New KAr age dates of Neogene and Quaternary volcanic rocks from the Ecuadorian Andes: Implications for the relationship between sedimentation, volcanism, and tectonics

Lavenu, Alain; Noblet, Christophe; Bonhomme, Michel; Eguez, Arturo; Dugas, François; Vivier, G.

doi:10.1016/0895-9811(92)90028-w

Cited by 37 publications

(41 citation statements)

References 26 publications

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“…The Oligocene to Early Miocene Saraguro Group crops out extensively in central-southern Ecuador and consists of welded tuffs of dacitic to rhyolitic composition, andesitic to rhyolitic lavas, volcaniclastic material and sediments (BGS and CODIGEM 1999;Figs. 2 and 3 Lavenu et al 1992) (Figs. 2 and 3).…”

Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

“…When ages of the sampled outcrops were not available we have used a representative age of the geologic units to which the samples belong (Table 1). Thus, a 25 Ma age has been attributed to samples collected within undated outcrops of the Saraguro Group (Lavenu et al 1992;Hungerbu¨hler et al 2002), an age of 15 Ma to undated samples of the Sta. Isabel Formation (Hungerbu¨hler et al 2002), an age of 9 Ma to undated samples of the Turi Formation (Hungerbu¨hler et al 2002), an age of 8 Ma to undated samples of the Pisayambo Formation (Lavenu et al 1992), and an age of 5 Ma to undated samples of the Tarqui Formation (Hungerbu¨hler et al 2002).…”

Section: Rock Samplingmentioning

confidence: 99%

“…2), although major magmatic pulses seem to have occurred in the Oligocene (35-27 Ma), Miocene (21-8 Ma) and Pliocene (4-2 Ma) (Lavenu et al 1992). The Paleocene to Early Eocene Sacapalca Unit, which consists of andesitic lavas, tuffaceous breccias, conglomerates, lacustrine lutites and dacitic tuffs, crops out in southwestern Ecuador (BGS and CODIGEM 1999;Figs.…”

Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

“…The tectonic and magmatic evolution of the Ecuadorian Andes during the Tertiary is controlled by the interplay of various factors, including changing subduction rates, obliquity and angle of subduction, and Fig. 2 Stratigraphy of the main lithologic units cropping out in central-southern and northern Ecuador, as well as of the magmatic and ore events (modified from Lavenu et al 1992, BGS and CODIGEM 1999, and Hungerbu¨hler et al 2002 subduction of aseismic ridges (Hungerbu¨hler et al 2002). Splitting of the Farallon plate into the Nazca and Cocos plates at $25 Ma forced subduction to become more orthogonal with respect to the trench and more shallow (Hey 1977;Daly 1989).…”

Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

“…Isabel Formation (N=6) and Turi Lavenu et al 1992 andHungerbu¨hler et al 2002) showing the locations of the samples investigated in the present study 3°20ÕS 3°33ÕS 3°45ÕS 3°45ÕS 3°57ÕS 3°56ÕS 4°05ÕS 4°06ÕS 4°15ÕS 3°20ÕS 2°54ÕS 2°50ÕS 3°06ÕS 2°59ÕS 79°10ÕW 79°13ÕW 79°14ÕW 79°14ÕW 79°26ÕW 79°28ÕW 79°35ÕW 79°34ÕW 79°55ÕW 79°45ÕW 79°09ÕW 78°54ÕW 78°50ÕW 78°52ÕW ELM ELM ELM ELM ELM ELM ELM ELM ELM ELM ELM ELM ELM Formation (N=3) as well as for five Eocene to Miocene ($50-20 Ma) intrusions: Tangula ( ‡48 Ma), Pungala´(42 Ma), San Lucas ( ‡39 Ma), Peggy (32 Ma), and El Tingo (21 Ma). We will refer to these rocks as ELM in the rest of this article (see Table 1 and Figs.…”

Section: Rock Samplingmentioning

confidence: 99%

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Cenozoic continental arc magmatism and associated mineralization in Ecuador

