Chemical Composition and Age Determination of Tholeiitic Rocks in the Basic Igneous Complex, Ecuador

Goossens, P. J.; Rose, William I.

doi:10.1130/0016-7606(1973)84<1043:ccaado>2.0.co;2

Cited by 86 publications

(35 citation statements)

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“…[7] Coastal Ecuador has been characterized as allochthonous terranes of oceanic origin [Goosens and Rose, 1973;Lebrat et al, 1987;Roperch et al, 1987], accreted on the western side of the Andes, during several accretion episodes between Late Jurassic and Eocene (Figure 4). The last episode of Early Tertiary accretion involved oceanic plateaus and island arc terranes forming the coastal block and the Western Cordillera [Jaillard et al, 1997;Hughes and Pilatasig, 2002].…”

Section: Introductionmentioning

confidence: 99%

Shallow seismogenic zone detected from an offshore‐onshore temporary seismic network in the Esmeraldas area (northern Ecuador)

Pontoise

Monfret

2004

Geochem Geophys Geosyst

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[1] For a given site, many factors control the seismic risk. Earthquake magnitude, hypocentral distance, rupture mechanism, site effects and site vulnerability are among the most important. This article deals with one of these factors: the depth of the seismogenic zone, in the northern Ecuadorian subduction system, beneath a highly vulnerable site, the city of Esmeraldas and its industrial complex, the Ecuadorian oil refinery and shipping terminal. To address this problem, we analyzed data from a three weeks passive seismological experiment, conducted in the spring of 1998, using 13 Ocean Bottom Seismometers and 10 portable land-stations. A preliminary interpretation of wide-angle data obtained in the fall of 2000, in the Manta area, 100 km South of the study area, unambiguously indicates the presence of a velocity inversion in the Ecuadorian margin velocity structure. This velocity inversion is characterized by a shadow-zone of $1 s on the record-sections, and is interpreted as the result of a velocity contrast between the upper plate structure and the sedimentary and basaltic layer II of the subducted oceanic Nazca plate. One-dimensional velocity models are deduced from these wide-angle data and are used for earthquake location in the Esmeraldas area. This highly improved the hypocentral parameter determinations. The updip limit of the seismogenic zone is found at a depth of $12 km, 35 km eastward of the trench, and the depth of the seismogenic zone below the Esmeraldas city is found at $20 km. This shallow depth of the seismogenic zone dramatically increases the seismic hazard of the area.

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Section: Introductionmentioning

confidence: 99%

Shallow seismogenic zone detected from an offshore‐onshore temporary seismic network in the Esmeraldas area (northern Ecuador)

Pontoise

Monfret

2004

Geochem Geophys Geosyst

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“…The Piñón basement was classically ascribed to the Early Cretaceous (Goossens & Rose 1973;Jaillard et al 1995a). It has been recently dated west of Guayaquil, where interpillow sediments yielded Coniacian-Campanian radiolarians and foraminifers (Vanmelle et al in press;Fig.…”

Section: Piñón Terranementioning

confidence: 99%

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

Jaillard

Lapierre²,

Ordóñez

et al. 2009

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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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“…Several ultramafic bodies are known to occur along the Romeral Fault System, where the large Cerromatoso nickel deposit is located. A similar geologic environment is recognized in Ecuador west of the Guayaquil Suture, where the Basic Igneous Complex (Goossens and Rose, 1973) and the Pinon Formation (Baldock, 1982) include ultramafic and mafic rocks of oceanic affinities.…”

Section: Ultramafic Rocksmentioning

confidence: 74%

“…Forearc associations are found along the coastal region of Ecuador (Basic Igneous Complex, Goossens and Rose, 1973), which include basaltic lava, diabase, and mafic intrusive rocks of Late Jurassic to Early Cretaceous age, and on the Western Cordillera (Formacidn DiaMsica-Porfiritica, Sauer, 1965), where a mafic to ultramafic unit contains intercalated nonfossiliferous lutite and silicic sedimentary rocks. Late Cretaceous forearc associations are found in western Ecuador, consisting of basaltic breccia, flows, and pillows, with tholeitic affinities, and interbedded turbiditic volcaniclastic sedimentary rocks and thin bedded pelagic sedimentary rocks (Pindn Formation, Baldock, 1982;Cayo Formation, Olsson, 1942).…”

Section: Forearc Island-arc and Marginal-basin Sequences Basinal Anmentioning

confidence: 99%

Mineral-resources map of the Circum-Pacific region, southeast quadrant

1996

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Chemical Composition and Age Determination of Tholeiitic Rocks in the Basic Igneous Complex, Ecuador

Cited by 86 publications

References 0 publications

Shallow seismogenic zone detected from an offshore‐onshore temporary seismic network in the Esmeraldas area (northern Ecuador)

Shallow seismogenic zone detected from an offshore‐onshore temporary seismic network in the Esmeraldas area (northern Ecuador)

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

Mineral-resources map of the Circum-Pacific region, southeast quadrant

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