DOI: 10.1016/j.epsl.2020.116643
论文题名: The fold illusion: The origins and implications of ogives on silicic lavas
作者: Andrews G.D.M. ; Kenderes S.M. ; Whittington A.G. ; Isom S.L. ; Brown S.R. ; Pettus H.D. ; Cole B.G. ; Gokey K.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 553 语种: 英语
中文关键词: obsidian
; ogives
; silicic lava
; tensile fractures
; viscometry
英文关键词: Tensile strength
; Viscosity
; Bound structure
; Ductile deformations
; Geological structures
; Planetary bodies
; Pressure ridge
; Rheological property
; Tensile fractures
; Western United States
; Planets
; crevasse
; crustal thickness
; emplacement
; fold
; folding
; fracture
; glacier
; lava
; obsidian
; rheology
; siliciclastic deposit
; stress analysis
; tensile strength
; trough
; viscosity
; Italy
; Sardinia
; United States
英文摘要: Folds on the surfaces of mafic lavas are among the most readily recognized geological structures and are used as first-order criteria for identifying ancient lavas on Earth and other planetary bodies. However, the presence of surface-folds on the surface of silicic lavas is contested in this study and we challenge the widely accepted interpretation that silicic lava surfaces contain folds using examples from the western United States and Sardinia, Italy. We interpret the ridges and troughs on their upper surfaces, typically referred to as ‘ogives’ or ‘pressure ridges’, as fracture-bound structures rather than folds. We report on the absence of large-scale, buckle-style folds and note instead the ubiquitous presence of multiple generations and scales of tensile fractures comparable to crevasses in glaciers and formed in ways similar to already recognized crease structures. We report viscosity data and results of stress analyses that preclude folding (ductile deformation in compression) of the upper surface of silicic lavas at timescales of emplacement (weeks to months). Therefore, analysis of fold geometry (wavelength, amplitude, etc.) is erroneous, and instead the signal produced reflects the strength and thickness of the brittle upper surface stretching over a ductile interior. The presence of ogives on the surfaces of lavas on other planetary bodies may help to elucidate their rheological properties and crustal thicknesses, but relating to their tensile strength, not viscosity. © 2020 The Author(s) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165398
Appears in Collections: 气候变化与战略
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作者单位: West Virginia University, United States; University of Missouri, United States; University of Texas at San Antonio, United States; West Virginia Geological and Economic Survey, United States
Recommended Citation:
Andrews G.D.M.,Kenderes S.M.,Whittington A.G.,et al. The fold illusion: The origins and implications of ogives on silicic lavas[J]. Earth and Planetary Science Letters,2021-01-01,553