Benthic macrofauna variations and community structure in Cenomanian cyclic chalk–marl from Southerham Grey Pit, SE England
Benthic macrofauna variations and community structure in Cenomanian cyclic chalk–marl from Southerham Grey Pit, SE England
复制标题
DOI：
10.1144/0016-76492007-164
复制
发表时间：
2009-01
影响因子：
2.7
通讯作者：
B. Lauridsen;A. Gale;F. Surlyk
中科院分区：
文献类型：
--
作者：
B. Lauridsen;A. Gale;F. Surlyk
摘要：英国Cenomanian白垩-泥灰岩对联代表了20 ka Milankovitch岁差旋回。鉴定了白垩和泥灰岩的化石群落，以测试轨道波动和相关的基质岩性和气候变化是否对底栖大型动物施加了任何控制。该材料包括从白垩和泥灰岩半循环中收集的24个散装样品的洗涤残留物。共检索到5055个无脊椎动物标本，涉及68个物种，构成了6个行业认可的基础。总体而言，泥沼区动物群的多样性高于白垩区，但泥沼区和白垩区的群落组合却没有差异，这是令人惊讶的。因此，尽管粘土含量相差约20%，但两种岩性的基质特征对底栖动物的生活方式没有任何影响。动物群显然很好地适应了这两种相，因此适应了基质的细粒度，而不是岩性。白垩和泥灰岩样品多样性的系统差异可能是由长期的气候和海洋变化引起的，因此可能代表了对米兰科维奇旋回的生物响应。
Abstract: Cenomanian chalk–marl couplets from England represent the 20 ka Milankovitch precession cycle. Fossil communities from both chalk and marl are identified to test if the orbital fluctuations and the associated changes in substrate lithology and climate exerted any control on the benthic macrofauna. The material comprises washing residues of 24 bulk samples collected from chalk and marl half-cycles. A total of 5055 invertebrate specimens were retrieved and referred to 68 species, forming the basis for the recognition of six guilds. In general, the fauna is more diverse in marl than in chalk, but it is remarkable and somewhat surprising that the guild assemblages of marl and chalk show no difference. Thus the substrate character of the two lithologies did not exert any influence on the modes of life of the benthic fauna in spite of a difference in clay content of about 20%. The fauna was clearly well adapted to both facies and thus to the fine grain size of the substrate rather than to lithology. The systematic difference in diversity between chalk and marl samples was possibly caused by long-term climatic and oceanographic changes and thus could represent a biological response to Milankovitch cyclicity.