修正的镜质体反射率剥蚀厚度恢复方法

针对目前用的地层剥蚀厚度恢复镜质体反射率差值法所存在问题，在考察地层沉降、抬升、再沉降埋藏史过程的基础上，根据有机质演化累积性和不可逆性原则，利用经典的有机质成熟度时温关系模型（ＴＴＩ），建立了修正的镜质体反射率剥蚀厚度恢复方法。该方法不仅考虑了剥蚀界面上下镜质体反射率的相对值，还考虑了各自绝对量，与以往仅考虑镜质体反射率差值相比，有较大改进。

A Corrected Method of Using Vitrinite Reflectance Data to Estimate the Thickness of Sediment Removed at an Unconformity

Dow(1977) observed that vitrinite reflectance profiles that pass through an unconformity commonly exhibit an offset at the unconformity.And the offset could be used to estimate the amount of missing section.The estimation is accomplished graphically by projecting the preunconformity portion of the profile upward to the point where it attains a value equal to the vitrinite reflectance immediately above the unconformity.The vertical distance between this point and the unconformity was presented as the amount of missing section.This method has been widely used since the late 70's.And its inaccuracy is getting more and more apparent through further application.This paper presents a detailed study on the organic maturation of vitrinite during the burying-uplifting-reburing process.An organic maturity modeling,which integrates complete thermal and burial histories,is used.By the principle of reaction kinetics,it is assuned that the maturation process of the section below the unconformity continues during the erosional phase and the reburial phase.During the reburial phase,the sections above and below the unconformity undergo continued maturation (increases in cumulative TTI values) at different reaction rates,and results in a difference of organic maturation between the two sections. So the difference can be used to trace their burial histories of these sections.And then we proposes a corrected method to estimate the thickness of sediment removed at an unconformity using vitrinite reflectance data of the formations blow and above the unconformity.which can get a more accurate result than Dow's one.