摘要
讨论了在岩浆长期分离结晶作用的模式,由于晚期残留熔体相对于早期结晶相其Rb/Sr比增高,当有一定滞留时间条件下,将导致晚期结晶相^(87)Sr/^(86)Sr初始比增高,因而在一个复式岩基内会形成具有不同锶同位素初始比的多个岩石单元。文中以安徽地洼阶段的黄山一狮子岭岩体为例,通过模拟计算,得到其初始岩浆(?)=0.7122,(Rb/Sr)0=3,该岩浆的80％分离结晶形成黄山岩体,其(?)=0.7143(t=130Ma),其余20％的残余熔体结晶后形成狮子岭岩体,其(?)=0.7180(t=123.1Ma)。
The Rb/Sr ratios of residual liqiuds relative to earlier crystallized accumulates increase significantly during protracted fractional crystallization, and the ^(87)Sr/^(86)Sr ratios in later crystallized accumulates will increase insignificance. Hence, a large composite granitiec botholith may usually consist of several individual rock units with different solidification ages and initial Sr ratios. For example, the initial magma of the Huangshan—Shiziling granitic batholith in Anhui Province has a ^(87)Sr/^(86)Sr ratio of 0. 7123 and a Rb/Sr ratio of 3, based on theoretical calculation. During protracted fractionation the 80% earlier fractionated accumulates of the magma formed the Huangshan granite with a I(?)= 0.7143(t= 130 Ma). The residual 20% melt crystallized to form the Shiziling granite with it I(?)=. 0. 7180 (t=123 Ma).
出处
《大地构造与成矿学》
EI
CAS
CSCD
1991年第2期152-159,共8页
Geotectonica et Metallogenia
基金
国家自然科学基金489701732
关键词
岩浆
分离
结晶
岩石
锶
同位素
magmatism,fractionational crystallization, initial Sr ratio,imitative calculation, Huangshan-Shiziling granitic batholith.
