Ancient crystalline basement provinces in the north chilean central andes — relics of continental crust development since the mid proterozoic

Baeza, L.; Pichowiak, S.

doi:10.1007/bfb0045171

Cited by 11 publications

(3 citation statements)

References 22 publications

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“…are unknown too. Information about these outcrops has been summarized by BAEZA &PICHOWlACK (1988) andDAMM et al (1988). BAEZA & PICHO-WIACK attempted to correlate the tectonic events affecting these highly deformed complexes with events affecting the Arequipa Massif.…”

Section: Low Grade Metamorphic Beltsmentioning

confidence: 98%

The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat.

Mon

Hongn

1991

Geol Rundsch

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ZusammenfassungIm Andenbasement dieser Region lassen sich drei diastrophische Hauptzyklen, die durch ihren strukturellen Baustil und ihre geographische Verbreitung definiert sind, unterscheiden. Die/iltesten Strukturen sind verkntipft mit den Bewegungen der Panamerikanischen Orogenese (500-700 m. a.), welche im Zentralkraton einen polydeformierten Komplex yon Schiefern, Gneissen und Graniten erzeugte. Diesem lagern diskordant kambrische und ordovizische Sequenzen ohne Metamorphose und prfiandiner Deformation auf. Nach Westen zu gibt es einen Gtirtel stark deformierter ordovizischer Sedimente, die einen einfacheren Baustil als das prfikambrische Basement aufweisen, und diskordant von undeformierten devonischen Abfolgen bedeckt sind. Die Faltung des Ordoviziums wird der Ocloyischen Phase der Kaledonischen Bewegung zugerechnet.Weiter westwfirts tritt ein jtingerer Faltengfirtel aus devonischen Sedimenten auf, die wfihrend der Chanischen Phase der Herzynischen Bewegung intensiv deformiert wurden, und von karbonischen und permischen Sequenzen diskordant tiberlagert sind.Der Ocloyische Gtirtel ist von postordovizischen Graniten die von devonischen Schichten iiberlagert sind, und der Chanische Gtirtel yon karbonischen und permischen Graniten intrudiert. Im pr~kambri-schen Basement des Zentralkratons treten einerseits prfikambrische Granite auf, denen diskordant kambrische Schichten auflagern. Andererseits findet man Granite mit pal/iozoischen Isotopenaltern, letztere aber in Gebieten, wo wegen des Fehlens von Deckschichten eine stratigraphische Kontrolle unm6glich ist.Die gemachten Beobachtungen scheinen darauf hinzudeuten, dab die palfiozoischen Faltengtirtel intrakratonisch sind. Ob es allochtone ,,terrains~ in der pazifischen Ktistenkordillere gibt, ist Gegenstand der Kontroverse. AbstractThree major diastrophic cycles, defined by their structural style and their spatial distribution are recognized in the Andean Basement of this region. The oldest structures are related to the Panamerican Orogeny (500 to 700 m. a.) which produced in the Central Craton multiply deformed complexes of schists, gneisses and granites, that are covered discordantly by unmetamorphosed Cambrian and Ordovician beds. West of the Central Craton Ordovician sedimentary beds are folded with a simple structural style and intruded by granites. Both the sedimentry beds and the granites are covered discordantly by undeformed Devonian sequences. The folding of the Ordovician is attributed to the ocloyic phase of the caledonian movements. West of the ocloyic belt is another foldbelt consisting of strongly folded Devonian beds attributed to the chanic phase (hercynian). The chanic belt is intruded by carboniferous and permian granites and covered discordantly by Carboniferous and Permian sequences.The features observed in the eastern slope of the Andes suggest that the Paleozoic foldbelts are intracratonic. Whether there are accreted terrains in the Pacific Coastal Cordillera is matter of controversy. ResumenEn el basamento de los Andes de esta regi6n s...

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Section: Low Grade Metamorphic Beltsmentioning

confidence: 98%

The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat.

