Provenance variations in the Late Paleozoic accretionary complex of central Chile as indicated by detrital zircons
Author
dc.contributor.author
Hervé Allamand, Francisco
es_CL
Author
dc.contributor.author
Calderón, M.
es_CL
Author
dc.contributor.author
Fanning, C. M.
es_CL
Author
dc.contributor.author
Pankhurst, R.J.
Author
dc.contributor.author
Godoy, E.
es_CL
Admission date
dc.date.accessioned
2014-03-10T20:12:22Z
Available date
dc.date.available
2014-03-10T20:12:22Z
Publication date
dc.date.issued
2013
Cita de ítem
dc.identifier.citation
Gondwana Research 23 (2013) 1122–1135
en_US
Identifier
dc.identifier.other
doi:10.1016/j.gr.2012.06.016
Identifier
dc.identifier.uri
https://repositorio.uchile.cl/handle/2250/126434
General note
dc.description
Artículo de publicación ISI
en_US
Abstract
dc.description.abstract
We present detrital zircon U\Pb SHRIMP age patterns for the central segment (34–42°S) of an extensive accretionary
complex along coastal Chile together with ages for some relevant igneous rocks. The complex consists
of a basally accreted high pressure/low temperature Western Series outboard of a frontally accreted
Eastern Series that was overprinted by high temperature/low pressure metamorphism. Eleven new
SHRIMP detrital zircon age patterns have been obtained for meta-turbidites from the central (34–42°S) segment
of the accretionary complex, four from previously undated metamorphic complexes and associated intrusive
rocks from the main Andean cordillera, and three from igneous rocks in Argentina that were
considered as possible sediment source areas. There are no Mesozoic detrital zircons in the accretionary
rocks. Early Paleozoic zircons are an essential component of the provenance, and Grenville-age zircons and
isolated grains as old as 3 Ga occur in most rocks, although much less commonly in the Western Series of
the southern sector. In the northernmost sector (34–38°30′S) Proterozoic zircon grains constitute more
than 50% of the detrital spectra, in contrast with less than 10% in the southern sector (39–42°S). The youngest
igneous detrital zircons in both the northern Western (307 Ma) and Eastern Series (345 Ma) are considered
to closely date sedimentation of the protoliths. Both oxygen and Lu\Hf isotopic analyses of a selection of
Permian to Neoproterozoic detrital zircon grains indicate that the respective igneous source rocks had significant
crustal contributions. The results suggest that Early Paleozoic orogenic belts (Pampean and Famatinian)
containing material recycled from cratonic areas of South America supplied detritus to this part of the
paleo-Pacific coast. In contrast, in the southern exposures of the Western Series studied here, Permian detrital
zircons (253–295 Ma) dominate, indicating much younger deposition. The northern sector has scarce Early
to Middle Devonian detrital zircons, prominent south of 39°S. The sedimentary protolith of the northern sector
was probably deposited in a passive margin setting starved of Devonian (Achalian) detritus by a topographic
barrier formed by the Precordillera, and possibly Chilenia, terranes. Devonian subduction-related
metamorphic and plutonic rocks developed south of 39°S, beyond the possible southern limit of Chilenia,
where sedimentation of accretionary rocks continued until Permian times.