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Liao Chang - One of the best experts on this subject based on the ideXlab platform.
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paleoMagnetic recording efficiency of sedimentary Magnetic Mineral inclusions implications for relative paleointensity determinations
Journal of Geophysical Research, 2019Co-Authors: Hoabin Hong, Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Kazuto Kodama, Greig A Paterson, Lisa TauxeAbstract:This study was supported by the National Natural Science Foundation of China (Grants 41574060, 41574063, and 41722402) and the Australian Research Council (Grants DP120103952 and DP160100805). G. A. P. is supported by a NERC Independent Research Fellowship (NE/P017266/1). L. T. acknowledges support from NSF Grant EAR1547263.
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Magnetic Mineral tracing of sediment provenance in the central Bengal Fan
Marine Geology, 2019Co-Authors: Pengfei Xue, Liao Chang, Shishun Wang, Shengfa Liu, Xuefa Shi, Somkiat Khokiattiwong, Narumol KornkanitnanAbstract:Abstract We present a comprehensive Magnetic Mineral analysis of surface sediments from 110 sites in the central Bengal Fan to trace sediment provenance. Multiple Magnetic parameters, including Magnetic Mineralogy, concentration, and grain size were generated. Rock Magnetic measurements indicate that the dominant Magnetic Minerals within the studied sediments are detrital magnetite and titanomagnetite, which is further confirmed directly by scanning electron microscope (SEM) and transmission electron microscope (TEM) observations on Magnetic extracts. Fuzzy c-means clustering analysis of Magnetic parameters indicates that the study area can be divided into three clusters. Considering the position of ‘active valley’, we further divide cluster 1 into clusters 1A and 1B. Cluster 1A primarily covers the west side of the ‘active valley’ with relatively high Magnetic concentrations and dominantly coarse-grained Magnetic Minerals, which likely correspond to basaltic materials derived from the Deccan Plateau. From the Godavari river mouth to the inner Bay of Bengal, Magnetic concentration gradually decreases with a fining trend of Magnetic grain size. Clusters 1B, 2, and 3 are on the east side of the ‘active valley’, where Magnetic concentration and Magnetic grain size decrease with increasing distance to the ‘active valley’. Combined with published data in the Indian region and the upper Bengal Fan, we suggest that the main provenances are the Himalayan and the Deccan Plateau, whose contributions to sediment distribution are quantitatively assessed. Our analysis suggests that the position of ‘active valley’ plays a key role in sediment distribution in the central Bengal Fan, while the effect of ocean currents is negligible.
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Widespread occurrence of silicate‐hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research: Solid Earth, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
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widespread occurrence of silicate hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Jinhua Li, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
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Characterizing magnetofossils from first‐order reversal curve (FORC) central ridge signatures
Geochemistry Geophysics Geosystems, 2014Co-Authors: David Heslop, Andrew P Roberts, Liao ChangAbstract:The central ridge structure of a first-order reversal curve (FORC) distribution is indicative of uniaxial noninteracting single domain Magnetic particles, which provides the opportunity to identify and characterize biogenic Magnetic Mineral remains (magnetofossils) in sediments. Recent studies have shown that magnetofossils are widespread in the geological record and that they carry useful environmental information and contribute to paleoMagnetic recording, which makes it essential to quantify how these biogenic components contribute to the Magnetic properties of sediments. We present results from six sedimentary sequences whose Magnetic Mineral assemblages contain a significant magnetofossil contribution. Using principal component analysis, we find that the central ridge properties exhibit both intra-sequnce and inter-sequence variability that may be ascribed to external environmental factors. While samples from individual sediment sequences tend to cluster together, there is a continuum of inter-sequence behavior that appears to be related to a variety of magnetofossil properties. We demonstrate the complexity of biogenic Magnetic components in sedimentary environments, but also the power and potential of FORC central ridges for understanding Magnetic mixtures and unraveling environmental information.
David Heslop - One of the best experts on this subject based on the ideXlab platform.
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paleoMagnetic recording efficiency of sedimentary Magnetic Mineral inclusions implications for relative paleointensity determinations
Journal of Geophysical Research, 2019Co-Authors: Hoabin Hong, Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Kazuto Kodama, Greig A Paterson, Lisa TauxeAbstract:This study was supported by the National Natural Science Foundation of China (Grants 41574060, 41574063, and 41722402) and the Australian Research Council (Grants DP120103952 and DP160100805). G. A. P. is supported by a NERC Independent Research Fellowship (NE/P017266/1). L. T. acknowledges support from NSF Grant EAR1547263.
