珠江三角洲PRD16孔微体生物记录与晚更新世以来的古环境重建  

Microfossil Records of Borehole PRD16 and Palaeoenvironment since the Late Pleistocene in the Pearl River Delta

作　　者：庄畅[1] 刘春莲[2] 吴洁[2] 杨婷婷[2,3] 殷鉴[2] 

机构地区：[1]广州海洋地质调查局,广东广州510760 [2]中山大学地球科学系,广东广州510275 [3]广东省地质过程与矿产资源探查重点实验室,广东广州510275

出　　处：《中山大学学报（自然科学版）》2013年第3期128-132,138,共6页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：国家自然科学基金资助项目(40872024);德国学术交流中心(DAAD)与国家留学基金委(CSC)国际合作交流基金联合资助项目

摘　　要：对珠江三角洲PRD16孔的微体动物群进行了分析,共发现底栖有孔虫12属24种,介形类9属13种,它们可分别划分为3种生态类型。根据有孔虫和介形类微体动物群的分布特征、并结合岩性和沉积粒度特征,推断PRD16孔研究区晚更新世以来沉积环境演化经历了5个阶段:①34 600 cal a BP以前为河流相环境,形成了研究区最早的第四纪河床相砂砾沉积;②34 600～23 900 cal a BP推测为河口湾环境;③23 900～7 960 cal aBP受末次盛冰期影响,研究区暴露地表遭受风化剥蚀,形成花斑黏土;④7 960～2 810 cal a BP为全新世大海侵时期,研究区为河口海湾环境,发育以广盐性有孔虫和中盐-多盐性介形类为主的微体动物群,其间发生了2次小规模海平面波动,受地块区域沉降作用影响,研究区在3 873 cal a BP左右水深达到最大,主要有孔虫和介形类属种的丰度达到全新世最高值;⑤2 810 cal a BP以来海平面持续下降,研究区由潮坪环境变为河口砂坝,随后河流作用增强,又逐渐变为河流冲积-潮上带环境。Microfaunas of borehole PRD16 in the Pearl River Delta have been quantitatively analyzed in this paper. A total of 24 benthic foraminifera species referred to 12 genera and 13 ostracod species referred to 9 genera were found in the borehole. They can be divided into 3 ecological groups. The microfaunal analytical results, combined with lithological and sedimentary grain characteristics, suggest that the study area experienced environmental changes since the Late Pleistocene. A riverine environment be- gan to develop before 34 600 cal a BP. Between 34 600 and 23 900 cal a BP, the environment generally changed to an estuarine condition. Between 23 900 and 7 960 ca1 a BP, the sediments experienced weathering and erosion, characterized by a layer of mottled clay. At around 7 960 cal a BP, sea level rose rapidly and an estuary environment with euryhaline foraminifera and brackish ostracod faunas existed until 2 810 cal a BP. Two second-order sea level fluctuations can be recognized based on the composition and abundance of microfaunas. The maximum water depth occurred at approximately 3 873 cal a BP, demonstrated by the highest abundance of foraminifera and ostracods in the borehole. Since 2 810 cal a BP, the environment gradually changed into a fluvial supratidal zone with increased influence of river processes.

关 键 词：珠江三角洲 有孔虫 介形类 晚第四纪 古环境 

分 类 号：P534.63[天文地球—第四纪地质学]