川西地区表土磁学性质及其环境意义
|
摘要
通过对川西地区表土样品进行系统的岩石磁学分析,并且结合气候要素探讨表土磁学性质与环境要素之间的关系。结果表明:(1)川西表土在成土过程中生成的细粒超顺磁(SP)和单畴(SD)的亚铁磁性矿物是磁化率增强的主导因素。该地区表土磁性增强机制与黄土高原类似。(2)在空间上,川西高原西部和南部地区的磁性矿物含量要高于东部和北部地区,而成都平原西部地区成土作用最强,磁颗粒细且含有较多高矫顽力磁性矿物。(3)川西表土的磁学参数和气候要素的研究发现年平均降水量(MAP)在600～1000 mm之间磁化率、频率磁化率与MAP呈正相关关系,而磁学参数组合χ_(fd)%/HIRM、ARM/HIRM、χ_(ARM)/SIRM与MAP在这一降雨区间也呈正相关关系,然而这些磁学参数与MAP的相关系数不如黄土高原,可能与研究区复杂的地形、相对湿润的成土条件有关。
【Objective】To clarify the relationship between magnetic susceptibility and climatic factors is the key to applying magnetic susceptibility to inversion of paleoenvironmental evolution. Therefore the study on magnetic properties of the modern topsoil is one of the effective means to establish the relationship between climate and magnetic susceptibility. As far little has been reported in the literature on magnetic properties of surface rock in West Sichuan, and the research in this field will sure help provide a theoretical basis for inversion of paleoclimate and establishment of climate models for the region. 【Method】This study was oriented to analyze variationof the topsoil magnetic properties of the region and its influencing factors and mechanism and to explore relationships between the topsoil magnetic properties and environmental factors by taking into account the environmental information, so as to provide scientific data for the study on paleosol and paleoclimate of the West Sichuan leoss region, through analysis of topsoil samples for room temperature magnetism and high temperature magnetism.【Result】The magnetic hysteresis loop shows that the ferrimagnetic minerallow in coercivity was the dominaral magnetic mineral in the soil sample, whileM-T curve analysis shows that ferrimagnetic mineral was, in addition to a small amount of magnetite hematite and weakly magnetic hematite, and some lepidocrocite in quite a number of the samples.【Conclusion】(1) The fine-grained superparamagnetic(SP) and single domain(SD) ferromagnetic minerals formed during in-situ pedogenic processes in the topsoil of West Sichuan is the dominant factor leading to higher magnetic susceptibility. The mechanism for magnetic enhancement of the topsoil in this area is similar to that in the Loess Plateau.(2) In terms of spatial distribution, the western and southern parts of the West Sichuan Plateau are higher than the eastern and northern parts in magnetic mineral content and in SP and SD particle content, too. Pedogenesisis the strongest in the western part of the Chengdu Plain, where the SP content is higher and the magnetic particles in the topsoil lower in average particle size than those all the other parts of the region. In addition, the topsoil in the area contains relatively more magnetic minerals high in coercivity, which demonstrates that the process of strongly magnetic minerals converting to weakly magnetic minerals did once occur.(3) The influence of climatic factors(especially precipitation) soil magnetic properties is the highest. Through the exploration of topsoil magnetic parameters and climatic factors in West Sichuan, it is found that in the region where the mean annual precipitation(MAP) varies in the range of 600～1000 mm, χ_(lf) and χ_(fd) is positively related with MAP in a whole and so are the magnetic parameters, i.e. χ_(fd)%/HIRM, ARM/HIRM, χ_(ARM)/SIRM in rainfall interval, but the correlation coefficients of these magnetic parameters with MAP are lower than those in the Loess Plateau, which may be attributed to the complex topography and relatively humid soil forming conditions in the study area.