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signatures of reductive Magnetic Mineral diagenesis from unmixing of first order reversal curves
Journal of Geophysical Research, 2018Co-Authors: Andrew P Roberts, David Heslop, Xiang Zhao, Richard J Harrison, Adrian R Muxworthy, Christopher J Rowan, Juancruz Larrasoana, Fabio FlorindoAbstract:This work was supported financially by the Australian Research Council through grant DP160100805, by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC grant agreement number 320750, and by the National Institute of Advanced Industrial Science and Technology, Ministry of Economy, Trade and Industry, Japan.
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Widespread occurrence of silicate‐hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research: Solid Earth, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
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widespread occurrence of silicate hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Jinhua Li, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
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Numerical strategies for Magnetic Mineral unmixing
Earth-Science Reviews, 2015Co-Authors: David HeslopAbstract:Abstract Iron-bearing Minerals are sensitive to a wide spectrum of natural processes and thus carry important environmental information. In environmental magnetism, various techniques are used to identify and quantify Magnetic Mineral assemblages in natural materials, with the aim of drawing inferences concerning past environments and environmental change. Natural materials typically contain a number of Magnetic Mineral subpopulations with different origins that can reflect multiple environmental processes. Thus, it is essential that the information carried by such mixed Magnetic Mineral assemblages can be quantified in terms of environmentally meaningful component parts. Magnetic unmixing techniques are designed to perform this quantification and can, thus, act as a cornerstone for interpreting complex environmental Magnetic data. In this review, numerical strategies for unmixing Magnetic Mineral assemblages are discussed and are illustrated with examples. Emphasis is placed on the extent of available a priori knowledge concerning a Magnetic Mineral mixture and the ways that such information can be incorporated into a meaningful unmixing model.
Andrew P Roberts - One of the best experts on this subject based on the ideXlab platform.
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Classification of a Complexly Mixed Magnetic Mineral Assemblage in Pacific Ocean Surface Sediment by Electron Microscopy and Supervised Magnetic Unmixing
Frontiers in Earth Science, 2020Co-Authors: Yan Liu, Andrew P Roberts, Shuangchi Liu, Hongmiao Pan, Tian Xiao, Yongxin PanAbstract:Unambiguous Magnetic Mineral identification in sediments is a prerequisite for reconstructing paleoMagnetic and paleoenvironmental information from environmental Magnetic parameters. We studied a deep-sea surface sediment sample from the Clarion Fracture Zone region, central Pacific Ocean, by combining Magnetic measurements and scanning and transmission electron microscopic analyses. Eight titanomagnetite and magnetite particle types are recognized based on comprehensive documentation of crystal morphology, size, spatial arrangements, and compositions, which are indicative of their corresponding origins. Type-1 particles are detrital titanomagnetites with micron- and submicron sizes and irregular and angular shapes. Type-2 and -3 particles are well-defined octahedral titanomagnetites with submicron and nanometer sizes, respectively, which are likely related to local hydrothermal and volcanic activity. Type-4 particles are nanometer-sized titanomagnetites hosted within silicates, while type-5 particles are typical dendrite-like titanomagnetites that likely resulted from exsolution within host silicates. Type-6 particles are single domain magnetite magnetofossils related to local magnetotactic bacterial activity. Type-7 particles are superparaMagnetic magnetite aggregates, while Type-8 particles are defect-rich single crystals composed of many small regions. Electron microscopy and supervised Magnetic unmixing reveal that type-1 to -5 titanomagnetite and magnetite particles are the dominant Magnetic Minerals. In contrast, the Magnetic contribution of magnetite magnetofossils appears to be small. Our work demonstrates that incorporating electron microscopic data removes much of the ambiguity associated with Magnetic Mineralogical interpretations in traditional rock Magnetic measurements.
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paleoMagnetic recording efficiency of sedimentary Magnetic Mineral inclusions implications for relative paleointensity determinations
Journal of Geophysical Research, 2019Co-Authors: Hoabin Hong, Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Kazuto Kodama, Greig A Paterson, Lisa TauxeAbstract:This study was supported by the National Natural Science Foundation of China (Grants 41574060, 41574063, and 41722402) and the Australian Research Council (Grants DP120103952 and DP160100805). G. A. P. is supported by a NERC Independent Research Fellowship (NE/P017266/1). L. T. acknowledges support from NSF Grant EAR1547263.
