Paleogene and Neogene diatoms from the Falkland Plateau and Malvinas Outer Basin : Leg 36, Deep Sea Drilling Project.
Paleogene and Neogene diatoms from the Falkland Plateau and Malvinas Outer Basin : Leg 36, Deep Sea Drilling Project.
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福克兰高原和马尔维纳斯外盆地的古近纪和新近纪硅藻：深海钻探项目第 36 段。
DOI：
10.2973/dsdp.proc.36.111.1977
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
A. Gombos
中科院分区：
文献类型：
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作者：
A. Gombos
新第三纪和古第三纪硅藻分布从六个地点位于阿根廷盆地，马尔维纳斯外盆地，和福克兰群岛高原。基于硅藻的生物地层分带建议的部分晚古新世从网站327和晚始新世和渐新世从网站328。描述了五个新的硅藻分类群。1.第36航段于1974年4月4日在阿根廷乌斯怀亚开始，1974年5月22日在巴西里约热内卢结束。最初的巡航计划要求调查斯科舍海的演变和绕极流系统的发展。然而，恶劣的天气和其他问题迫使重新安排了巡航计划。重点转移到福克兰高原和大西洋最南端的演变问题上。六个站点被占用（图1）。其中，四个是成功的（站点327，328，329和330）;其他两个（站点326和331）导致只有一个和两个近地表岩心回收，分别。其中三个成功的地点（327、329和330）位于福克兰高原东端的莫里斯尤因浅滩。第四个地点（328）位于福克兰高原以东的马尔维纳斯外盆地。在第36条腿的网站上遇到的年龄从晚古新世到最近的硅藻。在328号和329号站点，广泛的新近纪剖面被穿透。在328号现场穿透了上始新世至上渐新统层序。在327号遗址发现了古新世晚期。表1概述了第36航段取芯作业。方法：在钻井作业期间，当岩心收集器被带到甲板上时，对所有岩心收集器的样本进行常规检查。在时间允许的情况下，对岩心顶部和底部的样品进行了检查。在钻井作业期间对这些样品进行的检查确定了每个地点的淤泥质沉积物的范围。钻井作业完成后，对岩心进行常规取样，以备将来进行岸基调查。为此目的，从每个岩心剖面的顶部和底部附近以及从所有含碎屑沉积物的岩心中以约30至50 cm的间隔采集10 cc的样品。还在岩心内的选定间隔处（如岩性边界处）取样。根据McCollum（1975）描述的方法制备样品用于岸基调查。有必要对某些样品进行筛分（45 μ m），以浓缩硅藻。除非另有说明，否则从这些样品中获得的丰度均以稀有表示。将由每种制备物制备的载玻片固定在Hyrax中。使用配备100 ×、40 ×和16 ×物镜和Nomarski微分干涉衬度（DIC）的Zeiss Standard RA研究显微镜对制备的载玻片进行显微镜检查。所有显微照片均使用Nikon AFM 35-mm照相机在Panatomic-X胶片上拍摄。在佛罗里达州立大学的地质系，用连接到ISI Super Mini Scan电子显微镜的35 mm Nikon照相机拍摄扫描电子显微照片。选择的标本和模式种定位在显微镜载玻片上的方法是一个Leitz钻石针对象标记适用于蔡司显微镜。船上采集的所有样品均在海岸进行了检查，但329号现场采集的样品除外，共计103份。其中，每五个样品进行了检查，必要时检查了中间样品。使用Andrews（1972）建议的方法对分类群的相对频率进行了估计。如果在400 ×条件下10次扫描载玻片期间观察到一个或两个瓣膜或瓣膜碎片，则将样品定义为含有痕量硅藻。如果在400 ×下10次遍历期间未观察到瓣膜或瓣膜碎片，则将样品定义为无硅藻。总硅藻丰度的估计是罕见的，频繁的，常见的，丰富的。根据瓣膜破坏的程度，保存指示为差、中等或良好（P、M、G）。在160 ×和400 ×下系统扫描每个散布的载玻片，直至穿过约40%至50%的18 mm × 18 mm盖玻片。根据需要在400 ×或1000 ×下进行特异性鉴定。
The distribution of Neogene and Paleogene diatoms from six sites located in the Argentine Basin, the Malvinas Outer Basin, and on the Falkland Plateau is presented. Biostratigraphic zonations based on diatoms are proposed for part of the late Paleocene from Site 327 and for the late Eocene and Oligocene from Site 328. Five new diatom taxa are described. INTRODUCTION Leg 36 started at Ushuaia, Argentina, on 4 April 1974 and ended at Rio de Janeiro, Brazil, on 22 May 1974. The original cruise plan called for an investigation of the evolution of the Scotia Sea and the development of the Circumpolar Current system. However, bad weather and other problems forced a reorganization of the cruise plan. Emphasis was shifted to problems of the evolution of the Falkland Plateau and the southernmost Atlantic. Six sites were occupied (Figure 1). Of these, four were successful (Sites 327, 328, 329, and 330); the other two (Sites 326 and 331) resulted in the recovery of only one and two near surface cores, respectively. Three of the successful sites (327, 329, and 330) are located on the Maurice Ewing Bank on the eastern end of the Falkland Plateau. The fourth site (328) is located in the Malvinas