【Objective】To clarify the relationship between magnetic susceptibility and climatic factors is the key to applying magnetic susceptibility to inversion of paleoenvironmental evolution. Therefore the study on magnetic properties of the modern topsoil is one of the effective means to establish the relationship between climate and magnetic susceptibility. As far little has been reported in the literature on magnetic properties of surface rock in West Sichuan, and the research in this field will sure help provide a theoretical basis for inversion of paleoclimate and establishment of climate models for the region. 【Method】This study was oriented to analyze variationof the topsoil magnetic properties of the region and its influencing factors and mechanism and to explore relationships between the topsoil magnetic properties and environmental factors by taking into account the environmental information, so as to provide scientific data for the study on paleosol and paleoclimate of the West Sichuan leoss region, through analysis of topsoil samples for room temperature magnetism and high temperature magnetism.【Result】The magnetic hysteresis loop shows that the ferrimagnetic minerallow in coercivity was the dominaral magnetic mineral in the soil sample, whileM-T curve analysis shows that ferrimagnetic mineral was, in addition to a small amount of magnetite hematite and weakly magnetic hematite, and some lepidocrocite in quite a number of the samples.【Conclusion】(1) The fine-grained superparamagnetic(SP) and single domain(SD) ferromagnetic minerals formed during in-situ pedogenic processes in the topsoil of West Sichuan is the dominant factor leading to higher magnetic susceptibility. The mechanism for magnetic enhancement of the topsoil in this area is similar to that in the Loess Plateau.(2) In terms of spatial distribution, the western and southern parts of the West Sichuan Plateau are higher than the eastern and northern parts in magnetic mineral content and in SP and SD particle content, too. Pedogenesisis the strongest in the western part of the Chengdu Plain, where the SP content is higher and the magnetic particles in the topsoil lower in average particle size than those all the other parts of the region. In addition, the topsoil in the area contains relatively more magnetic minerals high in coercivity, which demonstrates that the process of strongly magnetic minerals converting to weakly magnetic minerals did once occur.(3) The influence of climatic factors(especially precipitation) soil magnetic properties is the highest. Through the exploration of topsoil magnetic parameters and climatic factors in West Sichuan, it is found that in the region where the mean annual precipitation(MAP) varies in the range of 600～1000 mm, χ_(lf) and χ_(fd) is positively related with MAP in a whole and so are the magnetic parameters, i.e. χ_(fd)%/HIRM, ARM/HIRM, χ_(ARM)/SIRM in rainfall interval, but the correlation coefficients of these magnetic parameters with MAP are lower than those in the Loess Plateau, which may be attributed to the complex topography and relatively humid soil forming conditions in the study area.
引文
[1]Kukla G,An Z S.Loess stratigraphy in CentralChina.Palaeogeography Palaeoclimatology Palaeoecology,1989,72(89):203-225
[2]郝青振,郭正堂.1.2Ma以来黄土-古土壤序列风化成壤强度的定量化研究与东亚季风演化.中国科学(D辑),2001,31(6):520-528Hao Q Z,Guo Z T.Quantitative studies on the weathering intensity of the loess-solid sequences and evolvement East Asia monsoon during past 1.2Ma(In Chinese).Science in China(Series D),2001,31(6):520-528
[3]Ding Z L,Yu Z W,Rutter N W,et al.Towards an orbital time scale for Chinese Loess deposis.Quaternary ScienceReviews,1994,13(1):39-70
