辽西早白垩世义县组砖城子层湖相碳酸盐岩地球化学特征及古湖泊学沉积意义  

Geochemistry of Zhuanchengzi lacudtrine carbonate rock layer of Early Cretaceous Yiliang formation and the paleolimnological significance

作　　者：梁俊红[1] 孙宝亮[1] 尹国英[2] LIANG Junhong;SUN Baoliang;YIN Guoying(Geology Department of School of Resources and Civil Engineering of Northeastern University, Shenyang 110819, China;Structural Engineering of Liaoning Urban Construction Technical College, Shenyang 110122, China)

机构地区：[1]东北大学资源与土木工程学院地质系,沈阳110819 [2]辽宁城市建设职业技术学院建筑工程系,沈阳110122

出　　处：《地质找矿论丛》2021年第4期475-485,共11页Contributions to Geology and Mineral Resources Research

基　　金：中央高校基本科研业务费项目(编号:N100401005)资助。

摘　　要：辽西义县盆地早白垩世义县组陆相湖盆沉积中常发育多个薄层碳酸盐岩沉积层,碳酸盐岩地球化学的研究对揭示湖盆沉积古环境具有重要理论意义。义县组砖城子层英窝山剖面湖相碳酸盐岩分析结果显示,岩石δ^(13)C值为-3.44×10^(-3)~0.27×10^(-3),均值为-1.21×10^(-3);δ^(18)O值为-15.73×10^(-3)~-9.93×10^(-3),均值为-10.88×10^(-3)。盐度Z值变化范围114.78~122.39。碳酸盐岩主量元素分析表明,w(CaO+MgO+LOI)=53.38%~97.04%,均值71.15%;陆源组分w(Al_(2)O_(3)+SiO_(2)+Fe_(2)O_(3))=2.19%~44.87%,均值为27.77%;x(Mg)/x(Ca)摩尔比介于0.92~1.01。碳酸盐岩微量元素地球化学提供了古湖泊学的古盐度、氧化还原和古气候证据。w(Sr)=110.4×10^(-6)~1360.2×10^(-6),w(Ga)=0.152×10^(-6)~14.13×10^(-6),w(Sr)/w(Ba)=0.34~131.49(多数>1),指示沉积湖泊水体为咸水环境;氧化-还原指标w(V)/w(V+Ni)=0.51~0.83,w(V)/w(Cr)=1.59~8.28(多数>2.0),w(U)/w(Th)=0.39~10.24,且变化范围较大,指示为半封闭—封闭的缺氧还原强分层水体沉积环境;w(Sr)/w(Cu)=54.94~1260.71,均值为213.79,反映炎热干旱气候类型。义县组砖城子层沉积期湖泊为干旱古气候背景下的半咸水—咸水、缺氧还原强分层的半封闭—封闭型。There are several thin carbonate rock layers deposited in continental lake basin of Early Cretaceous Yi Xian formation.Geo chemical study on such carbonate rock layer is theoretically important to reveal paleo-lake sedimentary environment.Analysis of Z Huanchengzi con carbonate rock layer of Yingwoshan section of Yiliang formation isδ^(13)C about-3.44×10^(-3) to 0.27×10^(-3),averagely-1.21×10^(-3);δ^(18)O about-15.73×10^(-3) to-9.93×10^(-3),averagely-10.88×10^(-3);Z value of salinity 114.78 to 122.39;major element analysis,w(CaO+MgO+LOl)=53.38%-97.04%,averagely 71.15%;terrestrial material w(Al_(2)O_(3)+SiO_(2)+Fe_(2)O_(3))=2.19%-44.87%,averagely 27.77%;the molar ratio of x(Mg)/x(Ca)0.92-1.01.Trace element geochemistry of the carbonate rocks provides paleosalinity,redox and paleo climate indices of paleolimnological.w(Sr)is 110.4×10^(-6) to 1360.2×10^(-6),w(Ga)is 0.152×10^(-6) to 14.13×10^(-6),w(Sr)/w(Ba)is 0.34 to 131.49,generally more than 1,the indication of the saline sedimentary lake water column.Redox reaction w(V)/w(V+Ni)=0.51-0.83,w(V)/w(Cr)=1.59-8.28,generally more than 2,w(U)/w(Th)=0.39-10.24,with wide variation range,indicates a semi-closed to closed sedimentary environment with strong stratification and anoxic reduction.w(Sr)/w(Cu)=54.94-1260.71,averagely 213.79 reflecting hot and arid paleo climate,semi-closed to closed paleo lake sedimentary environment of Zhuanchengzi layer with strong stratification,brackish and anoxic reduction type.

关 键 词：早白垩世 砖城子层 湖相碳酸盐岩 碳氧同位素 元素地球化学 古湖泊学 辽西 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.2[天文地球—地质学]