岩石矿物学杂志2025，Vol.44Issue(6)：1423-1432,10.DOI:10.20086/j.cnki.yskw.2025.4215
识别英云闪长岩和奥长花岗岩的新流程及其意义
A new procedure for discrimination of tonalite and trondhjemite and its implications
摘要
Abstract
Tonalite and trondhjemite(plagiogranite)are typical granitoid rocks that contains abundant plagioclase.IUGS defines tonalite as the plutonic rocks that contains more than 20％quartz and plagioclase portion higher than 90％of the feldspar minerals.Meanwhile,the trondhjemite is defined as the light-coloured(mafic minerals,M＜10％)tonalite.Tonalite and trondhjemite are the important constitute of Precambrian continental crust,and they also occurred in the plutonic assemblage of arc systems and in the ophiolite suites.The trondhjemites exposed with-in TTG suites exhibit high aluminous character,but many trondhjemites occurred in ophiolite suites have low alumi-nous content.Using the QAP classification results discriminated by the actual mineral modes as the benchmark,two chemical diagrams,i.e.,SiO2'-CaO/(CaO+K2O)plot and 100×(Mg+Fe)/Si-SiO2 plot are proposed as the tools to discriminate tonalite and trondhjemite from the other granitic rocks.Furthermore,the ACNK-Al/Si plot and ACNK-FeO*plot are suggested to separate the low-aluminous trondhjemite(LAT)from the high-aluminous trondhjemite(HAT).The case studies indicate that the new chemical procedure performs well for discrimination of tonalite and trondhjemite occurred within the TTG suites as well as those occurred in the ophiolite suites.Avoiding the calculation of normative minerals,the new chemical procedure is accurate,fast,and user-friendly than the scheme base on normative An-Ab-Or diagram,which is commonly used as the key plot to identify tonalite and trondhjemite for many years.关键词
英云闪长岩/奥长花岗岩/斜长花岗岩/岩石化学Key words
tonalite/trondhjemite/plagiogranite/petrochemistry分类
天文与地球科学引用本文复制引用
葛曼君,汪洋..识别英云闪长岩和奥长花岗岩的新流程及其意义[J].岩石矿物学杂志,2025,44(6):1423-1432,10.基金项目
中国地质调查局地质调查项目(D1912) Geological Survey Project of China Geological Survey(D1912) （D1912）
