Are Those Mafic Dikes in Hengshan-Xuanhua-Xinghe Area of North China Sanukitoids?(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2017年第01期
- Page:
- 65-82
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Are Those Mafic Dikes in Hengshan-Xuanhua-Xinghe Area of North China Sanukitoids?
- Author(s):
- ZHANG Ji; CHENG Su-hua
- School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
- Keywords:
- sanukitoid; mafic dike; hot subduction; intraplate rifting; fractional crystallization; crustal contamination; ferrobasalt; North China
- PACS:
- P588.1；P581
- DOI:
- -
- Abstract:
- In previous study, the mafic dikes in Hengshan-Xuanhua-Xinghe area of North China have been thought as the production of rifting and extension; some papers have already claimed that those mafic dikes may be sanukitouids. Therefore, the definition of those mafic dikes is of important significance to distinguish the tectonic background of subduction or extensional tectonic background. The hand specimens of rocks in Hengshan-Xuanhua-Xinghe area have typical ophitic texture. The mafic dikes in Hengshan area are made up of pyroxene with amphibole-symplektite, idiomorphic plagioclase and garnet; the mafic dikes in Xinghe area consist of andesine, amphibole and the amphibole fills into the triangle “skeleton” which is made up of plagioclase; and the mafic dikes in Xuanhua area without obvious ophitic texture consist of garnet, plagioclase, clinopyroxene, orthopyroxene and amphibole. Compared with the geochemistry standard of sanukitoids, the samples in Hengshan and Xuanhua areas are rich in FeOT, MgO and TiO2, lightly rich in both compatible and incompatible elements, and what‘s more, the contents of light rare earth elements are much more than those of heavy rare earth elements. However, the samples in Xinghe area, which are very different from sanukitoids, are also rich in FeOT and TiO2, and richer in incompatible elements, but with lower Mg#, and the compatible elements are not that rich. Therefore, those mafic dikes in Hengshan-Xuanhua-Xinghe area of North China are not typical sanukitoids, but belong to the ferrobasalts. They have experienced a degree of fractional crystallization and crustal contamination, and may be the production of intraplate rifting.
Last Update: 2017-01-20