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 cont...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.展开更多
第四纪处于气候的快速波动期,黄土记录了丰富的古气候信息。为探讨汉江上游地区晚更新世以来气候变化过程,对汉江上游洋县境内汉江Ⅰ级河流阶地朱家村剖面沉积特征、常量元素分布、地球化学参数及形成时代进行研究。结果表明:汉江上游...第四纪处于气候的快速波动期,黄土记录了丰富的古气候信息。为探讨汉江上游地区晚更新世以来气候变化过程,对汉江上游洋县境内汉江Ⅰ级河流阶地朱家村剖面沉积特征、常量元素分布、地球化学参数及形成时代进行研究。结果表明:汉江上游Ⅰ级河流阶地形成于50 ka BP前后;剖面由下到上具有典型黄土(L_(1))→古土壤(S_(0))→全新世黄土(L_(0))→表层土(TS)的地层序列;剖面主要化学成分为SiO_(2)、Al_(2)O_(3)和Fe_(2)O_(3),化学风化过程中Ca、Na元素迁移淋失程度较高,K、Mg元素迁移淋失程度相对较低;剖面化学风化程度呈现从典型黄土(L_(1))→古土壤(S_(0))逐渐增强,到全新世黄土(L_(0))层又略降低的规律,记录了该区域气候在50~11 ka BP干燥寒冷,由11.00 ka BP开始逐渐增温增湿,2.50 ka BP到达最暖湿,2.50~0 ka BP持续降温变干的演变过程。研究成果可为我国北亚热带古气候重建提供数据参考。展开更多
文摘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.
文摘第四纪处于气候的快速波动期,黄土记录了丰富的古气候信息。为探讨汉江上游地区晚更新世以来气候变化过程,对汉江上游洋县境内汉江Ⅰ级河流阶地朱家村剖面沉积特征、常量元素分布、地球化学参数及形成时代进行研究。结果表明:汉江上游Ⅰ级河流阶地形成于50 ka BP前后;剖面由下到上具有典型黄土(L_(1))→古土壤(S_(0))→全新世黄土(L_(0))→表层土(TS)的地层序列;剖面主要化学成分为SiO_(2)、Al_(2)O_(3)和Fe_(2)O_(3),化学风化过程中Ca、Na元素迁移淋失程度较高,K、Mg元素迁移淋失程度相对较低;剖面化学风化程度呈现从典型黄土(L_(1))→古土壤(S_(0))逐渐增强,到全新世黄土(L_(0))层又略降低的规律,记录了该区域气候在50~11 ka BP干燥寒冷,由11.00 ka BP开始逐渐增温增湿,2.50 ka BP到达最暖湿,2.50~0 ka BP持续降温变干的演变过程。研究成果可为我国北亚热带古气候重建提供数据参考。
