珠江口盆地白云深水区珠海组石英颗粒表面特征

摘要

Due to the hardness and chemical stability of quartz grains,their surfaces contain numerous microtextures that are formed during transport and deposition by various geological forces.These microtextures can provide evidence for interpreting sedimentary environments and transport mechanisms.The causes of sedimentary quartz grain surface microtextures in the Zhuhai Formation,Baiyun deep-water area,can be divided into three categories,mechanical,chemical,and mechanicalchemical,with 26 subclasses.The most dominant characteristics are subangular shape,V-shaped percussion cracks,straight/curved grooves and scratches,upturned plates,and abrasion fatigue.Sedimentary deposition in the late-Zhuhai Formation in the study area is characterized by medium transport distance,high-energy hydrodynamics(upper flow regime),and saltation.Although the specific sedimentary environment significance of the microfeatures remains to be addressed,this study provides new ideas and evidence for understanding sedimentary processes.%石英具有较大的硬度和较高的化学稳定性,较好地保留了搬运和沉积过程中各种地质营力所形成的微观形貌特征,这些微观形貌可为沉积物搬运机制、沉积环境解释提供依据.通过对珠江口盆地白云凹陷深水区珠海组单颗粒石英的表面形貌特征的研究发现,该组的沉积石英颗粒表面微观形貌类型可划分为机械、化学、机械化学成因等3大类和26小类.其中以次棱角状、V形撞击坑、直弯沟/刻痕、机械上翻片、磨蚀疲劳等碰撞磨蚀压刻等机械成因的微观形貌特征最为突出,表明研究区珠海晚期的沉积作用以中等的搬运距离、高能的水动力条件(上部流动体制)和跃移为主的搬运机制为特征.该研究填补了中国深水区此项研究的空白,虽然这些微观形貌的具体沉积环境意义还有待深入研究,但这将为沉积过程的研究提供新的思路和证据.