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摆浪河流域的ESR年代学与祁连山第四纪冰期新认识

ESR Chronology of Bailanghe Valley and New Understanding of Qilianshan Mountain’s Quaternary Glaciation

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【作者】 赵井东周尚哲崔建新潘小多许刘兵张小伟

【Author】 ZHAO Jing dong, ZHOU Shang zhe CUI Jian xin, PAN Xiao duo, XU Liu bing and ZHANG Xiao wei (College of Source and Environment, Lanzhou University,Lanzhou, 730000China)

【机构】 兰州大学资源与环境学院兰州大学资源与环境学院 甘肃兰州730000甘肃兰州730000甘肃兰州730000

【摘要】 摆浪河发源于走廊南山北坡 ,是黑河的一条支流。在河源区保存有六套完整的冰碛和较为完整的阶地序列。应用ESR技术对采自该处较老的第三、第五、第六套冰碛和冰水成因的主阶地上的砾石层与上覆黄土进行了测年研究 ,测试结果分别为 13.4ka、135 .3ka、46 2 .9ka、130 .1ka、130 .2ka。根据测试的结果并结合地貌地层学得出 :380 0m以上“U”型谷中的第一、第二套冰碛为全新世中小冰期、新冰期沉积的冰碛 ;第三套冰碛物是末次冰期晚期沉积的 ,与深海氧同位素 2阶段相对应 ;第五套冰碛物是与深海氧同位素 6阶段相对应的冰期沉积的 ;第六套冰碛物是与深海氧同位素 12阶段相对应冰期沉积的 ;由此推断介于第三套与第五套冰碛之间的第四套冰碛是末次冰期早期沉积的 ,即可与深海氧同位素 4阶段相对应。主阶地与第五套冰碛是同一时期形成的 ,这也与地貌地层学的推断相一致。从此处完整的冰川沉积序列还可以得出 :在更新世中 ,祁连山地区至少存在三次冰期 ,经历四次冰川作用。祁连山部分地段或是整体至少在 46 3ka前就已经抬升到与当时冰期气候相耦合的高度。ESR可以用于河流、冰川沉积物的测年。

【Abstract】 Bailanghe River is a tributary of Heihe River, Originating from the north slope of Nanshan mountain which stretches along the southern border of Hexi corridor. 6 sets integrated glacial tills and relative integrated terraces sequence remained at the head of Bailanghe River. The samples were derived from the third, the fifth and the sixth sets of glacial tills, the gravel and the loess of the main terrace respectively. The technique of ESR was applied to determine them. The results were 13.4ka, 135.3ka, 462.9ka, 130.1ka, 130.2ka respectively. A conclusion was drawn on the basis of results and the law of geomorphology and stratigraphy: The first set and the second set glacial tills were deposited during the Little Ice age and Neoglaciation in the "U" shape valley 3800m a.s.l. The third set, the fifth set and the sixth set glacial till were formed during the late period of the Last Glaciation, the penultimate Glaciation and the Last but two Glaciation. They were correlated to the deep sea oxygen isotope stage 2, 6, 12 respectively. It is reasonable to infer that the forth set of glacial till which locates between the third and the fifth was formed during the early period of the Last Glaciation which was correlated to the deep sea isotope stage 4. The main terrace and the fifth set of glacial till were formed at the same period on the basis of the ESR and the TL ages, this conclusion was also consistent with the law of geomorphology and stratigraphy. Another conclusion could also draw from the glacial deposited sequences at this site: at least four glaciations have happened at the Qilianshan mountain during Pleistocene. Before 463ka many segments or the whole of Qilianshan Mountain’s elevation have reached the coupling altitude with the glacial climate of that time. The technique of ESR can be applied in determining the fluvial and glacial deposits.

【关键词】 ESR测年冰碛物摆浪河祁连山
【Key words】 ESR datingglacial tillsBailanghe RiverQilianshan mountain.
【基金】 国家重点科学基金“河西地区环境演变与人地关系研究”(批准号 :497310 10 );国家自然科学基金“沙鲁里山第四纪冰川研究”(批准号 :499710 80 );教育部基金“祁连山冷龙岭地区第四纪冰川遗迹”资助
  • 【文献出处】 山地学报 ,Journal of Mountain Research , 编辑部邮箱 ,2001年06期
  • 【分类号】P533
  • 【被引频次】39
  • 【下载频次】327
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