东海北部陆架柱样中底栖有孔虫组合及其古环境研究

Study on Benthic Foraminiferal Assemblages in Core Samples and Their Paleoenvironment on the Northern East China Sea Continental Shelf

东海北部陆架区D-46C和D-74C柱样底栖有孔虫分析结果表明,D-46C柱样自下而上为压扁卷转虫(Am-moniacompressiuscula)组合,并可以进一步划分出压扁卷转虫—花朵虫(A.compressiuscula-Florilusspp.)亚组合、压扁卷转虫—叶状串珠虫(A.compressiuscula-Textularia foliacea)亚组合和压扁卷转虫—强壮箭头虫(A.compressiuscula-Bolivina robusta)亚组合;D-74C柱样自下而上可以划分出三个组合:叶状串珠虫—压扁卷转虫(Textularia foliacea-Ammonia compressiuscula)组合、大西洋花朵虫—异地希望虫(Florilus atlanticus-Elphidium advenum)组合和大西洋花朵虫—结缘寺卷转虫(Florilus atlanticus-Ammonia ketienziensis)组合。两个柱样中底栖有孔虫组合垂向变化明显,结合AMS14C测年结果,初步认为两个柱样均为全新世以来的沉积。其中,D-74C柱样为全新世中期(相当于亚北方期)以来的沉积,在全新世晚期一直受到陆地冲淡水的强烈影响;D-46C柱样为全新世早期(相当于前北方期和北方期)以来的沉积,受到陆地冲淡水流的影响较D-74C柱样小。

It is shown from the analysis results of bentic forminifera in Cores D-46C and D-74C on the East China Sea continental shelf that there is only an Ammonia compressiuscula assemblage in Core D-46C from bottom to top, and this assemblage can be further divided into 3 subassemblages, Ammonia compressiuscula-Florilus spp. subassemblage, A. Compressiuscula-Textularia foliacea subassemblage and A. compressiuscula-Boliuina robusta subassemblage; there are 3 assemblages in Core D-74C from bottom to top, and they are Textulania foliacea-Ammonia compressiuscula assemblage, Floriuls atlanticus-Elphidium advenum assemblage and Florilus atlanticus-Ammonia ketienziensis assemblage. The vertical variations in benthic foraminiferal assemblages in the two cores are obvious, and it is shown from the AMS 14^C dating results that the sediments in the two cores were formed since the Holocene, among them, the sediments in Core D-74C were formed since the Middle Holocene（Subboreal stage） and were strongly affected by the diluted water from the land since the late stage of Holocene; the sediments in Core D-46C were formed since the early stage of Holocene（Preboreal stage and Boreal stage） and were less affected by the diluted water from the land compared with the sediments in Core D-74C.