昭通盆地褐煤元素地球化学特征及对沉积环境的响应
Elemental geochemical characteristics of lignite in Zhaotong Basin and its response to sedimentary environment
杜芳鹏 1李聪聪 2谭富荣 3贺小元 1许文哲 1杨剑羽1
作者信息
- 1. 延安大学 石油工程与环境工程学院,陕西 延安 716000
- 2. 中国煤炭地总局航测遥感局,陕西 西安 710199
- 3. 陕西省地质调查院,陕西 西安 710054
- 折叠
摘要
昭通盆地是云南新近纪小型褐煤-泥炭盆地之一,为查明昭通盆地褐煤中金属元素富集特征,恢复褐煤沉积期古气候和沉积环境,采集了昭通盆地M2煤层上部褐煤样品开展了主-微量元素分析.结果表明,M2褐煤层主要特征为SiO2含量低,平均仅占灰成分的24.4%,明显低于中国煤平均值;微量元素均未达到富集,富集程度为正常或亏损.在褐煤样品的地质和煤质特征约束下,通过Sr/Ba、δCe、Sr/Cu等指标恢复M2煤层上部主要形成于湿润-半湿润气候,低盐度、弱氧化-弱还原环境,水体流动性较弱,陆源碎屑供给弱;气候特征与沉积环境在垂向上具有一定变化,根据地球化学指标可将其划分为5个不同的沉积演化阶段.气候经历了半湿润-湿润-半湿润-半湿润-湿润;响应地,泥炭沼泽沉积环境经历了弱氧化-弱还原-弱氧化-弱还原-弱氧化,水体流动性和陆源碎屑供给经历了减弱-增强-减弱-减弱-增强的周期性变化.该研究可为昭通褐煤关键金属元素富集研究及沉积环境研究提供重要支撑.
Abstract
Zhaotong Basin is one of the small Neogene lignite and peat basins in Yunnan Province.In order to identify the metal enrichment characteristics of lignite in Zhaotong Basin and restore the paleoclimate and sedimentary environment of lignite during the sedimentary period,the lignite samples from the upper M2 coal seam of Zhaotong Basin were collected for main-trace element analysis.The results show that the main feature of the M2 lignite layer is low SiO2 content,which only accounts for 24.4%of the ash composition on average,which is significantly lower than the average value of coal in China.All trace elements were not enriched,and the degree of enrichment was normal or deficit.Constrained by the geological and coal quality characteristics of lignite samples,the upper part of M2 coal seam recovered by Sr/Ba,δCe,Sr/Cu and other indexes is mainly formed in wet-subhumid climate,low salinity,weak oxidation-weak reduction environment,weak water mobility,and weak ter-rigenous debris supply.Climatic characteristics and sedimentary environment have certain vertical changes,which can be divided into 5 different sedimentary evolution stages according to geochemical indexes.The climate goes through sub-humid-sub-humid-sub-humid-sub-humid-humid;In response,the depositional environment of peat bogs experienced weak oxidation-weak reduction-weak oxidation-weak reduction-weak oxidation,and the water flow and terrigenous debris supply experienced a periodicity of weakening,strengthening,weakening,weakening and strengthening.This study can provide important support for the study of key metal element enrich-ment and sedimentary environment of Zhaotong lignite.
关键词
昭通盆地/褐煤/微量元素/沉积环境/古气候Key words
Zhaotong Basin/lignite/trace element/sedimentary environment/paleoclimate引用本文复制引用
基金项目
中国地质调查局资源调查项目(DD20160187)
陕西省自然科学基础研究计划项目(2020JQ-746)
陕西省自然科学基础研究计划项目(2024JC-YBMS-222)
出版年
2024
NETL
NSTL
万方数据