Famatinian orogeny

Source: Wikipedia, the free encyclopedia.
microcontinents such as Cuyania, Pampia and Chilenia
are omitted.

The Famatinian orogeny (

intrusion of magma along a Famatinian magmatic arc that formed a chain of volcanoes.[2] The igneous rocks of the Famatinian magmatic arc are of calc-alkaline character and include gabbros, tonalites, granodiorites and trondhjemites.[1][3] The youngest igneous rocks of the arc are granites.[1]

Part of the

dykes of the Pampean Pegmatite Province formed during the orogeny.[4] These dykes are thought to be derived from S-type granitic melts.[4]

The relationship of the orogeny with the Achala and Cerro Aspero batholiths of central Argentina is not fully understood. These Devonian batholiths are possibly of post-orogenic character.[5][6]

Outcrops and sediments

The Famatinian orogen's main

Sierras Pampeanas in northwestern Argentina.[1][7] Only the western part of Sierras Pampeanas bears evidence of the Famatinian orogeny; the eastern parts appear to have been largely unaffected.[1] In northern Chile the Belén Metamorphic Complex is thought to have been subject to metamorphism that was "time-equivalent" to the Famatinian orogeny in the early Paleozoic.[7] It can this be considered part of the orogen in a broad sense.[7] To the south in La Pampa Province, outcrops associated with the orogeny are scarce since most of that region has become blanketed by much more recent Quaternary sediments.[8]

In Peru's Cordillera Oriental a "Famatinian" orogeny exists which is coeval with the classical Famatinian orogeny found further south. In the time-span from 480 Ma to 435 Ma (Late Cambrian to Silurian) rocks of Cordillera Oriental were deformed and a magmatic arc developed.[9]

Towards what is now the east of the Famatinian magmatic arc a Precambrian sedimentary basin developed into a back-arc basin during the Ordovician. This basin went from Peru, through Bolivia to northwestern Argentina. The basin collected sediments from the Famatinian orogen and arc and while it did not contain oceanic crust it was a marine basin.[10]

peraluminous.[11] These rocks are remnants of the magmatism along the western rim of the Famatinian orogeny.[11]

Plate tectonic setting

Famatinian arc magmatism was caused by the subduction of Iapetus Ocean lithosphere beneath Gondwana.[8] As subduction went on, the peak of the orogeny resulted from the collision of the Cuyania terrane with Pampia in the Ordovician.[12]

It has been suggested that the coeval

genera in common with Laurentia but many species are endemic have led to some differing interpretations on what paleogeographic and tectonic history conditions are plausible explanations for this biogeography.[15]

Notes

  1. ^ All coordinates in this article are in relation to present-day geography and not to the past disposition of continents, terranes and oceans.
  2. ^ In other words: what is at present the northern end of the Famatinian orogen would have been connected with what is currently the southern end of the Taconic orogen.

References

  1. ^ a b c d e Alvarado, Patricia; Castro de Machuca, Brígida; Beck, Susan (2005). "Comparative seismic and petrographic crustal study between the Western and Eastern Sierras Pampeanas region (31ºS)" (PDF). Revista de la Asociación Geológica Argentina. 60 (4): 787–796.
  2. ^ González, Pablo Diego; Sato, Ana María; Basei, Miguel A.S.; Vlach, Silvio R.F.; Llambías, Jorge (2002). Structure, metamorphism and age of the Pampean-Famatinian orogenies in the western Sierra de San Luis (PDF). Actas XV Congreso Geológico Argentino. Retrieved 18 September 2015.
  3. S2CID 229455476
    .
  4. ^ .
  5. ^ Lira, Raúl; Kirschbaum, Alicia M. (1990). "Geochemical evolution of granites". In Mahlburg Kay, Suzanne; Rapela, Carlos W. (eds.). Plutonism from Antarctica to Alaska. Geological Society of America Special Paper. Vol. 241. pp. 67–76.
  6. .
  7. ^ .
  8. ^ .
  9. .
  10. .
  11. ^ .
  12. ^
    ISSN 1342-937X. Archived from the original
    (PDF) on 26 September 2015. Retrieved 18 September 2015.
  13. ^ . Retrieved 18 September 2015.
  14. ^ Dalla Salda, Luis H.; López de Luchi, Mónica.; Cingolani, Carlos A.; Varela, Ricardo (1998). "Laurentia-Gondwana collision: the origin of the Famatinian-Appalachian Orogenic Belt (a review)". In Pankhurst, R.J.; Rapela, C.W. (eds.). The Proto-Andean Margin of Gondwana. Vol. 142. Geological Society, London, Special Publications. pp. 219–234.
  15. ^ a b Bordonaro, Osvaldo (2016). "Trilobites laurénticos de la Formación La Laja (Cámbrico), Precordillera de San Juan, Argentina: un aporte biogeográfico al modelo alóctono de Precordillera". Revista de la Asociación Geológica Argentina (in Spanish). 73 (4).

External links