Cenozoic Sedimentary Evolution of the Amazonian Foreland Basin System

Abstract

In this chapter we present a synthesis of the Cenozoic evolution of the Amazonian foreland basin system, based on a review of the estimated ages, lithology and sedimentary structures, palaeontological content, and inferred depositional environments of sedimentary units in the basin. In addition, we have calculated maximum sedimentation rates for the Cenozoic formations of the northern Peruvian foreland basin and integrated these with existing data on sedimentation rates, subsidence analysis, migration of depocentre and depositional environments. Based on this information we propose a model for the Cenozoic evolution of the Amazonian foreland. The sedimentary architecture of this foreland basin indicates that Cenozoic evolution was marked by several periods, which were roughly synchronous and of similar effect, along the entire Amazonian foreland basin system. Tectonic loading of the Andes of Colombia, Ecuador, Peru and northern Bolivia, and development of the Amazonian foreland, was initiated during Late Cretaceous-Paleocene times and followed by an unloading stage during the Early-Middle Eocene period. The Middle-Late Eocene marine transgression and the increase in sedimentation rates, associated with westward migration of the depocentre, were all indicative of a renewed phase of tectonic loading of the Peruvian Western Cordillera and the Ecuadorian and Colombian Eastern Cordillera. Subsequent Oligo-Miocene increase in sedimentation rates and further migration of the depocentres towards the present-day sub-Andean zone, are all indicative for a thrust-induced uplift and loading of the Eastern Cordilleras of Peru, Bolivia and Colombia. This Oligo-Miocene loading stage maintained high subsidence rates that favoured the sedimentation of aggradational fl oodplain and coastal plain and tidally infl uenced deposits. Nevertheless, the processes that controlled the Early-Middle Miocene marine ingressions remain to be determined. Late Miocene ongoing thrust tectonic loading of the Eastern Cordillera, initial structuring of the sub-Andean zone and the onset of the main phase of Andean surface uplift induced fl exural subsidence in the foredeep depozones of the entire Amazonian foreland basin. This process also drove the Late Miocene marine transgressions that characterized the fi lled stage of the Ecuadorian, Peruvian and Bolivian Amazonian foreland basin system. Valley incisions and full relief development in the hinterland during the Late Miocene-Pliocene provided increased sediment supply and overfi lled the Amazonian foreland basin system. Finally, the fl at-slab subduction of the Nazca ridge induced Pliocene (~4 Ma) uplift of the Fitzcarrald Arch and subdivided the Amazonian foreland basin into the northern and southern Amazonian foreland basins.

A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru

“…These levels can be correlated with those of the Cruzeiro Formation in the upper Yuruá ("red beds" at the Peru/Brazil border; Oppenheim, 1937). The inferred time span also coincides with that documented by the NPFB for the Pozo Fm using low-temperature thermochronology (Hermoza et al, 2005;Roddaz et al, 2010). Although documenting somewhat distinct depositional environments (freshwater-dominated in the Ucayali basin; marine/tidal-dominated in the Huallaga basin), both units are laterally equivalent.…”

“…The Chambira Fm. is also recognized in the NPFB and SPFB (e.g., Roddaz et al, 2010). Based on observations in the NPFB, Marocco et al (1996) proposed that the deposits of the Chambira Fm.…”

“…(white massive sandstones, 60 m-thick in the Cushabatay area; Kummel, 1948) nor the hypothetic Yahuarango Fm. sensu stricto (see Roddaz et al, 2010 for further discussion), both of which were weathered and completely covered by vegetation. Nevertheless, given the dipping observed for Cenozoic deposits in the concerned sections, the position of the basal Huchpayacu marls and limestones can be estimated at about 1,500 m below the base of the lowermost levels observed in the Maquía Anticline, and here referred to the Lower Pozo Fm.…”

Continuous Miocene, Pliocene and Pleistocene Influences on Mitochondrial Diversification of the Capybara (Hydrochoerus Hydrochoeris; Hydrochoeridae, Rodentia): Incapacity to Determine Exclusive Hypotheses on the Origins of the Amazon and Orinoco Diversity for This Species

“…Miocene and the formation of the current Amazon River's drainage 2-Island model by recurrent Miocene marine introgressions caused by fluctuations of world sea-level and the appearance of internal Amazonian lakes 3-Appearance of geological arches, which changed the geomorphology of the Amazonian basin 1- [113,120,121,234] 2- [163] 3- [3,12,111,133,170] Riverine Barrier hypothesis, RBH The largest rivers of the Amazonian Basin formed in the late Miocene as a barrier to the dispersion of organisms [235,236] Recent lagoon hypothesis, RLH…”

“…The most important ones are the Stability-time Hypothesis (STH), Paleogeography Hypothesis (PH), Riverine Barrier Hypothesis (RBH), Recent Lagoon Hypothesis (RLH), Refugia Hypothesis (RH), River Refuge Hypothesis (RRH), Canopy-density Hypothesis (CDH), Disturbance-Vicariance Hypothesis (DVH), Museum Hypothesis (MH), Gradient Hypothesis (GH), and Hydrogeological Recent Change Hypothesis (HRCH) (all hypotheses are explained in Table 1). Excellent reviews on the question can be found in the literature [1][2][3][4][5][6][7][8][9][10][11][12].…”