[4]Maher B A,Roy T.Paleorainfall reconstructions from pedogenic magnetic susceptibility variations in the Chinese Loess and Paleosols.Quaternary Research,1995,44(3):383-391
[5]Zhou L P,Oldfield F,Wintle A G,et al.Partly pedogenic origin of magnetic variations in Chinese loess.Nature,1990,346(6286):737-739
[6]吕厚远,韩家懋,郭正堂,等.中国现代土壤磁化率分析及其古气候意义.中国科学(B辑),1994,24(12):1290-1297LüH Y,Han J M,Guo Z T,et al.Magnetic susceptibility of the modern soils in China and paleoclimatic significance(In Chinese).Science in Chinese(Series B),1994,24(12):1290-1297
[7]Evans M E,Rokosh C D,Rutter N W.Magneto climatology and paleo precipitation:Evidence from a north-south transect through the Chinese Loess Plateau.Geophysical Research Letters,2002,29(8):1271-1274
[8]Bloemendal J,Liu X M.Rock magnetism and geochemistry of two plio-pleistocene Chinese loess-palaeosol sequencesimplications for quantitative palaeoprecipitation reconstruction.Palaeogeography Palaeoclimatology Palaeoecology,2005,226(2):149-166
[9]Begét J E,Stone D B,Hawkins D B.Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the late Quaternary.Geology,1990,18(1):40-43
[10]Matasova G,PetrovskyE,Jordanova N,et al.Magnetic study of Late Pleistocene loess/palaeosol sections from Siberia:Palaeo environmental implications.Geophysical Journal of the Royal Astronomical Society,2010,147(2):367-380
[11]Pillans B,Wright I.500000-Year paleo magnetic record from New Zealand loess.Quaternary Research,1990,33(2):178-187
[12]Orgeira M J,Walther A M,Vásquez C A.Mineral magnetic record of paleoclimate variation in loess and paleosol from the Buenos Aires formation(BuenosAires,Argentina).Journal of South American Earth Sciences,1998,11(6):561-570
[13]Gao X B,Hao Q Z,Wang L,et al.The different climatic response of pedogenic hematite and ferromagnetic minerals:Evidence from particle-sized modern soils over the Chinese Loess Plateau.Quaternary Science Reviews,2018,179:69-86
[14]Balsam W L,Ellwood B B,Ji J F,et al.Magnetic susceptibility asa proxy for rainfall:Worldwide data from tropical and temperate climate.Quaternary Science Reviews,2011,30(19/20):2732-2744
[15]Liu X M,Liu Z,LüB,et al.The magnetic properties of Serbian loess and environmental significance.Chinese Science Bulletin,2013,58(3):353-363
[16]刘秀铭,夏敦胜,刘东生,等.中国黄土和阿拉斯加黄土磁化率气候记录的两种模式探讨.第四纪研究,2007,27(2):210-220Liu X M,Xia D S,Liu D S,et al.Discussion on two model of paleoclmatic records of magnetic susceptibility of Alaska and Chinese loess(In Chinese).Quaternary Sciences,2007,27(2):210-220
[17]昝金波,方小敏,聂军胜,等.塔里木盆地风积物表土磁学特征及其与物源物质、气候条件的关系.科学通报,2011,56(2):153-160Zan J B,Fang X M,Nie J S,et al.Magnetic properties of surface soils across the southern Tarim Basin and their relationship with climate and source materials(In Chinese).Chinese Science Bulletin,2011,56(2):153-160
[18]宋扬,郝青振,葛俊逸,等.黄土高原表土磁化率与气候要素的定量关系研究.第四纪研究,2012,32(4):679-690Song Y,Hao Q Z,Ge J Y,et al.Quantitative relationships between modern soil magnetic susceptibility and climatic variables of the Chinese Loess Plateau(In Chinese).Quaternary Sciences,2012,32(4):679-690
[19]温昌辉,刘秀铭,王涛,等.澳大利亚中部AliceSpring红色表土磁学特征分析.第四纪研究,2015,35(4):1041-1050Wen C H,Liu X M,Wang T,et al.Magnetic analysis of red topsoil in Alice Spring(In Chinese).Quaternary Sciences,2015,35(4):1041-1050
[20]李平原,刘秀铭,郭雪莲,等.西北戈壁沙漠-黄土高原区表土磁化率特征及其意义.第四纪研究,2013,33(2):360-367Ling P Y,Liu X M,Guo X L,et al.The magnetic susceptibility properties of top soil’s in GoBi-Loess Plateau,northwest China(In Chinese).Quaternary Sciences,2013,33(2):360-367
[21]Long X,Ji J,William B.Rainfall-dependent transformations of iron oxides in a tropical saprolite transect of Hainan Island,South China:Spectral and magnetic measurements.Journal of Geophysical Research Atmospheres,2011,116(F3):239-255
