Objective:In the central of Sichuan Basin,Xujiahe Formation sandstone of Upper Triassic existence a large number of authigenic chlorite,recent years,it has given more and more attention about chlorite characteristics,chemical composition,formation temperature,the relationship between chlorite and reservoirs in geology.In this paper,authigenic chlorite is the research object,On the basis of detailed geological survey,through the method of electron microprobe,scanning electron microscopy,X-diffraction to Identify chlorite characteristics and chemical composition.Methods:Using X-ray diffraction to determine the content of chlorite,The test conditions is Cu target,voltage 35kV,current 15mA.Using electron microprobe to analysis chemical composition of the authigenic chlorite,the equipment is JEOLJXA-8800M type electronic probe instrument,working conditions are:accelerating voltage 15kV,probe current 10mA,beam spot diameter ＜ 1 μm.Using scanning electron microscope to see chlorite crystal.Results:Xujiahe formation authigenic chlorite contains chlorophaeite aphrosiderite and Fe—Mg chlorite,With the burial depth from shallow to deep,chlorite species change from chlorophaeite to Fe—Mg chlorite,The temperatures calculated by authigenic chlorite have a good relation with burial depth(from 157 to 231℃).Thus it is estimated that the temperature gradient of the area is 34℃/km,the results show great consistent with the previous study paleogeotemperature dates,so paleogeotemperature calculating from chlorite is credible.Conclusions:The paleotemperature is much higher than current temperature in this area,high paleogeotemperature promote chemical densification effect,while it is more easier changed Solid type Ⅲ cheese to gaseous hydrocarbons,like CH4.There are a large number of oil and gas fields in the area,high paleotemperature should be an important factor to its formation.%四川盆地川中地区上三叠统须家河组砂岩中自生绿泥石广泛发育,近年来,绿泥石的特征、化学组成、形成温度、与储层之间的关系等方面研究在地学中越来越受到重视.针对该地区自生绿泥石,本文在详细野外地质调查的基础上,通过电子探针、扫描电镜、X-衍射等测试方法,结果表明须家河组主要有蠕绿泥石、铁绿泥石、铁镁绿泥石、假鳞绿泥石等;埋藏深度由浅至深,绿泥石种属主要表现为由蠕绿泥石向铁镁绿泥石种属转变,经计算绿泥石形成温度在157 ～231℃之间,古地温梯度为34℃/km,经过和前人研究成果相对比,得出经砂岩中自生绿泥石所计算的古地温可靠性高.川中地区古地温明显比现今温度高的多,高古地温促进致密化作用的化学过程,同时有机质从固态的Ⅲ型干酪根热解生成以CH4为主的气态烃,该地区须家河组存在大量油气田,高的古地温也应是其形成的一个重要因素.
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