Late Mesozoic Extension in the Coastal Area of oft-com:office:smarttags" />
详细信息
- 责任者：Dong Chuanwan (Department of Earth Sciences ; Zhejiang University ; Hangzhou 310027 ; China) ; Yan Qiang
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(4)
- 关键词：伸展构造 ; extension tectonics ; 镁铁质岩 ; mafic rocks ; 浙江 ; Zhejiang Province ; 福建 ; Fujian Province
- 页码：p.1195-1203
- 图表：illus., 3 tables, 50 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Large-scale mafic dike swarms occur in Dongji Island located in the Zhoushan archipelago in Zhejiang Province, and are termed as Dongji Island mafic dike swarms (DIMDS) in this paper. DIMDS emplaced along joints of the Late Mesozoic granites and pyroclastic rocks steeply contacted with the granite or pyroclastic rocks. The dike rocks are mainly hornblende diabase, and the Ar-Ar age of whole rock is 93.4 Ma. Geochemically, DIMDS are weak-alkaline series of basalt compositions. All these rocks are enriched in LREE, LILE(Sr, K, Rb, Ba), and depleted in HFSE, especially Ta and Nb. ISr values of DIMDS from 0.708 4 to 0.709 8, and εNd(t) values from -3.21 to -8.11. The overall elemental and Sr-Nd isotopic characteristics of DIMDS are similar to that of mafic dikes from the coastal area of Fujian Province, and in consistent with that of the Late Mesozoic basic igneous rocks in Zhejiang and Fujian provinces. The results suggest that DIMDS were probably derived from basaltic magma produced from partial melting of enriched iithospheric mantle and contaminated by crustal material. The DIMDS formed in the continental extension setting, and can be as a petrologic indicator of Late Mesozoic extension in the coastal area of Zhejiang and Fujian provinces.