Mon

Hongn

1991

Geol Rundsch

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“…Few reliable radiometric dates are available for the basement of the Occidentalia terrane, but there are several indications that it is broadly "Grenvillian" (1.3-1.0 Ga). The formation of continental crust in the northern Chilean Andes apparently started in the Mesoproterozoic (Baeza and Pichowiak, 1988). An Rb-Sr age of 1027 ±59 Ma has been obtained from a basement inlier in the westernmost Famatinian orogen (Varela and Dalla Salda, 1992), and a Grenvillian age for the basement of the Occidentalia terrane is also suggested by the presence of zircons yielding U-Pb ages of ca.…”

Section: Famatinian Orogenmentioning

confidence: 99%

Did the Taconic Appalachians continue into southern South America?

Salda

Dalziel

Cingolani

et al. 1992

Geol

128

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The Appalachian Mountains, now terminating abruptly at the Gulf of Mexico coastal plain, may have formerly continued into southern South America. Rocks forming the basement of the Argentine Andes can be interpreted as remnants of an early Paleozoic orogen, the Famatinian belt, not unlike the Taconic Appalachians. Both orogens are bordered to the west (present coordinates) by lower Paleozoic carbonate platforms bearing the Olenellid trilobite fauna that is characteristic of Laurentia. Paleomagnetic and geologic data indicate that they could have formed as one continuous mountain chain, possibly extending into Antarctica, during Ordovician closure of an ocean basin ("southern" Iapetus) between Laurentia and Gondwana. The Taconic and Famatinian segments of the chain may have been truncated during Late Ordovician separation of Laurentia and Gondwana along the preexisting (late Neoproterozoic to Cambrian) rift system that initiated formation of the Ouachita embayment and the southern margin of North America. SOUTHERN TERMINATION OF THE APPALACHIANSThe Appalachian mountain belt extends along the eastern seaboard of the North American Precambrian craton for more than 4000 km, from Newfoundland to Georgia (Fig. 1), where it is covered by Mesozoic and Cenozoic sedimentary strata of the Gulf of Mexico coastal plain. The mobile belt originated with a late Neoproterozoic to earliest Cambrian rift event that predated development of a Cambrian carbonate platform (Hoffman, 1989;Hatcher et al., 1989). Three main phases of regional dynamothermal metamorphism and granitic plutonism have long been recognized in the Appalachians: the Ordovician Taconic orogeny, the Devonian Acadian orogeny, and the late Paleozoic Alleghanian orogeny (Rodgers, 1970;Hatcher, 1989). The Alleghanian orogeny resulted from final collision of Laurentia with northwestern Africa, and it is best developed in the southern and central Appalachians. The effects of this collision are also recognizable in the Ouachita embayment (Fig. 1), which was not affected by the earlier compressional events (Hatcher et al., 1989). The Taconic belt, well developed immediately north of the coastal plain, is sharply truncated there. This constitutes a major problem of North American tectonics that has seldom been addressed.

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“…There are also a few outcrops of Precambrian to Palaeozoic polymetamorphic basement (e.g. Baeza and Pichowiak, 1988) and Palaeozoic sediments (e.g. Bahlburg et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

Generation and metamorphism of new crust in magmatic arcs: a case study from northern Chile

Lucassen

Franz

1992

Terra Nova

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In a deep section of the Jurassic Andean arc, coastal Cordillera of northern Chile, south of Antofagasta, basic magmas from a mantle source accreted large masses of crust in an early stage of arc development. These gabbroic intrusions were isochemically metamorphosed at moderate pressures (≤ 5 kbar) and high temperatures (∼ 800°C) into uniform garnet‐absent dino+ortho‐pyroxene gneisses (granulites). Subsequently they were partly transformed into amphibolites (T≤ 700°C) during tectonically controlled access of fluid without major changes in whole rock chemistry. Locally migmatization occurs in the amphibolites. The metamorphic unit was diversified by enduring magmatic activity in the form of chemically distinct gabbroic and quartz dioritic intrusions. Formation and composition of continental crust might be a typical example for the deeper plutonic sections of this continental magmatic arc.

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Ancient crystalline basement provinces in the north chilean central andes — relics of continental crust development since the mid proterozoic

Cited by 11 publications

References 22 publications

The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat.

The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat.

Did the Taconic Appalachians continue into southern South America?

Generation and metamorphism of new crust in magmatic arcs: a case study from northern Chile

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