海南岛万宁地区寒武纪地层及其沉积特征

The Cambrian Lithostratigraphical Sequence and Sedimentary Facies of Wanning Area, Hainan Island

海南岛万宁地区的寒武系为海南岛除三亚地区外迄今所见惟一有化石依据的寒武纪地层。该区寒武纪地层暂命名为美子林组，自下而上可分为３个岩性段：一段为滨—浅海相为主体的陆源碎屑沉积，厚度大于６７３ｍ ；二段为滨海—浅海相含灰质的细碎屑岩沉积，局部见灰岩条带，厚１５６ｍ 以上；三段以浅海—近滨相碳酸盐岩沉积为主体，主要为灰岩、泥灰岩、砂质—粉砂质灰岩、灰质粉砂岩，厚度大于１９６ｍ 。

The Cambrian exposed around Meizilin Village, Lelai Town, Yuanshui Reservoir, Damao Town, Wanning County is so far the only area of Cambrian rocks with palaeontological evidence in Hainan Island except Sanya area. The Cambrian of the Wanning area is named Meizilin Formation by the authors after its type locality, Meizilin Village, where the Cambrian vase shaped fossil Cambrothyra sp. was found in its upper part. The succession of the Meizilin Formation is divisible into three units. The lower unit is more than 670m of terrigenous clastic rocks of littoral facies which are dominated by fine to medium grained quartz and feldspathic sandstones partly containing large scale low angle cross beddings, intercalated with minor siltstone and muddy sandstone. The middle unit is a series of littoral neritic facies rocks consisting of fine terrigenous clasts mixed with calcareous matter of 105 to more than 156 meters thick. The main rock types are calcareous sandstone, calcareous siltstone, calcareous muddy sandstone and calcareous silty mudstone intercalated with a very small amount of siltstone and silty mudstone without calcareous matter. The upper unit is more than 196m of limestone, muddy limestone and sandy limestone with horizontal beddings, wavy beddings, and minor small scale cross beddings. This part was deposited in a neritic littoral environment.