[22]魏海涛,夏敦胜,陈发虎,等.新疆表土磁学性质及其环境意义.干旱区地理,2009,32(5):676-683Wei H T,Xia D S,Chen F H,et al.Magnetic characteristics of surface soil in arid region of Central Asia and their paleoenvironmental significance in Xinjiang,China(In Chinese).Arid Land Geography,2009,32(5):676-683
[23]张俊辉,夏敦胜,张英,等.阿勒泰地区表土磁学特性及变化机制研究.第四纪研究,2013,33(5):889-899Zhang J H,Xia D S,Zhang Y,et al.Study on the magnetic characteristics and variable mechanism of surface soils in Aletai area,Xinjiang China(In Chinese).Quaternary Sciences,2013,33(5):889-899
[24]郭雪莲,刘秀铭,吕镔,等.天山黄土区与黄土高原表土磁性特征对比及环境意义.地球物理学报,2011,54(7):1854-1862Guo X L,Liu X M,LüB,et al.Comparison of topsoil magnetic properties between the loess region in Tianshan Mountains and Loess Plateau,China,and its environmental significance(In Chinese).Chinese Journal of Geophysics,2011,54(7):1854-1862
[25]李珊,胡雪峰,杜艳,等.上海嘉定区表土磁性强度的空间分异及环境指示意义.土壤学报,2012,49(1):9-17Li S,Hu X F,Du Y,et al.Spatial variation of magnetic intensity of topsoils in JiaDing district,Shanghai and its environmental implication(In Chinese).Acta Pedologica Sinica,2012,49(1):9-17
[26]Evans M E,Heller F.Environmental magnetism:Principles and applications of enviromagnetics.New York:Academic Press,2003:1-299
[27]Thompson R,Oldfield F.Environmental magnetism.London:Allen&Unwin,1986:1-227
[28]Dearing J A.Magnetic susceptibility.London:Quaternary Research Association,1999:35-62
[29]Dearing J A,Bird P M,Dann R J L,et al.Secondary ferrimagnetic minerals in Welsh soils:A comparison of mineral magnetic detection methods and implications for mineral formation.Geophysical Journal of the Royal Astronomical Society,1997,130(3):727-736
[30]Hunt C P,Banerjee S K,Han J M,et al.Rockmagneticproxiesof climate change in the loess-palaeosol sequences of the western Loess Plateau of China.Geophysical Journal International,1995,123(1):232-244
[31]Dunlop D J,Ozdemir?.Rock magnetism:Fundamentals and frontiers.New York:Cambridge Univesity Press,1997
[32]Deng C L,Zhu R Y,Verosub K L,et al.Mineral magnetic properties of loess/paleosol couplets of the central loess Plateau of China over the last 1.2 Myr.Journal of Geophysical Research Solid Earth,2004,109(1):241-262
[33]Maher B A.Palaeoclimatic records of the loess/palaeosol sequences of the Chinese Loess Plateau.Quaternary Science Reviews,2016,154:23-84
[34]韩光中,黄来明,李山泉,等.水耕人为土磁性矿物的生成转化机制研究回顾与展望.土壤学报,2017,54(2):309-318Han G Z,Huang L M,Li S Q,et al.Review and prospect of researches on production and transformation of magnetic minerals in paddy soils during pedogenesis(In Chinese).Acta Pedologica Sinica,2017,54(2):309-318
[35]黄来明,邵明安,陈留美,等.水耕人为土时间序列铁氧化物与磁化率演变特征.土壤学报,2017,54(1):1-13Huang L M,Shao M A,Chen L M,et al.Evolution characteristics of iron oxides and magnetic susceptibility in stagnic anthrosols along chronosequences(In Chinese).Acta Pedologica Sinica,2017,54(1):1-13
[36]Geiss C E,Egli R,Zanner C W.Direct estimates of pedogenic magnetite as a tool to reconstruct past climates from buried soils.Journal of Geophysical Research Solid Earth,2008,113:B11102
[37]Nie J,Song Y,King J W,et al.Six million years of magnetic grain-size records reveal that temperature and precipitation were decoupled on the Chinese Loess Plateau during~4.5-2.6 Ma.Quaternary Research,2013,79(3):465-470
[38]LiuZF,Liu Q S,Torrent J,et al.Testing the magnetic proxyχfd/HIRM for quantifying paleoprecipitation in modern soil profiles from Shaanxi Province,China.Global and Planetary Change,2013,110:368-378
[2]郝青振,郭正堂.1.2Ma以来黄土-古土壤序列风化成壤强度的定量化研究与东亚季风演化.中国科学(D辑),2001,31(6):520-528Hao Q Z,Guo Z T.Quantitative studies on the weathering intensity of the loess-solid sequences and evolvement East Asia monsoon during past 1.2Ma(In Chinese).Science in China(Series D),2001,31(6):520-528
