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Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Published online by Cambridge University Press:  07 December 2017

OLADAPO AKINLOTAN Open the ORCID record for OLADAPO AKINLOTAN [Opens in a new window]
OLADAPO AKINLOTAN*
Affiliation:
School of Environment and Technology, University of Brighton, Lewes Road, Brighton, BN2 4GJ, UK
*
*Author for correspondence: [email protected]; [email protected]
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Abstract

The Lower Cretaceous Wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the Weald Basin in SE England. However, mineralogical and geochemical datasets on the ironstones are scarce in the literature. Geochemical and mineralogical data on the sideritic ironstones are presented from the Wadhurst Clay Formation within the Weald Basin. The mineralogy of the ironstones was examined using a PANalytical X'Pert Pro X-ray diffractometer and PANalytical's HighScore Plus software. Elemental composition of the ironstones was measured using a PANalytical MiniPal2 ED-XRF (benchtop X-ray spectrometer). The examination of the mineralogy of the Wealden ironstones confirms the presence of early diagenetic siderites. The trace-element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin. The sideritic ironstones reveal anoxic conditions and palaeo-salinity in the basin. More generally, it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins. This work reinforces the importance of the composition of sideritic ironstones as useful non-traditional data for understanding the depositional settings of sedimentary basins, especially when traditional datasets are not readily available or insufficient.

Keywords

sideritic ironstonesmineralogygeochemistryEarly Cretaceoussoutheast EnglandWeald Basin
Type
Original Articles
Information
Geological Magazine , Volume 156 , Issue 3 , March 2019 , pp. 533 - 546
Copyright
Copyright © Cambridge University Press 2017 

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