地球学报2018，Vol.39Issue(3)：306-318,中插7-中插9,16.DOI:10.3975/cagsb.2018.050301
武当山南缘房县地区早古生代镁铁质岩石成因及大地构造意义
Petrogenesis of the Early Paleozoic Mafic Rock in Fangxian Area on the Southern Margin of Wudang Mountain and Its Tectonic Significance
摘要
Abstract
The Qingfeng–Xiangguang fault on the southern margin of Wudang Mountain is a dominant boundary for the South Qinling and Yangtze plates and is also an important link between the Mianlue zone and its eastward extension. Detailed field route investigation and systematic research reveal that the formerly assigned Neoproterozoic Yaolinghe Group volcanic rocks outcropped in Mengu area should be meta-basalt block of Late Ordovician ((444.9 ± 2.5) Ma), and it consists of a distinct mélange feature with the formerly assigned Sinian to Cambrian limestone and siliceous blocks and sandy schist matrix; zircon U-Pb dating of diabase which intruded into Meiziya Formation of Wutai area indicates an Early Silurian magmatic age ((432.4±3.3) Ma). Whole rock geochemistry of these samples indicates that both Mengu meta-basalts and Wutai diabase are typically characterized by high concentrations of TiO2, Nb, Ta, and Zr. The ratio of incompatible elements, rare earth element distribution patterns and trace element spider diagrams all display the feature of affinity of Ocean-island basalt (OIB). In addition, samples from the two areas appear to have all originated from the asthenospheric mantle and the magma was mainly formed by the high-pressure and low degree of partial melting of garnet lherzolite and underwent varying degrees of fractional crystallization and slight crustal contamination. Regional geological and discrimination diagrams both indicate that these samples do not represent a plume or continental rift, but exhibit a setting of oceanic intraplate. These results provide the pivotal evidence for accurate investigation of the Phanerozoic tectonic evolution of South Qinling Orogeny.关键词
镁铁质岩/岩石成因/早古生代/武当山/南秦岭Key words
mafic rocks/petrogenesis/Early Paleozoic/Wudang Mountain/South Qinling分类
天文与地球科学引用本文复制引用
许光,王刚,王宗起,武昱东,王东升,王嘉玮..武当山南缘房县地区早古生代镁铁质岩石成因及大地构造意义[J].地球学报,2018,39(3):306-318,中插7-中插9,16.基金项目
本文由中国地质科学院基本科研业务费项目(编号:YK1701 （）
K1615)和国家青年自然基金项目(编号:41402180 （）
41602061)联合资助.This study was supported by Central Pub-lic-interest Scientific Institution Basal Research Fund(Nos.YK1701 and K1615),and National Natural Science Foundation of China(Nos.41402180 and 41602061). （Nos.YK1701 and K1615）
