Two feldspar and iron-titanium oxide equilibria in silicic magmas and the depth of origin of large volume ash-flow tuffs
Two feldspar and iron-titanium oxide equilibria in silicic magmas and the depth of origin of large volume ash-flow tuffs
复制标题
硅质岩浆中两种长石和铁钛氧化物平衡及大体积灰流凝灰岩成因深度
作者：
J. Stormer;J. Whitney
对于许多大体积灰流凝灰岩，双长石地温法测得的温度始终比铁钛氧化物地温法测得的温度低 150°C（假设低压）。铁钛氧化物温度基本上与压力无关，但二长石温度具有l8'C/kbar的压力依赖性。计算温度对应的压力应表明斑晶组合的起源深度。尽管目前这些地温计的实验校准尚不确定，但其他类型的数据表明
For a number of large volume ash-flow tuffs, the temperatures from two-feldspar geothermometry are consistently lower than temperatures obtained by iron-titanium oxide geothermometry by as much as 150'C (assuming low pressure). The iron-titanium oxide temperature is essentially independent of pressure, but the two-feldspar temperature has a pressure dependence of l8'C/kbar. The pressure for which the calculated temperatures correspond should indicate the depth oforigin ofthe phenocryst assemblage. Although the present experimental calibration of these geothermometers is uncertain, other types of data suggest that