Petrology
Jalil Ghalamghash; Meysam Akbari; Reza Jamal
Abstract
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate ...
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The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions enclosed by acidic groundmass, and disequilibrium textures in plagioclase phenocrysts including sieve texture, zoning, and dissolution margin, which may reflect magma mixing. These rocks record high-K calc-alkaline to calc-alkaline affinity with enrichment in LREE and LILE relative to HREE and HFSE, respectively. These features, coupled with the clear depletion in HFSE (such as Nb, Ta, and Ti) are consistent with typical subduction-related volcanic arcs. Taftan primary melts might have been produced by ~15% partial melting of spinel lherzolite mantle. The normalized multi-element patterns which mimic the upper continental crust values, and enrichment in Pb, Th, U, and Rb agree well with magma evolution by assimilation and fractional crystallization (AFC). The available isotopic geochronology dataset reveal that the youngest volcanoes of the Makran-Chagai magmatic arc are Bazman and Kuh-e-Sultan volcanoes. A geochemical comparison of these volcanoes highlights that magmatism in the Taftan where the crust is thick, underwent a higher degree of crustal assimilation en route to the surface.
H. Biabangard; A. Moradian; Y. Bavali
Abstract
Taftan is a stratovolcano, located to the SE of Zahedan, eastern Iran. Due to the highlands of the volcano, a microclimate is created in the region where precipitation provides some water in the arid region that the volcano is located. Field studies and chemical analyses of thirteen mine springs from ...
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Taftan is a stratovolcano, located to the SE of Zahedan, eastern Iran. Due to the highlands of the volcano, a microclimate is created in the region where precipitation provides some water in the arid region that the volcano is located. Field studies and chemical analyses of thirteen mine springs from western flanks of the volcano indicate that springwater in Taftan is somehow related to volcanic rocks. Based on hydrogeochemical analyses, significant variation in Mg2+(2-150), Ca2+(11-465), Na+(10.5-444), K+(1.5-330), SO42-(8-1050), HCO3-(0-353.8), NO3-(1.1-58.6), Cl-(10.65-1520) and mole fraction of SiO2(6.11-182.87) all in mg/L is affected by the chemical composition of volcanic rocks. Since springwater in Taftan shows significant compositional variation, it is concluded that the springs originated mainly due to precipitation, affected by water-rock interaction to some extent. However, a few springs show characteristic of juvenile water and some may have a mixture of juvenile and meteoric water.
