Geochemical characteristics and petrogenesis of the Badaling high Ba-Sr granitoids: A comparison of igneous rocks from North China and the Dabie-Sulu Orogen

Qing Qian*, Sun Lin Chung, Tung Yi Lee, Da Jen Wen


研究成果: 雜誌貢獻期刊論文同行評審

50 引文 斯高帕斯(Scopus)


The Mesozoic Badaling complex, emplaced in the northern part of the North China block (NCB), is composed of gabbrodiorite, quartz diorite, quartz monzonite, monzodiorite, adamellite, moyite and quartz syenite, which are predominantly high-K calc-alkaline and subordinately shoshonitic. Their major elements, except that of cumulative gabbrodiorite with substantive magnetite, range widely, e. g., SiO2 = 46.5% ∼ 75.3%, MgO = 5.6% ∼ 0.2%. K2O/Na2O ratio varies from 0.59 to 1.09 for the intermediate-felsic rocks. The moyite and quartz monzonite have low Ba and Sr abundances and strong negative Eu anomaly. However, most intermediate-felsic rocks are consistently characterized with high Ba, Sr and LREE and low Rb, Y and HREE abundances, high Sr/Y and La/Yb ratios, distinct Nb, Ta and Ti depletion, as well as absence of negative Eu anomalies, and are comprehensively called high Ba-Sr granitoids. In addition, the mafic rocks and high Ba-Sr granitoids have covariant major elements, and similar incompatible trace element and rare earth element (REE) patterns, with REE, Y, Sr, P and Ti abundances consistently decreasing from basic to felsic rocks. Initial 87Sr/86Sr (0.7051 ∼ 0.7068) and εNdi (-8.2 ∼ - 20.2) of mafic rocks and high Ba-Sr granitoids show EM1-type signature, and are negatively correlated. Geochemical data indicate that mafic rocks were derived from partial melting of an enriched subcontinental lithospheric mantle, and high Ba-Sr granitoids were produced from the mafic magmas mainly through fractional crystallization with some crustal contamination. Fractionation of P- and Ti-bearing accessory minerals, such as apatite and titanite, played an important role in causing the decrease of the REEs with progressive differentiation. The Yanshanian mafic rocks, high Ba-Sr and low Ba-Sr granitic rocks with comparable geochemical characteristics to their correspondents in the Badaling complex are widespread in the eastern part of NCB and the Dabie-Sulu Orogen (DSOB). Hence we propose that the occurrence of Yanshanian igneous rocks in NCB and DSOB had common geodynamic mechanism, and the geochemical characteristics of the Yanshanian igneous rocks from DSOB were not necessarily due to the interaction between the subducted continental crust (Yangtze block) and mantle peridotite. Delamination or lithospheric thinning probably caused the partial melting of the enriched subcontinental lithospheric mantle beneath NCB and DSOB. Mantle enrichment beneath NCB and DSOB may occur early in Proterozoic, implicated by the similarity of Nd depleted mantle model ages (TDM).

頁(從 - 到)275-292
期刊Acta Petrologica Sinica
出版狀態已發佈 - 2002 7月

ASJC Scopus subject areas

  • 地球化學與岩石學


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