论文部分内容阅读
已有研究表明,华北克拉通东部的山东费县岩石圈地幔在克拉通破坏峰期(早白垩世)时是高度富水的,其中橄榄石的H_2O含量>180×10~(-6);而同期克拉通西部的太行山符山地区岩石圈地幔具有贫水特征,其中橄榄石的H_2O含量为~10×10~(-6).这表明西向俯冲的古太平洋板块造成了华北东部早白垩世岩石圈地幔的富水特征,为克拉通破坏提供了力学前提.为了解古太平洋板块俯冲的影响范围,对介于费县和符山之间的山东铁铜沟地区早白垩世高镁闪长岩中的橄榄岩捕掳体进行了含水性分析,橄榄石的原始H_2O含量(6×10~(-6)~24×10~(-6),平均值为(15±7)×10~(-6))与符山地区相当,暗示太平洋板块俯冲造成的岩石圈富水效应可能仅局限在华北最东部,这和最东部地区克拉通破坏程度最高是一致的.
It has been reported that the lithospheric mantle in feexian county, eastern China, in the eastern part of North China Craton is highly water-rich at the time of the craton pass destruction (Early Cretaceous), in which the H 2 O content of olivine is> 180 × 10 -6. In the same period, the lithospheric mantle beneath the Fushan area of the Taihang Mountains in the western part of the craton is characterized by poor water, with the H 2 O content of olivine being ~10 × 10 -6 .This indicates that the western subduction of the Paleo-Pacific plate caused the Early Cretaceous The water-rich characteristics of the lithospheric mantle provide a mechanical prerequisite for the craton destruction.In order to understand the influence range of the Paleo-Pacific plate subduction, the pale-Cretaceous high-Mg-flash dilatancy in the Tieshugou area between Feixian and Fu-shan The peridotite entrapment in the rocks was analyzed for its water content. The original H 2 O content of olivine ranged from (6 × 10 ~ (-6)) to 24 × 10 ~ (-6) with an average of (15 ± 7) × 10 ~ (-6)) is similar to that in the Fu-shan area, suggesting that the lithospheric water-rich effect caused by subduction of the Pacific plate may be limited to the easternmost part of North China, which is consistent with the highest degree of craton destruction in the eastern part.