High resolution δ 13C stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge

Research output: Contribution to journalArticlepeer-review

Standard

High resolution δ 13C stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge. / Marshall, Carly; Thomas, Alan T.; Boomer, Ian; Ray, David C.

In: Bulletin of Geosciences, Vol. 87, No. 4, 2012, p. 669-679.

Research output: Contribution to journalArticlepeer-review

Harvard

APA

Vancouver

Author

Marshall, Carly ; Thomas, Alan T. ; Boomer, Ian ; Ray, David C. / High resolution δ 13C stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge. In: Bulletin of Geosciences. 2012 ; Vol. 87, No. 4. pp. 669-679.

Bibtex

@article{e017cab128574894967e4997c925d969,
title = "High resolution δ 13C stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge",
abstract = "High resolution δ 13C calb data are presented for two composite sections in England covering much of the Homerian Stage. Micrite samples collected at ~0.5 m intervals from outcrop and core in the Dudley area, West Midlands, span the upper-most Coalbrookdale, Much Wenlock Limestone and basal Lower Elton formations. Deposition there occurred in a mid-shelf setting. A similar suite of samples from the Wenlock type area, Wenlock Edge, Shropshire, represents a coeval sequence deposited closer to the shelf-basin margin. The successions concerned extend from the upper lundgreni to nilssoni graptolite biozones and provide a detailed record of variation in stable carbon isotope ratios across the well-known double-peaked Homerian positive excursion (Mulde Excursion), a time of significant global biological and chemical perturbation. In the West Midlands, this excursion occurs in the Much Wenlock Limestone Formation. The lower peak (Lower Quarried Limestone Member) has δ 13C calb values rising to +5.5%o VPDB. Values fall to +0.8%c VPDB higher in the section before rising again to +4.1%o VPDB (Nodular Beds Member). Analysis of lithofacies varia-tion in this interval indicates two transgressive-regressive cycles, the two positive peaks of the excursion correlating with relative sea-level lows and the intervening dip with a relative sea-level high, the local expression of Johnson's (2006) Highstand 5A. The double-peaked nature of the excursion at Dudley resembles that previously recorded for the area; however, our δ 13C carb values are consistently 2%c higher, and accord more closely with values published for sec-tions elsewhere. The lower of the two peaks found in the West Midlands cannot be identified on Wenlock Edge, where 813Ccarb values fluctuate somewhat around +2%c VPDB. The upper peak, though less distinct, can be identified on Wenlock Edge with values rising to +3.8%c VPDB. Correlations based on biostratigraphy, sequence stratigraphy and bentonite geochemistry suggest that not all changes in δ 13C calb occurred synchronously in the two areas studied, de-spite their close proximity.",
keywords = "δ C stratigraphy, English Midlands, Homerian, Mulde Excursion, Silurian, Wenlock",
author = "Carly Marshall and Thomas, {Alan T.} and Ian Boomer and Ray, {David C.}",
year = "2012",
doi = "10.3140/bull.geosci.1306",
language = "English",
volume = "87",
pages = "669--679",
journal = "Bulletin of Geosciences",
issn = "1214-1119",
publisher = "Czech Geological Survey",
number = "4",

}

RIS

TY - JOUR

T1 - High resolution δ 13C stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge

AU - Marshall, Carly

AU - Thomas, Alan T.

AU - Boomer, Ian

AU - Ray, David C.

