微烃渗漏遥感探测的机理主要是建立在烃类微渗漏异常地球化学表征和形成的基础上。本文主要依据Schum acher(1996)和Saunders等(1999)提出的烃类微渗漏异常地球化学原理和模型,以鄂尔多斯盆地伊盟隆起东部为研究区,以多光谱遥感和航空放射性遥感为探测手段,分别利用氧化铁指数(TM3/TM1)、亚铁指数(TM5/TM4)和黏土化指数(TM5/TM7)来识别Fe3 氧化物、Fe2 氧化物和有机质、黏土化和碳酸盐化的相对富集区,同时用矿物组合图像来增强显示上述信息。综合亚铁指数(TM5/TM4)分割图像、矿物组合图像、航放铀、钍、钾信息及钍归一化铀指数等信息,提取了研究区微烃渗漏地段。研究表明,研究区存在两条Fe2 氧化物和有机质相对富集区带。一条为与库布齐沙漠走向近于一致的北部近东西向带,它与石油部门发现和描述的油气渗漏区域基本一致。另一条为泊海子—准召—新庙不连续的北西向带,它的北界与泊海子—准召断裂展布基本一致。在垂直中部北西向微烃渗漏带的剖面上,清晰显示亚铁指数(Fe2 )、航放测量铀(U)、钍归一化铀(Ud)为正异常;氧化铁指数(Fe3 )、航放测量总道值(Tc)和钾(K)、钍归一化(Kd)为负异常的特点。研究认为地表还原带是由油气微渗漏形成的,推测受断裂、裂隙带控制的、主要由油气微渗漏形成的还原带对东胜铀矿带形成聚集起了重要作用。

The mechanism of remote sensing detecting the hydrocarbon microseepage is its geochemical abnormality.Referencing the geochemical models of hydrocarbon microseepage suggested by Schumacher(1996) and Saunders et al(1999),this study implements ferrics index(TM3/TM1),ferrous index(TM5/TM4) and clay index(TM5/TM7) to detect the abnormal areas of ferric-oxides,ferrous-oxides/organics,and clayzation/carbonation,respectively,in the east Yimeng Uplift of Ordos Basin.Integrated analysis the ferrous index,mineral composition,aeroradiometric data(U,Th and K),and thorium-normalized uranium index(Ud),two hydrocarbon microseepage belts in this area have been extracted.One is located in the northern Dongsheng which is along a nearly east-westward fault zone and Kubuqi desert.Its distribution is consistent with the ranger reported by the oil and gas investigation.The other one,named Pohaizi-Zhunzhao-Xinmiao zone,is located in the southern Dongsheng uranium mineralization zone and its northern boundary is along the northwestward Pohaizi-Zhunzhao fault.On the cross profiles of Pohaizi-Zhunzhao-Xinmiao zone,it is clear that the ferrous index(Fe2 ),aeroradiometric uranium(U),and thorium-normalized uranium(Ud) are positive abnormality,and the ferric index(Fe3 ),aeroradiometric total channel(Tc) and potassium(K),thorium-normalized potassium(Kd) are negative abnormality.The study suggests that the subaerial reduced areas are related to hydrocarbon microseepage and the hydrocarbon migration along the fault and fracture zone or penetrable strata played an important role for uranium mineralization in Zhiluo Formation near the northwestward fault zone.