Publication:
Subduction controls on Miocene back-arc lavas from Sierra de Huantraico and La Matancilla and new 40Ar/39Ar dating from the Mendoza Region, Argentina

dc.creatorDyhr, Charlotte T.
dc.creatorHolm, Paul H.
dc.creatorLlambias, Eduardo Jorge
dc.creatorScherstén, Anders
dc.date.issued2013-10-01
dc.description.abstractBack-arc volcanism in the western Argentinian provinces of Mendoza and Neuquén 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 40Ar/39Ar 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 (2σ) of alkali olivine basalts with OIB-type incompatible trace element enrichments at La Matancilla (~ 36.50°S) provide evidence for the presence of back-arc mantle devoid of subduction-related components. In contrast, the lower Huantraico lavas (~ 37.30°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. 87Sr/86Sr, 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.
dc.identifierDyhr, Charlotte T.; Holm, Paul H.; Llambias, Eduardo Jorge; Scherstén, Anders; Subduction controls on Miocene back-arc lavas from Sierra de Huantraico and La Matancilla and new 40Ar/39Ar dating from the Mendoza Region, Argentina; Elsevier Science; Lithos; 179; 1-10-2013; 67-83
dc.identifier0024-4937
dc.identifierhttp://hdl.handle.net/11336/24072
dc.identifierCONICET Digital
dc.identifierCONICET
dc.identifier.urihttps://naturalis.fcnym.unlp.edu.ar/handle/628872547/57396
dc.languageeng
dc.publisherElsevier Science
dc.relationinfo:eu-repo/semantics/altIdentifier/url/http://www.sciencedirect.com/science/article/pii/S0024493713002466
dc.relationinfo:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1016/j.lithos.2013.08.007
dc.subjectBack-Arc/Arc Transition
dc.subjectFlat Slab Subduction
dc.subject40ar/39ar Dating
dc.titleSubduction controls on Miocene back-arc lavas from Sierra de Huantraico and La Matancilla and new 40Ar/39Ar dating from the Mendoza Region, Argentina
dc.typeinfo:eu-repo/semantics/article
dc.typeinfo:ar-repo/semantics/artículo
dc.typeinfo:eu-repo/semantics/publishedVersion
dspace.entity.typePublication

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