Mass-occurrence of oncoids at the Cambrian Series 2–Series 3 transition: Implications for microbial resurgence following an Early Cambrian extinction
Mass-occurrence of oncoids at the Cambrian Series 2–Series 3 transition: Implications for microbial resurgence following an Early Cambrian extinction
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寒武纪系列 2 至系列 3 过渡期间类瘤体的大量出现：对早寒武纪灭绝后微生物复苏的影响
DOI：
10.1016/j.gr.2014.03.015
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发表时间：
2015-08
影响因子：
6.1
通讯作者：
Wang Xinqiang
中科院分区：
文献类型：
--
作者：
Shi Xiaoying;Jiang Ganqing;Tang Dongjie;Wang Xinqiang
传统的中寒武纪-下寒武纪（寒武系2 -寒武系3过渡）以显生宙的第一次生物大灭绝为标志。这种生物危机被认为与海洋化学和/或海洋环境的变化有关，但它们之间的偶然关系仍然存在争议。为了更好地了解这一关键转变时期微生物对古海洋变化的响应，我们研究了华北地台西部巨蜥类生物大量出现的环境条件。中下寒武统过渡时期的蛇状体形成1 ~ 3 m厚的块状层，呈球形-亚球形形态，包含8-14个明暗相间的皮质层状联。轻层较厚，含有密集缠绕的丝状蓝藻，具有钙化的鞘和匍匐生长模式。暗纹层较薄，富含有机质遗迹、黄铁矿树状体和异养细菌。在大多数瘤状体中，皮层层状体的生长方向相同，有5对以上的亮-暗层状体，这表明颗粒倾覆的频率比通常认为的要低得多。浅色和深色纹层均含有保存完好的有机矿化织物/织构，包括细胞外聚合物（eps）、纳米红球、多面体和微球体，表明在高碱度和硫酸盐活性还原的浅海环境中形成了癌状体。黄铁矿树状体和异养细菌遗迹的存在表明底水缺氧/厌氧条件。地层对比表明，时间等效肿瘤岩和其他微生物岩不仅在华北地区广泛存在，而且在全球其他早寒武世序列中也广泛存在。巨石阵的大量赋存与澳大利亚Kalkarindji大火成岩省相吻合，δ13C负偏移（ROECE或Redlichiid-Olenellid灭绝碳同位素偏移）显著，87sr /86Sr显著增加，δ34S正偏移较大。这些事件的巧合表明，早寒武纪生物危机可能是由火山释放的二氧化碳增加、全球变暖和大陆风化作用加剧造成的海洋缺氧事件引起的。大量肿瘤的保存可能与寒武纪早期生物危机后后生动物放牧减少有关，在此期间，古ocyathids和许多寒武纪早期三叶虫类群灭绝。蛇尾纲的大量出现为伴随早寒武纪灭绝事件的缺氧/厌氧海洋陆架环境中微生物生命的复苏提供了证据。
The traditional Lower–Middle Cambrian transition (Cambrian Series 2–Series 3 transition) is marked by the first major biotic extinction of the Phanerozoic Eon. This biotic crisis has been arguably linked to changes in ocean chemistry and/or marine environments but their casual relationships remain controversial. To better understand the microbial responses to paleoceanographic changes across this critical transition, we have studied the environmental conditions for mass–occurrence of oncoids in the western North China Platform. Oncoids at the Lower–Middle Cambrian transition form 1 to 3-m-thick massive beds, show spherical–subspherical morphology, and contain 8–14 light–dark cortical laminar couplets. The light laminae are thicker and contain densely intertwined filamentous cyanobacteria that have calcified sheaths and a prostrate growth pattern. The dark laminae are thinner and rich in organic matter relics, pyrite framboids, and heterotrophic bacteria. In most oncoids, cortical laminae show the same growth orientation for more than five light–dark laminar couplets, suggesting much less frequent grain overturning than generally thought. Both light and dark laminae contain well-preserved organomineralization fabrics/textures including extracellular polymeric substances (EPSs), nanoglobules, polyhedrons, and micropeloids, suggesting oncoid formation in shallow-marine environments with high alkalinity and active sulfate reduction. The presence of pyrite framboids and heterotrophic bacterial relics implies anoxic/dysoxic bottom-water conditions. Stratigraphic correlation indicates that time-equivalent oncolites and other microbialites are widespread not only in North China, but also in other Early Cambrian successions globally. The mass-occurrence of oncoids coincides with the Kalkarindji large igneous province of Australia, a prominent negative δ13C excursion (ROECE or Redlichiid–Olenellid Extinction Carbon isotope Excursion), a significant increase in87Sr/86Sr, and a large positive shift in δ34S. The coincidence of these events suggests that the Early Cambrian biotic crisis may have been caused by an ocean anoxic event resulting from enhanced volcanic release of CO2, global warming, and increased continental weathering. Preservation of massive oncolites is likely related to decreased metazoan grazing following an Early Cambrian biotic crisis, during which archaeocyathids and many Early Cambrian trilobite taxa went to extinction. The oncoid mass-occurrence provides evidence for the resurgence of microbial life in anoxic/dysoxic marine shelf environments concomitant with the Early Cambrian extinction event.
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DOI：
10.1016/s0031-0182(01)00476-x
发表时间：
2002-06
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
M. Whalen;J. Day;G. Eberli;P. Homewood
通讯作者：
M. Whalen;J. Day;G. Eberli;P. Homewood
DOI：
10.1016/j.palaeo.2010.07.001
发表时间：
2010-10
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
--
作者：
R. Howley;G. Jiang
通讯作者：
R. Howley;G. Jiang
影响因子：
2
作者：
B. C. Youngs
通讯作者：
B. C. Youngs
影响因子：
--
作者：
S. Peng
通讯作者：
S. Peng
影响因子：
5.8
作者：
A. Draut;P. Clift
通讯作者：
A. Draut;P. Clift