassic continental rift extension (Bayona, Bustamante, Nova, & Salazar-Franco, 2020;Sarmiento-Rojas et al, 2006). West of these continental rift systems, both the Cretaceous back-arc basin and volcanic arc are present and involved in the structures of the western Central Cordillera (Zapata et al, 2019).…”

“…The Eastern Cordillera contains 3-to 10-km-thick stratigraphic sequences of Jurassic to Cretaceous rocks that have been interpreted as the primary supply of sediments during the early stages of deformation (Bayona et al, 2013;Figure 2a). To the west of the Santander massif (Figure 1), Upper Jurassic immature feldspar-and lithic-bearing sandstones and conglomerates filled extensional basins (Figure 2a) overlying unconformably Upper Triassic to Middle Jurassic plutonic, volcanic and volcanoclastic strata (Bayona et al, 2020;Sarmiento-Rojas, 2018;Sarmiento-Rojas et al, 2006). Jurassic rocks are not recorded east of the Santander massif ( Figure 1).…”

Nueva propuesta de edades para el registro sedimentario de las formaciones Bocas y Jordán y su relación con el desarrollo de la actividad magmática del Grupo Plutónico de Santander (Cordillera Oriental, Colombia)

“…Las rocas ígneas, metamórficas y sedimentarias de edad situada en el Jurásica en los Andes del norte se encuentran expuestas en una franja de dirección NO-SE que se extiende desde Ecuador y Colombia hasta los límites con Venezuela (Mojica & Kammer, 1995;Spikings, et al, 2015;Bayona, et al, 2020). En los Andes colombianos las rocas ígneas plutónicas del Jurásico Inferior se dividen en dos cinturones subparalelos: el primero, ubicado en el Macizo de Santander, con edades comprendidas entre los 202 y 195 Ma (Mantilla, et al, 2013; Van der Lelij, 2016); el segundo, desarrollado sobre la Cordillera Central, la Serranía de San Lucas y la Sierra Nevada de Santa Marta, donde se estableció entre los 194 y 180 Ma (Leal-Mejía, 2011, Quandt, et al, 2018Leal-Mejía, et al, 2019;.…”

“…El registro de los eventos geológicos del Triásico Tardío-Jurásico Temprano en el sistema orogénico de los Andes Septentrionales permite suponer una historia compleja en un escenario con desarrollo principalmente de plutonismo, actividad volcánica y sedimentación (Bayona, et al, 2020). Varios modelos de desarrollo espacio-temporal del magmatismo y la sedimentación se han propuesto: 1) la formación de fisuras intracontinentales como resultado de un tectonismo extensivo que estuvo acompañado, a su vez, por actividad magmática (Mojica & Kammer, 1995;Cediel, et al, 2003); (2) la migración lateral de arcos magmáticos generados en una zona de subducción (Cochrane, et al, 2014;Spikings, et al, 2015;Bustamante, et al, 2017;Rodríguez, et al, 2018); (3) la generación de arcos magmáticos y su posterior desplazamiento a lo largo de la margen occidental de Gondwana (Bayona, et al, 2006;Bayona, et al, 2010;Toussaint, 1995), o la acreción de arcos magmáticos marginales (Rodríguez, et al, 2018).…”

Presentation

“…In chapter 5, Bayona et al (2020) synthesize knowledge about the metamorphic, plutonic, volcanic, and calcareous and clastic sedimentary rocks of the Jurassic exposed from northern Perú to Venezuela. From this synthesis, the authors evaluate three tectonic models proposed for the evolution of the northwestern corner of Gondwana and conclude that the presence of an orthogonal margin with a complex configuration such as the extreme northwest of Gondwana cannot be explained by the development of a single geodynamic process.…”