四川盆地都匀运动不整合及其油气意义

Unconformity of the Duyun Movement in the Sichuan Basin and its significance of petroleum geology

都匀运动在贵州南部表现最明显,得到了广泛的研究和认可,关于这期构造运动在四川盆地内部的表现及其影响的研究较少。根据露头、钻井和地震剖面对不整合的刻画,发现在川中和川西地区上奥陶统宝塔组碳酸盐岩地层上、下存在明显的角度不整合,而二叠系与志留系之间几乎不存在角度不整合。由此认为,都匀运动是影响川中古隆起变形的关键构造运动,志留纪末的广西运动在川中乃至整个四川盆地无褶皱作用发生。都匀运动在川西北地区造成了奥陶系宝塔组的暴露溶蚀,与上覆志留系烃源岩构成上生下储的成藏模式,在川中隆起及周缘造成了褶皱核部和翼部构造裂缝的发育,并加深了震旦系—奥陶系岩溶储层的发育程度。受此影响,川中隆起周缘志留系覆盖区发育震旦系—奥陶系岩溶储层,这些岩溶区是震旦系—奥陶系油气勘探的有利地区。

The Duyun Movement is the most prominent in the south of Guizhou Province and has been studied and accep-ted widely.However,the study on its geological performance and effect within the Sichuan Basin were seldom documen-ted.Unconformity description based on outcrop,drilling and seismic data shows that there is an obvious angle unconformi-ty between the Upper Ordovician Baota Formation and its overlying strata but no obvious angle unconformity is recognized between the Permian and the Silurian in the central and west of the Sichuan Basin,which means the Duyun Movement was the key tectonic movement effecting the formation of Chuanzhong paleo-uplift,the Kwangsian Orogeny occurred at the end of the Silurian did not cause any folding in central even the whole Sichuan Basin.The Duyun movement caused the exposure and erosion of the Ordovician Baota Formation in northwest of the Sichuan Basin,which constitute,together with the overlying Lower Silurian source rock,a new hydrocarbon accumulation model of upper source rock and lower reser-voir.The movement also caused the formation of fractures in the core and flank area of Chuanzhong paleo-uplift and strengthened the formation of karst in the Sinian-Ordovician.It is proved that the Sinia-Ordovician karst reservoirs are well developed in areas covered by the Silurian around the Chuanzhong paleo-uplift,which are favorable exploration areas.