2012年12月，第18卷，第4期，735-744页 December2012，Vol.18，No.4，p.735744
高校地质学报
Geological Journal of China Universities
江西铅山晚石炭世硅质岩地球化学特征与沉积环境李二恒，刘家润"，倪培"，蔡逸涛'，赵葵东，叶春林，朱筱婷3 1.内生金属矿床成矿机制研究国家重点实验室，南京大学地球科学与工程学院，南京210093；
2.四川省地质调查院，成都610081；3.南京地质矿产研究所，南京210016
摘要：江西铅山晚石炭世硅质岩大多呈条带状、少量量层状和结核状产出，赋存于灰岩层内或层间；主要由微晶石英组成，含有少量蛋白石或玉髓，未见硅质生物及硅化特点。地球化学分析结果显示，晚石炭世硅质岩的SiO，含量为 74.51%~98.48%，Al,0,，Ti0z，Mg0及REE含量低，分别为0.10%~3.42%（平均为0.45%），<0.01%~0.12%（平均 <0.02%），0.07%~1.46%（平均为0.20%）和<1.52×10~24.66×10（平均不足4.84×10*）；8Ce值为0.15~0.70（平均为 0.42），呈负异常。Al,O,与TiO,具有明显的相关性，而两者与SiO,相关性极低。在双变量SiO,-Al,O,，SiO,-MgO和三变量 Al-Fe-Mn，Fe-Mn-（Ni+Co+Cu）判别图上，硅质岩几乎都落人热液成因及生物沉积成因区；在双变量Fe,O,/TiO2-Al,O，/（AI,O,+Fe,O，）判别图上，落人大陆边缘沉积区范围。综合地球化学特征及岩石薄片观察结果，可以认为研究区硅质岩形成于大陆边缘，其成因主要与海底热液活动有关。
关键词：硅质岩；地球化学；沉积环境；晚石炭世；江西铅山
中图分类号：P539；P595
文献标识码：A
文章编号：1006-7493（2012)04-0735-10
Geochemistryand SedimentaryEnvironment oftheLate Carboniferous
SiliceousChertsfromYanshanCounty,JiangxiProvince
LIErheng',LIU Jiarun',NI Pei',CAI Yitao',ZHAO Kuidong',YEChunlin’,ZHU Xiaoting
1. State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China:
2. Sichuan Geological Survey, Chengdu 610081, China; 3. Nanjing Institute of Geology and Mineral Resources, Nanjing 210016, Chine Abstract: Late Carboniferous cherts interbedded with limestone occur extensively in of the county of Yanshan, Jiangxi Province. In this study, 22 chert samples were analyzed for major and rare earth elements. The results show the cherts have low amount of Al,0, (0.45%), Ti0, (<0.02%), Mg0 (0.20%) and ≥ REE (<4.84 × 10~) in average. Their 8Ce values vary from 0.15 to 0.70 with an average of O0.42, indicating negative Ce anomaly. Al,O, shows positive correlation with TiO,, SiO, shows correlation neither with
the chert samples fall mainly within the hydrothermally and biologically deposited areas. Moreover, the chert samples fall in the area of continental margin in the Fe,O,/TiO2Al,O,/(Al,O,+Fe,O,) binary discriminant diagram. All these geochemical and petrographic characteristics of cherts suggest that the origin of Late Carboniferous siliceous cherts in Yanshan county was chiefly related with submarine hydrothermal solution, and that the cherts were deposited in a continental margin setting with a little terrestrial matter. This study shows that Yanshan area was an marine environment with the activity of hydrothermal solution rich in silica during the deposition of the Late Carboniferous siliceous cherts.
Key words: cherts; geochemistry; sedimentary environment; late Carboniferous; Yanshan Country of Jiangxi Province
First author: LI Erheng. Master's degree Candidate; E-mail: leheq2000@163com 收稿日期：2012-01-11；修回日期：2012-02-23
基金项目：中国地质调查局全国危机矿山接替资源找矿项目《闽浙相邻区铜多金属矿床成矿规律总结研究》(20089935 作者简介：李二恒，男，1987年生，硕士研究生，古生物学及地层学专业；E-mail:lcheq2000@163.com