Genesis of Late Paleozoic Shangyi Potassic Granite in the Northern Margin of the North China Craton： Petrochemistry Evidence

详细信息   

• 责任者：Li Mengjiang (Key Laboratory of Mineralogy and Metallogeny ; Guangzhou Institute of Geochemistry ; Chinese Academy of Sciences ; Guangzhou 510640 ; China) ; Chen Yanjing
• 刊名：Geochimica
• 出版年：2012
• 卷期：41(3)
• 关键词：花岗岩 ; granite ; 岩石地球化学 ; lithogeochemistry ; 河北 ; Hebei Province
• 页码：p.227-239
• 图表：6 illus., 29 tables, 4 refs.
• 分类号：0801
• issnNo：ISSN0379-1726
• isbnNo：CN44-1398/P

摘要

The Shangyi potassic granite body in the central section of the northern margin of the North China Craton is small. It consists of biotite-bearing moyite and monzogranite with K-feldspar phenocrysts（~40%）. It consists mainly of K-feldspar （50%-60%）, plagioclase （10%-20%）, quartz （20%-30%）, biotite （~5%） and little epidote, clinopyxene, magnetite. The geochemical compositions are： SiO2 65.69%-70.90%, K2O＋Na2O 7.22%-9.14%, K2O/Na2O 0.85-1.75, Al2O3 13.58%-15.09%, A/CNK 0.89-0.93, Mg# 43-46. It is enriched in LILE and Cr, with moderately fractionated REE patterns and slight negative Eu anomalies, and negative Nb, Ta, Ti anomalies. Shangyi potassic granite is potassium-rich, metalulminous, I-type calc-alkaline granite. After field observation and petrochemistry analyses, we propose that the Shangyi potassic granite derived from fractional crystallization of basic magma of mantle origin, accompanied by assimilation of trondhjemite wallrock during emplacement. This potassic granite is located in the Shangyi-Chicheng fault zone, and its tectonic setting was active continental margin formed by subduction of the Paleo-Asian ocean plate beneath the North China Craton during Late Paleozoic.