SiO_(2)'-CaO/(CaO+K_(2)O)(S'CK)Diagram as a Petrochemical Tool for Deciphering the Tectono-Magmatic Characterization of Granitoid Suites  

作　　者：SUN Mingming WANG Yang 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2025年第2期598-610,共13页地质学报(英文版)

摘　　要：The SiO_(2)'-CaO/(CaO+K_(2)O)(S'CK)diagram is an empirically derived major element-based equivalent to the modal IUGS alkali feldspar-quartz-plagioclase classification scheme for granitoids.It employs the content of SiO_(2)and CaO/(CaO+K_(2)O)ratio to approximate the IUGS classification diagram and a normative-based Q'-ANOR plot.Four trends have been superimposed onto the SiO_(2)'-CaO/(CaO+K_(2)O)diagram based on published datasets from the Peninsular Ranges(calcic:C),Tuolumne(calc-alkalic:CA),Sherman(alkali-calcic:AC),and Bjerkreim-Sokndal(alkalic:A)batholiths,which were employed to constrain the positions of the C-CA,CA-AC and AC-A suite boundaries on the SiO_(2)versus(Na_(2)O+K_(2)O-CaO)(or modified alkali-lime index,MALI)granitic classification diagram.A merit of the SiO_(2)'-CaO/(CaO+K_(2)O)plot is identifying rock types comprising a suite and their relative abundances.The distinguished projections of five typical granitoid assemblages,which are summarized by Bonin et al.(2020),demonstrate the ability of SiO_(2)'-CaO/(CaO+K_(2)O)diagram to decipher their petrogenesis.The SiO_(2)'-CaO/(CaO+K_(2)O)plots for the plutonic suites of'known'tectonic settings can reveal their evolution paths and the lithological statistics.Accordingly,it is suggested that the SiO_(2)'-CaO/(CaO+K_(2)O)plot can distinguish the tectonic environments of plutonic suits by comparing the plutonic suites or batholiths of'unknown'tectonic context to the published datasets from granitoid suites formed within'known'tectonic settings.The modified SiO_(2)'-CaO/(CaO+K_(2)O)diagram links the bulk chemical composition of granitoid suites to the likely source,magmatic evolution,and tectonic setting;thus,it may be a useful tectono-magmatic classification scheme for granitoid suites.

关 键 词：classification of granitoid major-element chemistry SiO_(2)'–CaO/(CaO+K_(2)O)diagram tectono-magmatic character 

分 类 号：P588.12[天文地球—岩石学]