摘要
本文着重描述厂江苏溧水中生代火山岩盆地观山旋回岩石的岩石学、岩石化学和稀土元素等方面的特征.观山旋回火山岩普遍为高钾富碱的中偏碱性岩类;稀土元素特征为轻稀土富集,Eu 弱负异常,与大陆裂谷碱性玄武岩的稀土特征明显相似.最后就本区火山岩的岩浆来源作了初步讨论.
In this paper,the Petrology,Petrochemistry and REE characteristics of the vol- canic rocks of guanshan cycle are considered.The rocks of Guanshan cycle include basalt,andesite,tracbyandesite and trachyte.They are referred mainly to alkali rock series.TbeSiO_2 Contents Change between 51.11% and 57.84%;Na_2O+K_2O con- tents range from 6.71% to8.40%:contents of K_2O are greater than that of Na_2O in the rocks.∑REE range from 115.61 PPm to 161.67 PPm;LREE/HREE values cha- nge between 2.99 and 4.90;δEu varies between0.858 and 0.941.It shows that the REE distributiou of these rocks is similar to that of the continental rift alkaine basalts. According to field geology and REE Charateristics of the rocks,the volcanic rocks of Guanshan cycle of the Lisbui Mesozoic Volcanic Basin are thought to be formed throu- gh Partial melting of the upper mental material accompanied with the contamination of the uPPer Crust and with the fractional crystallization.