PY - 2012

Y1 - 2012

N2 - High resolution δ 13C calb data are presented for two composite sections in England covering much of the Homerian Stage. Micrite samples collected at ~0.5 m intervals from outcrop and core in the Dudley area, West Midlands, span the upper-most Coalbrookdale, Much Wenlock Limestone and basal Lower Elton formations. Deposition there occurred in a mid-shelf setting. A similar suite of samples from the Wenlock type area, Wenlock Edge, Shropshire, represents a coeval sequence deposited closer to the shelf-basin margin. The successions concerned extend from the upper lundgreni to nilssoni graptolite biozones and provide a detailed record of variation in stable carbon isotope ratios across the well-known double-peaked Homerian positive excursion (Mulde Excursion), a time of significant global biological and chemical perturbation. In the West Midlands, this excursion occurs in the Much Wenlock Limestone Formation. The lower peak (Lower Quarried Limestone Member) has δ 13C calb values rising to +5.5%o VPDB. Values fall to +0.8%c VPDB higher in the section before rising again to +4.1%o VPDB (Nodular Beds Member). Analysis of lithofacies varia-tion in this interval indicates two transgressive-regressive cycles, the two positive peaks of the excursion correlating with relative sea-level lows and the intervening dip with a relative sea-level high, the local expression of Johnson's (2006) Highstand 5A. The double-peaked nature of the excursion at Dudley resembles that previously recorded for the area; however, our δ 13C carb values are consistently 2%c higher, and accord more closely with values published for sec-tions elsewhere. The lower of the two peaks found in the West Midlands cannot be identified on Wenlock Edge, where 813Ccarb values fluctuate somewhat around +2%c VPDB. The upper peak, though less distinct, can be identified on Wenlock Edge with values rising to +3.8%c VPDB. Correlations based on biostratigraphy, sequence stratigraphy and bentonite geochemistry suggest that not all changes in δ 13C calb occurred synchronously in the two areas studied, de-spite their close proximity.

AB - High resolution δ 13C calb data are presented for two composite sections in England covering much of the Homerian Stage. Micrite samples collected at ~0.5 m intervals from outcrop and core in the Dudley area, West Midlands, span the upper-most Coalbrookdale, Much Wenlock Limestone and basal Lower Elton formations. Deposition there occurred in a mid-shelf setting. A similar suite of samples from the Wenlock type area, Wenlock Edge, Shropshire, represents a coeval sequence deposited closer to the shelf-basin margin. The successions concerned extend from the upper lundgreni to nilssoni graptolite biozones and provide a detailed record of variation in stable carbon isotope ratios across the well-known double-peaked Homerian positive excursion (Mulde Excursion), a time of significant global biological and chemical perturbation. In the West Midlands, this excursion occurs in the Much Wenlock Limestone Formation. The lower peak (Lower Quarried Limestone Member) has δ 13C calb values rising to +5.5%o VPDB. Values fall to +0.8%c VPDB higher in the section before rising again to +4.1%o VPDB (Nodular Beds Member). Analysis of lithofacies varia-tion in this interval indicates two transgressive-regressive cycles, the two positive peaks of the excursion correlating with relative sea-level lows and the intervening dip with a relative sea-level high, the local expression of Johnson's (2006) Highstand 5A. The double-peaked nature of the excursion at Dudley resembles that previously recorded for the area; however, our δ 13C carb values are consistently 2%c higher, and accord more closely with values published for sec-tions elsewhere. The lower of the two peaks found in the West Midlands cannot be identified on Wenlock Edge, where 813Ccarb values fluctuate somewhat around +2%c VPDB. The upper peak, though less distinct, can be identified on Wenlock Edge with values rising to +3.8%c VPDB. Correlations based on biostratigraphy, sequence stratigraphy and bentonite geochemistry suggest that not all changes in δ 13C calb occurred synchronously in the two areas studied, de-spite their close proximity.

KW - δ C stratigraphy

KW - English Midlands

KW - Homerian

KW - Mulde Excursion

KW - Silurian

KW - Wenlock

UR - http://www.scopus.com/inward/record.url?scp=84868156977&partnerID=8YFLogxK

U2 - 10.3140/bull.geosci.1306

DO - 10.3140/bull.geosci.1306

M3 - Article

AN - SCOPUS:84868156977

VL - 87

SP - 669

EP - 679

JO - Bulletin of Geosciences

JF - Bulletin of Geosciences

SN - 1214-1119

IS - 4

ER -