DOI: 10.1016/j.epsl.2019.116049
论文题名: Martian fan deposits: Insights on depositional processes and origin from mass balance survey
作者: Vaz D.A. ; Di Achille G. ; Hynek B.M. ; Nelson W. ; Williams R.M.E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 533 语种: 英语
中文关键词: delta
; fan mass balance
; fluvial
; Mars
英文关键词: Bioassay
; Drainage
; Landforms
; Offshore oil well production
; Sedimentation
; Sediments
; Topography
; delta
; Depositional environment
; fluvial
; Mars
; Mass balance
; Mass balance analysis
; Morphometric measurements
; Volumetric measurement
; Deposits
; deposition
; fan delta
; fluvial deposit
; Mars
; mass balance
; morphometry
; sediment transport
英文摘要: Fan deposits located at the mouths of Martian valleys have been interpreted as indicators of wet conditions during Mars history. However, the processes, time and amount of water needed to carve the valleys and form the fans are still debated. Here we present a detailed morphometric and mass balance analysis of valleys and fan-shaped deposits using high resolution topography, which provides new insights into past depositional environments. Based on morphometric and volumetric measurements, we found that several Martian fans previously interpreted as deltas can be categorized into two main types. Type I fans are more numerous, relatively well preserved, are associated with smaller and less mature drainage networks and were deposited on steeper gradients. The balance between eroded and deposited materials indicates that this set of fans might have been formed mainly in subaerial settings by depositional processes other than typical deltaic sedimentation (e.g. alluvial, glacial, mass-wasting in general), since a significant loss of sediment during deposition did not occur (we obtained a volume ratio of eroded vs. deposited materials of approximately 1). Therefore, we propose that the identified Type I fans were not deposited in prevailing subaqueous deltaic settings, but mainly in subaerial conditions with perhaps sporadic presence of ephemeral bodies of standing water within the basins. In contrast, Type II fans are less abundant, highly eroded, were deposited on flatter areas and formed downstream of more mature drainage networks with longer, deeper and wider valleys. The mass balance for this set of fans clearly shows that considerable amounts of sediment were not retained in the fans, implying large offshore transport of sediment during their formation (eroded vs. deposited volume ratios between 3 and 10 are probable). This evidence supports a fluvio-deltaic origin for this class of fans, indicating the existence of paleolakes over substantial periods of time. Based on the collected morphometric measurements and mass balance modeling we conclude that only a small percentage of the fans (Type II fans correspond to ∼1/3 of the sampled areas) are consistent with the occurrence of favorable and durable conditions for life, i.e. long-lived integrated fluvial, deltaic and lacustrine environments. Whereas, the majority of fans might have been formed in subaerial settings with significant contributions of alternative processes besides fluvial transport and deposition thus not necessarily requiring the occurrence of extended epochs of clement climatic conditions. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165324
Appears in Collections: 气候变化与战略
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作者单位: National Institute for Astrophysics (INAF), Astronomical Observatory of Abruzzo, Via Mentore Maggini, Teramo TE, 64100, Italy; Centre for Earth and Space Research of the University of Coimbra, Observatório Astronómico da Universidade de Coimbra, Almas de Freire, Coimbra, 3040-004, Portugal; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, 1234 Innovation Drive, Boulder, CO 80303, United States; Department of Geological Sciences, University of Colorado Boulder, Campus Box 600 UCB, Boulder, CO 80303, United States; Planetary Science Institute, Tucson, AZ, United States
Recommended Citation:
Vaz D.A.,Di Achille G.,Hynek B.M.,et al. Martian fan deposits: Insights on depositional processes and origin from mass balance survey[J]. Earth and Planetary Science Letters,2020-01-01,533