Oceanic plateau and island arcs of southwestern Ecuador: their place in the geodynamic evolution of northwestern South America

Reynaud, Cédric; Jaillard, Étienne; Lapierre, Henriette; Mamberti, Marc; Mascle, Georges

doi:10.1016/s0040-1951(99)00099-2

Cited by 127 publications

(157 citation statements)

References 55 publications

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“…However, the widespread hiatuses of Late SantonianLate Campanian deposits in the eastern Andean basins (Mathalone and Montoya, 1995;Jaillard, 1997) suggests that the accretion took place during the Late Santonian -Late Campanian time-span, i.e. between 85 and 77 Ma (Lebrat et al, 1987;Aspden et al, 1992;Reynaud et al, 1999;Kerr et al, 2002;Fig. 9).…”

Section: Discussion Geodynamic Implicationsmentioning

confidence: 99%

“…However, the nature, age and accretion date of these oceanic terranes are poorly known and still debated. According to various authors, accretions took place in the Campanian (Lebrat et al, 1987;Aspden et al, 1992;Hughes and Pilatasig, 2002), the Late Paleocene (Daly, 1989;Jaillard et al, 1995;Reynaud et al, 1999), and/or the Eocene (Feininger and Bristow, 1980;Egüez, 1986;Bourgois et al, 1990;Spikings et al, 2001;Kerr et al, 2002). Most authors agree that the Cordillera Occidental of central Ecuador comprises a western island arc terrane (Macuchi terrane, Kehrer and Van der Kaaden, 1979;Baldock, 1982;Egüez, 1986;Hughes and Pilatasig, 2002), and an eastern oceanic terrane of oceanic floor to oceanic plateau nature (Lebrat et al, 1987; Pallatanga terrane of McCourt et al, 1998;Hughes and Pilatasig, 2002;Kerr et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Stratigraphy of the late Cretaceous–Paleogene deposits of the cordillera occidental of central ecuador: geodynamic implications

Jaillard

Ordóñez²,

Suárez³

et al. 2004

Journal of South American Earth Sciences

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Two accreted oceanic terranes are classically recognized in the Cordillera Occidental of Central Ecuador, the Macuchi island arc to the West, and the Pallatanga oceanic terrane to the East. Detailed stratigraphic studies of the sedimentary cover of the "Pallatanga terrane" show that it actually comprises two terranes. During the late Campanian-early Maastrichtian, the eastern terrane received partially continent-derived turbidites, demonstrating that it was accreted to the Andean margin before mid Campanian times, i.e. 85-80 Ma ago. Meanwhile, the western terrane received fine-grained, pelagic siliceous black cherts indicating that it still belonged to the oceanic realm during mid Campanian-Maastrichtian times. Both series are unconformably overlain by a thick, coarsening upward siliciclastic series of Paleocene age, demonstrating that the western terrane accreted to the eastern one during the late Maastrichtian (≈ 69-65 Ma). The thick Paleocene clastic series recorded the uplift of the Eastern Cordillera, which was triggered by the latter accretion, and enhanced by the Late Paleocene accretion (≈ 58 Ma) of the Piñón oceanic terrane of southern coastal Ecuador.

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Section: Discussion Geodynamic Implicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stratigraphy of the late Cretaceous–Paleogene deposits of the cordillera occidental of central ecuador: geodynamic implications

Jaillard

Ordóñez²,

Suárez³

et al. 2004

Journal of South American Earth Sciences

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“…Feininger and Bristow 1980;Lebrat et al 1987;Reynaud et al 1999;Kerr et al 2002;Jaillard et al 2004;Luzieux et al 2006). Early petrographic and geochemical works on the magmatic basement of western Ecuador allowed to recognise oceanic floor basalts, and island arc basalts and andesites (Kehrer and Van der Kaaden 1979;Egüez 1986;Lebrat et al 1987;Wallrabe-Adams 1990).…”

Section: Fig 1: Geological Map Of Western Ecuador (Simplified Frommentioning

confidence: 99%

Accreted oceanic terranes in Ecuador: southern edge of the Caribbean Plate?

Jaillard

Lapierre²,

Ordóñez

et al. 2009

Self Cite

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The western part of Ecuador is made from several oceanic terranes, which comprise two oceanic plateaus, of Early (c. 120 Ma) and Late Cretaceous age (c. 90 Ma), respectively. The older oceanic plateau was accreted to the Andean margin in the Late Campanian (c. 75 Ma). Fragments of the Turonian–Coniacian plateau were accreted to the Ecuadorian margin in the Late Maastrichtian (c. 68 Ma, Guaranda terrane) and Late Paleocene (c. 58 Ma, Piñón–Naranjal terrane). The Guaranda terrane received either fine-grained oceanic sediments of Coniacian–Maastrichtian age, or island arc/back-arc volcanic suites of Middle Campanian–Middle Maastrichtian age. The Piñón–Naranjal terrane recorded a comparable history, completed in the Maastrichtian–Paleocene, either by pelagic cherts, or by island arc products (Macuchi arc). The Late Cretaceous plateau of Ecuador is interpreted as part of the Caribbean oceanic plateau (COP), because their evolutions are comparable. If so, the COP was not formed by the Galápagos hotspot, but on the Farallón oceanic plate, south of Ecuador and close to the South American margin. The COP belonged to the Farallón plate, until a subduction zone separated both plates in the Middle Campanian, giving way to a well-developed Mid Campanian–Mid Maastrichtian island arc. Accretion in the Late Maastrichtian triggered a change in the subduction system, and the development of a new arc system of Late Maastrichtian–Late Paleocene age, which crosscut the South America–COP plate boundary. The last accretion occurred in the Late Paleocene.

