Geochemistry and Zircon U-Pb ages of the Potassic Alkalic Rocks at Nangqian County,Qinghai Province
Geochemistry and Zircon U-Pb ages of the Potassic Alkalic Rocks at Nangqian County,Qinghai Province
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发表时间：
2013
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通讯作者：
Yuan Yajua
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作者：
Yuan Yajua
青海省囊谦县钾质碱性岩具有富碱的特点（Na 2 O + K2 O =7.20%-10.6%），高钾（Na_2 O/K_2 O =0.56-0.93）和高钙（CaO=1.65%-6.39%），大离子亲石元素钾质碱性岩中的大离子亲石元素（LILE、Rb、Ba、Th、U、Sr）和Pb相对富集，而高场强元素（HFSE，Nb，Ta，Zr，钾质碱性岩的稀土元素含量分布在336.8×10-6 ~ 611.31×10-6之间，轻稀土元素富集（LREE/HREE=19.78-33.58），Eu异常不明显（δEu=0.96-1.05），获得玄武岩、伊云岩和正长斑岩的LA-ICP-MS锆石U-Pb年龄为34.9± 1.2Ma，35.0± 1.1Ma和35.3± 0.5Ma，表明岩浆喷发过程是在岩浆侵入过程之后进行的，并由此得出印度板块与欧亚板块碰撞过程存在着某种内在联系的结论。
The potassic alkalic rocks at Nangqian County,Qinghai Province are characterized by alkali-rich(Na2O+K2O=7.20%-10.6%),high potassium(Na2O/K2O=0.56-0.93) and high calcium(CaO=1.65%-6.39%).The large-ion lithophile elements(LILE,Rb,Ba,Th,U and Sr) and Pb of the potassic alkalic rocks are more enriched while the high field strength elements(HFSE,Nb,Ta,Zr,Hf and Ti) are deficient.The concentration of rare earth elements(REE) the potassic alkalic rocks is distributed in a range from 336.8×10-6 to 611.31×10-6 with enriched light REE(LREE/HREE=19.78-33.58) and the Eu anomaly of the rocks is not obviously(δEu=0.96-1.05).LA-ICP-MS zircon U-Pb age of the basalt,ivernite and syenite porphyry were obtained as the values of 34.9±1.2 Ma,35.0±1.1 Ma and 35.3±0.5 Ma respectively,which shows a trend that the magma eruption process was followed the magma intrusion.And it comes to the conclusion that there exits some inherent relationship within the collision between the India slab and Europe-Asia slab.