نتایج جستجو برای: wind sediments
تعداد نتایج: 111368 فیلتر نتایج به سال:
Relations of landform types to wind regimes, bedrock composition, sediment supply, and topography are shown by field studies and satellite photographs of the Western Desert of Egypt. This desert, which lies at the core of the largest hyperarid region on earth, provides analogs of Martian wind-formed features. These include sand dunes, alternating light and dark streaks, knob 'shadows,' and yard...
a r t i c l e i n f o Pleistocene Lake Bonneville of the western U.S. and its associated alluvial systems present a unique opportunity to understand the relationship between prevailing winds of the time, lake circulation, and river incision. The lake underwent a catastrophic flooding event ∼ 18,300 yr B.P. resulting in the incision of streams entering the lake along its eastern border. Incision...
Introduction: Synthetic Aperture Radar images of Titan collected by the Cassini spacecraft show that dunes are abundant on Titan's surface, covering almost 20% of Titan's surface [1,2]. Nearly all of the dunes found on Titan are linear in form, are found near the equator (±30and have a west-east orientation. Since there is likely active linear dune formation presently on Titan [3], we can use T...
This study was conducted on selected sediments from the Iraqi dam reservoir to verify their quality, geotechnical properties including physical, engineering, chemical, and mineralogical characteristics. It found that area soil is similar in Mesopotamian plain areas where silts have low plasticity Samarra barrage medium at Wind dam. moisture content because sampling done summer season, high wind...
Oceanic iron inputs must be traced and quantified to learn how they affect primary productivity and climate. Chemical reduction of iron in continental margin sediments provides a substantial dissolved flux to the oceans, which is isotopically lighter than the crust, and so may be distinguished in seawater from other sources, such as wind-blown dust. However, heavy iron isotopes measured in seaw...
Climate in the tropical North Atlantic is controlled largely by variations in the strength of the trade winds, the position of the Intertropical Convergence Zone, and sea surface temperatures. A high-resolution study of Caribbean sediments provides a subdecadally resolved record of tropical upwelling and trade wind variability spanning the past 825 years. These results confirm the importance of...
Rapid climatic shifts across the last glacial to Holocene transition are pervasive feature of the North Atlantic as well as low latitude proxy archives. Our decadal to centennial scale record of summer monsoon proxy Globigerina bulloides from rapidly accumulating sediments from Hole 723A, Arabian Sea shows two distinct intervals of weak summer monsoon wind coinciding with cold periods within Ål...
Wind-driven upwelling in the ocean around Antarctica helps regulate the exchange of carbon dioxide (CO2) between the deep sea and the atmosphere, as well as the supply of dissolved silicon to the euphotic zone of the Southern Ocean. Diatom productivity south of the Antarctic Polar Front and the subsequent burial of biogenic opal in underlying sediments are limited by this silicon supply. We sho...
The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake bas...
Well-distributed eolian red clay in a wide area of northern China is believed to imply the onset of an ancient East Asian monsoon system since Late Miocene. Two continuous red clay sequences spanning the time interval 7-2.6 Ma and 11-2.6 Ma in the Chinese Loess Plateau was investigated to determine the magnetic orientation and grain alignment in the primary fabric of eolian sediments. The north...
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