饶阳凹陷留西留北构造带新近系地球化学特征及其地质意义  

Geochemical Characteristics and Geological Significance of Neogene System in Liuxi-Liubei Tectonic Zone in Raoyang Sag

作　　者：国景星[1] 巩逸文 Guo Jingxing;Gong Yiwen(School of Geosciences, China University of Petroleum, Qingdao Shandong 266580, Chin)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《地质科技情报》2018年第2期41-49,共9页Geological Science and Technology Information

基　　金：中国石油华北油田分公司2011年校企合作科研项目(HBYT-CY3-2011-JS-345)

摘　　要：为探明饶阳凹陷留西留北构造带新近系物源和古气候特征,采用ICP-MS详细研究了饶阳凹陷留西留北构造带新近系各体系域泥岩微量元素、稀土元素地球化学特征。研究表明:除Zr、Hf、Nb、Sr、Mo 5种元素平均含量低于上地壳均值以外,其余微量元素含量均略高于上地壳均值,其中Zn、V、Cr、Ni、U、Pb等元素更为富集。大部分样品微量元素蛛网图模式大体一致,但仍个别样品与主流模式特征不同,各体系域微量元素含量普遍低于上地壳均值,显示物源可能为混合物源。各体系域稀土元素总量w(ΣREE)相对较高,介于146.20×10-6~342.06×10-6之间,平均228.20×10-6。ΣLREE/ΣHREE比值为9.01~15.47,平均11.35,轻稀土元素富集。δEu为0.61~0.71,平均0.66,具明显的Eu负异常,Ce异常不明显。结合研究区一些敏感的微量元素及其比值和稀土元素的各特征参数研究认为:留西留北构造带新近系物源除少量沉积岩物源外,大部分为来自沧县隆起地区燕山期发育的花岗岩侵入体和中酸性火山岩;也可能来自岩浆岩和沉积岩经变质作用转化形成的片麻岩类或混合岩化的岩石,但不是主流来源。研究区新近系时期古水介质条件为弱氧化环境,为盐度较低的淡水环境。古气候经历了由低位体系域(LST)相对干热到水进体系域(TST)较为温湿再过渡到高位体系域(HST)相对干热的一个完整旋回。This paper studies the geochemical characteristics of trace elements-rare earth elements （REE） in various Neogene systems of Liuxi-Liubei tectonic zone in Raoyang Sag with inductively coupled plasma mass spectrometry method （ICP-MS）. Except for the 5 elements. Zr, Hf, Nb, Sr and Mo, the average content of the other elements is less than the corresponding upper crust mean, and the content of the trace elements is slightly higher than the corresponding mean value in upper crust. Among them, such elements as Zn, V, Cr, Ni, U, and Pb are more enriched. Trace element spidergram patterns of most samples are roughly consistent. However, the characteristics of several samples are still different from those of the mainstream models, and the content of trace elements is generally lower than the corresponding mean value in the upper crust, showing a possible mixture provenance. The ∑ REE values of REE are relatively high, ranging from 146.20×10^-6to 342.06×10^-6 , with an average value of 228.20 ×10^-6. ∑LREE/∑ HREE ranging from 9. 01 to 15. 47, with an average value of 11. 35, demonstrates the enrichment in LREE. While 8Eu is 0.61 to 0.71, with an average of 0.66, indicating a significant Eu negative anomaly. Ce a- nomaly is not obvious. The combination of trace elements and their ratios, as well as the characteristic pa- rameters of REE may lead to the conclusion that the Neogene provenance of the study area consists mainly of granite intrusions and intermediate acidic volcanic rocks, developed during Yanshanian in Cangxian up- lift region. Besides, some sedimentary rocks could be the provenance as well. The ancient water medium is weak oxidizing environment and the relatively low salinity indicates freshwater environment. Paleoclimate has undergone a complete cycle from the lowstand system tract （LST）-relatively hot and dry, to trans- gressive system tract （TST）-relatively warm and humid, then to highstand system tract （HST）, which is relatively hot and dry.

关 键 词：饶阳凹陷 新近系 地球化学特征 物源分析 古环境分析 

分 类 号：P534.62[天文地球—古生物学与地层学]