贵州凯里寒武系底部硅质岩系生物组成、沉积环境与烃源岩发育关系研究  

Depositional Environment,Organisms Components and Source Rock Formation of Siliceous Rocks in the Base of the Cambrian Niutitang Formation,Kaili,Guizhou

作　　者：谢小敏[1] 腾格尔[1] 秦建中[1] 张庆珍[1] 边立曾[2] 尹磊明[3] 

机构地区：[1]中石化无锡石油地质研究所,江苏无锡214151 [2]南京大学地球科学系,南京210093 [3]中国科学院南京古生物研究所,南京210008

出　　处：《地质学报》2015年第2期425-439,共15页Acta Geologica Sinica

基　　金：国家重点基础研究发展规划973项目(编号:2012CB214801与2014CB239101);国家自然科学基金项目(编号:40839910);中石化科技部青年创新计划项目<单种成烃生物生烃烃类特征及其同位素分析>共同资助的成果

摘　　要：贵州凯里麻江地区羊跳剖面寒武系牛蹄塘组底部发育了一套3.2m厚的硅质岩系。通过对其进行高频逐层采样68件,根据沉积环境-生物组成-烃源岩形成的思路,精细分析了生物组成及有机碳TOC含量,进而讨论了沉积环境与烃源岩发育的关系。结果表明,该剖面生物组成多样,包括有浮游藻、底栖宏观藻、疑源类、海绵骨针、须腕动物蠕虫等,并可归纳为三大类生物微相:浮游藻类、底栖藻类、其它生物类型。不同藻类体和不同疑源类所反映的水体深度特征显示,该套烃源岩沉积经历了先水进后水退的过程,水体深度最深时期,底栖红藻和Heliosphaeridium longum-Asteridium tornatum疑源类组合发育,烃源岩有机碳含量也较高(TOC平均值为4.73%,最高可达13.97%),说明利于烃源岩发育。总体而言,不同生物微相烃源岩TOC含量不同,底栖藻类(平均值3.50%)>浮游藻类(平均值1.46%)>其它生物类(平均值<1.0%)。而须腕动物蠕虫和海绵动物的发现反映了热液环境,受热水事件影响强烈的样品TOC最低(TOC含量为0.90%和0.94%),说明热液活动强烈对烃源岩发育可能具有一定的不利影响。A set of alternating siliceous rocks and siliceous shales over 3.2 meters thick at the base of the Cambrian Niutitang Formation provide a good outcrop to examine the relationship between the composition of organisms,depositional environment and source rock formation.A set of 68 samples was collected layer by layer and analysed for TOC（Total Organic Content）and organisms present.The organisms consist of planktonic microalgae,benthic macroalgae,acritarchs,sponge spicules and Pogonophoran worms.From the presence of different algae and acritarchs it is clear that the water level fluctuated with initial increases followed by a decrease.The deep water fauna is rich in benthic red algae and acritarch species（Heliosphaeridium longum and Asteridium tornatum）,and the TOC contents are relatively high.The benthic algae microfacies has the highest TOC contents（average 3.50%）,while the planktonic algae microfacies has an average TOC of 1.46%,and other microfacies having an average TOC 〈1.00%.The discovery of sponge spicules and Pogonophoran worms,which are typical of hydrothermal environments,suggests that source rock formation was influenced by hydrothermal events on several occasions.The sponge spicule and Pogonophoran worm microfacies have the lowest TOC content,suggesting the samples with strong hydrothermal activity may be not good for the source rock formation.

关 键 词：下寒武统 硅质岩系 生物组成 生物微相 沉积环境 烃源岩发育 

分 类 号：P618.13[天文地球—矿床学] P588.244[天文地球—地质学]