山东即墨地区下白垩统灰岩地球化学特征及沉积环境分析

为研究山东即墨周戈庄剖面下白垩统灰岩地球化学特征及沉积环境，对周戈庄剖面灰岩进行了系统的沉积学和元素地球化学测试.研究结果显示，周戈庄剖面灰岩样品中SiO₂和CaO含量较高，其平均含量分别为17.18%和39.10%，且SiO₂、Al₂O₃与CaO的值呈现负相关，表明灰岩沉积时期受陆源影响较大.微量元素中，Zr含量较低，Ti含量远大于碳酸盐岩中平均含量，表明其沉积作用主要受陆源影响.稀土总量丰富，重稀土富集，Gd和Eu显示轻微正异常，Ce轻微负异常，且Ce/Ce^*与Eu/Eu^*、ΣREE呈明显的相关性.MgO/Al₂O₃为0.33～0.74，Sr/Ba值为0.10～0.94，反映了陆相沉积环境.V/Cr值为1.64～1.92，Ni/Co值为1.83～2.45， U/Th值为0.48～0.84，反映了氧化沉积特征.MgO/CaO的值为0.03～0.14，Sr/Cu值为16.46～20.45，指示了干旱炎热的气候条件，表明周戈庄剖面灰岩沉积环境为炎热干旱的氧化陆相沉积环境.对周戈庄地区沉积环境的研究可以用来重建古气候、恢复古环境.

ANALYSIS ON THE GEOCHEMICAL CHARACTERISTICS AND SEDIMENTARY ENVIRONMENT OF THE LOWER CRETACEOUS LIMESTONE IN JIMO AREA,SHANDONG PROVINCE

In order to study the geochemical characteristics and sedimentary environment of the Lower Cretaceous limestone at Zhougezhuang section in Jimo,Shandong,the authors carry out systematic sedimentological and elemental geochemical tests on the limestone.The results show that the contents of SiO2 and CaO in the limestone samples are high,with average contents of 16.83%and 39.34%,respectively,and the values of SiO2 and Al2O3 are negatively correlated with that of CaO,suggesting that the sedimentation of limestone be notably influenced by terrigenous sources.Among the trace elements,the Zr content is low,while the Ti content is much greater than the average in carbonate rock,indicating that the sedimentation is mainly terrigenous matters.The total amount of rare earth elements is rich,with enriched HREE,slightly positive anomalies of Gd and Eu,and less negative anomaly of Ce.The ratio of Ce/Ce*is significantly correlated with Eu/Eu*and∑REE.The MgO/Al2O3 values range from 0.33 to 0.74,with Sr/Ba of 0.10-0.94,which reflects the continental depositional environment.The V/Cr value of 1.64-1.92,Ni/Co value of 1.83-2.45 and U/Th value of 0.48-0.84 represent the characteristics of oxidation deposition.The MgO/CaO value of 0.03-0.14 and Sr/Cu value of 16.46-20.45 indicate an arid and hot climatic condition.Therefore,the limestone of Zhougezhuang section shows a hot and dry oxidized continental facies sedimentary environment,which can be used to reconstruct and restore the paleoclimate.