DOI: 10.1016/j.palaeo.2013.03.024
论文题名: Late wenlock sequence and bentonite stratigraphy in the malvern, suckley and abberley hills, England
作者: Ray D.C. ; Richards T.D. ; Brett C.E. ; Morton A. ; Brown A.M.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 389 起始页码: 115
结束页码: 127
语种: 英语
英文关键词: Bentonites
; Midland Platform
; Much Wenlock Limestone Formation
; Sequence stratigraphy
; Silurian
; Wenlock Series
英文摘要: The Late Wenlock Series (Homerian Stage) of the central Midland Platform occupies an area stretching from Ledbury to the Malvern, Suckley and Abberley Hills. Based upon the establishment of a sequence stratigraphic framework for the Much Wenlock Limestone Formation, and the immediately under- and over-lying Coalbrookdale and Lower Elton Formations, comparisons can now be made with key sections across the northern Midland Platform and beyond. These correlations have been strengthened by the determination of apatite rare earth element (REE) geochemical signatures obtained from four volcanic ash layers (bentonites) at Whitman's Hill Quarry (Herefordshire), which allow for comparisons with published coeval sections at Wren's Nest Hill (West Midlands) and Wenlock Edge (Shropshire), as well as with bentonites described from the Island of Gotland (Sweden).Across the study area fifteen parasequences associated with two pronounced regressive episodes, separated by a marked transgression, can be identified. The lithological responses to these relative sea-level changes are the same as those reported from the West Midlands, including the threefold division of the Much Wenlock Limestone Formation into Lower Quarried Limestone, Nodular Beds and Upper Quarried Limestone Members. Apatite REE geochemical signatures from Whitman's Hill Quarry identify three bentonites which probably originated from a granodiorite magmatic source, while a fourth bentonite has a distinctively mafic composition, more akin to that of a gabbro or syenite. This distinctively mafic bentonite is preserved on a marked flooding surface within the Nodular Beds Member and appears compositionally and stratigraphically equivalent to a bentonite at Wren's Nest Hill (West Midlands). Furthermore in both sections this bentonite is of notable thickness (120-200. mm) allowing for its identification in other sections across the region. Comparisons with Gotland identify three closely spaced bentonites of a similar mafic composition to the bentonite described from the Midland Platform. While similarities in stratigraphic position and composition do not, at present, allow for the identification of a single ash fall event covering both the Midland Platform and Gotland, they are indicative of a shared source region, which may offer the possibility for future bentonite correlation between these regions. © 2013 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69602
Appears in Collections: 过去全球变化的重建
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作者单位: School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, United Kingdom; Neftex, 97 Jubilee Avenue, Milton Park, Abingdon, Oxfordshire, OX14 4RW, United Kingdom; Herefordshire and Worcestershire Earth Heritage Trust, Geological Records Centre, University of Worcester, Henwick Grove, Worcester, WR2 6AJ, United Kingdom; Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, United States; HM Research Associates, 2 Clive Road, Balsall Common, Coventry, CV7 7DW, United Kingdom; CASP, University of Cambridge, 181a Huntingdon Road, Cambridge, CB3 0DH, United Kingdom; 17 Shrubbery Street, Kidderminster, Worcestershire, DY10 2QZ, United Kingdom
Recommended Citation:
Ray D.C.,Richards T.D.,Brett C.E.,et al. Late wenlock sequence and bentonite stratigraphy in the malvern, suckley and abberley hills, England[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,389