摘要
中国东部橄榄安粗岩省以大范围内(约80000km^2)分布晚侏罗世—早白垩世(165—100Ma)橄榄安粗岩系为主、高钾钙碱岩系为次的火山岩组合为特征,它形成以拉张为主的区域构造应力场中。与国外岛弧及活动大陆边缘同类岩石相比,其火山岩的岩石—矿物—地球化学特征及有关的矿床组合均有一定的特殊性,这些特殊性是本区壳幔成分与结构及中生代区域构造背景特殊性的综合体现。
The shoshonite province in eastern China is characterized by extensive distribution of Meso-zoic (165 - 100 Ma) volcanic rocks consisting of shoshonite series with subordinate high-K calc-alkali series. The formation of the shoshonite province is the result of the combined action of three tectonic dynamic systems in the dominantly tensile stress field. In comparation with similar volcanic rocks in island arcs and active continental margins in other countries, volcanic rocks in the shoshonite province have higher SiO2 contents, lower ratios of K2O/Na2O and higher Fe2O3/ FeO ratios. Their contents of Ti, Mn and Co are relatively high, (87Sr/86Sr)i values (0. 7060 -0. 7092) are close to that to potash-rich volcanic rocks in the East African rift, εNd values are similar to that of the high-potash basalts in Wyoming, United States, the lead isotopic composition is alike to that of the lamproites and kimberlites derived from 'enrichment-type' mantle. The mineralizations of the shoshonite province are dominated by those of copper, gold and iron, which is different from the case with island arcs and active continental margins. The special association of volcanic and subvolcanic rocks and related mineralization are the integrated manifestation of the special composition and structure of the mantle and crust of the province, and the special Meso-zoic regional tectonic setting.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1996年第1期23-34,共12页
Acta Geologica Sinica
基金
国家自然科学基金(编号 9488010)
关键词
橄榄安粗岩省
火山岩
同位素组成
成矿作用
shoshonite province, regional tectonic setting, isotopic composition, miner- alogical, petrological and geochemical characteristics
eastern China
