Paleoclimatic significance of the mineral magnetic record of the Chinese loess and paleosols
China ; Climatic variation ; Loess ; Magnetic susceptibility ; Oxygen 18 ; Paleoclimatology ; Paleosols ; Quaternary ; Stratigraphy
The origins of the magnetic susceptibility variations of the Chinese loess and paleosols are explored by scanning and transmission electron microscopy of magnetic extracts, and by magnetic modeling of magnetic hysteresis data, to provide quantified
estimates of the major magnetic components. The AA. identify pedogenic formation of magnetite as the major contributor to the loess magnetic record. Matching this record against other paleoclimatic records, they find an high correlation with the standard 18O
record. The Chinese loess sequences record a very high resolution magnetic stratigraphy directly related to changing climate.
Factors affecting the magnetic susceptibility of a loess-soil sequence, Barton County, Kansas, USA
Chronostratigraphy ; Kansas ; Loess ; Magnetic susceptibility ; Palaeoclimatology ; Pedogenesis ; Soil ; Soil properties ; Stratigraphy ; United States of America
To interpret climatic signatures from magnetic susceptibility (MS) in the Barton County loess-soil sequence, the AA. test the influence of particle size and carbonate concentration on magnetic susceptibility. Discussion of the results.
Time dependence of magnetic susceptibility of soil chronosequences on the California coast
California ; Chronosequence ; Magnetic susceptibility ; Pedogenesis ; Quaternary ; Soil ; United States
The AA. discuss the magnetic mineralogy of a soil chronosequence formed from beach deposits on uplifted marine terraces in California that range in age from 1 700 to 240,000 yr. They compare the data from three chronosequences to show
the relationships between time and selected soil magnetic properties.
Sediment-magnetic signature of land-use and drought as recorded in lake sediment from south-central Minnesota, USA
Climatic variability ; Drought ; Holocene ; Human occupation ; Lacustrine sediment ; Land use ; Magnetic susceptibility ; Minnesota ; Palaeo-environment ; Palaeoclimate ; Sedimentology ; United States of America
Sediment magnetic properties of a short core from Sharkey Lake record the effects of Euroamerican settlement and climate change over the last 150 yr. The onset of European-style farming led to increase erosion, reflected in high values
of concentration-dependent parameters such as magnetic susceptibility (k), Isothermal Remanent Magnetization (IRM), and Anhysteretic Remanent Magnetization (ARM). High organic productivity in the lake during 1920s to 1940s drought increased the authigenic component
resulting in highly magnetic fine-grained sediment. The effects of dissolution and the superposition of climate and land-use signals complicate the use of recent sediments as modern analogs for sediment magnetic analyses.
The significance of various sediment magnetic mineral fractions for tracing sediment sources in Killimicat Creek
Australia ; Confluent ; Heavy minerals ; Magnetic susceptibility ; New South Wales ; Sediment load ; Sedimentology ; Tracer ; Watershed
This paper reports on experiments to measure the relative contributions of the magnetic constituents of sediments. The proportionate contributions of heavy and light mineral components of two different sediment streams delivered to the confluence
in the headwaters of Killimicat Creek, New South Wales, are determined from mineral magnetic measurements. The results show that most of the magnetic mineral component is associated with sediment particles, rather than the discrete heavy mineral component.
Comparison of magnetic particles in airborne dust on Mars and in the Harmattan dust from south of Sahara
The magnetic properties experiments on the Mars Pathfinder mission indicate that Martian airborne dust is slightly magnetic. For purposes of comparison similar experiments on the magnetic properties of terrestrial airborne dust on the Earth have
been performed at the University of Ghana. The main result of these experiments is that the airborne Harmattan dust in Ghana is substantially less magnetic than the dust suspended in the Martian atmosphere.
This study attempts to quantify post- and pre-1960 soil erosion in a small cultivated basin near Saskatoon, Saskatchewan, Canada, by measuring Cs 137 and magnetic susceptibility distribution with depth. The objective was to see if the differences
in magnetic susceptibility between topsoil and subsoil, and between soils of different slope positions could be used to quantify soil redistribution in a cultivated field.
