Analysis of Changes in Paleoenvironment using Diatoms from Iselin Bank in the Ross Sea

Abstract

In this study, we analyzed diatoms from core RS15-GC41 collected in Iselin Bank, Ross Sea. A total of 24 genera and 35 species of diatoms are identified, and the having valve abundance of diatoms varies from 0.2 to 28.6×106/g. Four diatom assemblage zones are established by the vertical distribution of diatoms, and changed with a cycle of 100 kyrs. RS15-GC41 were deposited over the last 400 kyrs (corresponding to Marine Isotope Stages 1-11). The open-water species Fragilariopsis kerguelensis, Rhizosolenia styliformis, and Thalassionema nitzschioides abundantly occurred in interglacial periods. Whereas, Actinocyclus actinochilus abundantly dominant during the glacial periods. The distribution of these diatoms indicated, it can be seen that the sea-ice extent was larger and lasted longer during MIS 7, 9, and 11 than that of MIS 1, 3, and 5. Moreover, Paralia sulcata was abundantly predominant in MIS 7, 9, and 11; this finding suggests likely indicating that P. sulcata was transported from the coastal/inner shelf area to the study site, during accumulated in the sediments, reworked with the influx of ice-rafted debris by the currents

로스해의 Iselin Bank 인근에서 채취한 RS15-GC41코어로부터 규조를 분석한 결과 총 24속 35종의 규조를 감정하였으며, 규조 개체수 농도는 0.2-28.6×106/g 범위에 해당하였다. 규조 군집 조성에 의해 4개의 규조 군집대를 설정 하였으며 규조 군집의 변화는 거의 10만년을 주기로 변화 하였다. Marine Isotope Stages 1-11 시기에 RS15-GC41이 퇴적되는 동안 간빙기(Interglacial)에는 open ocean을 지시하는 Rhizosolenia styliformis, Fragilariopsis kerguelensis와 Thalassionema nitzschioides등이 풍부하게 산출되며, 빙기(Glacial)에는 sea-ice종인 Actinocyclus actinocyclus의 산출이 풍부하게 나타난다. MIS 7, 9와 11의 간빙기 동안 MIS 1, 3과 5 시기보다 sea-ice의 분포가 더 넓고 지속 기간이 더 오래 계속되었음을 알 수 있다. Paralia sulcata는 이 시기(MIS 7, 9와 11) 동안 해류에 의한 ice-rafted debris의 유입과 함께 연안지역으로부터 재이동 되었음을 뒷받침 해 준다.