CAJ | 학술논문

珠江三角洲是世界上主要河口三角洲之一，自晚更新世开始形成，其沉积物中保存了丰富的微体动物壳体，它们是重建晚第四纪古环境极为有效的指标。本文对珠江三角洲东部PRD17孔的微体动物群（有孔虫和介形类）进行了分析，共发现有孔虫14属29种，介形类14属17种，将其分别划分为3种生态类型。根据微体动物群的组成特征，并结合测年数据、岩性、沉积物粒度及颜色反射率等特征，重建了PRD17孔晚第四纪以来的环境演化。约43400 cal a B.P．以前，钻孔所在地发育河流相沉积。晚更新世玉木亚间冰期开始，南海海平面回升，本区开始形成第四纪以来的第一个海相层位。从微体动物群的组成和丰度可识别出3次小规模的海平面波动。约35400～30900 cal a B.P．为晚更新世最大海侵时期，微体动物群的丰度和分异度都达到峰值。约25900 cal a B.P．以后，海水逐渐退出。末次冰盛期的海平面大幅下降，导致本区上更新统沉积物暴露地表遭受风化剥蚀，形成珠江三角洲普遍发育的花斑状黏土层。由于钻孔所在地地势相对较高，受全新世海侵的影响较珠江三角洲其它地区晚，直到6000 cal a B.P．左右才重新接受沉积，初期发育上潮间带沉积。约3700 cal a B.P．开始，逐渐变为受潮水影响较显著的潮坪环境。
주강삼각주시세계상주요하구삼각주지일，자만경신세개시형성，기침적물중보존료봉부적미체동물각체，타문시중건만제사기고배경겁위유효적지표。본문대주강삼각주동부PRD17공적미체동물군（유공충화개형류）진행료분석，공발현유공충14속29충，개형류14속17충，장기분별화분위3충생태류형。근거미체동물군적조성특정，병결합측년수거、암성、침적물립도급안색반사솔등특정，중건료PRD17공만제사기이래적배경연화。약43400 cal a B.P．이전，찬공소재지발육하류상침적。만경신세옥목아간빙기개시，남해해평면회승，본구개시형성제사기이래적제일개해상층위。종미체동물군적조성화봉도가식별출3차소규모적해평면파동。약35400～30900 cal a B.P．위만경신세최대해침시기，미체동물군적봉도화분이도도체도봉치。약25900 cal a B.P．이후，해수축점퇴출。말차빙성기적해평면대폭하강，도치본구상경신통침적물폭로지표조수풍화박식，형성주강삼각주보편발육적화반상점토층。유우찬공소재지지세상대교고，수전신세해침적영향교주강삼각주기타지구만，직도6000 cal a B.P．좌우재중신접수침적，초기발육상조간대침적。약3700 cal a B.P．개시，축점변위수조수영향교현저적조평배경。
The Pearl River Delta,formed since the Late Pleistocene,is one of the major delta in the world .There are abundant microfaunas preserved in sediments of the Pearl River Delta,which have been proved to be essential for reconstructing Quaternary environment.In this study,Microfaunas (foramini-fers and ostracods)of borehole PRD17 from the eastern Pearl River Delta have been analyzed quantita-tively.A total of 29 foraminiferal species belonging to 14 genera and 17 ostracod species referred to 14 genera were identified.They can be divided into three different groups with respect to their ecological ranges.Based on the comprehensive analysis of microfaunas,lithological and sediment grainsize charac-teristics of core samples,palaeoenvironmental changes since the Late Pleistocene can be reconstructed. Before ~43 400 cal a B.P.,a fluvial environment was recorded in the borehole until the late Wurm In-terglacial Stage when the first Quaternary marine unit began to lie down.During this transgressive inter-val,three short-term environmental fluctuations of water depth can be recognized base on microfaunal da-ta.A peak transgression of the Late Pleistocene was marked between ~35 400 and 30 900 cal a B.P.. Since about 25 900 cal a B.P.,sea waters gradually retreated from the study area and the Upper Pleis-tocene sediments were subsequently subaerially exposed during the Last Glaciation Maximum,which is indicated by a mottled clay layer in the core.Around ~6 000 cal a B.P.,the postglacial sea level rise initiated a new phase of the Holocene sedimentation.This timing was later than in other parts of the Pearl River Delta because core site is located in the Guangzhou-Panyu fault block with a higher elevation during the Early-Middle Holocene.A supralittoral-zone environment developed during the first phase of Hol-ocene sedimentation.Since ~3 700 cal a B.P.,the study area gradually changed into a tide flat envi-ronment with microfossils sporadically present.