Rb-Sr Whole Rock Dating of Metamorphic Events in the Iglesias Complex, Venezuelan Andes

Kovach, Adam; Hurley, Patrick; Fairbairn, H. W.

doi:10.1086/628306

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…References: 1-Olmeta (1968); 2-Hurley and Hess (1968); 3-Pimental et al (1985); 4-Morgan (1967); 5-Santamaría and Schubert (1974); 6-Urbani (1983); 7-Urbani (1988); 8-Kovach et al (1977); 9-Kohn et al (1984); 10-Loubet et al (1985).…”

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confidence: 99%

Overview of radiometric ages in three allochthonous belts of northern Venezuela: Old ones, new ones, and their impact on regional geology

Sisson¹,

Lallemant²,

Ostos³

et al. 2005

Caribbean-South American Plate Interactions, Venezuela

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The margin of northern Venezuela is a complex zone representing the orogenic events from basement formation to subsequent subduction and exhumation during transpressional collision. This boundary zone has six east-west-trending belts that each record a different segment of its development. This geologic complexity requires radiometric ages to unravel, and we herein provide 48 new ages including U-Pb (4), Rb-Sr (2), 40 Ar/ 39 Ar (24), zircon and apatite fi ssion-track (17), and 14 C (1) ages to constrain the evolution of three of these belts. These three belts are the Cordillera de la Costa, Caucagua-El Tinaco, and Serranía del Interior belts.In the Cordillera de la Costa belt, U-Pb geochronologic data indicate portions of the basement igneous and metaigneous rocks formed in the Cambro-Ordovician (513-471 Ma). New 40 Ar/ 39 Ar data from Margarita Island indicate that some of the subduction complex was rapidly cooled and exhumed, whereas other portions indicate slower cooling. This contrasts with new 40 Ar/ 39 Ar data from the Puerto Cabello on July 16, 2015 specialpapers.gsapubs.org Downloaded from 92 V.B. Sisson et al. spe394-03 page 92portion of the subduction complex that has Eocene to Oligocene (42-28 Ma) cooling ages. New fi ssion-track data imply the entire Cordillera de la Costa belt from Puerto Cabello to La Guaira (~150 km) was uplifted at the same time.In the Caucagua-El Tinaco belt, the oldest 40 Ar/ 39 Ar amphibole ages from the Tinaquillo ultramafi c complex are Jurassic (190 Ma). Additional amphibole 40 Ar/ 39 Ar cooling ages are older than previously recorded in either the Tinaco or Tinaquillo complex. One amphibole 40 Ar/ 39 Ar cooling age for the Tinaco complex is similar to previous U-Pb results.New apatite fi ssion-track results from the Serranía del Interior foreland fold and thrust belt are synchronous with exhumation in the Cordillera de la Costa belt. In addition, several zircon fi ssion-track ages in the Serranía del Interior belt are older than their fossil ages, indicating a Cretaceous minimum provenance age for Miocene beds.Signifi cant new fi ndings from these geochronologic studies include (1) several igneous and metaigneous bodies that may be correlated with orogenic events in the Appalachians occur within the subduction mélange; (2) the Tinaquillo complex may record Jurassic rifting; (3) Cretaceous source rocks for the Serranía del Interior sedimentary strata; (4) exhumation of the subduction complex is segmented because two regions have signifi cantly different cooling histories, with Margarita Island exhumed in the Cretaceous, whereas to the west, the Puerto Cabello region has widespread Paleogene cooling and exhumation ages; and (5) earthquake activity in 1812 caused uplift as recorded by exposure of Recent corals.