Outer Basin east of the Falkland Plateau. Diatoms ranging in age from late Paleocene to Recent were encountered at the Leg 36 sites. Extensive Neogene sections were penetrated at Sites 328 and 329. An upper Eocene to upper Oligocene sequence was penetrated at Site 328. The late Paleocene was encountered at Site 327. Table 1 summarizes coring operations on Leg 36. METHODS Samples were routinely examined from all core catchers as they were brought on deck during drilling operations. Samples from the top and bottom of core sections were examined as time permitted. Examination of these samples, during drilling operations, established the extent of diatomaceous sediment at each site. After completion of drilling operations cores were routinely sampled for future shore-based investigation. For this purpose, samples of 10 cc were taken from near the top and bottom of each core section as well as at approximately 30 to 50 cm intervals in between from all cores containing diatomaceous sediment. Samples were also taken at selected intervals, such as at lithologic boundaries, within the cores. Samples were prepared for shore-based investigation according to the method described by McCollum (1975). It was necessary to sieve (45 μm) certain samples in order to concentrate the diatoms. Unless noted otherwise, abundances derived from such samples are given as rare. Slides made from each preparation were mounted in Hyrax. Microscopic examination of prepared slides was carried out with the Zeiss Standard RA research microscope equipped with 100X, 40×, and 16× objectives and Nomarski differential interference contrast (DIC). All photomicrographs were taken on Panatomic-X film using a Nikon AFM 35-mm camera. Scanning electron micrographs were taken with a 35mm Nikon camera attached to the ISI Super Mini Scan electron microscope in the Geology Department of Florida State University. Selected specimens and type species were located on the microscope slides by means of a Leitz diamond stylus object marker adapted for use on the Zeiss microscope. All of the samples taken onboard ship were examined on shore with the exception of those from Site 329, which totaled 103. Of these, every fifth sample was examined, intervening samples being examined where necessary. Estimates of the relative frequency of taxa were made using the method suggested by Andrews (1972). A sample was defined as containing a trace amount of diatoms if one or two valves or fragments of valves were observed during 10 traverses of the slide at 400×. A sample was defined as being barren of diatoms if no valves or fragments of valves were observed during 10 traverses at 400 ×. Estimates of gross diatom abundance are given as rare, frequent, common, and abundant. Preservation is indicated as poor, moderate, or good (P, M, G), depending on the extent of valve destruction. Each strewn slide was systematically scanned at 160× and 400× until approximately 40% to 50% of the 18 mm × 18 mm cover slip was traversed. Specific identifications were made at 400× or lOOO× as necessary.