摘要
黄土-古土壤的化学风化特征对于理解亚洲内陆干旱化、东亚季风演化以及全球碳循环等具有重要意义。然而,对于亚洲内陆干旱化东进进程最前缘的哈尔滨黄土-古土壤的化学风化特征一无所知。本文对哈尔滨荒山岩芯的黄土-古土壤进行元素地球化学、磁化率和重矿物分析。哈尔滨古土壤的颜色为灰褐色-灰黑色,不同于其他地区的棕红色。黄土-古土壤的CIA(Chemical Index of Alteration)值为68~74(平均值为72),表明了中等程度的化学风化。然而,古土壤表现出与黄土相近甚至更低的化学风化程度。磁化率和重矿物结果显示,古土壤的磁化率明显低于黄土,铁磁性矿物含量明显低于黄土。因此本文认为尽管哈尔滨古土壤是间冰期气候的产物,但其成壤过程中的气候条件冷湿,导致古土壤层的化学风化甚至低于黄土层。冷湿的成壤环境也使得古土壤层的磁铁矿还原分解,导致古土壤层相对于黄土层具有更低的磁化率。哈尔滨古土壤的形成环境和现在的黑龙江黑土相似,可称之为古黑土。
The knowledge about chemical weathering characteristics of the loess-paleosol sequence is of great significance for understanding how inland Asia aridifies,East Asian monsoon evolves and how global carbon cycle goes.However,very little is known about chemical weathering characteristics of the loess-paleosol sequence in Harbin,which is located at the easternmost end of the Eurasian loess belt and the forefront of the eastward movement of the aridification process of inland Asia.【Objective】This study is to explore chemical weathering characteristics and paleosol formation environment of the Huangshan rock core in Harbin.【Method】Samples of the loess-paleosol sequence were collected and analyzed for elemental geochemical properties,magnetizability and heavy mineral contents.【Result】The color of the paleosol in Harbin is grey-brown and grey-black,which is dramatically different from those(brownish red)in other areas.The loess-paleosol sequence is 68-74(on average 72)in CIA(Chemical Index of Alteration),which suggests that the sequence is moderate in chemical weathering.However,compared with the loess layers,the paleosol layers do not show any signs of higher degree of chemical weathering,but are quite close to or even lower than the loess layers in chemical weathering degree.The S1 and S3 paleosol layers were the lowest even among the loess-paleosol sequence.The loess layers in Huangshan rock core contain mainly SiO2(61.02%),Al_(2)O_(3)(19.51%),Fe2O3(4.19%)and K2O(3.03%),together amounting to 87.75%of the total of the loess layer in mass,while the paleosol layers contain SiO2(65.85%),Al_(2)O_(3)(19.33%)and Fe2O3(4.23%),amounting to 89.41%.In terms ofαAl index characterizing element migration ability,the elements in the loess-paleosol core follow an order ofαAl Ca(6.2)>αAl Na(2.8)>αAl Sr(2.0)>αAl Fe(1.53)>αAl Mg(1.51)>αAl K(1.46)>αAl Ba(1.28)>αAl Rb(1.23)>αAl Ti(0.91)>αAl Cs(0.75),showing relative depletion of element Ca,Na,Sr,Fe,Mg,K,Ba and Rb and relative enrichment of Ti and Cs elements in the
作者
张曼
谢远云
康春国
迟云平
吴鹏
魏振宇
张月馨
刘璐
ZHANG Man;XIE Yuanyun;KANG Chunguo;CHI Yunping;WU Peng;WEI Zhenyu;ZHANG Yuexin;LIU Lu(College of Geographic Science,Harbin Normal University,Harbin 150025,China;Heilongjiang Province Key Laboratory of Geographical Environment Monitoring and Spatial Information Service in Cold Regions,Harbin Normal University,Harbin 150025,China;Geography Department,Harbin Institute,Harbin 150086,China)
出处
《土壤学报》
CAS
CSCD
北大核心
2021年第3期673-684,共12页
Acta Pedologica Sinica
基金
国家自然科学基金项目(41871013,41601200)
黑龙江省自然科学基金项目(D2017003)资助。
关键词
黄土-古土壤序列
哈尔滨
地球化学
化学风化
古黑土
Loess-paleosol sequence
Harbin
Geochemistry
Chemical weathering
Paleo-black soil
