Foraminifera, Leg 19 Deep Sea Drilling Project
Foraminifera, Leg 19 Deep Sea Drilling Project
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有孔虫，第 19 段深海钻探项目
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发表时间：
1973
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通讯作者：
R. J. Echols
中科院分区：
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作者：
R. J. Echols
在第19号钻探的11个地点中，有7个地点发现了大量本地有孔虫。其中6个位于白令海，分别是第184、185、188、189、190和191号遗址。第七个是Site 192，位于阿留申群岛以南西北太平洋的明治古约岛的顶端。在前面的站点报告中讨论了在每个站点发现的有孔虫。本节综合了Leg 19遗址的有孔虫生物地层学，并探讨了有孔虫组合的一些古气候意义。有必要采用多种方法对沉积物样品进行分解。来自孔上部的未固结样品在15%的过氧化氢溶液中煮沸时通常很容易分解。然而，在孔的深处，样品变得微固结并抵抗这种处理。在强洗涤剂季铵盐- o中煮沸，对后一种样品进行了尝试，但没有明显的成功。为了充分分解它们以供研究，通常需要使用机械方法，要么用手指将块状物掰开，要么在屏幕上擦来擦去。通过将完全干燥的样品放入varsol或煤油中数小时，然后在水中煮沸，可以分解岩性单元B和C的高度硬化沉积物。所有样品均在63μ目筛上洗涤，但仅对125μ目筛上保留的部分进行了研究。通过125μ筛的检查表明，它含有高达约30%的Globorotalia （Turborotalia）厚皮菌群。浮游有孔虫的种类非常小，以至于大多数通过125μ的筛子就会消失（例如，Globigerina quinqueloba和gloigerinita uvula），在更细的分数检查中从未发现常见。表1至表7显示了浮游生物种类和浮游有孔虫总数以及透明底栖、瓷栖和砂栖有孔虫的丰度估计。在最深的四个地点：183（4718米）、186（4522米）、187（4577米）和193（4811米），本土有孔虫极为罕见。第2章和第5章讨论了几个地点183和186的迁移组合的例子。在其他部位通常有少量砂质试验，但钙质试验是零星发生的。第四纪的特征是丰度从普通或丰富到零的急剧波动，通常在岩心的同一部分内。相比之下，上新世和上中新世在这方面特别差
Significant numbers of indigenous foraminifera were found at seven of the eleven sites drilled on Leg 19. Six of these, Sites 184, 185, 188, 189, 190, and 191, are in the Bering Sea. The seventh, Site 192, is at the top of Meiji Guyot in the northwest Pacific Ocean south of the Aleutian Islands. The foraminifera found at each of these sites is discussed in the preceding site reports. This section synthesizes foraminiferal biostratigraphy at Leg 19 sites and explores some of the paleoclimatic implications of the foraminiferal assemblages. It was necessary to apply several methods to disaggregate the sediment samples. Unconsolidated samples from the upper parts of the holes usually disaggregated readily when boiled in a 15% solution of hydrogen peroxide. However, deeper in the holes the samples become sèmiconsolidated and resist this treatment. Boiling in the strong detergent, Quaternary-O, was tried for these latter samples without noticeable success. In order to disaggregate them sufficiently for study, it was usually necessary to use mechanical methods, either breaking lumps apart with fingers or brushing them against the screen. Highly indurated sediment of lithologic Units B and C was disaggregated by placing thoroughly dried samples into varsol or kerosene for several hours and then boiling them in water. All samples were washed on a 63μ mesh sieve, but studies were carried out only on the fraction retained on a 125μ mesh sieve. Checks of the fraction passing through the 125μ sieve showed it to contain up to approximately 30% of Globorotalia (Turborotalia) pachyderma populations. Species of planktonic foraminifera so small that most would be lost through a 125μ sieve (for example, Globigerina quinqueloba and Globigerinita uvula) were never found to be common in checks of the finer fraction. Tables 1 to 7 show estimates of abundance for planktonic species and for total planktonic foraminifera and hyaline, porcelaneous, and arenaceous benthic foraminifera. Indigenous foraminifera are extremely rare at the four deepest sites: Sites 183 (4718 m), 186 (4522 m), 187 (4577 m), and 193 (4811 m). A few examples of displaced assemblages at Sites 183 and 186 are discussed in Chapters 2 and 5. At other sites there are usually a few arenaceous tests throughout, but occurrences of calcareous tests are sporadic. The Quaternary is characterized by sharp fluctuations in abundance from common or abundant to zero, often within the same section of a core. In contrast, the Pliocene and upper Miocene is exceptionally poor in