诸城盆地早白垩世砂岩主量元素地球化学特征及其对物源区构造环境的制约  

Characteristics of Major Element Geochemistry from Lower Cretaceous Sandstone in Zhucheng Basin and Their Constraint on Tectonic Setting of the Provenance

作　　者：倪金龙[1,2] 张红[2] 唐小玲[3] 史晓晓[4] 孙煜杰[2] 韩帅[2] 

机构地区：[1]山东省地质科学研究院国土资源部金矿成矿过程与资源利用重点实验室,山东济南250013 [2]山东科技大学地球科学与工程学院,山东青岛266590 [3]山东科技大学化学与环境工程学院,山东青岛266590 [4]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地球科学与环境学报》2016年第5期587-600,共14页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金重点项目(41172089);国土资源部金矿成矿过程与资源利用重点实验室基金项目(2013006);山东省自然科学基金项目(ZR2013DM007)

摘　　要：诸城盆地作为早白垩世伸展盆地,与其东南侧胶南造山带之间的耦合关系一直以来仍缺少相关研究。基于野外地质考察、砂岩碎屑组分统计及主量元素特征分析,探讨了早白垩世诸城盆地的物源方向、莱阳群砂岩的地球化学组成、物源区风化特征及大地构造背景。结果表明：诸城盆地莱阳群砂岩地球化学类型主要为铁砂岩和杂砂岩,其源岩具有长英质火成岩或中性岩特点;砂岩的化学蚀变指数（45~58）、化学风化指数（47~69）、斜长石蚀变指数（58~73）和化学组分变化指数（0.86~1.02）体现了源区风化作用很弱的特征;Dickinson分类图解及古流向指示砂岩源区主要为盆地东南侧的胶南造山带,砂岩的地球化学组成、风化特征等共同说明早白垩世时期胶南造山带经历了快速隆升事件;结合前人关于该地区岩浆岩地球化学特征,胶南造山带的本次快速隆升是岩石圈减薄作用的结果,因而诸城盆地的快速沉降与胶南造山带的隆升是相互耦合的。上述结果一方面从地球化学角度证实了胶南造山带早白垩世时期经历了快速隆升事件,另一方面也说明了诸城盆地原型是伸展断陷盆地,二者均是华北东部岩石圈减薄作用的产物。The coupling relationship between Zhucheng Basin as Early Cretaceous extensional basin and Jiaonan orogenic belt is still lack of relevant research.Based on the field geology observations,sandstone detrital component statistics and the analysis of major elementcharacteristics,the provenance of Zhucheng Basin in Early Cretaceous,the geochemical composition of sandstone from Laiyang Group,the weathering characteristics of provenance and the tectonic background were discussed.The results show that the geochemical types of sandstone in Laiyang Group of Zhucheng Basin are mainly iron sandstone and greywacke,and the source rocks have the characteristics of felsic igneous rock or intermediate rock;the chemical index of alteration（45-58）,chemical index of weathering（47-69）,plagioclase index of alteration（58-73）and index of compositional variability（0.86-1.02）reflect the relative weak weathering in provenance;Dickinson classification diagrams and the paleocurrent direction indicate that the provenance of sandstone is mainly Jiaonan orogenic belt at the southeastern side of Zhucheng Basin,and the geochemical composition and weathering characteristics of sandstone suggest that Jiaonan orogenic belt experiences rapid uplift event during Early Cretaceous;combined with the previous research on the geochemical characteristics of magma rock,the rapid uplift of Jiaonan orogenic belt results from the lithosphere thinning,so the rapid subsidence of Zhucheng Basin and the uplift of Jiaonan orogenic belt are coupled with each other.From the view of geochemistry,the above-mentioned results confirm that Jiaonan orogenic belt experiences a rapid uplift event during Early Cretaceous;on the other hand,it also illustrates that the prototype of Zhucheng Basin is an extensional fault basin,and both of them are the produce of lithosphere thinning in the eastern North China.

关 键 词：莱阳群 早白垩世 岩石地球化学 岩石圈减薄 盆山耦合 盆地原型 风化指数 诸城盆地 

分 类 号：P588.212.3[天文地球—岩石学] P595[天文地球—地质学]