在实测绵竹汉旺和广元何家湾小塘子组(T3t)地层剖面的基础上,详细研究了它们的沉积相.何家湾T3t属浅水环境:滨面砂坝、陆架泥、潮坪和浪控三角洲.汉旺T3t则以显著的深水相为特征:滨面砂坝,海湾泥、中缓坡水道与滑塌席、三角洲前缘沉积.对汉旺剖面所含黄铁矿结核作了初步研究.T3t总的说符合富砂泥缓坡的沉积模式.指出汉旺剖面中部的半深水泥岩标志着龙门山活跃的逆冲构造运动,而以上的HST以至须二段下部厚砂体才是构造活动平静期的产物.认为小塘子组底部滨面砂体极具天然气勘探远景.%Based on the measurements of the Upper Triassic Xiaotangzi Formation (T3t) at Hanwang of Mianzhu and Hejiawan of Guangyuan,this study analyzed its sedimentary environments and facies in details.The Hejiawan T3t is attributed to shallow-water environments:shoreface bar,shelf mud,intertidal flat and wave-dominated delta.The Hanwang T3t is especially characterized by deep-water faces:shoreface bar,gulf-mud,medial-ramp channel and slumping sheets,and delta deposits.Preliminary study of pyrithe nodules collected from the Hanwang profile was also preformed.On the whole,the Xiaotangzi Formation is believed to correspond to the sedimentary model of sand-mud rich ramps.It can be pointed out that the deep-water mudstone at the middle part of Hanwang profile should mark the active thrusting tectonism of Longmenshan while the thick sandstone bodies of HST to lower part of the 2nd Member of Xujiahe Formation might deposit in the quiescence period of Longmenshan tectonic activity.This study suggests that the basal shoreface sandstone body of T3t is of highly potential for natural gas exploration.
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