气候变化领域集成服务门户(CCPortal): Development of stratigraphically controlled, eolianmodified unconsolidated gravel surfaces and yardang fields in the wind-eroded Hami Basin, northwestern China

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DOI	10.1130/B31734.1
	Development of stratigraphically controlled, eolianmodified unconsolidated gravel surfaces and yardang fields in the wind-eroded Hami Basin, northwestern China
	Pullen A.; Kapp P.; Chen N.
发表日期	2018
ISSN	167606
起始页码	630
结束页码	648
卷号	130 期号:2021-03-04
英文摘要	Here, we present a stratigraphic and geomorphologic study of the northern part of the hyperarid and internally drained Hami Basin, located south of the Tian Mountains in northwestern China. The Hami Basin exposes wind-eroded Neogene sedimentary bedrock and was potentially an important source of atmospheric dust transported by westerly winds and deposited in the northern Pacific Ocean in the past. The northern Hami Basin exposes at least 430 m of subhorizontal (dipping locally < 1° to the south) Neogene strata. The strata consist of interbedded paleosol, siltstone, sandstone, and massive and cross-bedded matrix- and clast-supported pebble conglomerate associated with alluvial-fan to playa deposition. The Neogene strata are sculpted into widespread ( > 2000 km2) but spatially discontinuous fields of megayardangs, separated and locally overlain by spatially extensive (1 × 104-106 m2) subhorizontal planar surfaces of unconsolidated gravel. These gravel surfaces are topographically tiered and coincide spatially with prominent conglomerate beds within the wind-eroded Neogene stratigraphy. Conversely, the yardang fields developed in finer-grained and presumably more easily eroded intervals of the stratigraphy between the conglomerate beds. Unconsolidated gravels are also exposed within interyardang corridors, on yardang flanks and tops, in Pleistocene-Holocene ephemeral stream channels, and atop fluvial terraces. There is a scarcity of unconsolidated sediment composed of sand- to smaller-sized particles, which implies the basin is sandstarved and/or that near-surface winds are efficient in removing sand and fine-grained sediment from the basin. We suggest that the rate of eolian-dominated downcutting through the heterogeneous lithologies within the Neogene strata was modulated, in part, by the distribution of conglomerate beds. The distribution of conglomerates, which are more abundant in the lower part of the wind-eroded section, would be consistent with initially higher wind erosion rates and a decreasing trend through time as gravel surfaces coalesced, armored the landscape, and suppressed wind deflation. We estimate a minimum vertically integrated average of 178 m of erosion based on the projection of wind-eroded strata within the field area. We infer that the abundance of dark-colored (low-albedo) unconsolidated gravels in the Hami Basin has contributed to its anomalously high land skin temperatures and frequent extreme near-surface wind events. © 2017 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/185066
作者单位	Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634, United States; Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States; Department of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang, 310027, China
推荐引用方式 GB/T 7714	Pullen A.,Kapp P.,Chen N.. Development of stratigraphically controlled, eolianmodified unconsolidated gravel surfaces and yardang fields in the wind-eroded Hami Basin, northwestern China[J],2018,130(2021-03-04).
APA	Pullen A.,Kapp P.,&Chen N..(2018).Development of stratigraphically controlled, eolianmodified unconsolidated gravel surfaces and yardang fields in the wind-eroded Hami Basin, northwestern China.Bulletin of the Geological Society of America,130(2021-03-04).
MLA	Pullen A.,et al."Development of stratigraphically controlled, eolianmodified unconsolidated gravel surfaces and yardang fields in the wind-eroded Hami Basin, northwestern China".Bulletin of the Geological Society of America 130.2021-03-04(2018).