[3]Ding Z L,Yu Z W,Rutter N W,et al.Towards an orbital time scale for Chinese Loess deposis.Quaternary ScienceReviews,1994,13(1):39-70
[4]Maher B A,Roy T.Paleorainfall reconstructions from pedogenic magnetic susceptibility variations in the Chinese Loess and Paleosols.Quaternary Research,1995,44(3):383-391
[5]Zhou L P,Oldfield F,Wintle A G,et al.Partly pedogenic origin of magnetic variations in Chinese loess.Nature,1990,346(6286):737-739
[6]吕厚远,韩家懋,郭正堂,等.中国现代土壤磁化率分析及其古气候意义.中国科学(B辑),1994,24(12):1290-1297LüH Y,Han J M,Guo Z T,et al.Magnetic susceptibility of the modern soils in China and paleoclimatic significance(In Chinese).Science in Chinese(Series B),1994,24(12):1290-1297
[7]Evans M E,Rokosh C D,Rutter N W.Magneto climatology and paleo precipitation:Evidence from a north-south transect through the Chinese Loess Plateau.Geophysical Research Letters,2002,29(8):1271-1274
[8]Bloemendal J,Liu X M.Rock magnetism and geochemistry of two plio-pleistocene Chinese loess-palaeosol sequencesimplications for quantitative palaeoprecipitation reconstruction.Palaeogeography Palaeoclimatology Palaeoecology,2005,226(2):149-166
[9]Begét J E,Stone D B,Hawkins D B.Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the late Quaternary.Geology,1990,18(1):40-43
[10]Matasova G,PetrovskyE,Jordanova N,et al.Magnetic study of Late Pleistocene loess/palaeosol sections from Siberia:Palaeo environmental implications.Geophysical Journal of the Royal Astronomical Society,2010,147(2):367-380
[11]Pillans B,Wright I.500000-Year paleo magnetic record from New Zealand loess.Quaternary Research,1990,33(2):178-187
[12]Orgeira M J,Walther A M,Vásquez C A.Mineral magnetic record of paleoclimate variation in loess and paleosol from the Buenos Aires formation(BuenosAires,Argentina).Journal of South American Earth Sciences,1998,11(6):561-570
[13]Gao X B,Hao Q Z,Wang L,et al.The different climatic response of pedogenic hematite and ferromagnetic minerals:Evidence from particle-sized modern soils over the Chinese Loess Plateau.Quaternary Science Reviews,2018,179:69-86
[14]Balsam W L,Ellwood B B,Ji J F,et al.Magnetic susceptibility asa proxy for rainfall:Worldwide data from tropical and temperate climate.Quaternary Science Reviews,2011,30(19/20):2732-2744
[15]Liu X M,Liu Z,LüB,et al.The magnetic properties of Serbian loess and environmental significance.Chinese Science Bulletin,2013,58(3):353-363
[16]刘秀铭,夏敦胜,刘东生,等.中国黄土和阿拉斯加黄土磁化率气候记录的两种模式探讨.第四纪研究,2007,27(2):210-220Liu X M,Xia D S,Liu D S,et al.Discussion on two model of paleoclmatic records of magnetic susceptibility of Alaska and Chinese loess(In Chinese).Quaternary Sciences,2007,27(2):210-220
[17]昝金波,方小敏,聂军胜,等.塔里木盆地风积物表土磁学特征及其与物源物质、气候条件的关系.科学通报,2011,56(2):153-160Zan J B,Fang X M,Nie J S,et al.Magnetic properties of surface soils across the southern Tarim Basin and their relationship with climate and source materials(In Chinese).Chinese Science Bulletin,2011,56(2):153-160
[18]宋扬,郝青振,葛俊逸,等.黄土高原表土磁化率与气候要素的定量关系研究.第四纪研究,2012,32(4):679-690Song Y,Hao Q Z,Ge J Y,et al.Quantitative relationships between modern soil magnetic susceptibility and climatic variables of the Chinese Loess Plateau(In Chinese).Quaternary Sciences,2012,32(4):679-690
[19]温昌辉,刘秀铭,王涛,等.澳大利亚中部AliceSpring红色表土磁学特征分析.第四纪研究,2015,35(4):1041-1050Wen C H,Liu X M,Wang T,et al.Magnetic analysis of red topsoil in Alice Spring(In Chinese).Quaternary Sciences,2015,35(4):1041-1050
[20]李平原,刘秀铭,郭雪莲,等.西北戈壁沙漠-黄土高原区表土磁化率特征及其意义.第四纪研究,2013,33(2):360-367Ling P Y,Liu X M,Guo X L,et al.The magnetic susceptibility properties of top soil’s in GoBi-Loess Plateau,northwest China(In Chinese).Quaternary Sciences,2013,33(2):360-367
