首页|Zircon U-Pb ages and Sr-Nd isotope ratios for the mafic microgranular enclaves in the sirstan cretaceous granitoids, NE Iraq: Evidence of cogenetic magmatic origin

Zircon U-Pb ages and Sr-Nd isotope ratios for the mafic microgranular enclaves in the sirstan cretaceous granitoids, NE Iraq: Evidence of cogenetic magmatic origin

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  • NETL
  • NSTL
  • Elsevier
Mafic microgranular enclaves (MMEs) are observed in the Sirstan granitoid (SG) body in the Shalair Valley area, northeastern Iraq, within the Zagros Orogenic Belt. Zircon U-Pb ages for the MMEs are 110 Ma with an I-type affinity closely resembling the enclosing rocks. The MMEs are gabbroic-diorite to diorite in composition, and the main mineral assemblage are plagioclase, hornblende, and K-feldspar. The MMEs are intermediate in composition and have low SiO2 (52.0-60.2 wt%) and high Fe2O3, Al2O3, TiO2 and CaO contents (Fe2O3 = 8.7-13.3 wt%; Al2O3 = 14.8-17.2 wt%; TiO2 = 0.71-1.02 wt%; CaO = 3.4-11.4 wt%). The enclaves have analogous Sr and Nd isotope compositions with positive epsilon Nd(t) values (87Sr/86Sr(i) = 0.7047 to 0.7058; epsilon Nd(t) = +2.0 to +2.5) as their host granitoids (87Sr/86Sr(i) = 0.7044 to 0.7057; epsilon Nd(t) = +0.1 to +2.7). The uniform REE patterns and the fractionation trends of major and trace elements of the MMEs with their host rocks indicate simultaneous crystallization by fractionation from the same magma source. According to the geochemical aspects of the MMEs and their host SG rocks with young TDM ages (676-720 Ma), the low ratios of the Rb/Sr and Nb/Y ratios, in addition to the same ages and Sr-Nd isotope ratios, infer that the same source magma was derived from a young depleted mantle without the contribution of ancient crustal components.

Mafic microgranular enclavesEarly crystallizationSanandaj-sirjan zoneNE IraqGeochronologyAutolithsSANANDAJ-SIRJAN ZONEZAGROS SUTURE ZONESIERRA-NEVADA BATHOLITHA-TYPE GRANITESI-TYPETECTONIC EVOLUTIONSOUTHEAST CHINAPLUTONIC ROCKSOROGENIC BELTGEOCHEMISTRY

Abdulzahra, Imad Kadhim、Asahara, Yoshihiro、Mohammad, Yousif、Yara, Irfan

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Iraq Geol Survey

Nagoya University Graduate School of Environmental Studies Department of Earth and Environmental Sciences

University of Sulaimani College of Science

2025

10.1016/j.jafrearsci.2025.105665

Journal of African earth sciences

Journal of African earth sciences

SCI
ISSN：1464-343X
年,卷(期)：2025.228(Aug.)
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