| 靖远黄土剖面磁性地层的初步研究 |
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| 引用本文： | 岳乐平,雷祥义,屈红军.靖远黄土剖面磁性地层的初步研究[J].第四纪研究,1991,11(4):349-353. |
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| 作者姓名： | 岳乐平 雷祥义 屈红军 |
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| 作者单位： | 西北大学地质系
(岳乐平，雷祥义)，西北大学地质系(屈红军) |
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| 摘 要： | 曹岘黄土剖面位于甘肃省靖远县,系黄河中游六级阶地黄土堆积,厚约505m,含33层古土壤,系黄土-古土壤系列,是目前已知世界上最厚的黄土剖面。作者对该剖面进行了古地磁学研究,结果表明:曹岘黄土剖面含布容正极性时和松山反极性时,B/M 界线位于L8中部,加拉米洛正极性亚时位于L10—L13,位置。曹岘黄土堆积始于1.40MaB.P.,该黄土剖面可以与兰州、洛川和蓝田等黄土剖面对比。
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| 关 键 词： | 黄土 古土壤 古地磁 |
A MAGNETOSTRATIGRAPHIC STUDY ON THE JINGYUAN LOESS SECTION,GANSU,CHINA |
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| Institution: | Loess Research Section of Geology Department, Northwest University |
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| Abstract: | The thickest loess deposits in the world at present are observed at the Chaoxian Village,Jingyuan,Gansu,China.Being a typical loess-paleosol series,this loess section is about 505 min thickness,with 33 layers of paleosol.There were 315 samples collected from the loess sec-tion.All the samples were measured after thermal demagnetization by TSD-1 thermal demag-netizer and the Miniapin magnetometer.The results show that the Jingyuan section containsBrunhes Normal Polority Zone and Matsuyama Reversal Polarity Zone.B/M boundary is lo-cated in L8 （8th layer of loess from top downward）.The Blake excursion （0.11 Ma B.P.） andEmperor excursion （0.47 Ma B.P.） were found at S1 and S5 in the section respectively.TheJaramillo （J） Polarity Subchron corresponds to the interval from L10 to L13.Jingyuan loess be-gan to form at 1.40Ma B.P.The rate of loess deposition in dingyuan loess section is about 3.6mm/a.The Jingyuan section may be compared with the Lanzhou section,the Luochuan sectionand the Lantian section.The magnetostratigraphical division of Jingyuan section is as follows:Holocene loess:consists of black loam and upper loess,thickness 2m,dated at about 8000a B.P.Late Pleistocene loess:includes L1 and S1,thickness about 64m,dated at 0.13 Ma B.P.Middle Pleistocene loess:includes the layers of soil from L2 to B/M boundary (L8),thick-ness about 219m,dated at about 0.73 Ma B.P.Early Pleistocene loess:includes the layers from B/M boundary to the basal part of the loesssection,about 220m in thickness,dated at about 1.40 Ma B.P. |
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