松辽盆地东缘上古生界的成因矿物学及有机质热演化研究

The Project, combined the geological survey and indoor comprehensive research method, through detailed research on the typomorphic features of minerals in form, composition and texture, and through detailed research on the parameters of the thermal evolution of the organics materials in the Upper Paleozoic strata in the Songliao Basin, mainly deals with the relations between the features of typomorphic minerals and the parameters of the thermal evolution of the organics materials, and their relations to very low grade metamorphism, brittle-ductile deformation and contact metamorphism of the area, reveals the effects of paleo- temperature, stress and buried depth on the composition and contents of minerals and on the kerogen type and organic maturity. By studying the mineral composition and content of argillaceous rocks, the features of brittle and clay minerals, the grain size and textural space and the relative density and porosity of rocks, as well as their relations to the kerogen type and vitrinite reflectance, the projects will also deal with the micro- texture of clay minerals and the interface interaction of organic materials. It is hoped that the implementation of the project will promote the crossover and advancement of both traditional geology and petroleum geology, and aid to finding out the intensity of very low grade metamorphism of the Paleozoic strata in the area and its temperal-spatial distribution, as well as to finding the effects of dynamic and contact metamorphism on them. The carrying out of the project will be of theoretical and practical significance to understanding both the tectonic setting, thermal evolution history of the area and to appraising the hydrocarbon generating potential of the Upper Paleozoic strata in the Songliao basin and the chance to host oil and gases.

本项目采用野外地质调查与室内综合研究相结合的方法，通过对松辽盆地东缘上古生界的矿物成分标型特征、结构标型特征、微形貌标型特征等和有机质热演化参数的系统研究，探讨矿物标型特征和有机质热演化参数与极低级变质作用、脆韧性变形作用和接触变质作用的关系，揭示古地温、压力、埋藏深度对矿物组成、含量和干酪根类型、有机质成熟度的影响，研究泥质岩石的矿物组成和含量、脆性矿物特征、黏土矿物特征、矿物粒度和结构空隙、岩石的相对密度、孔隙度等储层性能与干酪根类型、镜质体反射率的关系，讨论黏土矿物的显微结构与有机质的界面作用。本项目的实施，将促进传统地质学与石油地质学学科的交叉和发展，对查明研究区上古生界极低级变质作用的强度和时空分布规律、以及动力变质作用和接触变质作用对其的改造影响，对认识区内大地构造背景和热演化历史及其评价松辽盆地上古生界的生烃能力，储气可行性具有重要的理论意义和现实意义。

松辽盆地东缘连续出露的上古生界泥盆系、石炭系和二叠系及中生界三叠系沉积的碎屑岩（泥质岩石）含有较多的黏土矿物和有机质。XRD分析揭示：泥质岩石的主要矿物组成为石英、钠长石、钾长石和黏土矿物，黏土矿物含量占矿物总量的40%±；上古生界泥质岩石黏土矿物以伊利石为主，含少量的伊利石/蒙皂石混层、高岭石、绿泥石；伊利石结晶度指数（Kl）多≥ 0.42，伊利石多型主要是2M1型，伊利石b0值一般＞9.000Å；三叠系泥质岩石黏土矿物，以伊利石/蒙皂石混层为主，伊利石次之，含有少量的绿泥石；伊利石结晶度指数（Kl）远＞0.42，伊利石b0值一般＜9.000Å。EPMA测试表明：上古生界绿泥石与三叠系绿泥石的化学成分相对比，上古生界泥质岩石的绿泥石表现出相对低SiO2、高Al2O3、富MgO、贫FeO的特征。采用伊利石结晶度地质温度计、伊利石多型地质温度计、绿泥石化学成分地质温度计估算的上古生界成岩-极低级变质温度通常≥200℃，估算的三叠系老龙头组经历的后生作用温度在150℃±。上古生界泥质岩石有机质的拉曼光谱不具备石墨的谱峰特征，表明其承受的热演化温度＜350℃；利用前人提出的和项目组成员建立的拉曼光谱地质温度计，估算的有机质热演化温度＞200℃。利用有机质镜质体反射率地质温度计估算的上古生界泥质岩石有机质热演化温度通常＞200℃。依据Guidotti and Sassi (1986)提出的白云母b0值与温度、压力图解，项目组成员采用数学方法，将该b0值曲线延伸，构建了新的伊利石（白云母）b0值与温度、压力关系图解，可以半定量的估算地质体经历的压力。应用该图解，估算出的上古生界和中生界遭受的压力值一般在2.0Kb以下。应用XRF 和LA-ICP-MS分析，研究了泥质岩石的常量元素、微量元素和稀土元素的地球化学特征，为讨论其沉积环境奠定了基础，部分成果尚在整理中。