摘要
冀晋辽地区燕山期岩浆岩十分发育,从中可以识别出一套超钾过铝质斑岩。它们由浅成相和火山颈相的流纹斑岩、石英斑岩以及石英长石斑岩组成。前两种岩石92个样品的SiO_2、K_2O、Na_2O、K_2O/Na_2O的平均值分别为75.47%、7.13%、0.85%、10.12,后一种岩石3个样品平均值依次为64.76%、8.18%、0.38%、21.53。这些岩石的A/CNK变化范围在0.98～1.45之间;14个酸性岩石稀土元素样品的∑REE、δEu平均值是107.64、0.41,表现出岩性和岩相稳定、呈独立地质体形式产出和形成于晚侏罗纪的特点。本文以选择的11个岩体为代表,初步论述和讨论了这类岩石的地质学、岩石学、主要和稀土元素特征;提出其属于超钾过铝质岩类,代表了一种特殊壳源岩石的看法。
Yanshan period igneous rocks occur extensively in the Hebei—Shanxi—Liaoning area, and a suit of ultrapotassic peraluminous porphyry can be recognized from them. They are composed of ryhyolite porphyry, quartz porphyry and quartz feldspar porphyry,of hypabyssal and volcanicneck facies. The average amount of SiO_2, K_2O, Na_2O and K_2O/Na_2O for 92 samples of ryhyolite porphyry and quartz porphyry are respectively 75. 47%, 7.13%, 0. 85% and 10. 12; and for 3 samples of quartz feldspar porphyry are 64. 76%,8. 18%,0. 38% and 21. 53,with ratios of A/ CNK ranging from 0. 98 to 1. 45 for all samples. The average value of ΣREE and δEu_n for 14 samples of acid rocks are 107. 64 and 0.14. The characteristics of stable petrography and lithofacies, independent occurrence and late Jurassic formation can be recognized. Taking the selected 11 rockbodies as examples,this paper reviews and discusses briefly the geological,petrological and geochemical features and the characteristics of major and rare elements of this type of rocks. It is considered that those rocks are ultrapotassic peraluminous ones derived from custal sources.
出处
《地质论评》
CAS
CSCD
北大核心
1999年第S1期520-527,共8页
Geological Review
基金
高等学校博士学科点专项科研基金(编号9500104)资助课题
关键词
冀晋辽地区
燕山期
超钾过铝质岩石
地球化学
Hebei—Shanxi—Liaoning area
Yanshan Period
ultrapotassic porphyry
geochemistry
