摘要
根据磷灰石裂变径迹分析结果，确定松辽盆地中央坳陷约３０×１０６ａ以前有一次地热降温事件。地层年龄对比表明，白垩纪末（６５×１０６ａ）至中、晚渐新世（３４×１０６ａ）甚至到第三纪末，该坳陷为沉积间断。磷灰石封闭径迹长度分布定量模拟证明，古热流大于今热流，１６００ｍ以下地层曾经历１１５℃左右的高温。古热流反演模拟表明，自盆地形成至８３×１０６ａ以前古热流为快速衰减，８３×１０６ａ至现今为缓慢衰减。本区有机质生烃在白垩纪末达到最高峰，以后的持续抬升剥蚀和大地热流值衰减、降温使生烃作用停止。依安期以来的再埋藏（约２００ｍ）不能引起二次生烃。
Based on the result of apatite fission track analysis from the Central Depression, Songliao basin, this paper presents that the phase of cooling was initiated before 30×106a ago approximately. The chronology of the stratigraphic units indicates that there was a long-term sedimetary gap in the Central Depression from Cretaceous end (65×106a) to middle-late Oligocence (34×106a) or even to Quaternary (2×106a). A quantitative modelling of the distribution of confined tracks length testified that stratigraphic at depth below 1,600m was subjected to a high temperature (approximate 115℃). This conclusion is in accord with vitrinite reflectance, authigenic mineral data. The paleothermal value is higher than present. An inversion of paleothereal flow shows that paleothermal flow decayed rapidly before 83×106a and being slow down after 83 ×106a. Organic thermal matuation has been controlled mainly by paleotemperature, the hydrocarbon generation from organic matters reached a peak value at the end of Cretaceous in the depression. Since later uplift and erosion, decayed heat the flow and decreased the temperature, the coalification process was'Freezed' and hydrocarbon generation ceased. Thin sediment (Ca. 200m) deposited during Neogene and Quaternary can't allow the source rock to regenerate hydrocarbon. This is a main reason that large to medium-sized nature gas fields hasn't been found in the basin.
出处
《石油勘探与开发》
EI
CAS
CSCD
北大核心
1995年第6期20-25,共6页
Petroleum Exploration and Development
关键词
磷灰石
松辽盆地
地热场
热演化
石油生成
Apatite, Analysis paleotemperature, Settling, Unconfirmity, Songliao basin
