Dbk: Created page with "This zonal concept is only used in parts of East Anglia, where the standard zonal equivalents (= ''O. pilula'' & ''G. quadrata'' zones) cannot always be separately recognised...."

2013-09-26T14:18:42Z

Created page with "This zonal concept is only used in parts of East Anglia, where the standard zonal equivalents (= ''O. pilula'' & ''G. quadrata'' zones) cannot always be separately recognised...."

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This zonal concept is only used in parts of East Anglia, where the standard zonal equivalents (= ''O. pilula'' & ''G. quadrata'' zones) cannot always be separately recognised. However, in the BGS Trunch Borehole [TG 2933 3455], Wood & Morter (1994) were able to tentatively infer the limits of the traditional ''O. pilula'' and ''G. quadrata'' zones.

'''Base''': The base of the zone is placed at the top of the underlying ''M. testudinarius'' Zone (Peake & Hancock, 1970), presumably immediately above the highest occurrence of ''M''. ''testudinarius''. In Norfolk, there is no evidence of the ''U. anglicus'' Zone that usually immediately overlies the ''M. testudinarius'' Zone, and Wood & Morter (1994) suggested that there might be a non-sequence between the ''testudinarius'' and ''pilula'' zones in the Trunch Borehole.

'''Top''': The top of the zone is immediately below the base of the Pre-Weybourne Chalk.

'''Range of index species''': Peake & Hancock (1970) implied that ''Gonioteuthis'' 'belonging to the ''granulata-quadrata'' evolutionary series' occurred throughout the zone, but there is no precise range data, presumably because of poor exposures through this interval in East Anglia.

'''Key fauna''':
{| class="Wikitable"
| Porifera: || ''Retispinopora arbusculum''
|-
| Bivalvia: || ''Hypoxytoma tenuicostatum''
|-
| ||''Sphenoceramus'' (''Inoceramus'') ''lingua''
|-
| Belemnoidea: || ''Actinocamax versus''
|-
| ||''Belemnitella'' spp.
|-
| ||''Gonioteuthis'' spp.
|-
| Asteroidea: || ''Pycniaster magnificus''
|-
| ||''Stauranderaster senonensis''
|-
| Crinoidea: || ''Bourgueticrinus'' sp.
|-
| Echinoidea: || ''Echinocorys tectiformis''
|-
| ||''E''. spp.
|-
| ||''Micraster schroederi''
|-
| ||''Offaster pilula ''
|}
'''Faunal abundance & preservation''': The zone is poorly fossiliferous.

'''Bio-markers''': Locally the equivalent of the ''O. pilula'' or ''G. quadrata'' Zone of the standard zonal scheme can be recognised. The best example of this is a quarry at Wells [TF 928 429], where morphotypes of ''Echinocorys'' in the lower part of the succession possibly equate with the upper ''E. depressula'' Subzone, and are overlain by moderately common ''Offaster pilula'' and ''Echinocorys'' aff. ''cincta'', suggesting assignment to the Subzone of abundant ''O. pilula'' (Peake & Hancock, 1970). A prominent marl in the Wells succession (Wells Marl) might equate with a marl (Old Nore Marl) in the middle of the ''O. pilula'' Zone in southern England (Wood & Morter, 1994). The first down-hole occurrence of ''Hypoxytoma tenuicostata'' in the Trunch Borehole was in the top of the ''O. pilula'' Zone, and this bivalve occurs in the lower part of the ''Sphenoceramus'' (''Inoceramus'') ''lingua'' Zone (below the ''Discoscaphites binodosus'' Subzone) in northern England (Whitham, 1993).

'''Age''': Campanian.

[[category:Standard zonation | 037]]

Gonioteuthis Zone - Revision history

Dbk: Created page with "This zonal concept is only used in parts of East Anglia, where the standard zonal equivalents (= ''O. pilula'' & ''G. quadrata'' zones) cannot always be separately recognised...."