| 1 | K-Ar Geochronology of Mesozoic Mafic Dikes in Shandong Province, Eastern China: Implications for Crustal Extension显示文摘Based on K-Ar isotope analyses, Mesozoic mafic (and alkali ultramafic) dikes from western and eastern Shandong Province, China, are dated at 88.2±1.70 Ma to 169.5±3.7 Ma with the majority of ages ranging from 90 Ma to 140 Ma. The emplacement of the dikes suggests a major Yanshanian (Cretaceous) crustal extension in Shandong province.Together with other available age data, this study suggests four periods of crustal extension at about 80 Ma, 100 Ma, 120 Ma and 140 Ma, respectively. Besides the effect of collapse of the Yanshanian orogenic belt on the emplacement of the mafic dikes in Shandong in the Cretaceous, the mantle plume and the extensive left-lateral advection and extension of the Tanlu fault also have controlled the crustal extension and the emplacement of the mafic dikes in eastern Shandong and western Shandong, respectively. | LIUShen HURuizhon ZHAOJunhong FENGCaixia | 2004 | Acta Geologica Sinica(English Edition)2004，78，6： | 17 |
| 2 | Cenozoic Adakite-type Volcanic Rocks in Qiangtang,Tibet and Its Significance显示文摘Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that therocks are characterized by SiO2>59%, enrichment in Al2O3 (15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g)and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg#<0.35),weak Eu anomaly (Eu/Eu*=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd andSr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magmaresulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and thepetrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will givean insight into the uplift mechanism of the Tibetan plateau. | LIUShen HURuizhong FENGCaixia CHIXiaoguo LICai YANGRihong WANGTianwu JINWei | 2003 | Acta Geologica Sinica(English Edition)2003，77，2： | 11 |
您所在的机构暂未开通此部分的功能，请联系管理员