华南地质2026，Vol.42Issue(3)：436-450,15.DOI:10.3969/j.issn.2097-0013.2026.03.006
粤西云开岩群中"变质超镁铁质岩"的原岩识别
Identification of the Protolith of"Meta-ultramafic Rocks"in the Yunkai Group in Western Guangdong
摘要
Abstract
[Objective]The meta-supracrustal rocks of the Yunkai Group in the Yunkai area host various types of"meta-mafic-ultramafic rocks."Identifying their protoliths is of great significance for deepening the understanding of Precambrian sedimentation and multiphase episodic orogenic processes in the Yunkai region.[Methods]This study conducts petrological and mineralogical investigations of the"meta-ultramafic rocks"from Luoxia,Luoding,using zircon chronology and electron probe microanalysis.[Results]Minera-logical analysis reveals a type of"meta-ultramafic rock"within the Yunkai Group that is mainly composed of Ca-Fe-Al-rich garnet,Ca-rich diopside and hedenbergite,and epidote,similar to calc-silicate skarn mineral assemblages.Whole-rock geochemistry of the Luoxia samples shows significantly high CaO(17.8-20.8 wt.%),MnO(1.28-2.45 wt.%),and low total alkali contents(<1 wt.%).Geochemical evidence suggests that this type of"meta-ultramafic rock"was formed by hydrothermal metasomatism of magnesian calcareous carbonate rocks.Zircon U-Pb dating indicates that the protolith was deposited later than 630-519 Ma.[Conclusion]Combined with existing data,it is concluded that the protolith of some"meta-ultramafic rocks"in the Yunkai Group is carbonate rock,which may represent part of the Ediacaran to Early Cambrian littoral facies fine-grained clastic-carbonate sedimentary sequence in the Yunkai area.关键词
云开岩群/华南/原岩判别/新元古代Key words
Yunkai Group/South China/protolith discrimination/Neoproterozoic分类
天文与地球科学引用本文复制引用
周岱,王佳红,柯贤忠..粤西云开岩群中"变质超镁铁质岩"的原岩识别[J].华南地质,2026,42(3):436-450,15.基金项目
广东省地质调查院科研专题(H2024084F) （H2024084F）
地质联合基金项目(U2244212) （U2244212）
中国地质调查局地质调查项目(DD202401024) （DD202401024）
