欢迎您！东篱公司
退出
-
申报数据库
-
立项数据库
-
成果数据库
-
项目获奖数据库
中文摘要：
澳大利亚内陆广大而干旱，发育着大面积沙漠，却没有多少黄土的报道。本文对惟一报道的黄土，新南威尔士州Mackenzie地区WaterholesCreek剖面进行了详细的采样和磁学参数测量，并与中国黄土高原洛川和西峰经典剖面进行了对比。结果表明该剖面磁学性质与中国黄土高原有许多异同。它成土特征强，百分比频率磁化率较高，但是磁化率值较低，硬磁性矿物含量远远高于中国黄土高原。磁性矿物种类与黄土高原相似，强磁性矿物为磁铁矿和磁赤铁矿，弱磁性矿物为针铁矿／褐铁矿和赤铁矿。但是磁赤铁矿和赤铁矿含量明显少，顺磁性矿物占很大的比例，相对含量高于中国黄土高原。而且，这个比例随深度增加而增高。相对而言，磁赤铁矿对氧化与湿润滞水环境比磁铁矿更为敏感，它在中国洛川黄土剖面随磁化率增加而增多；而在澳大利亚剖面随磁化率增加而减少，表明该剖面成土环境是在磁赤铁矿／磁铁矿不稳定条件下进行的。当地现代年均降水量924．2mm，比洛川高出300mm。可能是因为当地土壤湿度超过磁赤铁矿／磁铁矿临界湿度范围，使其不稳定而被改变成为低磁化率的针铁矿，导致磁化率降低。该剖面普遍可见铁锰质从上部被溶解并迁移到下部沉积，形成铁质胶结和铁质结核，说明成土过程发生了较多水分参与的化学风化。这个过程也导致了原生风积物中强磁化率矿物磁赤铁矿／磁铁矿改变成为铁的氢氧化物（如针铁矿褐铁矿）或者顺磁性矿物，使得磁化率降低。尽管该剖面磁化率大部分与粒度正相关，似乎符合阿拉斯加“风速论”的解释。但剖面下部有明显铁质胶结和结核，说明已经发生了铁的化学风化和物质迁移，“风速论”的前提条件已经不能满足，磁化率变化只能从成土过程寻求解答。
英文摘要：
There are vast and dry areas of deserts in the interior of Australia, but none of loess section has been reported until 2003, Mackenzie＇s Waterholes Creek （MWC）profile in New South Wales was first studied as loess. In this paper,various measurements of magnetic parameters from MWC were carried out, comparison was made with those of Luochuan profile, which lies in the Central Chinese Loess Plateau （ CLP）. The types of magnetic minerals are similar to the CLP： magnetite, maghemite, limonite and hematite. However, the magnetic properties of Australian aeolian sediment show quite different. Frequency-dependent magnetic susceptibility （χfd%）is rather high, while values of magnetic susceptibility is low. The relative content of hard（paramagnetic）-magnetic components is much higher than CLP,whereas the content of maghemite and hematite is obviously much less. Furthermore this proportion increases along with the depth. Maghemite is more sensitive than magnetite under pedogenic condition of experiencing humid and stagnant watered environment. Maghemite increases along with enhancement of magnetic susceptibility in Luochuan section; however,decreases with that in MWC profile. This very likely indicate that the pedogenic process in MWC took place under environment that maghemite/magnetite are unstable. The modern annual precipitation is 924.2mm in MWC area, which is about 300mm higher than that in Luochuan. That extra moisture may lead MWC exceeding stable range for maghemite/magnetite. Those minerals therefore gradually converted to more stable goethite under the condition, causing magnetic susceptibility to decrease. Fe and Mn nodules are commonly observed in the lower part of section,implying pedogenic chemical weathering happened that Fe was dissolved and migrated downward and enriched in certain position,indicating that wind-blown maghemite/ magnetite under such moisture condition were transformed to iron hydroxides, such as goethite/limonite, or paramagnetic minerals, resulting in magnetic suscept
同期刊论文项目
同项目期刊论文
A long-term increasing aridification and cooling trend at the Chinese Loess Plateau during the Plioc
Paleoclimatic evolution of Holocene loess and discussion of the sensitivity of magnetic susceptibili
Dendroclimatic response of Picea crassifolia along an altitudinal gradient in the eastern Qilian Mou
Late Quaternary (30.7-9.0 cal ka BP) vegetation history in Central Asia inferred from pollen records
A high-resolution record of Holocene environmental and climatic changes from Lake Balikun (Xinjiang,
Spatial and temporal variety of prehistoric sites and its influencing factors in the upper Yellow Ri
Glacier changes from 1966-2009 in the in the Gongga Mountains, on the south-eastern margin of the Qi
A 16-ka lake-level record inferred from macrofossils in a sediment core from Genggahai Lake, northea
Influence of household biogas digester use on household energy consumption in a semi-arid rural regi
A comparative study of radiocarbon dating charcoal and charred seeds from the same flotation samples
Precipitation variations and possible forcing factors on the Northeastern Tibetan Plateau during the
Glacier variations in response to climate change from 1972 to 2007 in the western Lenglongling mount
Comparison of topsoil magnetic properties between the loess region in Tianshan Mountains and Loess P
Interannual precipitation variations in the mid-latitude Asia and their association with large-scale
Process of paleofloods in Guanting basin, Qinghai Province, China and possible relation to monsoon s
Soil Microbial and Enzymatic Activities Across a Chronosequence of Chinese Pine Plantation Developme
A 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau, China using tr
Patterns and dynamics of tree-line response to climate change in the eastern of Qilian Mountains, no
Compound-specific hydrogen isotopes of long-chain n-alkanes extracted from topsoil under a grassland
Magnetostratigraphy and palaeoenvironmental records for a Late Cenozoic sedimentary sequence from La
Late Cenozoic orogenic history of Western Qinling inferred from sedimentation of Tianshui basin, nor
Cenozoic tectonic uplift history of Western Qinling: Evidence from sedimentary and fission-track dat
Stable carbon and oxygen isotopic study of carbonate along a loess/paleosol section located in south
Conifer stomata analysis in paleoecological studies on the Loess Plateau: an example from Tianchi La
Annual precipitation reconstruction since AD 775 based on tree rings from the Qilian Mountains, nort
The ultrafine component in Chinese loess and its variation over the past 7.6 Ma: implications for th
Holocene vegetation and climate histories in the eastern Tibetan Plateau: controls by insolation-dri
Eocene to Pliocene exhumation history of the Tianshui-Huicheng region determined by Apatite fission-
Spatiotemporal drought variability for central and eastern Asia over the past seven centuries derive
Is the maximum carbon number of long-chain n-alkanes an indicator of grassland or forest? Evidence f
Variation and paleoclimatic significance of organic carbon isotopes of Ili loess in arid Central Asi
A high-resolution multi-proxy record of late Cenozoic environment change from central Taklimakan Des
Palaeomagnetic and palaeoenvironmental study of two parallel sections of late Cenozoic strata in the
Vegetation history, climate change and human activities over the last 6200 the Liupan Mountains in t
Magnetic properties and correlation with heavy metals in urban street dust: A case study from the ci
期刊信息
位置：