摘要
据冲绳海槽和琉球海岭东坡17个站位沉积样及定量分析,介形虫分布可划分三个区:槽底区,水深820至2295m,介形虫属种单调,23属60种,Krithe,Cytheropteron等属居优势。北部槽坡区,水深415至932m,介形虫36属44种,其大部分属种系非原地居群。琉球海岭两侧坡区,水深1405至1540m,属种及个体数较多,52属85种,其绝大部分生活在滨海至浅海不同地区,只少数生活在深海区,形成复杂的混合群体。 介形虫分布与水深、盐度、暖流、沉积物、海底地形地貌、浊流及火山活动等环境因素有关。
Based on taxonomic study and quantitative analysis of ostracods in the surface sediment samples collected from 17 sampling stations in the Okinawa Trough and on the eastern slope of the Ryukyu Ridge, three regions different in ostracod distribution may be recognized as follows:1. Trough bottom region: This region covers a wide area of the bottom extending along the bottom axis of the Okinawa Trough, with the southern part broader than the northern. Stations 865, 872, 816, 894, 839, 819, etc. are in this region with water depths ranging from 820 to 2295m. The ostracods are very monotonous in taxa, totalling about 23 genera and 60 species, and the average number of specimens per subsample of dried sediment (20g) is7.7, with Krithe and Cytheropteron as dominant genera of the bathyal and abyssal forms2. Northern trough slope region: This region includes the two northern slopes of the trough covering a rather narrow area. Stations 837, 920 and 841 are in this region, with water depths of Stations 837 and 920 ranging from 415 to 456m and Station 841 measuring 932m. The ostracod assemblage comprises about 36 genera and 44 speeies; its abundance is higher than that of the ostracod assemblage in the trough bottom region, amounting to 73 specimens per subsample of dried sediment (20g), with Argilloecia, Krithe, Cytheropteron, Bradleya, etc.,as the dominant genera. This is a guide evidence indicating that most of them are not autochthonous populations of this region but are accumulated as a result of transportation.3. Ryukyu Ridge slope region: This region covers both slopes of the Ryukyu Ridge, i. e., the area between Kumejima and Miyako on the eastern part of Chiwei Yu in the southern Okinawa Trough. Stations 814 and 881 are in this region, with water depths ranging from 1405 to 1540m. Both abundance and diversity of the ostracods are much higher in this region than in the other two regions, with about 52 genera and 85 species. The average number of specimens per subsample of dried sediment(20g) is 200. Besides the most dominant genera Xestoleberis, Krithe and Cytheropteron, other genera such as Cushmanidea, Loxoeoncha. Cornucoquimba, Parac'ytheridea and Aurila are also abundant. Most of the genera are characteristic of littoral to neritic environment, only a few are cha- racteristic of deep water. Therefore, the ostracod assemblage in this region is in f(?)et a mixed accumulation with a large part of its components transported from adjacent environments. The ostracod assemblages from Stations 882 and 884 on the eastern slope of the Ryukyu Ridge are very similar to that of the Trough bottom region. A brief account on the influence of environmental factors, such as water depth, salinity, warm current, surface sediments, bottom topography, tarbidity current, volcanic activities, etc., on the distribution of ostracods in the Okinawa Trough is included.
出处
《微体古生物学报》
CSCD
北大核心
1989年第1期1-10,共10页
Acta Micropalaeontologica Sinica
