摘要

牙克石地区出露一套早白垩世玄武质火山岩,其SiO2含量为52.81%~53.39%,K2O含量为1.86%~2.87%,岩性为玄武质粗面安山岩。富集大离子亲石元素Rb和Ba,高场强元素Nb和Ta亏损明显,Zr和Hf无明显异常,δEu为0.77~0.82。从同位素的特点看,(87Sr/86Sr)i变化于0.704762~0.704941之间,εNd(t)为2.00~2.54;在εNd(t)-(87Sr/86Sr)i图解上,样品投影点落入洋岛玄武岩(OIB)和美国盆岭省范围内。206Pb/204Pb为18.3288~18.4225,207Pb/204Pb为15.4566~15.4893,208Pb...