济阳坳陷中新生代古地温分析

本文在系统取样分析的基础上,根据干酪根镜质体反射率对济阳坳陷中、新生代的古地温状况进行了探讨。选用的几口研究井的镜质体反射率对数值与深度呈线性关系。研究认为,本区中、新生代各自具有较简单的受热史,不存在明显的温度间断和畸变。但中、新生代之间具有明显的温度跃变,表明中生代地层因地壳抬升曾一度受到剥蚀。文中根据镜质体反射率资料对部分井进行了剥蚀厚度的恢复。文中利用最小二乘法分别对中、新生代建立了几口研究井的镜质体反射率与古地温之间的关系式,并进而确定了各井不同地质时期的古地温梯度值。结果表明,本区中生代地温梯度略高于新生代。新生代早期地温梯度较高,中期稍有下降,晚期复又回升,呈现明显的“马鞍形”演变趋势。本区新生代平均古地温梯度与今地温梯度接近,故在研究有机质演化史时基本上可用今地温梯度代替新生代时期的古地温梯度。

PALEOGEOTHERMAL ANALYSES OF THE MESOZOIC AND THE CENOZOIC IN JIYANG DEPRESSION

Based on the systematic sampling and analysis, the paleogeo-thermal conditions of the Mesozoic and Cenozoic in Jiyang Depression have been studied with kerogen vitrinite reflectance data. The logarithm of the vitrinite reflectance varied linear y with well depth for some researched wells. Simple geothermal histories were found in Mesozoic and Cenozoic groups separately no geothermal interruption and distortion existed. But in-between the two groups clear geothermal interruption was observed, which showed that Mesozoic group suffered denudation owing to crustal lift.