东北及邻区中生代盆地片钠铝石的分布、产状及其油气地质意义

东北及邻区中生代地层中的片钠铝石分布于海拉尔盆地、塔木察格盆地、二连盆地、开鲁盆地和阜新盆地的早白垩世地层及松辽盆地南部的早白垩世晚期-晚白垩世早期地层中。片钠铝石主要发育在油气储层或CO₂气储层中富含长石的砂岩和火山碎屑岩中。在含片钠铝石砂岩和火山碎屑岩中，片钠铝石以放射状、束状、杂乱毛发状、球状和板状等集合体充填孔隙，或呈束状和板状交代长石和岩屑。片钠铝石及其共生的铁白云石都是最晚形成的自生矿物组合。越来越多的证据表明，片钠铝石是富CO₂流体的指示矿物，记录了CO₂和油气双重充注现象。在含片钠铝石碎屑岩中可以解读出CO₂充注的时间和CO₂分压的变化。

Distribution,Occurrence and Their Petroleum Significance of Dawsonite from Mesozoic Basins in Northeastern China and Adjacent Area

Dawsonite of Mesozoic strata in Northeast China and adjacent area distribute in Lower Cretaceous strata from Hailaer basin,Tamtsag basin, Erlian basin, Kailu basin and Fuxin basin, and Upper part of Lower Cretaceous and Lower part of Upper Cretaceous from southern Songliao basin. Optical microscope, scanning electron microscope and X-ray diffraction analysis have revealed that dawsonite mainly occur in the feldspar-rich sandstone and pyroclastic rocks, either as cements filling inter-grain pores as radical, bunchy, rosette, intricately trichoid, and platy collectives, or as replacement of feldspar and lithic grains with bunchy and paty shapes. More and more evidences suggest that dawsonite is a indicative mineral of CO₂ rich fluids and record CO₂ and petroleum dual infilling. The infilling time of CO₂ and variation of partical pressure of CO₂ during infilling process can be determined from dawsonite-bearing clastic rocks.