Modeling of contribution of the Late Cretaceous-Miocene sediments of the Makran accretionary wedge to the petrogenesis of basalts from Makran volcanic arc, SE Iran

Document Type : Original Article

Authors

1 Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran

2 Department of Geology, Faculty of Science, University of Sistan and Baluchestan, Zahdan, Iran

3 Department of Geology, ّFaculty of Science, University of Sistan and Baluchestan, Zahedan, Iran

Abstract

Late Cretaceous-Miocene sedimentary rocks from the Fanouj-Bent area are mainly composed of claystone- feldspatic greywacke of turbidite sequences. These samples seem to be the most enriched sediments among all oceanic trenches of active subduction zones (GLOSS II), while they are depleted in Ba, and Sr relative to the GLOSS II. Basalts from Makran volcanic arc are remarkably enriched in LILE's, Th and Pb and relatively depleted in Rb. The contents of Sr, Ba and Rb in coastal Makran sample (CM) are more comparable to those of the basaltic samples. To evaluate the rate of sediment contribution as a melt or fluid in magma generation, two models have been provided in this study. Variations of Th/Ce versus Th/Yb and Sm/Yb versus log Th/Yb in basaltic samples show relative consistency with MM-Av.M binary mixing trend. Using these ratios, the sediment melt contribution rate is determined to be up to 10 %. Binary mixing between MM and about 10% to more than 50% fluid derived from the coastal Makran sampleat 650oC, is fairly comparable to the variations of Rb/Nd versus Ba/La and Rb/La versus Sr/Nd. Elevated Sr/Nd, Ba/La and somehow Ce/Pb are indicative of the contribution of slab derived fluids to the petrogenesis of the basalts.

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Petrological Journal

Articles in Press, Accepted Manuscript
Available Online from 13 August 2024

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History

  • Receive Date: 04 June 2024
  • Revise Date: 29 July 2024
  • Accept Date: 13 August 2024

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