DOI: 10.1016/j.palaeo.2014.12.001
论文题名: Paleoecology of pelmatozoan attachment structures from a hardground surface in the middle Silurian Massie Formation, southeastern Indiana
作者: Thomka J.R. ; Brett C.E.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 420 起始页码: 1
结束页码: 12
语种: 英语
英文关键词: Crinoidea
; Echinodermata
; Holdfasts
; Holocystites Fauna
; Wenlock
英文摘要: The contact between the basal limestone and overlying mudstone interval of the Massie Formation (Silurian: Wenlock, Sheinwoodian) represents a major flooding surface that is well exposed at the New Point Stone quarry at Napoleon, southeastern Indiana. At this locality, this surface is a locally microbiohermal hardground encrusted by numerous attachment structures of both crinoids and blastozoan echinoderms. The distribution of attachment structure morphologies is nonrandom with respect to variations in substrate properties and microtopographic relief. Discoidal structures and thecal attachments, predominantly representing diploporites, are concentrated on fine-grained, winnowed crests of the undulatory surface, reflecting the stability of this substratum. Complex root-like and runner-type structures, attributable to long-stemmed crinoids and rhombiferans, dominate the coarser, muddier, poorly sorted hardground troughs, reflecting the need for greater surface area in more unstable, rubbly areas. Microbioherms are densely encrusted by thickened radix systems belonging to long-stemmed pelmatozoans. The cause of thickening is unclear but may represent a pathologic response to some biotic interaction or investment by encrusting taxa in crustose holdfasts in order to prevent dislodgement. This study supports previous interpretations of pelmatozoan attachment paleoecology wherein solid, permanent discoids preferentially encrusted stable, homogenous substrata, whereas more complex structures were needed to occupy more heterogeneous and presumably less stable substrata. Thus, the hardground studied here highlights the strong influence of substrate variations in influencing paleoecological dynamics in topographically complex carbonate settings, possibly leading to locally increased alpha diversity and development of biofacies not typically encountered in certain normal marine environments. © 2014 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69044
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geosciences, University of Akron, Akron, OH, United States; Department of Geology, University of Cincinnati, Cincinnati, OH, United States
Recommended Citation:
Thomka J.R.,Brett C.E.. Paleoecology of pelmatozoan attachment structures from a hardground surface in the middle Silurian Massie Formation, southeastern Indiana[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,420