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“…Various geodynamic models for the Western Cordillera of Ecuador have proposed the accretion of several oceanic terranes and multiple subduction events that produced islandarc sequences during the Early Tertiary (e.g., van Thournout et al, 1992;Jaillard and Soler, 1996;Jaillard et al, 1997;Reynaud et al, 1999;Chiaradia and Fontboté, 2001;Hughes and Pilatasig, 2002).…”

Section: Regional Geologic Settingmentioning

confidence: 99%

Geologic Setting, Mineralogy, and Geochemistry of the Early Tertiary Au-Rich Volcanic-Hosted Massive Sulfide Deposit of La Plata, Western Cordillera, Ecuador

Chiaradia¹,

Tripodi²,

Fontboté³

et al. 2008

Economic Geology

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La Plata is, economically, the most important of several volcanic-hosted massive sulfide (VHMS) deposits of the Western Cordillera of Ecuador, with preliminary estimated reserves of 840,000 metric tons (t) at 4.8 g/t Au, 54 g/t Ag, 4.1 percent Cu, 0.7 percent Pb, and 4.2 percent Zn. Like the other VHMS deposits of the Western Cordillera, it is hosted by the Early Tertiary Macuchi unit, which represents an oceanic island-arc sequence, composed of submarine volcanic and volcaniclastic sequences of basaltic to andesitic compositions, accreted to the continent along the Chimbo-Toachi shear zone in the late Eocene.La Plata displays a typical VHMS vertical zonation, from bottom to top, of a pyrite stockwork, disseminated sulfides, massive sulfide lenses, and a thin red jasper bed with exhalative-sedimentary textures. The massive sulfide lenses are located within footwall andesitic volcanic and volcaniclastic rocks that are pervasively altered to a quartz-pyrite-sericite assemblage, and immediately below a hanging-wall sequence consisting of at least two basaltic to basaltic-andesitic lava flows, each capped by autoclastic breccia intervals. The hanging-wall rocks, especially the autoclastic breccias, are hematite altered up to 300 m above the ore level. Hanging-wall volcanic rocks have geochemical features typical of arc tholeiites. Dolerite dikes in the hanging wall have middle-ocean ridge basalt (MORB)-type geochemical features likely indicating deposit formation in an intra-arc extensional environment.The massive sulfide lenses are situated mainly on the eastern side of an antiform with footwall rocks at the core and hanging-wall rocks on both flanks. Lithologic contacts, volcanic strata, and axial planes of folds have a consistent north-south strike. Footwall rocks at the core of the antiform are locally affected by meter-thick, north-south-trending subvertical shear bands that result in an intense tectonic foliation. Deformation structures are absent in the hanging-wall rocks suggesting that the footwall rocks, due to a different rheology, were ductile during deformation. Centimeter-to decimeter-sized massive sulfide clasts are incorporated into a mylonitic matrix of altered footwall rocks within these shear bands that contain dextral movement indicators. The larger massive sulfide lenses (up to 100 m long) probably result also from tectonic dismembering, within the footwall rocks, of a former, larger, massive sulfide body. The deformation is probably related to the ChimboToachi dextral shear zone situated a few kilometers to the east of La Plata.The main ore minerals are pyrite, chalcopyrite, sphalerite, bornite, and galena, with minor tennantite and digenite. The gangue minerals are barite, quartz, and sericite. Mineralogical banding, defined by chalcopyriterich layers alternating with pyrite-and/or sphalerite-rich layers, is mostly the result of tectonic injection of ductile chalcopyrite, bornite, and galena within shear bands of cataclastic pyrite and sphalerite. Pyrite and sphalerite also show mild r...

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Oceanic plateau and island arcs of southwestern Ecuador: their place in the geodynamic evolution of northwestern South America

Cited by 127 publications

References 55 publications

Stratigraphy of the late Cretaceous–Paleogene deposits of the cordillera occidental of central ecuador: geodynamic implications

Stratigraphy of the late Cretaceous–Paleogene deposits of the cordillera occidental of central ecuador: geodynamic implications

Accreted oceanic terranes in Ecuador: southern edge of the Caribbean Plate?

Geologic Setting, Mineralogy, and Geochemistry of the Early Tertiary Au-Rich Volcanic-Hosted Massive Sulfide Deposit of La Plata, Western Cordillera, Ecuador

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