Magnetic properties of the urban soils in Shanghai and their environmental implications
China ; Comparative study ; Cultivated land ; Heavy minerals ; Magnetic susceptibility ; Pollution ; Shanghai ; Soil ; Soil pollution ; Soil properties
To evaluate the feasibility of using magnetic techniques for monitoring soil pollution in Shanghai, magnetic properties and heavy metals in the topsoils in an urban site (Songnan Town) and a less-urbanized agricultural site (Luojing Town) in Baoshan
Paleoenvironmental significance investigation of loess magnetic fabric in a semiarid region
Arid area ; China ; Climatic change ; Gansu ; Loess ; Magnetic susceptibility ; Mountain ; Palaeo-environment ; Pleistocene ; Semi-arid area
The AA. report their recent magnetic fabric investigation of loess deposition in Shagou section, located at the northeastern Qilian Mountains, the northeastern rim of the Tibetan plateau. On the basis of environmental magnetism data, they indicate
that the variation of anisotropy of magnetic susceptibility (AMS) parameters, especially the foliation (F) and degree of anisotropy (P), might be more sensitive to the environmental change in the arid and semiarid regions than the magnetic susceptibility fluctuation
Mapping contemporary magnetic mineral concentrations in peat soils using fine-resolution digital terrain data
Cartography ; Digital elevation model ; England ; Gully erosion ; Hydromorphic soil ; Magnetic susceptibility ; Peat bog ; Soil properties ; Topography ; United Kingdom ; Yorkshire
Recent adavances in the field od digital terrain analysis and the avaibility of fine-resolution digital elevation models means that the relationship between the concentration of magnetic minerals in peat soils and topography can be explored using
quantitative methods. Alport Moor is an ombotrophic peat moorland in the Peak District National Park, UK, where 24 peat cores were collected. Each core was analysed for mass specific magnetic susceptibility. The mapping results demonstrate that the contemporary
concentration of magnetic minerals in the peat soils of Alport Moor is controlled by micro- and local-scale variations in water table position.
A comparison of mineral-magnetic and distributed RUSLE modeling in the assessment of soil loss on a southeastern U.S. cropland
Alabama ; Catena ; Cultivated land ; Magnetic susceptibility ; Model ; Soil erosion ; Soil properties ; United States of America
This study addresses the capacity of rapidly and cheaply acquired mineral-magnetic data to provide detailed spatially distributed assessments of long-term cumulative soil loss from agricultural fields. Model output from a simple distributed
implementation of the Revised Universal Soil Loss Equation (RUSLE) and from a field-data-oriented soil magnetism-based erosion model are compared for a small Alabama (USA) farm lot. RUSLE underpredicted denudation relative to magnetism-model results over upper
Use of mineral magnetic measurements to investigate soil erosion and sediment delivery in a small agricultural catchment in limestone terrain
Alabama ; Cultivated land ; Forecast ; Magnetic susceptibility ; Methodology ; Model ; Sediment budget ; Slope gradient ; Soil erosion ; Thematic mapping ; United States of America ; Watershed
In this study, variations in surface magnetism are analyzed to determine patterns of erosion and sedimentation in a small agricultural catchment in northwestern Alabama (USA). Magnetic indicators of erosion are combined with published soil
morphology, Cs-137 and short-term suspended sediment data from this former experimental watershed to evaluate long-term sediment delivery. The results suggest the need for continued refinement of magnetic techniques for purposes of erosion model validation
Verification of a simple gravity technique for separation of particle size fractions suitable for mineral magnetic analysis
Techniques for the separation of sediment samples into size fractions are reviewed and the use of repeated decantations to provide samples for mineral magnetic analysis is described. Results from a series of trials are presented and compared
The purpose of this paper is to discuss the significance of magnetotactic bacteria with respect to biomineralization, ecology, sediment magnetism, and their potential use as environmental indicators.
A multivariate mixing model for identifying sediment source from magnetic measurements
A sequential method for quantitative identification of sediment source components, based on magnetic measurements, has been developed and tested for sediments from the Rhode River, Maryland.
This paper outlines some progress toward an improved understanding of processes involving magnetic mineral authigenesis in lake systems. Magnetic and geochemical data are presented. A model depicts the stratigraphic locations in which authigenesis
is most likely, and the implications for the interpretation of magnetic data are discussed.
Magnetic susceptibility of soils in different slope positions in Saskatchewan, Canada
Canada ; Catena ; Chernozem ; Cold area ; Grain size distribution ; Magnetic susceptibility ; Saskatchewan ; Slope gradient ; Soil ; Soil properties
The magnetic susceptibility (χ) of soils varies with the slope position due to some factors, such as texture and drainage class. This study attempts to link χ to soil profile characteristics for different landscape positions at two chernozemic sites
Pattern of cumulative soil erosion and redistribution pinpointed through magnetic signature of Chernozem soils
Agricultural practice ; Agropedology ; Bulgaria ; Chernozem ; Cultivated land ; Magnetic susceptibility ; Methodology ; Slope gradient ; Soil erosion ; Soil properties ; Water erosion
The experimental test field is situated in NE Bulgaria, southward from the city of Russe. An agricultural land of 4.5 ha, utilized for crop production, has been mapped at 10 × 10 m grid interval by using magnetic methods. Field measurements
of magnetic susceptibility show high sensitivity to the present soil surface conditions (crop residue cover, soil compaction, sealing) in addition to the main response to erosional removal of the uppermost soil horizons. Laboratory measurements of magnetic
susceptibility (χ), frequency dependent magnetic susceptibility (χfd) and Isothermal Remanent Magnetization on soil samples allow construction of surface maps of these magnetic characteristics. Comparison of the maps with terrain slope reveals that in the upper