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mentioning

confidence: 99%

Overview of radiometric ages in three allochthonous belts of northern Venezuela: Old ones, new ones, and their impact on regional geology

Sisson¹,

Lallemant²,

Ostos³

et al. 2005

Caribbean-South American Plate Interactions, Venezuela

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“…Ma) e Ordoviciano-Silurianas (42O47A Ma), e possivelmente do Paleozóico tardio (Burkley, 1926, Kovach, 1977, cordåni et al 1982 A paleogeografia do teneno Chibcùa (TG), na Colômbia, é objeto de extensas discussões, sendo considerado um alóctone transferido da Laurentia possivelmente no Ordovic¡ano-siluriano, ou como a margem conl¡nental autoctone da alual Colômb¡a (Mojica e Villaroel, 1988, Toussaint et Restrepo, 1988, Forero-Suarez, 1990, Toussa¡nt, 1993, Restrepo-pace, 1995 (Gannser, 1955, Forero, 1967, Rabe, 1977.…”

Section: Trazó Los Rios Caminos De Los Primeros Hombresunclassified

“…Ma) e Ordoviciano-Silurianas (42O47A Ma), e possivelmente do Paleozóico tardio (Burkley, 1926, Kovach, 1977, cordåni et al 1982. ldades modelo sm-Nd r9'" e herançås em zircões magmáticos de -1.0 Ga e -1.6 Ga sugerem a presença de um embasamento Mesoproterozóico (Burkley, 1976 (Litherland e Aspden, 1992, Litherland et al, 1994.…”

Section: "34 Península Da Guajiraunclassified

Correlações entre fragmentos do embasamento pré-mesozóico da terminação setentrional dos Andes Colombianos, com base em dados isotópicos e geocronológicos

Molina¹

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El Padre Sol marcó su sendero dorado sobre las altas cumbres, asi creó a las montañas, los templos del sol.Fertilizó las lagunas, madres de la tierra y origen de la gente. Trazó los rios, caminos de los primeros hombresTodo esto fue creado del mar, cuando el sol y la luna llegaron al cielo El sol es un hombre con máscara de oro.De ella salen Éyos, y esos rayos hacen que la vida nazca y que todo crezca.Mitología Kogi (Tribu da Serra Nevada de Santa Marta, Coraçäo do Mundo) A mis padres Silvia y Mario por su eterna complicidad y amistad.A Marcela por la fuerza y la inspiración.A los tres por el gran amor que merecen.Um homem sáb¡o d¡sse faz alguns anos que nossas "conquistas" são possíveis porque såo feitas sobre os "ombros de gigantes". Eu quero agradecer às pessoas e entidades que contribuíram no desenvolvimento deste trabalho de mestrado.A meu orientador Prof. Dr. Umberto Cordani por ter aberto as portas para in¡ciar estudos de pós-graduaçåo, pela constante e fundamental guia, e pelo apoio neste processo de (Mueller et al., 1994, Nance e Murphy, 1994, Tosdal, 1996, Kepp¡e et al., 1998, Dickin, 2000 Paleozóico (Dalziel, 1994, Sadowsky e Bettencourt, 1996, Tosdal, 1996 (MgO, SiO2, MnO, CaO) ao longo do rnetamorfismo (W¡nchester e FLoyd,1977, Beccaluva et al., 1983, Mclenann et al, 1993 Os outros barômetros (Hammarstrom e zen,1986, Hollister et al., 1987, Johnson e Rutherford, 1989, Schmidt, 1992 (Dahl, 1996(Dahl, , V¡llä, '1997 (Galvis et al , 1979). Diques e s¡lls máficos aparecem intrusivos nas diferentes unidades (Priem et al., 1982 Na nomenclatura e definição dos tenenos såo utilizadas as propostas de Restrepo e Toussaint (1988) na Colômbia, Litherland et al (1994) A un¡dade ma¡s antiga está const¡tuída por um embasamento metamórfico de alto grau (fácies anfibolito alto -fácies granulito), e idâde entre 1.'1 e 1-0 Ga (Kroonemberg, 1982, Priem et al., 1989, Toussaint, 1993, Restrepo-Pace, 1997.Em discordância sobre estas unidades mais antigas encontra-se uma serie de seqüências metamórficas e sedimentares do Paleozóico lnferior (Ward et al, 1973, Toussa¡nt, 1993. Uma e),.tensa atividade plutônica com 500 Ma e 440 Ma, sin a pos{ectônica, com afinidade de arco mâgmático, encontra-se estreitamente relacionada ao metamoffismo regional e à evolução destas seqùências Paleozóicas (Ward et al, 1973, Boinet et al., 1985, Toussaint, 1993, Restrepo-Pace, 1995, Schafer et al., 1998 (Tschanz et al., 1969, Mojica et al., 1984, Toussa¡nt, 1993. Ativiclade magmática estâria associada a este evento, e inclui a ativ¡dade plutônica e vulcânica da Sena de perijá e a serra Nevada de santa Marta (Tschanz et al., 1969, Rabe, 1977 O Mesozóico está caracterizado por um magmatismo de caráter plutônico e vulcánico, em parte de natureza cátc¡o-alcalina (Maze, 1984, Alvarez, 19g6, Aspden et al., 1987 Toussaint, 1999, Toussaint, 1996. conesponde a uma sene de comprexos metamórfìcos e gran¡tóides associados, formados em amb¡entes tectônicos ainda não totalmente comprêendidos (Toussaint, 1993 (Lockwood, 1966, Alvarez, 1...

