| Citation: | Fengmei Chai, Zhaochong Zhang, Jingwen Mao, Abudukadir Parat, Lijin Wang, Lianhui Dong, Huishou Ye, Li Chen, Rongfen Zheng. Lamprophyre or Lamproite Dyke in the SW Tarim Block? —Discussion on the Petrogenesis of These Rocks and Their Source Region. Journal of Earth Science, 2006, 17(1): 13-24.
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The mineralogical, petrological and geochemical studies on Keliyang(克里阳) potassic dykes have been carried out to understand their rock types, the petrogenesis and the nature of their mantle sources. They are potassic lamprophyre, not lamproites as the previous researchers believed. In this study, the whole-rock major and trace element compositions of another 6 lamproite dykes recently discovered are reported. Major elements were determined by X-ray fluorescence spectrometry(XRF)techniques, while REE and trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). They can be classified into phlogopite-diopside lamprophyre, leucite-diopside lamprophyre and granular carbonatite-bearing diopside lamprophyre on the basis of their mineral components. They are all characterized by relatively low SiO2(41.31% - 44.84%), TiO2(0.75% - 0.86%) and high MgO(7.30% - 11.33%), K2O(4.01% - 6.01%)concentrations with K2O/Na2O ratios of 2.77 12.49. In addition, they display enrichment in large-ion lithophile elements(LILEs, e.g., Rb, Sr, Ba)and LREE, but a relative depletion in high-field-strength elements(HFSEs, e.g., Nb, Ta, Zr, Hf and Ti). They display similar chondrite-normalized REE patterns with slight negative Eu anomalies (
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