CAJ | 학술논문

首次报道的低纬度晚第三纪(新近纪)丰富多样的海相沟鞭藻类,产自南海北部大陆架琼东南盆地西南部的两钻孔(主要是Ya21-1-2井,少量为Ya21-1-1井),经鉴定达40余种.文中仅对其中的31种4亚种进行了照相和对15种2亚种和1新种 (Impletosphaeridium capillare sp. nov.)在我国进行了首次描述;在新近系建立2个沟鞭藻组合:即 Hystrichosphaeropsis obscura组合(下部)和Reticulatosphaera actinocoronata-Polysphaeridium zoharyi组合(上部),并讨论了它们的组合特征及其地质时代,认为其下部的组合时代为中新世,上部的组合时代为上新世.
수차보도적저위도만제삼기(신근기)봉부다양적해상구편조류,산자남해북부대륙가경동남분지서남부적량찬공(주요시Ya21-1-2정,소량위Ya21-1-1정),경감정체40여충.문중부대기중적31충4아충진행료조상화대15충2아충화1신충 (Impletosphaeridium capillare sp. nov.)재아국진행료수차묘술;재신근계건립2개구편조조합:즉 Hystrichosphaeropsis obscura조합(하부)화Reticulatosphaera actinocoronata-Polysphaeridium zoharyi조합(상부),병토론료타문적조합특정급기지질시대,인위기하부적조합시대위중신세,상부적조합시대위상신세.
Rich and varied dinoflagellate cysts dealt with in this paper are obtained from the Neogene subsurface sediments of two offshore wells (mainly from well Ya21-1-2 with a depth of 1827.77-4562.79m, but a few from well Ya21-1-1 with a depth of 2413.98-3703.87m) drilled in the southwestern Qiong Dongnan(or Southeast) Basin, the North Continental Shelf of the South China Sea. More than fourty species belonging to 20 genera of dinoflagellates, Granodiscus granulatus of acritarchs, Pterospermella spp. of chlorophytes, and microforaminifer linings have been identified from well Ya21-1-2, of which 31 species of dinoflagellates are only illustrated and described in this work, including one new species, Impletosphaeridium capillare sp. nov. Two dinoflagellate assemblages have been recognized from the Neogene sediments of well Ya21-1-2 which are as follows in ascending order. 1. Hystrichosphaeropsis obscura Assemblage (at a depth of 3727.65-4562.79m) is marked by the latest occurrences of several species including Cordosphaeridium cantharellus, Bosedinia granulata, Hystrichosphaeropsis obscura and by the presence of Edwardsiella sexispinosa, Selenopemphix crenata and Impletosphaeridium capillare sp. nov. In the assemblage Hystrichokolpoma rigaudiae, H. denticulatum, Lingulodinium machaerophorum, Operculodinium centrocarpum, Polysphaeridium zoharyi, Selenopemphix nephroides, Spiniferites pseudofurcatus and S. ramosus subsp. ramosus are common; Nematosphae-ropsis labyrinthus, Tuberculodinium vancampoae and Stelladinium abei subsp. abei,etc. are rare or low in number. 2. Reticulatosphaera actinocoronata-Polysphae-ridium zoharyi Assemblage (at a depth of 1828.77-3727.65m) is characterized by: the high abundance and diversity,especially Polysphaeridium zoharyi having two times of high abundance in the assemblage, the absolute predominance of chorate cysts or gonyaulacaleans, lacking cavate cysts. Besides,"the highest occurrence"of Reticulatosphaera actinocoronata is interpreted herein as the base of this assemblage. Lingulodinium solarum is restricted to the assemblage, and Tectatodinium pellitum more occurs in the lower part of the assemblage. The above dinoflagellate assemblages are mainly dominated by four genera: Polysphaeridium, Lingulodinium, Operculodinium and Spiniferites. Although occuring in low numbers, the dinocyst taxa Cordosphaeridium cantharellus, Bosedinia granulata, Hystrichosphaeropsis obscura and Impagidinium parado-xum are considered useful for biostratigraphy in our study of the Qiong Dongnan Basin. Age control for the Neogene dinoflagellate assemblages in well Ya21-1-2 is mainly based on unpublished planktic foraminiferas and nannofossils, also on the latest appearances of several dinoflagellate taxa including Cordosphaeridium cantharellus, Bosedinia granulata and Hystrichospha-eropsis obscura. Therefore, the old Hystrichosphae-ropsis obscura Assemblage is considered to be of Miocene in age, and the younger Reticulatosphaera actinocoronata-Polysphaeridium zoharyi Assemblage to be of Pliocene age.