| 浙西新路盆地晚白垩世钾玄岩的厘定及其地质意义 |
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| 关键词:shoshonite 40Ar-39Ar dating petrogeochemistry lithospheric thinning Xinlu volcanic basin |
| 基金项目:国家自然科学基金项目(编号: 41040019) |
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| 摘要: |
| Chronology and Geochemical Characteristics of the Diabase in Xinlu Basin of Western Zhejiang and Their Significance |
| The laser microprobe 40Ar-39Ar dating and detailed study of petrogeochemical characteristics of the diabase developed in Xinlu volcanic basin of western Zhejiang were carried out. The results indicate that the diabase was formed in Late Cretaceous with an age of (93±3) Ma. The diabase contains two kinds of pyroxenes (clinopyroxene and orthopyroxene), the plagioclase is labradorite, and the content of SiO2 is between 44.00% and 50.09%, characterized by rich alkali, (5.15% on average), high K (K2O/Na2O 1.08), and low Ti (TiO2 1.15%).Its petrological and geochemical characteristics show typical shoshonite. The shoshonite is enriched in LREE, LILE and incompatible elements, without Eu depletion, (87Sr/86Sr)i and (143Nd/144Nd)i are in the ranges of 0.70707 to 0.70870 and 0.512338 to 0.512407 respectively, Δ7/4Pb=6.0~9.2, Δ8/4Pb=48.5~68.0, and DSr=70.73~87.04, showing relatively enriched mantle signatures. It is concluded that the shoshonite in Xinlu basin is the product of lithospheric thinning combined with hotspot activity in the post-collision period of the orogenic zone. The age of shoshonite fundamentally restricts the time limit of the large-scale lithospheric thinning in Xinlu area, and suggests that dynamic processes of lithospheric thinning was affected by hotspot and the sources of crust-mantle interaction migtht have played an important role in controlling volcanics-type uranium mineralization. |
| WANG Zheng-qi,LI Zi-ying,FAN Hong-hai,TANG Jiang-wei.2013.Chronology and Geochemical Characteristics of the Diabase in Xinlu Basin of Western Zhejiang and Their Significance[J].Acta Geoscientica Sinica,34(2):139-153. |
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