辽西阜新—彰武—黑山区白垩系火山岩U-Pb同位素年龄、层序和找煤研究  

A study of the U-Pb isotope age and the sequence of the Cretaceous volcanics and coal-searching in FuxinZhangwuHeishan Area,West Liaoning Province

作　　者：徐德斌[1] 李宝芳[1] 常征路 张俊宝 蔡厚安[1] 

机构地区：[1]中国地质大学(北京),北京100083 [2]东北煤田地质局107勘探队,辽宁阜新123000

出　　处：《地学前缘》2012年第6期155-166,共12页Earth Science Frontiers

基　　金：全国危机矿山项目"阜新盆地沙海组煤层预测研究(200621012)"和"辽宁省彰武-黑山区找煤综合研究"(200421006)

摘　　要：研究区中、新生代火山喷发作用频繁,火山岩分布广泛,火山、沉积地层命名不一,层位及其与主要含煤地层的关系存在争议。通过对区内义县组、吐呼噜组、冮台山组、榆树沟组、大兴庄组和大凌河组等火山岩的野外调查研究和采样,用SHRIMP法进行了U-Pb同位素年龄测定,得出仅1块样品年代属古近纪,其他10块样品的U-Pb同位素年龄都在115.5～132Ma,且大多数集中在125～127Ma,时代应属早白垩世中期。早白垩世火山-沉积岩系按岩性、岩相和层序自下而上可分为4个喷发-沉积旋回:义县组-金刚山组旋回、吐呼噜组-九佛堂组旋回、榆树沟组(冮台山组)旋回和沙海组-阜新组旋回。义县组总体为裂隙式喷发的玄武安山岩、粗安岩和粗面岩夹湖相沉积岩,吐呼噜组为中心式喷发的英安岩,冮台山组为裂隙式玄武安山质潜火山岩,金刚山组和九佛堂组是火山喷发间歇期的湖相沉积,沙海组、阜新组是火山活动期后的含煤沉积。研究区东部彰武—黑山一带广泛分布的大兴庄组火山岩与阜新盆地南部义县县城附近义县组火山岩的年龄相当,都比主要含煤地层八道壕组(沙海组)的时代要老,而所谓覆盖在含煤地层之上的晚白垩世大凌河组火山岩实际是早白垩世火山岩,时代比含煤地层更老,据此否定了火山岩覆盖之下寻找早白垩世煤的希望。There are several kinds of Mesozoic and Cenozoic volcanic rocks distributed in the study area,and the same horizon volcanic rocks in different places were named differently.Various opinions exist on the relationship between the coal-bearing strata and the volcanic rocks.In this study,by using the SHRIMP zircon U-Pb dating method,the test was carried out on the samples picked from different places and formations of the volcanic rocks.The results indicate that only one sample belongs to the Tertiary and the other 10 samples all belong to the Early Cretaceous with the geological ages between 115.5132 Ma,and most of them are 125127 Ma.According to the lithology and the sequence,the Early Cretaceous volcanic-sedimentary rocks can be divided into four eruption cycles： from the bottom to the top,they are YixianJingangshan Cycle,TuhuluJiufotang Cycle,Yushugou（Gangtaishan） Cycle and ShahaiFuxin Cycle.Volcanic rocks of Yixian and Gangtaishan Formations are basaltic andesite formed by crevasse eruption,whereas those of the Tuhulu Formation are ducite formed by crater eruption.The Jingangshan and Jiufotang Formations consist mainly of volcanic ash and tuff deposited in crater lakes during the intermittent eruption.The Shahai and Fuxin formations are coal-bearing formations developed during the post-eruption stage.Volcanic rocks of Daxingzhuang Formation distributed widely in the ZhangwuHeishan Area are equivalent to the Yixian Formation in Yixian County of southern Fuxin Basin,their geological ages are not younger but older than the coal-bearing Shahai（Badaohao） and Fuxin formations.The so-called Late Cretaceous volcanic rocks of Dalinghe Formation distributed along the Daling River not overlie but underlie the coal-bearing strata,so there is no hope to search the Early Cretaceous coals under those volcanic rocks.

关 键 词：阜新-彰武-黑山区 白垩系 火山-沉积岩层序 U-PB同位素年龄 找煤 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学]