摘要
根据钾长石与斜长石的结构状态和黑云的成分,得出岩带三个主要组成岩体岩浆结晶温度的定性变化规律。根据岩体侵入岩层的厚度、二长石地温计、熔体包裹体测温和黑云母逸度计,定量估算了岩浆定位结晶时的P、T、fO_2和fH_2O。估算结果表明,岩带岩浆定位条件差异大:P为4.86～0.4×10~8Pa,T从627至862℃,fO_2 5.01×10^(-11)～10^(-8)Pa,fH_2O2.06～3.11×10~8Pa。岩体定位条件的差异与不同岩体分别形成于钦州地槽褶皱回返的不同时期有关。
The Hercynian to Indosinian Darongshan granite belt is a typical example of peraluminous granites in South China. It is mainly composed of coarse-or intermediate-grained cordierite-biotite monzonitic granite(Darongshan body), intermediateor fine-grained porphyroid garnet-cordierite-biotite monzonitic granite (Jiuzhou body), and hypersthene granite porphyry with fine- or intermediate-grained phenocrysts (Taima body). In this paper, the relationship of magma crystallization temperatures of the three bodies is discussed based on Al-Si order-disorder and cell parameters of feldspars, and the composition of biotites. P, T, f_(O2) and f_(H2O) for each granite body when the magma emplaced and crystallized are evaluated by means of estimating the thickness of the overlying strata, two-fieldspar geothermometer, homogenization temperaure of fluid inclusions in quartz, and biotite fugacity indicator. The results show that, for Darongshan body, the magma emplaced at a depth of 14～18.7km, crystallized at T=627～700℃, fo2 =5 10^(-16) bar and f_(H2O)=3.1kbar; for Jiuzhou body, the magma emplaced at a depth of 10～12km, crystallized at T=750-764℃, f_(O2)=10^(-14) bar and f_(H2O)=2.3kbar; for Taima body, the magma croplaced at 1.5～2.4km, crystallized at T=780～862℃, f_(O2) and f_(H2O) when biotite crystallized were 10^(-18) bar and 2.1kbar respectively.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第2期72-79,共8页
Acta Petrologica Sinica
关键词
花岗岩
过铝质
定位
岩体
Peraluminous granite
Emplacement conditions
Darongshan
