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Discriminating faunal assemblages and their palaeoecology based on museum collections : the Carboniferous Hurlet and Index limestones of western Scotland [abstract only]

Dean, Mark; Owen, A.O.; Bowdler-Hicks, A.; Akhurst, Maxine. 2008 Discriminating faunal assemblages and their palaeoecology based on museum collections : the Carboniferous Hurlet and Index limestones of western Scotland [abstract only]. In: Exploiting Geoscience Collections, London, 12-13 May 2008. 21-22.

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Abstract/Summary

Carboniferous macrofossils from the Scottish Midland Valley, historically accumulated and stored at BGS Edinburgh, often represent the sole remaining source of palaeontological data from the region. Explorative numerical analyses have been undertaken on part of this collection to attempt to discriminate faunal assemblages and their palaeoenvironments and trophic structures in the Hurlet and Index limestones of western Scotland. These analyses compare favourably with published qualitative assessments of the relationship between lithofacies and shelf palaeoenvironment and thus demonstrate that old collections can still be used in modern palaeoecological investigations. Faunas from the limestone units comprise mainly infaunal or epifaunal brachiopods and molluscs. They were collected from 67 localities that yielded 20 and 94 samples from the Hurlet and Index limestones respectively. The raw data was presented by sample locality, subdivided by lithology, and the fossil content was described by major groups, genera and species. Limitations of the data, e.g. differing sample size and its binary (presence/absence) nature, were at least partly overcome by consolidation and restriction of aspects of the dataset. Seriation, cluster analysis and non-metric multidimensional scaling techniques were used on the consolidated binary data using the statistical package PAST, and cluster analysis and Principal Components Analysis (PCA) were used on the abundance data derived from the dataset in terms of numbers of genera in higher taxa. Seriation indicated the lithological and environmental gradients of taxa. Cluster analysis revealed major and nested clusters of samples, linking lithology and the diversity and distribution of taxa. PCA explained the distribution of the clusters in terms of differences in taxonomic composition, trophic structure, lithology and environment. The cluster analysis results were plotted on triangular diagrams of feeding habits and substrate-niches (distinguishing epifaunal suspension and vagrant detrital feeders). Plotting the geographical distribution of the clusters for each limestone provided a synthesis of palaeoenvironmental data. Draping the palaeoenvironmental interpretations over a 3D computer model of the subsurface enhanced our understanding of the influence and control exerted over sedimentation and environments by penecontemporaneous fault movement.

Item Type: Publication - Conference Item (Paper)
Programmes: BGS Programmes 2008 > Information Management
Additional Keywords: Museums, Carboniferous, Limestones, Western Scotland
NORA Subject Terms: Earth Sciences
Date made live: 03 Nov 2008 15:34
URI: http://nora.nerc.ac.uk/id/eprint/4790

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