Eclogite and Related High-Pressure Regional Metamorphic Rocks from the Andes of Ecuador

Feininger, Tomás

doi:10.1093/petrology/21.1.107

Cited by 63 publications

(32 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1) and constitutes the only known eclogite occurrence among the Andean HP rocks (Arculus et al, 1999;Feininger, 1980). It represents an exhumed terrane fragment of oceanic lithosphere (Arculus et al, 1999), which can be interpreted as a highpressure ophiolite .…”

Section: Geological Settingmentioning

confidence: 99%

“…It represents an exhumed terrane fragment of oceanic lithosphere (Arculus et al, 1999), which can be interpreted as a highpressure ophiolite . The complex is subdivided into the Raspas Formation, which comprises eclogites, blueschists and metasediments, and the El Toro Formation, which consists of eclogite-facies, serpentinized peridotites (Feininger, 1980;Gabriele et al, 2003).…”

Section: Geological Settingmentioning

confidence: 99%

See 1 more Smart Citation

A stable (Li, O) and radiogenic (Sr, Nd) isotope perspective on metasomatic processes in a subducting slab

et al. 2011

View full text Add to dashboard Cite

Two distinct types of eclogites from the Raspas Complex (Ecuador), which can be distinguished based on petrography and trace element geochemistry, were analyzed for their stable (Li, O) and radiogenic (Sr, Nd) isotope signature to constrain metasomatic changes due to fluid-overprinting in metabasaltic rocks at high-pressure conditions and to identify fluid sources. MORB-type eclogites are characterized by a relative LREE depletion similar to MORB. High-pressure (HP) minerals from this type of eclogite have highly variable oxygen isotope compositions (garnet: +4.1 to +9.

show abstract

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

A stable (Li, O) and radiogenic (Sr, Nd) isotope perspective on metasomatic processes in a subducting slab

et al. 2011

View full text Add to dashboard Cite

show abstract

“…2). The Raspas Metamorphic Complex consists of greenschists, serpentinised peridotites, pelitic schists, blueschists and eclogites, first described in detail by Feininger (1980). Phengite K -Ar data (132 ± 5 Ma; Feininger and Silberman, 1982) points to a lowermost Cretaceous age for the HP metamorphism (Duque, 1993), thus suggesting that it is related to the latest Jurassic -Early Cretaceous accretion episode (Aspden et al, 1995).…”

Section: Geological Settingmentioning

confidence: 99%

“…There is no consensus on their tectonic and geodynamic significance and they have been interpreted as related either to subduction, accretion, or collision processes (e.g. Feininger, 1980;Aspden and McCourt, 1986;Bourgois et al, 1987;Aspden et al, 1995;Lucassen et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Geodynamic significance of the Raspas Metamorphic Complex (SW Ecuador): geochemical and isotopic constraints

et al. 2002

View full text Add to dashboard Cite

The Raspas Metamorphic Complex of southwestern Ecuador is regarded as the southernmost remnant of oceanic and continental terranes accreted in the latest Jurassic -Early Cretaceous. It consists of variably metamorphosed rock types. (1) Mafic and ultramafic rocks metamorphosed under high-pressure (HP) conditions (eclogite facies) show oceanic plateau affinities with flat REE chondrite-normalized patterns, eNd 150 Ma ranging from + 4.6 to 9.8 and initial Pb isotopic ratios intermediate between MORB and OIB. (2) Sedimentary rocks metamorphosed under eclogitic conditions exhibit LREE enriched patterns, strong negative Eu anomalies, Rb, Nb, U, Th, Pb enrichments, low eNd 150 Ma values (from À 6.4 to À 9.5), and high initial 87 Sr/ 86 Sr and 206,207,208 Pb/ 204 Pb isotopic ratios suggesting they were originally sediments derived from the erosion of an old continental crust. (3) Epidote-bearing amphibolites show N-MORB affinities with LREE depleted patterns, LILE, Zr, Hf and Th depletion, high eNd 150 Ma (> + 10) and low initial Pb isotopic ratios. The present-day well defined internal structure of the Raspas Metamorphic Complex seems to be inconsistent with the formerly proposed interpretation of a ''tectonic mélange''. The association of oceanic plateau rocks and continent-derived sediments both metamorphosed in HP conditions suggests that the thin edge of the oceanic plateau first entered the subduction zone and dragged sediments downward of the accretionary wedge along the Wadatti -Benioff zone. Subsequently, when its thickest part arrived into the subduction zone, the oceanic plateau jammed the subduction processes, due to its high buoyancy. In Ecuador and Colombia, the latest Jurassic -Early Cretaceous suture involves HP oceanic plateau rocks and N-MORB rocks metamorphosed under lower grades, suggesting a composite or polyphase nature for the latest Jurassic -Early Cretaceous accretionary event. D

