华北地区龙王庙期岩相古地理分析

以层序地层学理论为指导,根据野外露头和钻井资料,建立了华北地区龙王庙期层序地层格架,并在等时地层格架内对岩相古地理特征进行了详细分析,指出龙王庙阶地层以杂色云泥岩、泥云岩、白云岩、页岩和灰岩为主,认为该期地层具有明显的南北厚中间薄、东厚西薄的特点,且研究区东北部和东南部是当时的沉积沉降中心,沉积厚度较大。研究发现,该期沉积相类型主要有陆棚相和潮坪相(泥坪、云坪、泥灰坪和灰坪),华北地台东南部和东侧郯庐断裂附近基底沉降较为强烈,发育陆棚相沉积,其余大部分地区广泛发育潮坪,尤以泥坪相最为发育。值得指出的是,华北地区龙王庙期石家庄-济南一带发育云坪沉积,形成了优质白云岩储层发育区。

Analysis on Lithofacies Palaeogeography at Longwangmiao Stage in North China

Under the guidance of sequence stratigraphic theory and based on outcrops and well drilling data,the sequence stratigraphic framework at Longwangmiao Stage in North China was established,the lithofacies palaeogeographic characters within isochronous stratigraphic framework were analyzed in detail.It was pointed out that during the period there were mainly variegated dolomitic mudstone,argillaceous dolomite,dolomite,shale and limestone,and strata were obviously thicker in the north and south;and thinner in the middle and thicker in the east while thinner in the west.The sedimentary settlement center was in the northeast and southeast of the studied area,where it was the thickest position of deposition.According to the research,there are mainly two kinds of sedimentary facies in the period,such as the shallow continental shelf and tidal flat.Because the areas nearby the Tanlu Fault is subsided more intensively in the southeast and the east of North China platform,continental shelf facies is mostly developed.Tidal flat facies is mostly developed in the rest of areas,especially the mud flat is developed.It is worth to point out that dolomite flat deposits are developed in Shijiazhuang-Jinan Area,where high-quality dolomite reservoirs are developed.