[21]Long X,Ji J,William B.Rainfall-dependent transformations of iron oxides in a tropical saprolite transect of Hainan Island,South China:Spectral and magnetic measurements.Journal of Geophysical Research Atmospheres,2011,116(F3):239-255
[22]魏海涛,夏敦胜,陈发虎,等.新疆表土磁学性质及其环境意义.干旱区地理,2009,32(5):676-683Wei H T,Xia D S,Chen F H,et al.Magnetic characteristics of surface soil in arid region of Central Asia and their paleoenvironmental significance in Xinjiang,China(In Chinese).Arid Land Geography,2009,32(5):676-683
[23]张俊辉,夏敦胜,张英,等.阿勒泰地区表土磁学特性及变化机制研究.第四纪研究,2013,33(5):889-899Zhang J H,Xia D S,Zhang Y,et al.Study on the magnetic characteristics and variable mechanism of surface soils in Aletai area,Xinjiang China(In Chinese).Quaternary Sciences,2013,33(5):889-899
[24]郭雪莲,刘秀铭,吕镔,等.天山黄土区与黄土高原表土磁性特征对比及环境意义.地球物理学报,2011,54(7):1854-1862Guo X L,Liu X M,LüB,et al.Comparison of topsoil magnetic properties between the loess region in Tianshan Mountains and Loess Plateau,China,and its environmental significance(In Chinese).Chinese Journal of Geophysics,2011,54(7):1854-1862
[25]李珊,胡雪峰,杜艳,等.上海嘉定区表土磁性强度的空间分异及环境指示意义.土壤学报,2012,49(1):9-17Li S,Hu X F,Du Y,et al.Spatial variation of magnetic intensity of topsoils in JiaDing district,Shanghai and its environmental implication(In Chinese).Acta Pedologica Sinica,2012,49(1):9-17
[26]Evans M E,Heller F.Environmental magnetism:Principles and applications of enviromagnetics.New York:Academic Press,2003:1-299
[27]Thompson R,Oldfield F.Environmental magnetism.London:Allen&Unwin,1986:1-227
[28]Dearing J A.Magnetic susceptibility.London:Quaternary Research Association,1999:35-62
[29]Dearing J A,Bird P M,Dann R J L,et al.Secondary ferrimagnetic minerals in Welsh soils:A comparison of mineral magnetic detection methods and implications for mineral formation.Geophysical Journal of the Royal Astronomical Society,1997,130(3):727-736
[30]Hunt C P,Banerjee S K,Han J M,et al.Rockmagneticproxiesof climate change in the loess-palaeosol sequences of the western Loess Plateau of China.Geophysical Journal International,1995,123(1):232-244
[31]Dunlop D J,Ozdemir?.Rock magnetism:Fundamentals and frontiers.New York:Cambridge Univesity Press,1997
[32]Deng C L,Zhu R Y,Verosub K L,et al.Mineral magnetic properties of loess/paleosol couplets of the central loess Plateau of China over the last 1.2 Myr.Journal of Geophysical Research Solid Earth,2004,109(1):241-262
[33]Maher B A.Palaeoclimatic records of the loess/palaeosol sequences of the Chinese Loess Plateau.Quaternary Science Reviews,2016,154:23-84
[34]韩光中,黄来明,李山泉,等.水耕人为土磁性矿物的生成转化机制研究回顾与展望.土壤学报,2017,54(2):309-318Han G Z,Huang L M,Li S Q,et al.Review and prospect of researches on production and transformation of magnetic minerals in paddy soils during pedogenesis(In Chinese).Acta Pedologica Sinica,2017,54(2):309-318
[35]黄来明,邵明安,陈留美,等.水耕人为土时间序列铁氧化物与磁化率演变特征.土壤学报,2017,54(1):1-13Huang L M,Shao M A,Chen L M,et al.Evolution characteristics of iron oxides and magnetic susceptibility in stagnic anthrosols along chronosequences(In Chinese).Acta Pedologica Sinica,2017,54(1):1-13
[36]Geiss C E,Egli R,Zanner C W.Direct estimates of pedogenic magnetite as a tool to reconstruct past climates from buried soils.Journal of Geophysical Research Solid Earth,2008,113:B11102
[37]Nie J,Song Y,King J W,et al.Six million years of magnetic grain-size records reveal that temperature and precipitation were decoupled on the Chinese Loess Plateau during~4.5-2.6 Ma.Quaternary Research,2013,79(3):465-470
[38]LiuZF,Liu Q S,Torrent J,et al.Testing the magnetic proxyχfd/HIRM for quantifying paleoprecipitation in modern soil profiles from Shaanxi Province,China.Global and Planetary Change,2013,110:368-378