show abstract

“…Metamorphic rocks of Paleozoic age outcrop in extreme NW Peru (Cardona et al 2009) and appear to continue northward into Ecuador (Figure 1) where they are juxtaposed against Mesozoic eclogite and blueschist in the Amotape massif (Feininger 1980). The Paleozoic rocks of northern Peru and southern Ecuador apparently constitute basement within the Tahuín terrane, interpreted to be exotic with respect to South America (Feininger 1987).…”

Section: Other Considerationsmentioning

confidence: 99%

Arc and Slab-Failure Magmatism in Cordilleran Batholiths I – The Cretaceous Coastal Batholith of Peru and its Role in South American Orogenesis and Hemispheric Subduction Flip

Hildebrand¹,

Whalen

2014

View full text Add to dashboard Cite

We examined the temporal and spatial relations of rock units within the Western Cordillera of Peru where two Cretaceous basins, the Huarmey-Cañete and the West Peruvian Trough, were considered by previous workers to represent western and eastern parts respectively of the same marginal basin. The Huarmey-Cañete Trough, which sits on Mesoproterozoic basement of the Arequipa block, was filled with up to 9 km of Tithonian to Albian tholeiitic–calc-alkaline volcanic and volcaniclastic rocks. It shoaled to subaerial eastward. At 105–101 Ma the rocks were tightly folded and intruded during and just after the deformation by a suite of 103 ± 2 Ma mafic intrusions, and later in the interval 94–82 Ma by probable subduction-related plutons of the Coastal batholith. The West Peruvian Trough, which sits on Paleozoic metamorphic basement, comprised a west-facing siliciclastic-carbonate platform and adjacent basin filled with up to 5 km of sandstone, shale, marl and thinly bedded limestone deposited continuously throughout the Cretaceous. Rocks of the West Peruvian Trough were detached from their basement, folded and thrust eastward during the Late Cretaceous–Early Tertiary. Because the facies and facing directions of the two basins are incompatible, and their development and subjacent basements also distinct, the two basins could not have developed adjacent to one another. Based on thickness, composition and magmatic style, we interpret the magmatism of the Huarmey-Cañete Trough to represent a magmatic arc that shut down at about 105 Ma when the arc collided with an unknown terrane. We relate subsequent magmatism of the early 103 ± 2 Ma syntectonic mafic intrusions and dyke swarms to slab failure. The Huarmey-Cañete-Coastal batholithic block and its Mesoproterozoic basement remained offshore until 77 ± 5 Ma when it collided with, and was emplaced upon, the partially subducted western margin of South America to form the east-vergent Marañon fold–thrust belt. A major pulse of 73–62 Ma plutonism and dyke emplacement followed terminal collision and is interpreted to have been related to slab failure of the west-dipping South American lithosphere. Magmatism, 53 Ma and younger, followed terminal collision and was generated by eastward subduction of Pacific oceanic lithosphere beneath South America. Similar spatial and temporal relations exist over the length of both Americas and represent the terminal collision of an arc-bearing ribbon continent with the Americas during the Late Cretaceous–Early Tertiary Laramide event. It thus separated long-standing westward subduction from the younger period of eastward subduction characteristic of today. We speculate that the Cordilleran Ribbon Continent formed during the Mesozoic over a major zone of downwelling between Tuzo and Jason along the boundary of Panthalassic and Pacific oceanic plates.SOMMAIRENous avons étudié les relations spatiales et temporales des unités de roches dans la portion ouest de la Cordillère du Pérou, où deux bassins crétacés, la fosse d’accumulation de Huarmey-Cañete et la fosse d’accumulation péruvienne de l’ouest, ont été perçues par des auteurs