Geochemical Characteristics and Their Tectonic Implications of the Mafic Dykes in Maotan Area of Western Zhejiang, China(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第05期
- Page:
- 582-594
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Geochemical Characteristics and Their Tectonic Implications of the Mafic Dykes in Maotan Area of Western Zhejiang, China
- Author(s):
- WANG Ting-ting; ZENG Wen; ZHOU Han-wen; LI Yi-long; LI Fu-lin
- 1. School of Earth Sciences, China University of Geosciences, Wuhan 430074, Hubei, China; 2. Three Gorges Research Center for Geohazards of Ministry of Education, China University of Geosciences, Wuhan 430074, Hubei, China; 3. Wuhan Center of China Geological Survey, Wuhan 430205, Hubei, Chin
- Keywords:
- geochemistry; mafic dyke; tholeiite; Neoproterozoic; mantle plume; crustal contamination; Jiangnan orogen; Zhejiang
- PACS:
- P597
- DOI:
- -
- Abstract:
- The Neoproterozoic mafic dykes are widespread in Jiangnan orogen. The study on genesis and tectonic setting has significant implications for the tectonic process of Jiangnan orogen and Neoproterozoic tectonic evolution in South China plate. A systematic geochemical study on Neoproterozoic mafic dykes from Maotan area of western Zhejiang at the northeastern part of Jiangnan orogen was carried out. The results show that mafic dykes are mainly diabases and a small amount of gabbros; they are tholeiitic series according to petrography and geochemical characteristics; the REE characteristics show the transition from tholeiitic series to high-alumina series; the negative Nb, Ta, Ti anomalies on primitive mantle-normalized trace element spider diagram show the characteristics of island arc tholeiite, but the mafic dyke samples mainly fall in tectonic environment areas of ocean island, mid-ocean ridge and intraplate basalt on the diagrams of MgO-FeO*-Al2O3, Ti/100-Zr-3Y, TiO2-FeOT/MgO, Zr/Y-Zr, Ti-Zr, Zr/4-2Nb-Y and Th/Yb-Ta/Yb, etc.; the mafic dykes are formed on extensional tectonic setting, mainly on the intraplate rift environment, and suffers crustal contamination during ascending emplacement to varying degrees; all the w(Th)/w(Ta) and w(La)/w(Yb) of the mafic dykes are relatively low; combined with the tectonic environment discrimination diagrams of the rocks and their tholeiitic properties, the mafic dykes show the mantle plume characteristic in geochemistry. The above characteristics indicate that the mafic dykes are formed by the intrusion of the basic magma along the regional fractures, caused by the rifting of crust; the magma is generated by partial melting of lower mantle during the asthenosphere upwelling; it is related to Neoproterozoic plume event and the breakup of Rodinia supercontinent.
Last Update: 2018-10-01