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Study area. (A) Inset map of eastern North America showing the Delaware River Basin (gray) (modified from Stinchcomb et al., 2013). (B) The Delaware Water Gap National Recreation Area showing profile locations (T3, T2, and T0) mentioned in text (modified from Stinchcomb et al., 2012). The environmental magnetic properties of these three profiles were examined in detail here and span three unique geomorphic surfaces: a modern T0 active floodplain surface (C), a Holocene T2 alluvial terrace (D), and a late Pleistocene T3 periglacial meltwater terrace (C). The additional profiles noted in B were used to constrain the weathering duration of buried soils along the T2 (Table 1) and analyzed for their Xlf (Supplementary Table 5).
Source publication
Magnetic susceptibility of soils is a common proxy for rainfall, but other factors can contribute to magnetic enhancement in soils. Here we explore influence of century- to millennial-scale duration of soil formation on periglacial and alluvial soil magnetic properties by assessing three terraces with surface and buried soils ranging in exposure ag...
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Purpose
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Citations
... Reference soil samples CX1 and CX2 were associated with clusters "c" and "e" and were collected in the A and B horizons from a Haplic Cambisol in a dry forest environment. A dry forest is a vegetation community that hosts frequent natural fires, and the data prove the capacity of wildfire to produce magnetic signatures in the natural soil, as previously shown by Ketterings et al. (2000) and Stinchcomb and Peppe (2014). ...
This study provides the first survey of Brazilian magnetic susceptibility (MS) data from varying archaeological and geological contexts, including open‐air sites, quartzite, and limestone rockshelters, and Amazonian dark earths. Our MS analyses associated with archaeological findings allow us to propose MS values as proxies of intense anthropogenic burning activities for archaeological sites with (i) systematic use of large hearth lit in the same places; (ii) systematic burns and highly diverse uses; (iii) higher diversity use with few fire activities and knapping playing an essential role; and (iv) incipient human activities and the initial use of the archaeological site. Our data are limited to understanding anthropogenic burning activities and cannot be extended to reveal other archaeological aspects. The results have implications for understanding human occupation in a large area with numerous archaeological sites. This study was the first step in distinguishing archaeological fires from natural fires and provided a new perspective for further research that attempts to identify distinct types of human fires.
... As mentioned earlier, magnetic enhancement was observed in the upper horizons of all the pedons, as was also found by other authors (Stinchcomb and Peppe 2014;Mahmoodi et al. 2016). Researchers have ascribed this enhancement to a number of origins. ...
In order to investigate the development of forest soils formed on loess, six representative modern soil pedons were selected along a precipitation gradient extending from eastern Golestan (mean annual precipitation, MAP = 500 mm) to eastern Mazandaran Provinces (MAP = 800 mm). Physiochemical, micromorphological and magnetic properties, as well as clay mineralogy of soils were studied using standard methods. Soils are mainly classified as Alfisols and Mollisols. Downward decalcification and the subsequent clay illuviation were the main criteria of soil development in all study areas. Pedogenic magnetic susceptibility of pedons studied varied systematically across the precipitation gradient in Northern Iran, increasing from 14.66 × 10⁻⁸ m³ kg⁻¹ at the eastern part to 83.75 × 10⁻⁸ m³ kg⁻¹ at the western margin of this transect. The frequency-dependent magnetic susceptibility showed an increasing trend with rainfall as well. The micromorphological study of soils indicated that there is a positive relationship between climate gradient (increasing rainfall) and the micromorphological index of soil development (MISECA). The area and thickness of clay coatings showed an increasing trend with rainfall. Grain size analysis indicates that pedogenic processes are responsible for changing original grain size distribution of loess in our soils. The correlation achieved among modern soil properties and precipitation could be applied to the buried paleosols in the whole study area to refer degree of paleosol development and to reconstruct the paleoclimate.