précédents comme les portions ouest et est d’un même bassin de marge. La fosse de Huarmey-Cañete, qui repose sur le socle mésoprotérozoïque du bloc d’Arequipa, a été comblée par des couches de roches volcaniques tholéitiques – calco-alcalines de l’Albien au Thithonien atteignant 9 km d’épaisseur. Vers l’est, l’ensemble a fini par former des hauts fonds. Vers 105 à 101 Ma, les roches ont été plissées fortement puis recoupées par une suite d’intrusions vers 103 ± 2 Ma, durant et juste après la déformation, et plus tard dans l’intervalle 94 – 82 Ma, probablement par des plutons de subduction du batholite côtier. Quant à la fosse d’accumulation péruvienne de l’ouest, elle repose sur un socle métamorphique paléozoïque, et elle est constituée d’une plateforme silicoclastique – carbonate à pente ouest et d’un bassin contigu comblé par des grès, des schistes, des marnes et des calcaires finement laminés atteignant 5 km d’épaisseur et qui se sont déposés en continu durant tout le Crétacé. Les roches de la fosse d’accumulation péruvienne de l’ouest ont été décollées de leur socle, plissées et charriées vers l’est durant la fin du Crétacé et le début du Tertiaire. Parce que les facies et les profondeurs de sédimentation de ces deux fosses d’accumulation dont incompatibles, et que leur développement et leur socle sont différents, ces deux fosses ne peuvent pas s’être développées côte à côte. À cause de l’épaisseur accumulée, de sa composition et du style de son magmatisme, nous pensons que la fosse d’accumulation de Huarmey-Cañete représente un arc magmatique qui s’est éteinte vers 105 Ma, lorsque l’arc est entré en collision avec un terrane inconnu. Nous pensons que le magmatisme subséquent aux premières intrusions mafiques syntectoniques et aux réseaux de dykes de 103 ± 2 Ma sont à mettre au compte d’une rupture de plaque. Le bloc Huarmey-Cañete-batholitique côtier et son socle mésoprotérozoïque sont demeurés au large jusqu’à 77 ± 5 Ma, moment où il est entré en collision et a été poussé par-dessus la marge ouest sud-américaine partiellement subduite, pour ainsi former la zone de chevauchement de vergence est de Marañon. Nous croyons que la séquence majeure de plutonisme et d’intrusion de dykes qui a succédé à la collision finale à 73–62 Ma doit être reliée à une rupture de la plaque lithosphérique sud-américaine à pendage ouest. Le magmatisme de 53 Ma et plus récent qui a succédé à la collision finale, a été généré par la subduction vers l’est de la lithosphère océanique du Pacifique sous l’Amérique du Sud. Des relations temporelles et spatiales similaires qui existent tout le long des deux Amériques représentent la collision terminale d’un ruban continental d’arcs avec les Amériques durant la phase tectonique laramienne de la fin du Crétacé–début du Tertiaire. Elle a donc séparé la subduction vers l’ouest de longue date de la période de subduction vers l’est plus jeune caractérisant la situation actuelle. Nous considérons que le ruban continental de la Cordillère s’est constitué durant le Mésozoïque au-dessus d’une zone majeure de convection descendante entre Tuzo et Jason, le long de la limite entre les plaques océaniques Panthalassique et Pacifique.

show abstract

Eclogite and Related High-Pressure Regional Metamorphic Rocks from the Andes of Ecuador

Cited by 63 publications

References 15 publications

A stable (Li, O) and radiogenic (Sr, Nd) isotope perspective on metasomatic processes in a subducting slab

A stable (Li, O) and radiogenic (Sr, Nd) isotope perspective on metasomatic processes in a subducting slab

Geodynamic significance of the Raspas Metamorphic Complex (SW Ecuador): geochemical and isotopic constraints

Arc and Slab-Failure Magmatism in Cordilleran Batholiths I – The Cretaceous Coastal Batholith of Peru and its Role in South American Orogenesis and Hemispheric Subduction Flip

Contact Info

Product

Resources

About