贵州锦屏青白口系清水江组浅变质岩系地球化学特征及原岩恢复的意义

Geochemical Characteristics and Original Rock Recovery Significance of Epimetamorphic Rock Series in Qingshuijiang Formation of Qingbaikou System in Jinping,Guizhou

通过对贵州锦屏地区青白口系清水江组浅变质岩系的调查研究,查明了其岩石类型及地球化学特征。岩石类型主要为板岩类、沉凝灰岩类及变余砂岩类等。该套岩石具有中等含量的Si O2(65.36%78.39%,平均71.15%,),较低的TFe2O3+Mg O(3.41%6.71%,平均4.71%)和较高的K2O/Na2O(0.18 2.67,平均1.31)及Al2O3/Ti O2(18.69 44.07,平均26.36)。通过一系列的分析,认为青白口系清水江组浅变质岩原岩仍为沉积岩,组成较为复杂,主要为低成熟度的亚岩屑砂岩和长石质泥岩,少许高成熟度的陆源碎屑岩;沉积物物源主要来自被动大陆边缘,构造背景为活动大陆岛弧环境,可能与江南造山带有关。

By investigate the epimetamorphic rock Series in Qingshuijiang formation of Qingbaikou system,the rock type and geochemical characteristics are found out. The rock types include slate,sedimentary tuff and blastopsammite. This rock series has middle content Si O2（ 65. 36 78. 39%,average 71. 15%）,the little TFe2O3＋Mg O（ 3. 41 6. 71%,average 4. 71%） and more K2 O / Na2O（ 0. 18 2. 67,average 1. 31） and Al2O3/ Ti O2（ 18.69 44.07,average 26.36）. By a series of analyses,it thought the original epimetamorphic rock still is sedimentary rock,the component is complex,mainly are subnitric acid rock and feldspathic mud stone of low grade maturity,with little terrigenous clastic rock of high grade maturity. The sedimentary source mainly is passive continental margin,the structural background is continental island arc environment and may has relation with Jiangnan orogenic belt.