Difference between revisions of "Category:Faunal provincialism in the UK Chalk Group"

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[[category:Biostratigraphy in the Chalk Group | 008]]
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Many authors (e.g. Peake & Hancock, 1970; Wood, 1980; Mortimore, 1986; Mortimore & Wood, 1986 & Wood, 1992) have noted regional differences in chalk facies and fauna, and their published observations are the basis for the following account.
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The fauna and facies of the chalk of Lincolnshire, Yorkshire and north Norfolk differs markedly from that of the rest of England, and the terms Northern Province and Southern Province have generally been applied to these distinct regions. Mortimore (1983) identified a third region, covering much of East Anglia, where the facies and fauna seemed to be transitional between the typical Northern and Southern Province types; this was named the Transitional Province.
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In the Southern Province, the chalk is typically soft, with many nodular flints and intervals containing well developed hardgrounds. The succession contains a diverse fauna, ranging up to the ''B. mucronata'' Zone, and many features are shared with the Chalk Group in northern France.
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In the Northern Province, the chalk is typically much harder, with few nodular flints, and many bands of tabular flint. Intervals containing hardgrounds are rare, and the fauna is generally less diverse, with differences particularly in the brachiopods, inoceramid bivalves and echinoids compared to the Southern Province. The youngest exposed chalk (''O. pilula'' Zone) is older than in the Southern Province, and there is greater similarity with coeval successions in northern Germany. Faunal differences between the two provinces prevents detailed correlation at some levels, and is reflected by differences in the biostratigraphical nomenclature for the two regions. Gaunt ''et al''. (1992) suggested that the lower faunal diversity in the Northern Province might have been caused by a deeper palaeo-marine environment.
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Peake & Hancock (1970) suggested that the boundary between the Northern and Southern provinces might be in the vicinity of Swaffham, in north Norfolk, based on the  occurrence there in the ''S. plana'' Zone of a sponge (''Cystispongia bursa'') and echinoid fauna (''Micraster'' spp. with unusual combinations of morphological features &  common ''Influaster excentricus'') with Northern Province affinities alongside other faunas typical of this zone in southern England. This locality also marked the most northerly development in East Anglia of the hardgrounds that characterise the Chalk Rock and Top Rock, and at both Swaffham and Kipplingcotes (Yorkshire) there are asteroid ossicles in the ''S. plana'' Zone that are more typical of the ''M. coranguinum'' Zone in southern England (Peake & Hancock, 1970).
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[[category:Biostratigraphy of the Chalk Group | 008]]

Revision as of 14:45, 30 September 2013


Many authors (e.g. Peake & Hancock, 1970; Wood, 1980; Mortimore, 1986; Mortimore & Wood, 1986 & Wood, 1992) have noted regional differences in chalk facies and fauna, and their published observations are the basis for the following account.

The fauna and facies of the chalk of Lincolnshire, Yorkshire and north Norfolk differs markedly from that of the rest of England, and the terms Northern Province and Southern Province have generally been applied to these distinct regions. Mortimore (1983) identified a third region, covering much of East Anglia, where the facies and fauna seemed to be transitional between the typical Northern and Southern Province types; this was named the Transitional Province.

In the Southern Province, the chalk is typically soft, with many nodular flints and intervals containing well developed hardgrounds. The succession contains a diverse fauna, ranging up to the B. mucronata Zone, and many features are shared with the Chalk Group in northern France.

In the Northern Province, the chalk is typically much harder, with few nodular flints, and many bands of tabular flint. Intervals containing hardgrounds are rare, and the fauna is generally less diverse, with differences particularly in the brachiopods, inoceramid bivalves and echinoids compared to the Southern Province. The youngest exposed chalk (O. pilula Zone) is older than in the Southern Province, and there is greater similarity with coeval successions in northern Germany. Faunal differences between the two provinces prevents detailed correlation at some levels, and is reflected by differences in the biostratigraphical nomenclature for the two regions. Gaunt et al. (1992) suggested that the lower faunal diversity in the Northern Province might have been caused by a deeper palaeo-marine environment.

Peake & Hancock (1970) suggested that the boundary between the Northern and Southern provinces might be in the vicinity of Swaffham, in north Norfolk, based on the occurrence there in the S. plana Zone of a sponge (Cystispongia bursa) and echinoid fauna (Micraster spp. with unusual combinations of morphological features & common Influaster excentricus) with Northern Province affinities alongside other faunas typical of this zone in southern England. This locality also marked the most northerly development in East Anglia of the hardgrounds that characterise the Chalk Rock and Top Rock, and at both Swaffham and Kipplingcotes (Yorkshire) there are asteroid ossicles in the S. plana Zone that are more typical of the M. coranguinum Zone in southern England (Peake & Hancock, 1970).

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