Chiaradia

Fontboté

Beate

2004

Mineralium Deposita

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Most of the economic ore deposits of Ecuador are porphyry-Cu and epithermal style gold deposits associated with Tertiary continental arc magmatism. This study presents major and trace element geochemistry, as well as radiogenic isotope (Pb, Sr) signatures, of continental arc magmatic rocks of Ecuador of Eocene to Late Miocene ($50-9 Ma, ELM) and Late Miocene to Recent ($8-0 Ma, LMR) ages. The most primitive ELM and LMR rocks analyzed consistently display similar trace element and isotopic signatures suggesting a common origin, most likely an enriched MORB-type mantle. In contrast, major and trace element geochemistry, as well as radiogenic isotope systematics of the whole sets of ELM and LMR samples, indicate strikingly different evolutions between ELM and LMR rocks. The ELM rocks have consistently low Sr/Y, increasing Rb/Sr, and decreasing Eu/Gd with SiO 2 , suggesting an evolution through plagioclase-dominated fractional crystallization at shallow crustal levels (<20 km). The LMR rocks display features of adakite-type magmas (high Sr/Y, low Yb, low Rb/Sr) and increasing Eu/Gd and Gd/Lu ratios with SiO 2 . We explain the adakitetype geochemistry of LMR rocks, rather than by slab melting, by a model in which mantle-derived melts partially melt and assimilate residual garnet-bearing mafic lithologies at deeper levels than those of plagioclase stability (i.e., >20 km), and most likely at sub-crustal levels (>40-50 km). The change in geochemical signatures of Tertiary magmatic rocks of Ecuador from the ELM-to the LMR-type coincides chronologically with the transition from a transpressional to a compressional regime that occurred at $9 Ma and has been attributed by other investigations to the onset of subduction of the aseismic Carnegie ridge.The major districts of porphyry-Cu and epithermal deposits of Ecuador (which have a small size, <<200 Mt, when compared to their Central Andean counterparts) are spatially and temporally associated with ELM magmatic rocks. No significant porphyry-Cu and epithermal deposits (except the epithermal highsulfidation mineralization of Quimsacocha) appear to be associated with Late Miocene-Recent (LMR, $8-0 Ma) magmatic rocks. The apparent ''infertility'' of LMR magmas seems to be at odds with the association of major porphyry-Cu/epithermal deposits of the Central Andes with magmatic rocks having adakite-type geochemical signatures similar to LMR rocks. The paucity of porphyry-Cu/epithermal deposits associated with LMR rocks might be only apparent and bound to exposure level, or real and bound (among other possibilities) to the lack of development of shallow crustal magmatic chambers since $9 Ma as a result of a prolonged compressional regime in the Ecuadorian crust. More work is needed to understand the actual metallogenic potential of LMR rocks in Ecuador.

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Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

Section: Rock Samplingmentioning

confidence: 99%

Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

Section: Geological Setting Geodynamic Evolution and Magmatismmentioning

confidence: 99%

Section: Rock Samplingmentioning

confidence: 99%

See 3 more Smart Citations

Cenozoic continental arc magmatism and associated mineralization in Ecuador

Chiaradia

Fontboté

Beate

2004

Mineralium Deposita

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Partitioning of oblique convergence in the Northern Andes subduction zone: Migration history and the present‐day boundary of the North Andean Sliver in Ecuador

et al. 2016

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Along the Ecuadorian margin, oblique subduction induces deformation of the overriding continental plate. For the last 15 Ma, both exhumation and tectonic history of Ecuador suggest that the northeastward motion of the North Andean Sliver (NAS) was accompanied by an eastward migration of its eastern boundary and successive progressively narrowing restraining bends. Here we present geologic data, earthquake epicenters, focal mechanisms, GPS results, and a revised active fault map consistent with this new kinematic model. All data sets concur to demonstrate that active continental deformation is presently localized along a single major fault system, connecting fault segments from the Gulf of Guayaquil to the eastern Andean Cordillera. Although secondary faults are recognized within the Cordillera, they accommodate a negligible fraction of relative motion compared to the main fault system. The eastern limit is then concentrated rather than distributed as first proposed, marking a sharp boundary between the NAS, the Inca sliver, and the Subandean domain overthrusting the South American craton. The NAS limit follows a northeast striking right‐lateral transpressional strike‐slip system from the Gulf of Guayaquil (Isla Puná) to the Andean Cordillera and with the north‐south striking transpressive faults along the eastern Andes. Eastward migration of the restraining belt since the Pliocene, abandonment of the sutures and reactivation of north‐south striking ancient fault zones lead to the final development of a major tectonic boundary south and east of the NAS, favoring its extrusion as a continental sliver, accommodating the oblique convergence of the Nazca oceanic plate toward South America.

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Cenozoic Evolution of Hinterland Basins in the Andes and Tibet

Horton

2011

Tectonics of Sedimentary Basins

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Sedimentary basins have been generated in hinterland regions of the Andean and Himalayan-Tibetan orogens during Cenozoic plate convergence. These hinterland basins record nonmarine sediment accumulation (commonly in high-elevation, lowrelief, internally drained, arid/semiarid settings) during protracted deformation and surface uplift of continental crust. In South America, Andean hinterland basins are produced between the western magmatic arc and craton-directed fold-thrust belt to the east. In the India-Asia collision zone, hinterland basins develop as elements of the growing Tibetan plateau between the Himalayan thrust belt and Asian plate interior to the north. Hinterland sedimentary basins in the Andes and Tibet are distinguished from foreland basins adjacent to their respective fold-thrust belts by structural position, elevation, and stratigraphic evolution. Sediment accommodation in these hinterland basins is created by flexure, fault-induced subsidence, and topographic ponding, with common examples of remnant foreland basins succeeded by younger hinterland basins.

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New KAr age dates of Neogene and Quaternary volcanic rocks from the Ecuadorian Andes: Implications for the relationship between sedimentation, volcanism, and tectonics

Cited by 37 publications

References 26 publications

Cenozoic continental arc magmatism and associated mineralization in Ecuador

Cenozoic continental arc magmatism and associated mineralization in Ecuador

Partitioning of oblique convergence in the Northern Andes subduction zone: Migration history and the present‐day boundary of the North Andean Sliver in Ecuador

Cenozoic Evolution of Hinterland Basins in the Andes and Tibet

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