Quantitative analysis of Ostracoda and water masses around Japan; application to Pliocene and Pleistocene paleoceanography
Quantitative analysis of Ostracoda and water masses around Japan; application to Pliocene and Pleistocene paleoceanography
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DOI：
10.2307/1485900
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发表时间：
1993-10
影响因子：
1.5
通讯作者：
N. Ikeya;T. Cronin
中科院分区：
文献类型：
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作者：
N. Ikeya;T. Cronin
为确定日本群岛周围海域的动物地理格局，并将其应用于该地区的上新世和更新世古海洋学，建立了一个介形虫数据库，其中包括273个来自眼镜蛇的样本，包括226个物种。对0-300m水深范围内最常见的59个类群的定量分析表明，介形虫群落受日本周围主要海洋水团的控制，底层水温是影响物种分布的关键因素。研究了黑潮暖流、对马流(津津流和大豆流)、日本海中流、日本海固有水和冷水Oyashio流中的介形类。为了将MODEM CORE TOP数据库应用于介形类化石组合，测试了使用平方弦距离(SCD)相异度量的现代模拟技术(MAT)作为比较化石和现代组合的一种手段。值为0.25或更低的SCD值在当地生态水平(即，在相同的现代海湾内)从岩心顶部数据集中充分识别调制解调器模拟，而值0.25-0.5识别动物地理省水平的调制解调器模拟。MAT方法在日本的3个上新世和11个更新世地层上进行了测试，以检验MAT方法在古海洋重建中的应用。日本群岛横跨广泛的海洋气候带，从北海道东北部的鄂霍次克冷海到琉球群岛外温暖的亚热带海域。日本南部和西部太平洋一侧的海洋气候主要由温暖的黑潮洋流和日本东北部附近寒冷的Oyashio洋流主导。1)。在日本海一侧，地表水主要是对马流，这是黑潮的一个分支，通过狭窄的对马海峡进入日本海。对马洋流还影响到日本群岛的西部沿海地区：一条支流流经本州北部和北海道之间的津沽海峡，另一条支流向东流经大豆海峡，为这两个地区带来了温暖的水。深水由日本海特有的水组成，温度均匀(0℃)，盐度为34/00，含氧量很高。因此，在日本许多地区发现的新近纪晚期和第四纪海洋沉积物为确定日本海和西太平洋一系列气候带的古海洋学历史提供了一个极好的机会。然而，介形虫等古气候工具尚未得到充分开发，无法进行此类研究。海洋介形类在古海洋学研究中很有用，因为许多物种的地理和/或水深分布受到底层水温、氧气和盐度等水团属性的限制。当广泛的物种现代分布的岩心样本数据集与物理海洋学参数的数据相结合时，介形类的实用性最大，基于介形类的古海洋学推断也最可靠。例如，Cronin和Dowsett(1990)扩展了Hazel(1970,1975)和瓦伦丁(1971)的早期工作，根据北大西洋西部100个现代介形虫样本中59个属的最近分布，发展了一个因子分析传递函数来估计古温度。这种方法被应用于化石组合，以估计上新世和更新世的古温度(Cronin 1991a，1991b)。Wood et al.(正在出版中)为从西非到挪威海的北大西洋东部开发了一个类似的最近数据集，该数据集也显示了物种对温度的强烈控制。Dingle和Lord(1990)已经证明，中水和深水介形虫分类群是北大西洋深水、南极底层水和大西洋深层其他水团的有用指示器。在日本，石崎一郎(1977)的开创性研究显示了介形类在古海洋学应用中的潜力。在这项研究中，我们描述了日本群岛附近海域广泛的现代介形虫样本数据集，并将其应用于日本各地新近纪晚期和第四纪沉积的古海洋学。我们的主要目标是1)确定生活在日本群岛及其周围海域的最常见的介形虫物种和属；2)确定现代介形虫组合与日本近海主要水团之间的动物地理关系；3)测试现代模拟技术(MAT)作为一种定量和客观地比较化石和现代组合以及估计古温度和古深度的方法。材料和方法我们研究了342个现代样本的介形虫组合，其中一些来自没有数据的未研究地区，另一些来自已发表的文献。样品来自各种类型的箱型芯、活塞型芯和抓斗样品。文本-图2显示了这些样本的分布以及下面讨论的主要区域。本文重点研究了273个海水盐度正常的水域样品，排除了内湾、微咸水环境，从而消除了盐度作为控制物种分布的一个因素。站点微体古生物学，第39卷，第3期，第263-281页，文本-图1-10，表1-5,1993263本内容从WED，255.55.39.255下载，2016年5月25日05：38：16UTC所有使用服从http://about.jstor.org/terms N.Ikeya和T M.Cronin：定量分析日本周围的介形虫和水团：应用于古海洋学
An ostracode data base consisting of 273 samples from coretops and comprising 226 species was developed for the seas around the Japanese Islands to determine zoogeographic patterns and for application to Pliocene and Pleistocene paleoceanography in the area. Quantitative analyses of the 59 most common taxa between 0 and 300m water depth indicate that ostracode associations are controlled by the main oceanic water masses around Japan and that bottom water temperature is a key factor influencing species distributions. Ostracodes from the following water masses were studied: warm Kuroshio Current, Tsushima Current (Tsugaru Current and Soya Current), Japan Sea intermediate water, Japan Sea proper water and cold Oyashio Current. In order to apply the modem coretop data base to fossil ostracode assemblages, the modem analog technique (MAT) using a squared chord distance (SCD) measure of dissimilarity was tested as a means of comparing fossil and modem assemblages. SCD values of 0.25 or less adequately identify modem analogs from the coretop data set at the local ecological level (i.e. within the same modern bay), while values of 0.25-0.5 identify modem analogs at the level of the zoogeographic province. The MAT method was tested against 3 Pliocene and 11 Pleistocene formations in Japan to examine the use of the MAT in paleoceanographic reconstruction. INTRODUCTION The Japanese Islands span a wide range of marine climatic zones from the cold Sea of Okhotsk off NE Hokkaido to the warm, subtropical seas off the Ryukyu Islands. Marine climates on the Pacific side of southern and western Japan are dominated by the warm Kuroshio Current and by the cold Oyashio Current off northeast Japan (text-fig. 1). On the Sea of Japan side, surface water is dominated by the Tsushima Current, a branch of the Kuroshio Current entering the Sea of Japan through the narrow Tsushima Strait. The Tsushima Current also influences western coastal regions of the Japanese Islands: one branch flows through the Tsugaru Strait between northern Honshu and Hokkaido, while another branch flows east through the Soya Strait, bringing warm water to both these regions. Deep water, consisting of Japan Sea proper water, is uniformly cold (0?C), of 34/oo salinity and well oxygenated. Thus, late Neogene and Quaternary marine sediments exposed throughout many regions of Japan provide an excellent opportunity to determine the paleoceanographic history of the Sea of Japan and the western Pacific Ocean across a range of climatic zones. However, paleoclimatic tools such as ostracodes have not yet been adequately developed to conduct such studies. Marine ostracodes are useful in paleoceanographic studies because many species have geographic and/or bathymetric distributions limited by water mass properties such as bottom water temperature, oxygen and salinity. The utility of ostracodes is greatest, and the paleoceanographic inferences based on them are most reliable, when an extensive coretop sample data set of species' modern distributions is coupled with data on physical oceanographic parameters. For example, Cronin and Dowsett (1990), expanding on early work by Hazel (1970, 1975) and Valentine (1971), developed a factor analytic transfer function to estimate paleotemperatures on the basis of the Recent distributions of 59 genera from 100 moder ostracode samples from the western North Atlantic Ocean. This method was applied to fossil assemblages to estimate Pliocene and Pleistocene paleotemperatures (Cronin 1991a, 1991b). Wood et al. (in press) developed a similar Recent data set for the eastern North Atlantic Ocean, from West Africa to the Norwegian Sea, that also showed strong temperature control of species. Dingle and Lord (1990) have shown that intermediate and deep-water ostracode taxa are useful indicators of North Atlantic deep water, Antarctic bottom water and other water masses in the deep Atlantic Ocean. In Japan, Ishizaki's (1977) pioneering study showed the potential of ostracodes for paleoceanographic application. In this study, we describe an extensive modern ostracode sample data set for seas off the Japanese Islands and apply it to the paleoceanography of late Neogene and Quaternary deposits from various parts of Japan. Our main goals are 1) to determine the most common ostracode species and genera living off the Japanese Islands and in surrounding seas 2) to determine the zoogeographic relationship between modern ostracode assemblages and major water masses off Japan and 3) to test the modern analog technique (MAT) as a method designed to quantitatively and objectively compare fossil and modern assemblages and to estimate paleotemperature and paleodepth. MATERIAL AND METHODS We studied ostracode assemblages from a total of 342 moder samples, some from unstudied areas for which there were no data and others from the published literature. Samples came from various types of box cores, piston cores and grab samples. Text-figure 2 shows the distribution of these samples and the major regions discussed below. In this paper we focus our study on 273 samples from waters of normal marine salinity, excluding inner-bay, brackish-water environments, thereby eliminating salinity as a factor controlling species' distributions. Station micropaleontology, vol. 39, no. 3, pp. 263-281, text-figures 1-10, tables 1-5, 1993 263 This content downloaded from 157.55.39.255 on Wed, 25 May 2016 05:38:16 UTC All use subject to http://about.jstor.org/terms N. Ikeya and T M. Cronin: Quantitative analysis of Ostracoda and water masses around Japan: Application to paleoceanography