应用磷灰石裂变径迹研究大民屯凹陷的古地温

为深刻认识辽河盆地古地温特征，利用裂变径迹分析方法，对大民屯凹陷钻井岩心中19块磷灰石样品的裂变径迹年龄和长度做了测试。结果表明，随井深增加，径迹年龄和平均径迹长度有减少、变短的显著趋势，ES3^4地层磷灰石裂变径迹表观年龄比地层年龄年轻得多，说明沉积后曾长时间处于退火带中，退火带古地温为74～130℃，有效加热时间为4l～45Ma，2300～4000m深度地层处于退火过渡带。将径迹长度分布特征与地史、热史模拟结果相结合，认为该区在ES4段末经历一次短时间迅速增温后，ES3^1亚段存在一个区域抬升降温的热事件过程，其后地层稳定下降，沉降幅度小、沉积物较薄，温度增加缓慢，古地温梯度高于今地温梯度，对生、排烃较为有利。

Study on paleotemperature of Damingtun Depression in Liaohe Basin using apatite fission track data

For the first time, apatite fission track analysis was carried out to study the geothermal characteristics of Damintun Depression, for master avail timing of hydrocarbon generation and migration. Fission track ages and lengths of apatite samples both decrease with increasing well depths. Apatite fission track ages of the samples from the ES34stratum are all much younger than their stratigraphic a-ges, suggesting that the strata were heated to higher paleotemperture after deposition. The strata between 2 300 - 4 000 m in depth are the transitional annealing zone, valid time belong to 41 - 45 Ma. Combining track characteristics and thermal simulating experiment, the authors believe that there was the rapid evolution of subsurface temperature in last stage of ES4 and the uplift event in ES31. Therefore, which benefit to hydrocarbon generating and migrating as well as preservation of reservoirs.