Middle–late Miocene palaeoenvironments, palynological data and a fossil fish Lagerstätte from the Central Kenya Rift (East Africa)
Middle–late Miocene palaeoenvironments, palynological data and a fossil fish Lagerstätte from the Central Kenya Rift (East Africa)
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中新世中晚期古环境、孢粉学数据和肯尼亚中部裂谷（东非）的鱼类化石沉积
DOI：
10.1017/s0016756815000849
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发表时间：
2017
影响因子：
2.3
通讯作者：
Brüsch
中科院分区：
文献类型：
--
作者：
Rasmussen;Reichenbacher;Altner;Prieto;Brüsch
中新世是东非裂谷系统（EARS）发生重大变化的时期，森林栖息地转变为草原，原始人类出现在景观中。在这里，我们提供了中上新世 Ngorora 地层（图根山、肯尼亚中部裂谷、EARS）的新沉积学和孢粉学数据，以及粘土矿物特征、哺乳动物发现和 Ngorora 鱼 Lagerstätte 的描述。此外，我们引入了c的修订年龄。 13.3 Ma 为 Ngorora 地层的起始点。恩戈罗拉地层的较老部分（约 13.3-12 Ma）记录了湖泊、漫滩和古土壤的低能量环境，方沸石的证据表明湖泊呈碱性。孢粉形态谱由树木花粉（杜松、罗汉松）、大戟科花粉（铁苋菜、巴豆）和禾本科和菊科草本花粉组成，暗示树木繁茂的草原或草木林地。碱性湖泊、洪泛区和古土壤继续上升（约12-9Ma），但环境波动变得更加动态。孢粉型的缺乏和马科动物的存在可能表明气候逐渐干燥。从几乎所有研究部分的独特层中总共发现了约 500 块有节鱼化石，代表了 Haplotilapines（Pseudocrenilabrinae、Cichlidae）的不同谱系。一些鱼类死亡可能是由于水体快速酸化和/或间歇性火山灰坠落造成的窒息。许多地段反复发生的水深突然变化更有可能是由于肯尼亚中部裂谷的同沉积构造活动，而不是气候变化。总体而言，恩戈罗拉鱼 Lagerstätte 的保存是地质构造、碱性湖泊的形成和爆发性火山活动相互作用的结果。由于早于中新世晚期的草原记录很少，我们在肯尼亚中部裂谷发现的中新世中期（12-13Ma）草原草原也与东非人类进化模型有关。
The Miocene epoch was a time of major change in the East African Rift System (EARS) as forest habitats were transformed into grasslands and hominids appeared in the landscape. Here we provide new sedimentological and palynological data on the middle–upper Miocene Ngorora Formation (Tugen Hills, Central Kenya Rift, EARS), together with clay mineral characterizations, mammal finds and a description of the Ngorora fish Lagerstätte. Furthermore, we introduce a revised age of c. 13.3 Ma for the onset of the Ngorora Formation. The older part of the Ngorora Formation (c. 13.3–12 Ma) records low-energy settings of lakes, floodplains and palaeosols, and evidence of analcime indicates that lakes were alkaline. The palynomorph spectrum consists of tree pollen (Juniperus, Podocarpus), Euphorbiaceae pollen (Acalypha, Croton) and herbaceous pollen of Poaceae and Asteraceae, suggestive of wooded grasslands or grassy woodlands. Alkaline lakes, floodplains and palaeosols continue upsection (c. 12–9 Ma), but environmental fluctuations become more dynamic. Paucity of palynomorphs and the presence of an equid may point to progressively drier conditions. A total of about 500 articulated fish fossils were recovered from distinctive layers of almost all sections studied and represent different lineages of the Haplotilapiines (Pseudocrenilabrinae, Cichlidae). Some of the fish kills may be attributable to rapid water acidification and/or asphyxiation by episodic ash falls. Repeated instances of abrupt change in water depth in many sections are more likely to be due to synsedimentary tectonic activity of the Central Kenya Rift than to climatic variation. Overall, the preservation of the Ngorora fish Lagerstätte resulted from the interplay of tectonics, formation of alkaline lakes and explosive volcanism. As records of grasslands that pre-date late Miocene time are rare, our finding of middle Miocene (12–13 Ma) grassy savannah in the Central Kenya Rift is also relevant to models of human evolution in East Africa.
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坦噶尼喀慈鲷的系统学（Teleostei：Perciformes）
影响因子：
1.2
作者：
Tetsumi Takahashi
通讯作者：
Tetsumi Takahashi
影响因子：
3.7
作者：
Gierl C;Reichenbacher B;Gaudant J;Erpenbeck D;Pharisat A
通讯作者：
Pharisat A
DOI：
10.1155/2012/716209
发表时间：
2012
期刊：
International journal of evolutionary biology
影响因子：
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作者：
Kirchberger PC;Sefc KM;Sturmbauer C;Koblmüller S
通讯作者：
Koblmüller S
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影响因子：
--
作者：
M. Pickford
通讯作者：
M. Pickford
影响因子：
3.5
作者：
R. L. Hay
通讯作者：
R. L. Hay