SHRIMP zircon U-Pb geochronology of the diorites for southern Taihang Mountains in the North China Interior and its petrogenesis.
SHRIMP zircon U-Pb geochronology of the diorites for southern Taihang Mountains in the North China Interior and its petrogenesis.
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发表时间：
2004
影响因子：
1.8
通讯作者：
Peng Tou;W. Yue
中科院分区：
文献类型：
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作者：
Peng Tou;W. Yue
太行山南部中生代闪长质岩石的年代学和地球化学资料为认识华北大陆中生代岩石圈地幔的性质提供了新的思路。以福山和东冶角闪长岩为代表的中生代闪长质侵入岩的SHRIMP锆石U-Pb年龄分别为126.7 ± 1.1Ma和125.9 ± 0.9Ma。与北太行山及华北陆块内部其他地区的年龄一致。闪长质岩石的SiO_2 = 54.8~65.8%，MgO = 1.31%~3.89%，K_2O + Na_2O = 6.53%~11.40%。Mg数为0.36~0.58，（La/Yb）_（cn）= 9.86~22.77，（Gd/Yb）_（cn）= 1.51~2.00，Eu/Eu~*= 1.00~1.23。它们富集大离子亲石元素和轻稀土元素，亏损高场强元素，其特征为87Sr/86Sr（t）= 0.705363~0.706165，eNd（t）=-13.8~-16.8，与类EMI源有密切关系。这些特征表明它们很可能起源于类似EMI的岩石圈地幔。中生代岩石圈的伸展作用可能导致富集的岩石圈地幔熔融，以响应软流圈的上升，从而产生了这些闪长质岩石。
The geochronological and geochemical data of the Mesozoic dioritic rocks from the southern Taihang Mountains provide an insight into the understanding of the nature of the Mesozoic lithospheric mantle beneath the North China interior. The Fushan and Dongye hornblende-diorites, the representative for the Mesozoic dioritic intrusions in the region, yield the SHRIMP zircon U-Pb ages of 126.7±1.1 Ma and 125.9±0.9 Ma, respectively. The ages are consistent with those of the North Taihang Mountains and other areas in the North China Block interior. These dioritic rocks have SiO_2=54.8～65.8%, MgO=1.31%～3.89%, K_2O+Na_2O=6.53%～11.40%. mg-number=0.36～0.58, (La/Yb)_(cn)=9.86～22.77, (Gd/Yb)_(cn)=1.51～2.00; Eu/Eu~*=1.00～1.23. They are enriched in LILEs and LREEs, depleted in HFSEs, and are characterized by ~(87)Sr/~(86)Sr(t)=0.705363～0.706165, e_(Nd)(t)=-13.8～-16.8 with an affinity to EMI-like source. Such characteristics suggest that they were most likely originated from an EMI-like lithospheric mantle. Mesozoic lithospheric extension might induce the melting of the enriched lithospheric mantle in response to the asthenosphere uprising for generating these dioritic rocks in the region.