济阳坳陷惠民凹陷中央隆起带与邻区黏土矿物成岩演化及古地温变化

惠民凹陷中央隆起带是胜利油田重要的油气富集带，对其成岩演化及古地温研究有助于进一步弄清该构造带的地质作用过程。选取了中央隆起带及临南洼陷带沙河街组大量样品，通过X-射线衍射、电子探针等进行黏土矿物成分分析及古地温计算，结果表明：该区沙河街组黏土矿物主要为高岭石、伊/蒙混层、伊利石和绿泥石，总体反映黏土矿物演化程度不高，盆地热演化程度较低的特点；成岩作用基本处于中成岩阶段，可进一步划分为早期和晚期2个阶段，早期主要是无序伊/蒙混层矿物(伊利石含量=38.2%~60.3%）；晚期是有序伊/蒙混层矿物(伊利石含量=60.3%~82.4%）。在中央隆起带，早期和晚期的转换深度界线大致为1 700m，而在临南洼陷带该界线大致为2 600m；中央隆起带沙二段（Es₂）矿物热演化程度明显低于洼陷带，表明中央隆起带可能在沙二段沉积期开始了快速抬升，形成了与洼陷带不同的成岩环境；洼陷带沙河街组古地温梯度为40.8℃/km，中央隆起带的古地温梯度计算结果明显异常（76.72℃/km），表明该构造带遭受了强烈抬升与剥蚀作用，剥蚀量大约为880m。

Diagenetic and paleogeothermal evolution of the clay minerals in the Center Uplift Belt and its adjacent region of Huimin Sag,Jiyang Depression

Huimin sag,located in Shengli Oilfield of Shandong province,is one of the most important enrichment zones of oil and gas.It is favorable to further understand the geologic process about this tectonic belt by study of the diagenetic and paleogeothermal evolution of the clay minerals.Abundant samples were picked from the Central Uplift and Linnan sub-sag,and we carried out the analysis of clay mineral component and paleogeotherm by X-ray and electronic probe experiment.The results are as follows:(1)The clay minerals in the central uplift and Linnan sub-sag of Huimin Depression of Shahejie Formation(Es)are composed of kaolinite(K),illite/smectite mixed-layer mineral(I/S),illite(I)and chlorite(Chl).As the whole,the mineral composition indicates that it is at low thermal evolution stage of the clay minerals and the tectonic zones.(2)The diagenesis is generally middle diagenetic stage,and two sub-stage were divided,namely,the early stage,the content of illite in the I/S between 38.2% and 60.3%;and the late stage,the content of illite in the I/S between 60.3% and 82.4%.The change depth boundary of the two sub-stages is different,such as,1 700 meter in the Central Uplift Belt,and 2 600 meter in Linnan Sub-sag.(3)The thermal evolution level is lower in the Central Uplift Belt than that in the Linnan Sub-sag,which indicated the Central Uplift Belt possibly rapidly uplifted from the depositional stage ofEs₂,and resulted in the different diagenesis background from the Linnan Sub-sag;The Paleogeotherm gradient in Linnan Sub-sag is 40.8℃/km,but the obviously abnormal calculated result was obtained in the center uplift belt,e.g.76.72℃/km,which indicates the strong uplift and erosion(the denuded thickness is 880m)in the central uplift belt.