DOI: 10.1016/j.palaeo.2014.05.016
论文题名: Evidence for climate shifts in the ~2.0 Ga upper Makgabeng Formation erg, South Africa
作者: Heness E.A. ; Simpson E.L. ; Bumby A.J. ; Eriksson P.G. ; Eriksson K.A. ; Hilbert-Wolf H.L. ; Okafor O.J. ; Linnevelt S. ; Fitzgerald Malenda H. ; Modungwa T.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 409 起始页码: 265
结束页码: 279
语种: 英语
英文关键词: Eolian
; Ephemeral river
; Makgabeng Formation
; Paleoproterozoic
; Playa
英文摘要: Eolian ergs and associated environs are sensitive to short- and long-term climatic changes. In one of the oldest erg deposits, the ~ 2.0 Ga Makgabeng Formation, vertical changes in facies associations reflect one of the earliest records of short-term climatic shifts in a continental setting. The Makgabeng Formation is separated into lower and upper erg deposits by a playa or saline pan deposit. The lower erg deposit consists of dune sets with thin lenses of dry and deflationary interdune strata that transition vertically to thicker damp to wet interdune strata. A laterally persistent playa deposit in the middle of the section consists of mudstone with deep and shallow penetrating mud cracks and subordinate siltstone and sandstone interbeds. Above this lower mudstone interval, the playa strata are sandy. Overlying the playa deposit, the upper erg deposit consists of thick eolian sets with thin lenses of dry interdune deposits. Grain size change near the top of the upper erg deposit corresponds with the appearance of fluvial, sheet flood, eolian cross-beds sculpted by mass flows, and thin playa deposits. Vertical stacking of facies associations demonstrates temporal shifts in precipitation and fluctuating water tables. Fluvial and playa deposits record high-water tables whereas low-water tables are reflected in the core erg. The transition from a lower to higher water table is recorded by wet interdune interspersed within the dune strata toward the top of this interval. Rapid climatic amelioration occurred near the termination of the Makgabeng erg resulting in impingement of ephemeral river systems, development of playas, and generation of massive sand flows. This 2.0 Ga erg demonstrates the impact of climate change on erg development, resulting from shifts in monsoonal impingement through time. © 2014 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69293
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Physical Science, Kutztown University, 425 Boehm, P.O. Box 730, Kutztown, PA, United States; Department of Geology, University of Pretoria, Pretoria, South Africa; Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA, United States; School of Earth and Environmental Sciences, James Cook University, Townsville, QLD, Australia; Department of Geological Sciences, University of Texas, El Paso, El Paso, TX, United States
Recommended Citation:
Heness E.A.,Simpson E.L.,Bumby A.J.,et al. Evidence for climate shifts in the ~2.0 Ga upper Makgabeng Formation erg, South Africa[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,409