北海外沙泻湖全新世硅藻、有孔虫组合与沉积相演化

Diatom,Foraminifera Assemblages and Evolution of Sedimentary Facies in the Holocene Strata of Waisha Lagoon,Beihai

关键词:  全新世泻湖  硅藻  有孔虫  沉积相

Key words:  Holocene lagoon  diatom  foraminifera  sedimentary facies

摘要:

系统分析北海外沙泻湖CK10钻孔岩芯的硅藻、有孔虫、介形虫化石,并进行¹⁴C年代测定,探讨硅藻、有孔虫组合特征、沉积相演化和地层年代。该孔全新世地层硅藻化石群自下而上划分为:Ⅰ.波缘曲壳藻(Athnanthes crenulata)-亲缘桥弯藻(Cymbella affinis)-披针桥弯藻(Cym.lanceolata),Ⅱ.亲缘桥弯藻-波缘曲壳藻-卵形菱形藻(Nitzschia cocconeiformis),Ⅲ.亲缘桥弯藻-波缘曲壳藻-史密斯双壁藻(Diploneis smithii),Ⅳ.波缘曲壳藻-亲缘桥弯藻-条纹小环藻(Cyclotella striata),Ⅴ.卵形菱形藻-具槽直链藻(Melosira sulata)-柱状小环藻(Cyc.stytorum),Ⅵ.条纹小环藻-柱状小环藻,Ⅶ.具槽直链藻-条纹小环藻-卵形菱形藻,Ⅷ.柱状小环藻等8个硅藻组合带。有孔虫群自下而上划分为:Ⅰ.毕克卷转虫变种(Ammonia beccarii var.)-瘦瘪雅得虫(Jadammina macrescens),Ⅱ.毕克卷转虫变种-异地希望虫(Elphidium advenum)-球室刺房虫(Schackoinella globosa),Ⅲ.毕克卷转虫变种-卡纳利拟单拦虫(Haplophragmoides canariensis),Ⅳ.毕克卷转虫变种-异地希望虫,Ⅴ.毕克卷转虫变种-褐色砂粟虫(Miliammina fuasca)。北海外沙泻湖自全新世早期以来经历了河漫滩相→河口沼泽相→河漫滩相→河口沼泽相→河口湾相→半封闭泻湖相→河口湾相→半封闭泻湖相的演化过程。北海外沙泻湖全新世地层可划分为早全新世(10000 aB.P.~8000aB.P.),中全新世(8000aB.P.~2500aB.P.),晚全新世(2500aB.P.~现代)。

Abstract:

Diatom, Foraminifera, Ostracoda fossils and its features of assemblages, evolution of sedimentary facies in Waisha Lagoon, Beihai, were analysed systematically. Strata ages had been discussed by ¹⁴C dating. Holocene Diatom fossils of the drill hole could be divided from bottom to top:Ⅰ. Athnanthes crenulata-Cymbella affinis-Cym. lanceolata, Ⅱ. Cym. affinis-Ath. crenulata-Nitzschia cocconeiformis, Ⅲ. Cym. affinis-Ath. crenulata-Diploneis smithii, Ⅳ. Ath. crenulata-Cym.affinis-Cyclotella striata,Ⅴ. Nit. cocconeiformis-Melosira sulata-Cyc.stytorum, Ⅵ. Cyc. striata-Cyc.stytorum, Ⅶ. Mel. sulata-Cyc. striata-Nit. cocconeiformis, Ⅷ. Cyc. stytorum. Foraminifera groups from bottom to top:Ⅰ. Ammonia beccarii var.-Jadammina macrescens, Ⅱ. A.beccarii var.-Elphidium advenum-Schackoinella globosa, Ⅲ. A.beccarii var.-Haplophragmoides canariensis, Ⅳ. A.beccarii var.-E.advenum, Ⅴ. A.beccarii var.-Miliammina fuasca. Since early Holocene Waisha Lagoon, Beihai, underwent revotution:riverine flood-plain → river mouth-marsh→ riverine flood-plain → river mouth-marsh→ estuary→ semi-enclosed lagoon → estuary→ semi-enclosed lagoon. Holocence strata could be divided into early-Holocene (1000 aB. P.~8000 aB. P.), middle-Holocence (8000 aB.P.~2500 aB.P.), late-Holocence (2500 aB. P.~present).