مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

U-Th zircon SHRIMP and U-Th-total Pb monazite CHIME ages of 6 typical samples were established among different rock types outcropped into the Chah-Dozdan batholith from Iran. The zircon population displays simple internal structures in samples of the Chah-Dozdan batholith. The zircon crystals have well-preserved magmatic characteristics. In all population, the rims display younger ages than the cores, presumably due to late-magmatic crystallization. Zircon grains of anorthosites exhibit magmatic ages c. 170.5 ± 1.9 Ma and 173.0 ± 1.6 Ma. Zircon SHRIMP U-Th ages of metapelitic xenoliths and S-type granites from Chah-Dozdan pluton are c. 167.0 ± 3.1 Ma and 164.3 ± 8.1 Ma, respectively. Monazite grains are generally concordant in electron microprobe analysis and give Th-U-total Pb isochron ages in agreement with zircon SHRIMP U-Pb ages. The sub-grain analyses of monazite are plotted on the coordinates of PbO and ThO* (ThO plus the equivalent of UO2). Data points fit linearly and clearly defined an isochron which passes thorough the origin. Small patches of the S-type granites and metapelitic xenoliths yield chemical Th-U-total Pb isochron ages of monazite c. 171 ± 16 Ma and 165 ± 42 Ma, respectively. Emplacement of anorthositic magma into metapelites from the Qori metamorphic complex at midcrustal depth resulted into fundamental contamination of this magma via breaking down of blocks of host rock into it, in the form of xenoliths within intruded magma, and s-type granite via partial melting of metapelitic xenoliths.