山东昌潍古近系原型盆地粘土矿物的成岩演化与古地温  

Diagenetic and paleogeothermal evolution of the clay minerals in the Paleogene Changwei prototype basin of Shandong province

作　　者：赵明[1] 陈小明[1] 季峻峰[1] 张耘[2] 张哲[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学系南京210093 [2]江苏省工程物理勘探局,南京210008

出　　处：《岩石学报》2006年第8期2195-2204,共10页Acta Petrologica Sinica

基　　金：山东胜利油田研究项目(项目名称为"胜利油田济阳-昌潍坳陷原型盆地研究")经费的资助

摘　　要：山东昌潍盆地形成于古近系的古新世-始新世早期(Ek-Es_4),本文主要研究昌潍盆地的粘土矿物特征及其古地温。昌雄古近系(Ek-Es_4)原型盆地的粘土矿物种类有:无序高岭石、伊/蒙混层矿物、伊利石和辉绿泥石(铁斜绿泥石)。利用粘土矿物温度计估算了盆地埋藏深度的古地温,探讨了古近系(Ek-Es_4)原型盆地的成岩作用和有机质热演化阶段。研究表明:随着埋藏深度的增加,伊/蒙混层矿物(L/S)由无序向有序连续转变;高岭石的有序性、伊利石和绿泥石的结晶程度趋于增强。根据伊/蒙混层矿物(L/S)地温计获得盆地不同深度的成岩温度范围;成油深度约为3000～4000m±。现今地温与古地温的对比,显示盆地存在热异常,导致热异常的形成可能有以下几方面因素:(1)盆地曾经历过地壳抬升阶段;(2)盆地内有岩浆活动热事件发生;(3)盆地裂陷期的构造动力学作用导致古地温梯度过高。昌潍原型盆地较高的古地温梯度吻合于裂陷盆地构造动力学演化的模式。The Changwei basin located in Shandong province was formed during the Paleocene and the early Eocene Epoch （ Ek-Es4 ）. This paper mainly studies the characteristics of the clay minerals and the paleotemperature in the Changwei basin. The clay minerals in the Changwei prototype basin of the Paleocene-Eocene Epoch （Ek-Es4） are composed of the disorder kaolinite, illite/ smectite mixed-layer mineral（ I/S）, illite and diabantite. By means of clay mineral thermometer we estimate the paleotemperatures in the basin and investigate the diagenetic evolvement of the prototype basin and the thermal evolution stages of the organic matters. The study shows that along with the increasing of the layer depth, mixed-layer illite/smectite（I/S） continually transforms from disorder to order type; the order degree of kaolinite and the crystallinities of illite and chlorite increase. The diagenetic temperatures are determined from samples with different depths of the basin based on the mixed-layer illite/smectite （I/S） geothermometer： as following the forming temperatures was 〈 100 - 110℃ for the depths less than 3000m; 110 - 178℃ at the depths of 3000 -4000m and 〉 170 - 178℃ with the depths 〉4000m. The depths of the Oil formation in the basin are about 3000 to 4000m. By comparing the present geothermal gradient with the Paleo-geothermal gradient, it is found that the paleo-geothermal gradient（3000 - 4000m, 7.8℃/100m） is higher than the present geothermal gradient （3.5℃/100m） in the basin. This phenomenon was previously recognized as the thermal anomaly resulted from the magmatic activities and the crustal uplift in the basin. Whereas, it is coincided with the dynamic evolution model of rift basins （Kusznir, et al, 1995; McKenzie, 1978）. According to the model, there was higher heat energy associated with the stretching and thinning of the lithosphere and uprising of the asthenosphere during the formation of depressed basin. This instance in the Changwei prototype basin is consisitent

关 键 词：山东 昌潍古近系原型盆地 粘土矿物 伊/蒙混层矿物(I/S) 成岩演化 温度计 

分 类 号：P588.22[天文地球—岩石学]