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Palaeozoic to Early Jurassic history of the northwestern corner of Gondwana, and implications for the evolution of the Iapetus, Rheic and Pacific Oceans

et al. 2016

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The Palaeozoic to Mesozoic igneous and metamorphic basement rocks exposed in the Mérida Andes of Venezuela and the Santander Massif of Colombia are generally considered to define allochthonous terranes that accreted to the margin of Gondwana during the Ordovician and the Carboniferous. However, terrane sutures have not been identified and there are no published isotopic data that support the existence of separate crustal domains. A general paucity of geochronological data led to published tectonic reconstructions for the evolution of the north- western corner of Gondwana that do not account for the magmatic and metamorphic histories of the basement rocks of the Mérida Andes and the Santander Massif. We present new zircon U–Pb (ICP-MS) data from 52 igneous and metamorphic rocks, which we combine with whole rock geochemical and Pb isotopic data to constrain the tectonic history of the Precambrian to Mesozoic basement of the Mérida Andes and the Santander Massif. These data show that the basement rocks of these massifs are autochthonous to Gondwana and share a similar tectono- magmatic history with the Gondwanan margin of Peru, Chile and Argentina, which evolved during the subduc- tion of oceanic lithosphere of the Iapetus Ocean. The oldest Palaeozoic arc magmatism is recorded at ~500 Ma, and was followed shortly by Barrovian metamorphism. Peak metamorphic conditions at upper amphibolite facies are recorded by anatexis at ~477 Ma and the intrusion of synkinematic granitoids until ~472 Ma. Subsequent retrogression resulted from localised back-arc or intra-arc extension at ~453 Ma, when volcanic tuffs and interfingered sedimentary rocks were deposited over the amphibolite facies basement. Continental arc magmatism dwindled after ~430 Ma and terminated at ~415 Ma, coevally with most of the western margin of Gondwana. After Pangaea amalgamation in the Late Carboniferous to Early Permian, a magmatic arc developed on its western margin at ~ 294 Ma as a result of subduction of oceanic crust of the palaeo-Pacific ocean. Intermittent arc magmatism recorded between ~ 294 and ~ 225 Ma was followed by the onset of the Andean subduction cycle at ~ 213 Ma, in an extensional regime. Extension was accompanied by slab roll-back which led to the migration of the arc axis into the Central Cordillera of Colombia in the Early Jurassic

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Rb-Sr Whole Rock Dating of Metamorphic Events in the Iglesias Complex, Venezuelan Andes

Cited by 5 publications

References 4 publications

Overview of radiometric ages in three allochthonous belts of northern Venezuela: Old ones, new ones, and their impact on regional geology

Overview of radiometric ages in three allochthonous belts of northern Venezuela: Old ones, new ones, and their impact on regional geology

Correlações entre fragmentos do embasamento pré-mesozóico da terminação setentrional dos Andes Colombianos, com base em dados isotópicos e geocronológicos

Palaeozoic to Early Jurassic history of the northwestern corner of Gondwana, and implications for the evolution of the Iapetus, Rheic and Pacific Oceans

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