Geochemistry, Sr-Nd-Pb isotopes and geochronology of amphibole- and mica-bearing lamprophyres in northwestern Iran: Implications for mantle wedge heterogeneity in a paleo-subduction zone

Aghazadeh, Mehraj, Prelević, Dejan, Badrzadeh, Zahra, Braschi, Eleonora, van den Bogaard, Paul and Conticelli, Sandro (2015) Geochemistry, Sr-Nd-Pb isotopes and geochronology of amphibole- and mica-bearing lamprophyres in northwestern Iran: Implications for mantle wedge heterogeneity in a paleo-subduction zone Lithos, 216-217 . pp. 352-369. DOI 10.1016/j.lithos.2015.01.001.

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Supplementary data:

Abstract

Highlights

• Northwestern Iranian lamprophyres have alkaline and calc-alkaline nature.
• Studied lamprophyres are emplaced during Late Cretaceous to Late Miocene time.
• Lamprophyres originated from different metasomatised lithospheric mantle.

Abstract

Lamprophyres of different age showing distinctive mineralogy, geochemistry and isotopic ratios are exposed in northwestern Iran. They can be divided into Late Cretaceous sannaite, Late Oligocene-Early Miocene camptonite (amphibole-bearing) and Late Miocene minette (mica-bearing) and spessartite (amphibole-bearing) lamprophyres.

Sannaites have high-Ti amphibole along with high-Ti and Al clinopyroxene, and they are characterised by homogeneous enrichment in incompatible trace elements with troughs at Pb. Spessartites have hornblende and low-Al and Ti clinopyroxene, and they are characterised by enriched incompatible trace element pattern with depletions of Nb, Ta, Pb, and Ti with respect to large ion lithophile elements. Minettes have high-Ti and Al brown mica and low-Al and Ti clinopyroxene, and similarly to spessartite, are characterised by fractionation of high field strength elements with respect to large ion lithophile elements, with troughs at Nb, Ta, and Ti and a peak at Pb. Minettes show high initial 87Sr/86Sr values up to 0.70760 and low initial 143Nd/144Nd down to 0.512463 with a negative correlation, consistent with the trace element distribution related with an enriched mantle source modified after sediment recycling during subduction and continental collision.

Cretaceous sannaites and Early Miocene spessartites show low initial 87Sr/86Sr approaching 0.70447 and high 143Nd/144Nd values up to 0.512667, which are consistent with a depleted within-plate mantle source. Minette and spessartite lamprophyres show high initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values, whereas sannaites have lower, but variable, initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values with respect to those of calc-alkaline lamprophyres. Minettes originated by partial melting of a metasomatised lithospheric mantle following siliciclastic sediment recycling by subduction. In contrast, sannaites were generated from the partial melting of a similar lithospheric mantle that was metasomatised by within-plate agents.

Document Type: Article
Additional Information: WOS:000353851300025
Keywords: Alkaline and calc-alkaline lamprophyres; Geochemistry; Sr-Nd-Pb isotopes; Geochronology; Mantle heterogeneity; Iran
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1016/j.lithos.2015.01.001
ISSN: 0024-4937
Related URLs:
Date Deposited: 20 Jan 2015 08:19
Last Modified: 28 May 2015 11:55
URI: http://eprints.uni-kiel.de/id/eprint/27019

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