Crescentic dune migration and stabilization: Implications for interpreting paleo-dune deposits as paleoenvironmental records
Crescentic dune migration and stabilization: Implications for interpreting paleo-dune deposits as paleoenvironmental records
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新月形沙丘迁移和稳定：将古沙丘沉积物解释为古环境记录的意义
DOI：
10.1007/s11442-017-1439-8
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发表时间：
2017-09
影响因子：
4.9
通讯作者：
Zhiyong Han
中科院分区：
文献类型：
--
作者：
Zhiwei Xu;Joseph A. Mason;Huayu Lu;Shuangwen Yi;Yali Zhou;Jiang Wu;Zhiyong Han
古沙丘沉积物已被广泛用作过去沙丘活动的代理指标，并进一步用于重建古气候。然而，最近的研究批判性地检验了沙丘年代学的再现性和古沙丘沉积物作为古环境记录的复杂性。本文以新月形沙丘为例，通过中国中北部毛乌素沙丘地区的案例研究，解决了这些评论中提出的沙丘年代地层的古环境影响问题。首先通过观测证据研究相对较小的新月形沙丘的翻转和稳定过程。结合简化的防沙模型和地层记录分析，论证了沙丘形态动力学对防沙的影响。特别明显的是，厚的、几乎瞬时沉积的沙单元记录了沙丘活动事件结束时沙丘的稳定性，而薄沙单元可能表明活动事件中早期沉积的沙的保存。解释表明沙子沉积随时间变化的发光年龄的分布并不像以前的一些工作中假设的那么简单。沙年龄的低频率可能表明沙丘场稳定或广泛的沙丘活动但沙保存不良的时间间隔。沙龄频率的峰值可能代表沙丘现场活动向稳定的转变，而不是活动沙丘范围的峰值，特别是如果它与独立确定的稳定区间部分重叠（例如古土壤记录的稳定区间）。随着时间的推移，沙龄分布偏差的性质和程度受到沙子净积累量的强烈影响，而沙子净积累量又与沙子供应、运输能力和沙子可用性以及最终的气候变化有关。相对较短的沙丘稳定和周转时间（101至102年）表明沙丘地貌过程可以快速响应短期扰动，但必须根据这些过程如何影响年龄分布来解释该响应的年代顺序。
Paleo-dune deposits have been widely used as a proxy indicator of past dune activity, which is further used to reconstruct paleoclimates. However, recent studies have critically examined the reproducibility of dune chronologies and the complexity of paleo-dune deposits as paleoenvironmental records. This paper addresses questions on the paleoenvironmental implications of dune chronostratigraphies that have been raised by those reviews, in the specific case of crescentic dunes, using a case study from the Mu Us dune field, north-central China. The processes of turn-over and stabilization of relatively small crescentic dunes are first investigated by observational evidence. In combination with the analysis of a simplified sand preservation model and stratigraphic records, the effect of dune morphodynamics on sand preservation is demonstrated. It is especially evident that thick, nearly instantaneously deposited sand units record dune stabilization near the very end of a dune activity episode, while thin sand units may signal the preservation of sand deposited earlier in episodes of activity. Interpreting the distribution of luminescence ages that indicate sand deposition over time is not as simple as assumed in some previous work. Low frequency of sand ages could indicate an interval of either dune field stabilization or extensive dune activity but poor sand preservation. A peak of sand age frequency likely represents a shift in dune field activity towards stabilization, not a peak of active dune extent, especially if it partially overlaps with an independently identified interval of stabilization (e.g. one recorded by paleosols). The nature and magnitude of these biases in the distribution of sand ages over time are strongly affected by the magnitude of net sand accumulation, which is in turn related to sand supply, transport capacity and sand availability, and ultimately climate change. Relatively short dune stabilization and turn-over time (101to 102yrs) indicate that dune geomorphic processes can quickly respond to short-term disturbance, but the chronology of that response must be interpreted in light of how those processes influence age distributions.
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影响因子：
64.8
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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影响因子：
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