摘要
山东济阳坳陷盆地是受太平洋板块构造俯冲运动的影响,形成于古近系的古新世-始新世(Ek-Es).本文通过对济阳坳陷盆地中Es4-Ek地层自生伊/蒙混层矿物的研究,探讨了其经历的古地温和古地温梯度,在此基础上,对Es4-Ek地层的剥蚀深度进行了估算.研究发现,东营凹陷郝科1井处自生伊/蒙混层矿物反映的Es4-Ek古地温梯度为3.90℃/100 m,剥蚀厚度为360 m左右;惠民凹陷盘深3井中Ek古地温梯度为3.92℃/100 m,剥蚀厚度为135 m左右;沾化凹陷桩深1井中Es4-Ek古地温梯度为3.82℃/100 m,而该处Es4-Ek地层基本没有剥蚀.但从沾化凹陷中自生伊/蒙混层矿物的分布特征看,在义170井处的Es4地层剥蚀厚度达390 m,可见沾化凹陷中Es4-Ek地层剥蚀厚度变化较大.另外,济阳坳陷盆地的古地温梯度普遍高于现今地温梯度,该盆地自形成以来一直处于降温状态.研究结果说明利用伊/蒙混层矿物特征来探讨古地温,获取古地温梯度,并恢复剥蚀厚度是一个比较有效的方法.
The Jiyang basin of Shandong province was formed by the subduction of the Pacific Plate during the Paleocene and the Eocene （Es-Ek）. In this paper, based on the analyses of the mixed-layer illite/smectite from the Jiyang basin, we discussed the paleotemperature and paleo-geothermal gradient when it formed, and calculated the eroded thickness. The study shows that, （1） for Paleocene-Eocene strata in the Dongying depression, the paleogeothermal is about 3.90 ℃/100 m, and the eroded strata is about 360 meters thick; （2） for Paleocene-Eocene strata in the Huimin depression, the paleo-geothermal gradient is about 3.92 ℃/100 m, and the eroded strata is about 135 meters thick; （3） for Paleocene-Eoeene strata in the Zhanhua depression, the paleo-geothermal gradient is about 3.82 ℃/100 m. The eroded strata thickness in the Zhanhua depression has a wider range （0-390 m）. Clearly, the paleo-geotbermal gradient of the Jiyang basin is applrenthy higher than the present geothermal gradient. Finally we suggest that the temperature of this basin had been decreasing at all time since it formed. The results of this study show that we can trace the paleo-geothermal gradient and estimate the eroded strata thickness based on the characteristic of the mixed-layer illite/smectite.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2008年第6期621-631,共11页
Journal of Nanjing University（Natural Science）
基金
国家自然科学基金(40772027)
