Its age determined by Rb - Sr isochron is 306 Ma , suggesting that it was formed at Hercynian.据Rb -Sr 等时线测定,其年令值为306Ma, 说明它形成于海西期....

n.等时线...

isochron的音标：isochron的英式发音音标为：['aɪsəʊkrɒn]isochron的美式发音音标为：['aɪsoʊkrɒn]...