桦甸盆地桦甸组油页岩段地球化学特征及地质意义  

Geochemical Characteristics and Their Geological Implications of Oil Shale Member of Huadian Formation,Huadian Basin

作　　者：孙平昌[1,2] 刘招君[1,2,3] 李宝毅[1,2] 柳蓉[1,2,3] 孟庆涛[1,2,3] 周人杰[4] 姚树青[1,2] 徐银波[1,2] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学油页岩与共生能源矿产成矿及勘查开发重点实验室,长春130061 [3]东北亚生物演化与环境教育部重点实验室,长春130026 [4]多伦多大学地质系

出　　处：《吉林大学学报（地球科学版）》2012年第4期948-960,共13页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(40972076);吉林大学科学前沿与交叉学科创新项目(200903035);高等学校博士学科点专项科研基金项目(20110061120066;20110061110050)

摘　　要：桦甸盆地位于敦密断裂带之上,是我国著名的古近纪含油页岩断陷盆地。其中桦甸组油页岩段发育厚层的泥岩沉积。长期以来对该段油页岩特征研究较多,但对其物源区特征和构造背景研究甚少。对油页岩段厚层泥岩进行系统的地球化学分析结果表明:泥岩中w(SiO2)整体较低,K2O/Na2O值较高(大于1),w(MgO+Fe2O3T)为3.91%～11.66%,Al2O3/(Na2O+K2O)为3.77～6.29,表明泥岩中含有一定的铁镁质组分和较多的稳定组分。微量元素PAAS标准化分配曲线显示不同样品之间元素富集、亏损趋势不一致,同时稀土元素标准化曲线呈现出稀土含量变化较大、轻稀土富集和明显Eu负异常,表明油页岩段沉积时期存在多个物源。泥岩风化蚀变指数为74～82,Th/U值多集中在4.65～6.07,表明泥岩源区经历了相对中等的风化作用。Th/Sc和Zr/Sc值表明泥岩基本受源岩成分控制。由源岩和构造背景判别图解,并结合前人研究资料得知:桦甸盆地油页岩段母岩主要来自于海西期和燕山期花岗岩以及少量的燕山期中酸性喷发岩;源岩形成于大陆边缘造山带,为大陆岛弧火山岩系。Huadian basin, which is located within Dunhua-Mishan fault zone, is well known as a Paleogene oil shale-bearing fault-basin in China. Previous studies mostly focus on the sedimentary characteristics of oil shale, but there was little concern on provenance features and tectonic settings. Thegeochemical analysis based on the mudstone samples from the Oil Shale Member of Huadian Formation shows that the SiO2 content is respectively low, The K20/Na20 ratio is relatively high（〉 1）. The parameter of （MgO＋Fe2O3T） ranges from 3.91% to 11.66% and the Al2O3/（Na2O＋K2O）ratio ranges from 3.77% to 6. 290%, all of which demonstrate that the mudstones contain a certain amount of femic constituents and a considerable quantity of stable components. The PAAS-standardized distribution curves of trace elements show variable enrichment and depletion trends among different samples, significant variations in the REE contents, enrichment in light REE and negative anomalies of Eu. These features suggest that the material sources of the Oil Shale Member came from several provenances. The mudstone weathering and alteration indexes range from 74 to 82 and the Th/U ratio mainly ranges from 4.65 to 6.07, both of which suggest that provenances had underwent moderate weathering processes. The Th/Sc and Zr/Sc ratios illustrate that these mudstones were mainly controlled by source rocks. On the basis of source rocks, discrimination diagrams of the tectonic setting and previous research material, we conclude that the provenances of the Oil Shale Member of Huadian Formation in Huadian Basin were mainly Hercynian and Yanshanian granites, and also involve some andesitic to rhyolitic effusive rocks. Source rocks were formed in the continental margin volcanic series. orogenic belt and belonged to continental island arcvolcanic series.

关 键 词：油页岩 地球化学 物源区 构造背景 古近纪 桦甸盆地 

分 类 号：P618.12[天文地球—矿床学] P59[天文地球—地质学]