摘要
青海省囊谦县钾质碱性岩岩石化学成分富碱（Na2O＋K2O=7．20％～10．6％），高钾（Na2O／K2O=0．56-0．93）和富钙（CaO=1．65％-6．39％），富集Rb，Ba，Th，U，Sr等大离子亲石元素（LILE）和Ph，亏损Nb，Ta，Zr，Hf，Ti等高场强元素（HFSE）。∑REE范围为336．8×10-661131×10^-6，富集轻稀土（LREE／HREE=19．78-33．58）和铕异常不明显（gEu=0．96～1．05）。粗面玄武岩、二长斑岩、正长斑岩LA—ICP—MSU—Pb定年结果分别为34．9±1．2Ma，35．0±1．1Ma，35．3±0．5Ma，均属于古近纪，相当于晚始新世。从本文定年结果还表明斑岩（花岗斑岩）成岩时间略早于火山岩，暗示该区的岩浆作用，有先侵入后喷发的趋势。囊谦钾质碱性岩的成因与印度、欧亚两大陆碰撞有内在的联系。
The potassic alkalic rocks at Nangqian County, Qinghai Province are characterized by alkali-rich （Na20＋K20=7.20%-10.6%）, high potassium （NazO/K20=0.56-0.93） and high calcium（ CAO=1.65%-6.39% ）. The large-ion lithophile elements （LILE, Rb, Ba, Th, U and St） 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 x 10-6 to 611.31 x 10-6 with enriched light REE （LREE/HREE=19.78-33.58） and the Eu anomaly of the rocks is not obviously （3Eu=0.96-1.05）. LA-ICP-MS zircon U-Pb age of the basah, iveruite 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.
出处
《高校地质学报》
CAS
CSCD
北大核心
2013年第4期611-619,共9页
Geological Journal of China Universities
基金
国家重点基础研究发展计划(973)(2009CB219401)
中国科学院知识创新项目(0734021)
广州市科技计划项目(2012420004205008)联合资助
关键词
锆石U—Pb年龄
元素地球化学
钾质碱性岩
囊谦县
青海省
zircon U-Pb age
element geochemistry
potassic alkalic rocks
Nangqian County
Qinghai Province
