The Kooh-Shah region located in a Tertiary volcanic-plutonic belt of the Lut Block in eastern Iran comprises several subvolcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, which have in...The Kooh-Shah region located in a Tertiary volcanic-plutonic belt of the Lut Block in eastern Iran comprises several subvolcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, which have intruded into volcanic rocks. The Kooh-Shah granitoid rocks are characterized by enrichment in large ion-lithophile elements （LILE： e.g. Sr, Ba, Rb） and depletion in high field-strength elements （HFSE： e.g. Nb, Ta, Ti）. The chondrite-normalized REE patterns are characterized by moderate LREE enrichment （La/Yb）N=6.01-10.01, medium-heavy REE enrichment, and absence of Eu anomalies. The Kooh-Shah intrusive rocks are metaluminous, shoshonitic with calc-alkaline affinity and high values of magnetic susceptibility, and classified as the magnetite-series of oxidant I-type granitoids. The age of Kooh-Shah granitoid rocks based on zircon U-Pb age dating is 39.7±0.7 Ma （=Middle Eocene） and the ranges of their initial 87Sr/86Sr and 143Nd/144Nd ratios are from 0.704812 to 0.704920 and 0.512579 to 0.512644, respectively, when recalculated to an age of 39 Ma. The initial ？Nd isotope values for the Kooh-Shah intrusive rocks range from -0.18 to 1.09. This geochemical data indicates that the Kooh-Shah granitoid rocks formed from depleted mantle in an island arc setting. The geochemical signature of the studied granitoid rocks represents a characteristic guide for future exploration of copper-gold porphyry-type deposits in the Lut block.展开更多
文摘The Kooh-Shah region located in a Tertiary volcanic-plutonic belt of the Lut Block in eastern Iran comprises several subvolcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, which have intruded into volcanic rocks. The Kooh-Shah granitoid rocks are characterized by enrichment in large ion-lithophile elements （LILE： e.g. Sr, Ba, Rb） and depletion in high field-strength elements （HFSE： e.g. Nb, Ta, Ti）. The chondrite-normalized REE patterns are characterized by moderate LREE enrichment （La/Yb）N=6.01-10.01, medium-heavy REE enrichment, and absence of Eu anomalies. The Kooh-Shah intrusive rocks are metaluminous, shoshonitic with calc-alkaline affinity and high values of magnetic susceptibility, and classified as the magnetite-series of oxidant I-type granitoids. The age of Kooh-Shah granitoid rocks based on zircon U-Pb age dating is 39.7±0.7 Ma （=Middle Eocene） and the ranges of their initial 87Sr/86Sr and 143Nd/144Nd ratios are from 0.704812 to 0.704920 and 0.512579 to 0.512644, respectively, when recalculated to an age of 39 Ma. The initial ？Nd isotope values for the Kooh-Shah intrusive rocks range from -0.18 to 1.09. This geochemical data indicates that the Kooh-Shah granitoid rocks formed from depleted mantle in an island arc setting. The geochemical signature of the studied granitoid rocks represents a characteristic guide for future exploration of copper-gold porphyry-type deposits in the Lut block.
