Buckman, J, Mahoney, C orcid.org/0000-0002-2052-3576, März, C orcid.org/0000-0003-2558-4711 et al. (2 more authors) (2017) Identifying biogenic silica: Mudrock micro-fabric explored through charge contrast imaging. American Mineralogist, 102 (4). pp. 833-844. ISSN 0003-004X
Abstract
Visual inspection (optical microscope point counting) and silica abundance show that laminated shale from the Late Cretaceous of Colombia contains high levels of detrital quartz silt and sand particles. Closer examination using the charge contrast imaging (CCI) technique, however, illustrates that much of the quartz is authigenic micro-quartz, and thus not exclusively of detrital origin. In addition, many "sand" grains that otherwise appear to represent simple detrital quartz particles are actually of biogenic origin, representing the tests of agglutinated foraminifera, formed from cemented silt-sized quartz particles. Finally, CCI shows that original detrital grains have undergone authigenic modification, with both syntaxial overgrowths and micro-quartz. Without recognition of these features, the relative proportion of detrital quartz (sand) would otherwise be greatly overestimated, with important implications for environmental interpretation. Furthermore, the recognition of biogenic structures, including agglutinated foraminifera, provides additional environmental information that otherwise could be easily overlooked.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2017 Mineralogical Society of America. This is an author produced version of a paper published in American Mineralogist. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Shale; Silt; quartz cementation |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Dec 2016 12:19 |
Last Modified: | 31 Jan 2019 12:12 |
Status: | Published |
Publisher: | Mineralogical Society of America |
Identification Number: | 10.2138/am-2017-5797 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:108775 |