Palaeoenvironment of Maastrichtian ostracods from ODP Holes 1049B, 1050C and 1052E in the Western North Atlantic
Palaeoenvironment of Maastrichtian ostracods from ODP Holes 1049B, 1050C and 1052E in the Western North Atlantic
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北大西洋西部 ODP 孔 1049B、1050C 和 1052E 中马斯特里赫特介形类的古环境
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发表时间：
1999
影响因子：
2
通讯作者：
S. Majoran
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作者：
S. Majoran
对北大西洋西部布莱克鼻湾1049B、1050C和1052E孔中发现的马斯特里赫斯介形类进行了研究。这三处遗址位于一条涵盖中、下半深海、晚白垩世古深度的深度断面上。从马斯特里斯特早期到晚期的14个样品在1052E孔被调查，这是最浅的地点。1052E孔的早期Maastrahtian G.fasostuarti-G.Gansseri带出产罕见的介形类。物种丰富度、丰度和动物群密度在1052E洞的马斯特里赫斯蒂安R.Fucticosa晚期和A.mayaroensis区平均要高得多，这可能至少部分是由于古海洋学变化，这也是该地区双壳类的消失的原因。1049B、1050C和1052E孔记录的马斯特里赫斯晚期介形类组合的对比表明，动物群密度和平均类群数量与古深度呈负相关，而鸭嘴兽属的优势度随着古深度的增加而增加。鸭嘴兽的优势可能意味着与低氧含量有关的环境胁迫。1049B和1050C孔的晚白垩世底栖有孔虫Nuttalides trumpeyi的优势为缺氧提供了额外的证据。在1049B、1050C和1052E孔记录的28个属中，有14个属以前在南大洋的高纬度孔689B记录到，表明许多介形类属在晚白垩世深海表现出广泛的纬度分布，但也存在更多的地理限制的属，类似于现代和第三纪海洋。
The Maastrichtian ostracods recovered from ODP Holes 1049B, 1050C and 1052E on the Blake Nose, Western North Atlantic, are investigated. The three sites are located on a depth transect encompassing middle to lower bathyal, Late Cretaceous palaeodepths. Fourteen samples ranging in age from early to late Maastrictian are investigated from Hole 1052E, which is the shallowest site. The early Maastrichtian G. falsostuarti–G. gansseri Zone of Hole 1052E yields rare ostracods. The species richness, abundance and faunal density are on average considerably higher in the late Maastrichtian R. fructicosa and A. mayaroensis Zones of Hole 1052E, possibly, at least partly, as a result of palaeoceanographical changes that were also responsible for the disappearance of the inoceramid bivalves at this location. A palaeobathymetrical comparsion among the late Maastrichtian ostracod assemblages recorded from Holes 1049B, 1050C and 1052E shows that the faunal density and mean number of taxa are inversely correlated with palaeodepth; however, the dominance of the platycopid genus Cytherella increases with palaeodepth. A dominance of platycopids may signify environmental stress related to low oxygen content. The dominance of the benthic foraminifer Nuttalides trumpeyi in the Late Cretaceous of Holes 1049B and 1050C provides additional evidence of oxygen deficiency. From a total of 28 genera recorded from Holes 1049B, 1050C and 1052E, 14 were previously recorded from Hole 689B, a high latitude hole in the Southern Ocean, and show that many ostracod genera display a wide latitudinal distribution in the Late Cretaceous deep sea, although more geographically restricted genera are also present, analogous with modern and Tertiary oceans.