本文關鍵詞：六盤山東麓涇河上游河流階地的形成年代及新構造運動意義，由筆耕文化傳播整理發(fā)布。

六盤山東麓涇河上游河流階地的形成年代及新構造運動意義

Age of Upper Jinghe River Terraces at the Eastern Piedmont of Liupanshan and Its Significance for Neotectonic Movement

[1] [2] [3] [4] [5] [6] [7]

ZHAO Qiu-chen, ZHANG Xu-jiao, HE Ze-xin, HE Xiang-li, WANG Jian-yong, FU Lian-zhen, JIA Li-yun （School of Earth Sciences and Resources, China University of Geosciences, Belting

中國地質大學(北京)地球科學與資源學院,北京100083

文章摘要：六盤山是研究青藏高原東北緣隆升與構造變形的關鍵部位,其東麓涇河河流階地是第四紀以來六盤山構造隆升的地貌載體。通過對涇河上游河流階地的剖面實測,厘定了河流階地的級序,涇河上游主要發(fā)育5級河流階地T5—T1,不同地段階地的形態(tài)類型不同,柳樹溝T5、T4和T3為堆積階地,T2和T1為基座階地,高家山均為侵蝕或基座階地;利用光釋光（OSL）、電子自旋共振（ESR）測年并與黃土-古土壤序列進行對比,建立了河流階地的年代格架,T5—T1年代分別為541 ka B.P.、477 ka B.P.、279 ka B.P.、60 ka B.P.和8 ka B.P。階地的形態(tài)類型、形成年代與氣候階段的對應關系研究表明,涇河上游河流階地以構造隆升驅動為主,氣候變化影響為輔;541-279 ka B.P.期間柳樹溝地區(qū)為堆積區(qū),堆積速率為0.31 m/ka,而高家山為構造隆升區(qū),河流下切速率為0.37 m/ka,堆積速率與侵蝕速率基本一致,說明T5、T4和T3階面上較厚的礫石層是六盤山隆升的相關沉積;279 ka B.P.時期由于六盤山快速隆升驅使山前柳樹溝地區(qū)由堆積區(qū)轉為侵蝕區(qū),河流侵蝕作用加強造成T2、T1平均下切速率增大為1.13 m/ka,這次地貌轉換事件是在青藏高原擴展隆升的背景下六盤山向東擠出隆升的結果。研究結果為青藏高原東北緣以面積和體積擴張的觀點提供了新的依據(jù)。

Abstr：Liupanshan is the key region to research the uplift and tectonic deformation of the northeastern Tibet-an Plateau.Jinghe River terraces at the eastern piedmont are geomorphology carriers to record tectonic uplift process of Liupanshan since the Quaternary.The detailed study of profiles of the upper Jinghe River terraces shows that Jinghe River mainly developed 5 river terraces,i.e.T5 -T1.Terraces of T5,T4 and T3 in Liu-shugou are accumulation terraces,and T2 and T1 are pedestal terraces;terraces in Gaojiashan are erosional terraces or pedestal terraces.Trough dating results of OSL and ESR and combined with loess-paleosol sequences the ages of 5-level terraces were defined as 541 ka B.P.,477 ka B.P.,279 ka B.P.,60 ka B.P.and 8 ka B.P.,respectively.The morphological types of terraces and the relationship between age of terraces and cli-mate change indicate that the upper Jinghe River terraces are mainly driven by tectonic uplift while the effects of climate change are complementary.During 541 ka B.P.to 279 ka B.P.,Liushugou region is accumulation area and the accumulation rate is 0.31m /ka,correspondingly,the incision rate of Jinghe River in Gaojiashan is averaged as 0.37 m /ka,which is located in tectonic uplift region,and the accumulation rate is almost equal to the incision rate,indicating the thick gravel layers in T5,T4 and T3 related to Liupanshan rapid uplift.In 279 ka B.P.,Liushugou transforms to an erosion area under sustained uplift in Liupanshan,resulting the incision rate in T1 and T2 increasing to be 1.13 m /ka,indicating eastward extrusion uplifting under the background of expansive uplift of the northeastern Tibetan Plateau.The study provides a new evidence for the cognition that the Tibetan Plateau ex

文章關鍵詞：

Keyword：:Liupanshan tectonic uplift northeastern Tibetan Plateau Jinghe River river terrace ESR dat-ing OSL dating

課題項目：國土資源部公益性行業(yè)科研專項“我國不同季風區(qū)古氣候演化差異及成因機制研究”（201211077-3）; 中國地質調查局地質礦產調查評價項目“青藏高原與貝加爾裂谷動力學背景與古地磁響應”（1212011120182）

  本文關鍵詞：六盤山東麓涇河上游河流階地的形成年代及新構造運動意義，由筆耕文化傳播整理發(fā)布。