Latest Cenomanian—earliest Turonian low-oxygen tolerant benthonic foraminifera: a case-study from the Sergipe basin (N.E. Brazil) and the western Anglo-Paris basin (southern England)
Latest Cenomanian—earliest Turonian low-oxygen tolerant benthonic foraminifera: a case-study from the Sergipe basin (N.E. Brazil) and the western Anglo-Paris basin (southern England)
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最新塞诺曼阶—最早土伦阶耐低氧底栖有孔虫：塞尔希培盆地（巴西东北部）和盎格鲁-巴黎盆地西部（英格兰南部）的案例研究
DOI：
10.1016/0031-0182(90)90130-y
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
M. Hart
中科院分区：
文献类型：
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作者：
E. Koutsoukos;P. Leary;M. Hart
独特的沉积学，地球化学，同位素和micropalaeontological的反应，在缺氧/缺氧的底部条件下沉积的沉积物的性质，在最新的Cenomanian最早的Turonian的世界上大多数盆地。生物区系的组成是对整体环境条件的直接反应。因此，对耐低氧微型动物分布模式的认识，在评估和重建发生此类事件的区域古海洋环境中具有首要重要性。本文以巴西东北部的塞尔吉佩盆地和英格兰南部的盎格鲁-巴黎盆地两个同时代地层层序为例，研究了贫氧环境中的底栖有孔虫组合，它们主要由“机会性”的r-选择物种组成。群落营养结构的基本模式似乎主要决定了生物群的组成。从外陆棚到陆坡上部缺氧环境的生物组合的共同特征是：（1）低多样性;（2）有限的种内变异;（3）优势（c.表生动物、存款摄食、平/凹凸、轮旋、钙质-透明形态型（gavelinellids、conorboidids、rosalinids和bagginids）; 10-30%）的底栖动物，细菌/碎屑清道夫，锥形和细长的形态型（turrilinids，bolivinids，buliminellids，fursenkoinids，polymorphinids和caucasinids）;（5）表栖动物/浅底栖动物，存款进食，透镜状形态型（卷曲vaginulinids）（c. 5-19%）;（6）变量数（c.（7）优势种（约60-80%）为微小（c. 100-200 μm的最大直径，宽度或长度）石灰质-透明类群在广泛的dysaerobic/准厌氧发作。在氧气高度枯竭的海底条件下，没有底栖微型动物。这两个研究区域之间的微小分类差异主要是由于古生物地理的省域性。
Distinctive sedimentological, geochemical, isotopic and micropalaeontological response characterise the nature of sediments deposited under hypoxic/anoxic bottom conditions during the latest Cenomanian to earliest Turonian of most of the world's basins. The composition of the biota is a direct response to overall environmental conditions. The recognition of distribution patterns of low-oxygen tolerant microfauna is, therefore, of primary importance in evaluating and reconstructing the regional palaeoceanographic settings where such events took place. A case-study is presented from two coeval stratigraphic sequences, the Sergipe basin (northeastern Brazil) and the western Anglo-Paris basin (southern England).The associated benthonic foraminiferal assemblages from oxygen depleted environments consist mostly of “opportunistic”, r-selected species. Basic patterns in community trophic structures appear to have primarily dictated the composition of the biota. The assemblages from outer shelf to upper slope oxygen depleted environments are commonly characterised by: (1) low-diversity; (2) limited intraspecific variation; (3) predominance (c. 40–60% of the total foraminiferal assemblage) of epifaunal, deposit feeding, plano/concavo-convex, trochospiral, calcareous-hyaline morphotypes (gavelinellids, conorboidids, rosalinids and bagginids); (4) variable numbers (c. 10–30%) of infaunal, bacterial/detrital scavengers, tapered and elongate morphotypes (turrilinids, bolivinids, buliminellids, fursenkoinids, polymorphinids and caucasinids); (5) epifaunal/shallow infaunal, deposit feeding, lenticular morphotypes (coiled vaginulinids) (c. 5–19%); (6) variable numbers (c. 10–30%) of agglutinated specimens (lituolids, discamminids, eggerellids, textulariids, trochamminids, ammodiscids, tritaxiids and valvulinids); and (7) dominance (about 60–80%) of minute (c. 100–200 μm in maximum diameter, width or length) calcareous-hyaline taxa during widespread dysaerobic/quasi-anaerobic episodes. Highly oxygen depleted bottom conditions are marked by the absence of benthonic microfauna. Minor taxonomic differences between the two studied areas are mostly due to palaeobiogeographic provincialism.