Zircon LA-ICP-MS U-Pb age and whole-rock geochemistry data are presented for the Hutouya grano-diorite porphyries in Mengyin, western Shandong, to restrict its petrogenesis. The analyzed zircons exhibit os-cillatory g...Zircon LA-ICP-MS U-Pb age and whole-rock geochemistry data are presented for the Hutouya grano-diorite porphyries in Mengyin, western Shandong, to restrict its petrogenesis. The analyzed zircons exhibit os-cillatory growth zoning and core-rim textures in the cathodoluminescence images and have high Th/U ratios （0.04-1.66）,indicating its magmatic origin. The youngest group of magmatic zircon yields weighted mean 206Pb/238U age of 132 ±2 Ma, which represents the forming age of the granodiorite porphyries, i. e., the Early Cretaceous. The oldest group of magmatic zircon 207Pb/206Pb ages ranges from 2 398 Ma to 2 370 Ma, yielding a weighted mean age of 2 389 ±23 Ma,suggesting that the basement of the North China Craton should exist in the research area. Geochemically, the samples are characterized by high Si02（70. 38% and 64. 87% ） , low MgO （0.60% and 1. 53% ） and Mg# values （42. 92 and 50. 42）. Moreover, they show enrichment of light rare earth elements and large ion lithophile elements （e. g. Rb, Ba and K） , depletion of heavy rare earth ele-ments and high field strength elements （e. g. Nb and Ta） , positive anomaly of Pb, and negative anomaly of Ti. These results, together with previously published data, indicate that the Hutouya granodiorite porphyries were derived from partial melting of a delaminated lower continental crust and subsequent interaction with the mantle peridotites. They are consistent with the period of lithospheric thinning beneath the eastern North China Craton and may be formed in an extensional tectonic environment.展开更多
The geochemical features of the monzonitic granite in Qimantage Hutouya deposit area,Qinghai,in respect to the mineralization,suggest that this granite belongs to weak peraluminous and high-k calc alkaline rock series...The geochemical features of the monzonitic granite in Qimantage Hutouya deposit area,Qinghai,in respect to the mineralization,suggest that this granite belongs to weak peraluminous and high-k calc alkaline rock series. The REE of the samples show right slope with obvious LREE/HREE differentiation and negative Eu abnormity. The trace elements show enrichment of LILE( Rb,Th,U,La,Nd),and deleption of Ba,Sr,Nd,P,Ti. The Sr-Nb isotopic data indicate that the magma source is mainly aluminosilicate lower crust with a small amount of new crustal materials. The weighted mean zircon U-Pbage of the Hutouya monzonitic granite is 221±1.7 Ma,belonging to Late Triassic. The Hutouya monzonitic granite was formed in the tectonic setting of transition from compression to extension during Middle-Late Triassic.展开更多
基金Supported by projects of the Natural Science Foundation of China(41472052)Basic Scientific Research Foundation of Central Universities of China
文摘Zircon LA-ICP-MS U-Pb age and whole-rock geochemistry data are presented for the Hutouya grano-diorite porphyries in Mengyin, western Shandong, to restrict its petrogenesis. The analyzed zircons exhibit os-cillatory growth zoning and core-rim textures in the cathodoluminescence images and have high Th/U ratios （0.04-1.66）,indicating its magmatic origin. The youngest group of magmatic zircon yields weighted mean 206Pb/238U age of 132 ±2 Ma, which represents the forming age of the granodiorite porphyries, i. e., the Early Cretaceous. The oldest group of magmatic zircon 207Pb/206Pb ages ranges from 2 398 Ma to 2 370 Ma, yielding a weighted mean age of 2 389 ±23 Ma,suggesting that the basement of the North China Craton should exist in the research area. Geochemically, the samples are characterized by high Si02（70. 38% and 64. 87% ） , low MgO （0.60% and 1. 53% ） and Mg# values （42. 92 and 50. 42）. Moreover, they show enrichment of light rare earth elements and large ion lithophile elements （e. g. Rb, Ba and K） , depletion of heavy rare earth ele-ments and high field strength elements （e. g. Nb and Ta） , positive anomaly of Pb, and negative anomaly of Ti. These results, together with previously published data, indicate that the Hutouya granodiorite porphyries were derived from partial melting of a delaminated lower continental crust and subsequent interaction with the mantle peridotites. They are consistent with the period of lithospheric thinning beneath the eastern North China Craton and may be formed in an extensional tectonic environment.
基金Supported by Project of China Geological Survey(No.20150209-01-079)
文摘The geochemical features of the monzonitic granite in Qimantage Hutouya deposit area,Qinghai,in respect to the mineralization,suggest that this granite belongs to weak peraluminous and high-k calc alkaline rock series. The REE of the samples show right slope with obvious LREE/HREE differentiation and negative Eu abnormity. The trace elements show enrichment of LILE( Rb,Th,U,La,Nd),and deleption of Ba,Sr,Nd,P,Ti. The Sr-Nb isotopic data indicate that the magma source is mainly aluminosilicate lower crust with a small amount of new crustal materials. The weighted mean zircon U-Pbage of the Hutouya monzonitic granite is 221±1.7 Ma,belonging to Late Triassic. The Hutouya monzonitic granite was formed in the tectonic setting of transition from compression to extension during Middle-Late Triassic.