... The formation of magnetic minerals in soils due to factors other than the change in pH and Eh caused by the oscillation of the water table was reported by Viana et al. (2006), who detected the presence of magnetite in the surface horizons of savanna (Cerrado) soils and attributed the genesis of the magnetite to natural and frequent burnings. Stinchcomb and Peppe (2014) also reported the genesis of magnetite in burnt soils along the Delaware River in the USA. In paleoenvironmental studies, magnetite and magnetic minerals are commonly reported (Bourne et al., 2015;Dong et al., 2015;Hu et al., 2015;Maxbauer et al., 2016), Marmet et al. (1999) mentioned the production of magnetite and maghemite due to the heating of soils, resulting in the increase in the magnetic susceptibility of the soil. ...
... PET is dependent on a variety of factors including climate and vegetation 8 . Targeted studies investigating the influence of other soil factors have improved our understanding into how the duration of soil development [22][23][24][25] , parent material [26][27][28] , and topography 29,30 impact the magnetic mineralogy of soils. Yet, the role of vegetation on magnetic mineral assemblages in soils remains largely unconstrained. ...
Pedogenesis produces fine-grained magnetic minerals that record important information about the ambient climatic conditions present during soil formation. Yet, differentiating the compounding effects of non-climate soil forming factors is a nontrivial challenge that must be overcome to establish soil magnetism as a trusted paleoenvironmental tool. Here, we isolate the influence of vegetation by investigating magnetic properties of soils developing under uniform climate, topography, and parent material but changing vegetation along the forest-prairie ecotone in NW Minnesota. Greater absolute magnetic enhancement in prairie soils is related to some combination of increased production of pedogenic magnetite in prairie soils, increased deposition of detrital magnetite in prairies from eolian processes, or increased dissolution of fine-grained magnetite in forest soils due to increased soil moisture and lower pH. Yet, grain-size specific magnetic properties associated with pedogenesis, for example relative frequency dependence of susceptibility and the ratio of anhysteretic to isothermal remanent magnetization, are insensitive to changing vegetation. Further, quantitative unmixing methods support a fraction of fine-grained pedogenic magnetite that is highly consistent. Together, our findings support climate as a primary control on magnetite production in soils, while demonstrating how careful decomposition of bulk magnetic properties is necessary for proper interpretation of environmental magnetic data.
... A study of alluvial vertisols in Texas documented magnetic enhancement that developed over the course of centuries ( Fig. 7; Lindquist et al., 2011). However, recent observations of magnetism in alluvial soils developed on differently aged river terraces along the Delaware River Valley suggest that time does influence magnetic mineralogy in this system (Stinchcomb and Peppe, 2014). ...
Magnetic properties of soil are widely utilized to study soil development in a variety of settings due to the formation of strongly magnetic iron oxides during pedogenesis. Similarly, soil organic matter (SOM) is commonly measured in soil surveys conducted on agricultural lands due to the essential role SOM plays in the soil ecosystem. Here, we present data from two agricultural fields in southeastern Minnesota that demonstrate a relationship between soil magnetic properties and SOM. In each field, we collected 100 topsoil samples along a 40 m by 20 m grid to determine spatial variability in soil magnetic properties and SOM, as well as two soil cores to constrain variability with depth (∼0–60 cm). Magnetic susceptibility, low-field remanence, and hysteresis properties were used to characterize magnetic mineral abundance and grain-size in the soils. There are strong positive correlations between SOM and three magnetic properties: the frequency dependence of susceptibility (χfd), anhysteretic remanent magnetization (ARM), and the ratio of ARM to isothermal remanent magnetization (ARM/IRM). All three of these magnetic properties (χfd, ARM, and ARM/IRM) are sensitive to the concentration (or relative abundance) of fine-grained (<75 nm) magnetite/maghemite known to form in well-drained soils during pedogenesis. Correlation between SOM and magnetic properties persist in each field despite differences in the management strategy over the past three decades. Our results support a functional link between SOM and soil-formed magnetite/maghemite, where increasing SOM (up to a threshold) enhances the production and stability of soil-formed magnetite due to its role in soil redox processes and iron-organic complexes. Agricultural soils seem particularly well suited to demonstrate correlations between SOM and pedogenic magnetic minerals due to their relatively low SOM and typically well-drained environments, supporting the utility of soil magnetism in agricultural soil survey studies.
