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南盘江盆地秧坝凹陷自海西晚期以来曾遭受多次抬升剥蚀和改造，凹陷内上三叠统及以上地层缺失，上二叠统一下三叠统亦大部残缺。为此，依据秧l井镜质体反射率和测温资料，应用Hood法与古地温换算公式对该井的剥蚀厚度进行计算。计算结果表明，该井印支晓-燕山期(T3末-KI)剥蚀厚度为3745．9m，剥蚀层位主要为上三叠统，海西晚期(P3末)剥蚀厚度为364．8m，剥蚀层位主要为上二叠统长兴组和吴家坪组。同时，结合该井烃源岩成熟度资料，将上述二期抬升剥蚀对油气成藏的影响进行分析，认为海西晚期泥盆系烃源岩刚进入生油期，该期抬升剥蚀对油气成藏影响不大；印支晚-燕山期全部烃源岩进入高—过成熟阶段，由于该期抬升剥蚀厚度大、时间长、对油气藏的破坏较大。

Calculations of the Denudated Thickness and Analysis of the Preserving Conditions in Yangba Depression

??Elevations,denudations and reconstructions happened many times in Yangba depression in Nanpanjiang basin since late Hercynian,Where Upper Triassic formations and those over them are absent,and Upper Permian formations and Lower Triassic formations are almost absent too.On the basis of R_o and temperature materials of well Yang 1,the denudated thickness in Yangba depression is calculated by Hood method and paleotemperature formula.The results show that the denudated thickness between late Indosinian and Ranshanian (late T₃-K₁) is 3 745.9 m and the denudated stratum mainly is Lower Triassic formations,and that the denudated thickness in late Hercynian (late P₃) is 364.8 m and the denudated strata are Changxin and Wujiaping formations.At the same time,combining the materials of the source rock maturation of well Yang 1,the influence of the two elevations and denudations on oil gas pool formation is analysed.They are considered that the source rocks in late Hercynian Devonian system just came into oil generating,the influence of the elevations and denudations on oil gas pool formation was small;and that all of the source rocks between late Indosinian and Ranshanian came into high over maturation,the damage of the elevations and denudations to oil gas pool was great because of the big thickness and long time.