Subduction controls on Miocene back-arc lavas from Sierra de Huantraico and La Matancilla and new Ar-40/Ar-39 dating from the Mendoza Region, Argentina
(2013) In Lithos 179. p.67-83- Abstract
- Back-arc volcanism in the western Argentinian provinces of Mendoza and Neuquen has been widespread from the Miocene to historic times. We present a detailed investigation of profiles through two of the major Miocene volcanic areas of the region, the neighboring Huantraico and La Matancilla plateaus, including new Ar-40/Ar-39 age results of major and trace elements as well as Nd, Sr and Pb isotopic data. Four million years of eruptions from 24.4 +/- 0.3 Ma (2 sigma) of alkali olivine basalts with OIB-type incompatible trace element enrichments at La Matancilla (similar to 36.50 degrees S) provide evidence for the presence of back-arc mantle devoid of subduction-related components. In contrast, the lower Huantraico lavas (similar to 37.30... (More)
- Back-arc volcanism in the western Argentinian provinces of Mendoza and Neuquen has been widespread from the Miocene to historic times. We present a detailed investigation of profiles through two of the major Miocene volcanic areas of the region, the neighboring Huantraico and La Matancilla plateaus, including new Ar-40/Ar-39 age results of major and trace elements as well as Nd, Sr and Pb isotopic data. Four million years of eruptions from 24.4 +/- 0.3 Ma (2 sigma) of alkali olivine basalts with OIB-type incompatible trace element enrichments at La Matancilla (similar to 36.50 degrees S) provide evidence for the presence of back-arc mantle devoid of subduction-related components. In contrast, the lower Huantraico lavas (similar to 37.30 degrees S) require an atypical back-arc mantle, almost devoid of arc-like components (e.g. low La/Ta = 15-18 and Ba/La = 12-18), but with a more depleted isotopic signature (e.g. Sr-87/Sr-86, 0.7033-0.7037) than observed elsewhere in the Andean back-arc. The Lower to Upper Series development in the Huantraico sequence represents a gradual change from basaltic to trachyandesitic back-arc lavas with a weak but temporally increasing arc geochemical signature (e.g. La/Ta = 15-21; Ba/La = 12-45), which is accompanied by Sr, Nd and Pb isotopic compositions approaching present day values of the Andes arc. The compositional change is accompanied by a gradually decreasing role for garnet in the mantle source, a decreasing degree of melting, but also simultaneously increasing influence from subducted fluids, probably as the slab geometry changes through time. The volcanism at Huantraico ceased when a flat slab was established around 15 Ma. (C) 2013 Elsevier B.V. All fights reserved. (Less)
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https://lup.lub.lu.se/record/4272127
- author
- Dyhr, Charlotte T. ; Holm, Paul M. ; Llambias, Eduardo J. and Scherstén, Anders LU
- organization
- publishing date
- 2013
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Back-arc/arc transition, Flat slab subduction, Ar-40/Ar-39 dating
- in
- Lithos
- volume
- 179
- pages
- 67 - 83
- publisher
- Elsevier
- external identifiers
-
- wos:000328592900006
- scopus:84878119883
- ISSN
- 0024-4937
- DOI
- 10.1016/j.lithos.2013.08.007
- language
- English
- LU publication?
- yes
- id
- 0ebe25f5-3fee-4420-b52d-8afb288a948a (old id 4272127)
- date added to LUP
- 2016-04-01 10:55:19
- date last changed
- 2022-02-17 22:35:14
@article{0ebe25f5-3fee-4420-b52d-8afb288a948a, abstract = {{Back-arc volcanism in the western Argentinian provinces of Mendoza and Neuquen has been widespread from the Miocene to historic times. We present a detailed investigation of profiles through two of the major Miocene volcanic areas of the region, the neighboring Huantraico and La Matancilla plateaus, including new Ar-40/Ar-39 age results of major and trace elements as well as Nd, Sr and Pb isotopic data. Four million years of eruptions from 24.4 +/- 0.3 Ma (2 sigma) of alkali olivine basalts with OIB-type incompatible trace element enrichments at La Matancilla (similar to 36.50 degrees S) provide evidence for the presence of back-arc mantle devoid of subduction-related components. In contrast, the lower Huantraico lavas (similar to 37.30 degrees S) require an atypical back-arc mantle, almost devoid of arc-like components (e.g. low La/Ta = 15-18 and Ba/La = 12-18), but with a more depleted isotopic signature (e.g. Sr-87/Sr-86, 0.7033-0.7037) than observed elsewhere in the Andean back-arc. The Lower to Upper Series development in the Huantraico sequence represents a gradual change from basaltic to trachyandesitic back-arc lavas with a weak but temporally increasing arc geochemical signature (e.g. La/Ta = 15-21; Ba/La = 12-45), which is accompanied by Sr, Nd and Pb isotopic compositions approaching present day values of the Andes arc. The compositional change is accompanied by a gradually decreasing role for garnet in the mantle source, a decreasing degree of melting, but also simultaneously increasing influence from subducted fluids, probably as the slab geometry changes through time. The volcanism at Huantraico ceased when a flat slab was established around 15 Ma. (C) 2013 Elsevier B.V. All fights reserved.}}, author = {{Dyhr, Charlotte T. and Holm, Paul M. and Llambias, Eduardo J. and Scherstén, Anders}}, issn = {{0024-4937}}, keywords = {{Back-arc/arc transition; Flat slab subduction; Ar-40/Ar-39 dating}}, language = {{eng}}, pages = {{67--83}}, publisher = {{Elsevier}}, series = {{Lithos}}, title = {{Subduction controls on Miocene back-arc lavas from Sierra de Huantraico and La Matancilla and new Ar-40/Ar-39 dating from the Mendoza Region, Argentina}}, url = {{http://dx.doi.org/10.1016/j.lithos.2013.08.007}}, doi = {{10.1016/j.lithos.2013.08.007}}, volume = {{179}}, year = {{2013}}, }