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signatures of reductive Magnetic Mineral diagenesis from unmixing of first order reversal curves
Journal of Geophysical Research, 2018Co-Authors: Andrew P Roberts, David Heslop, Xiang Zhao, Richard J Harrison, Adrian R Muxworthy, Christopher J Rowan, Juancruz Larrasoana, Fabio FlorindoAbstract:This work was supported financially by the Australian Research Council through grant DP160100805, by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC grant agreement number 320750, and by the National Institute of Advanced Industrial Science and Technology, Ministry of Economy, Trade and Industry, Japan.
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Widespread occurrence of silicate‐hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research: Solid Earth, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
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widespread occurrence of silicate hosted Magnetic Mineral inclusions in marine sediments and their contribution to paleoMagnetic recording
Journal of Geophysical Research, 2016Co-Authors: Liao Chang, Andrew P Roberts, David Heslop, Akira Hayashida, Jinhua Li, Xiang Zhao, Wei Tian, Qinghua HuangAbstract:Magnetic Mineral inclusions occur commonly within other larger Mineral phases in igneous rocks and have been demonstrated to preserve important paleoMagnetic signals. While the usefulness of Magnetic inclusions in igneous rocks have been explored extensively, their presence in sediments has only been speculated upon. The contribution of Magnetic inclusions to the magnetization of sediments, therefore, has been elusive. In this study, we use transmission electron microscope (TEM) and Magnetic methods to demonstrate the widespread preservation of silicate-hosted Magnetic inclusions in marine sedimentary settings. TEM analysis reveals detailed information about the microstructure, chemical composition, grain size, and spatial arrangement of nanoscale Magnetic Mineral inclusions within larger silicate particles. Our results confirm the expectation that silicate Minerals can protect Magnetic Mineral inclusions from sulfate-reducing diagenesis, and increase significantly the preservation potential of iron oxides in inclusions. Magnetic inclusions should, therefore, be considered as a potentially important source of fine-grained Magnetic Mineral assemblages, and represent a missing link in a wide range of sedimentary paleoMagnetic and environmental Magnetic studies. In addition, we present depositional remanent magnetization (DRM) modeling results to assess the paleoMagnetic recording capability of Magnetic inclusions. Our simulation demonstrates that deposition of larger silicate particles with Magnetic inclusions will be controlled by gravitational and hydrodynamic forces rather than by geoMagnetic torques. Thus, even though these large silicates may contain ideal single domain particles, they can not contribute meaningfully to paleoMagnetic recording. However, smaller silicate grains (e.g., silt- and clay-sized) silicates with unidirectionally magnetized Magnetic inclusions can potentially record a reliable DRM.
Longsheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Magnetic characteristics of sediments from a radial sand ridge field in the south yellow sea eastern china and environmental implications during the mid to late holocene
Journal of Asian Earth Sciences, 2018Co-Authors: Longsheng Wang, Shouyun Hu, Mengna Liao, Liangtao Ye, Ge Yu, Zhenhua Zhang, Qing Wang, Xiaohui WangAbstract:Abstract Proxy records from radial sand ridge fields are essential for understanding sedimentary environmental changes forced by climate-driven coast and sea level variations that affect large river inlets. We conducted a systematic environmental Magnetic study on sediments from a radial sand ridge field in the South Yellow Sea, eastern China. From 41.6 to 0 m, the sediments of core YZ07 derive from river mouth, littoral and modern tidal flat environments. Magnetic measurements indicate that magnetite and hematite dominate the studied Magnetic Mineral assemblages. Magnetic Mineral contents are highest in the river mouth environment and lowest in the modern tidal flat environment. The Magnetic Minerals in the core YZ07 sediments can be attributed primarily to detrital inputs rather than biogenic sources. The highest χ and SIRM values and lowest χARM/SIRM and χARM/χ values reflect relatively warm and humid climate conditions respectively during the period ∼7000 to 2900 a B.P. (41.6–24.73 m). Compared with the period ∼7000 to 2900 a B.P. (41.6–24.73 m), the period between ∼2900 and 870 a B.P. (24.73–5.14 m) is characterized by lower χ, χARM and SIRM values and higher χARM/SIRM and χARM/χ values, which indicate cool and dry climatic conditions. Our results reconfirm known regional climatic events that demonstrate Holocene climatic instability. Gradual decreases in χ and SIRM and increases in χARM/SIRM, χARM/χ and χfd characterize the sediments after 870 a B.P. (5.14–0 m). As indicated in previous studies, these changes were influenced by diversion of the Yellow River. Additionally, spectral analysis of the χ and χARM/SIRM records reveals rapid climatic fluctuations on millennial and centennial scales that coincide with those recorded in marine sedimentary records from adjacent regional seas. These results are important for investigations into the interactions between regional systems and global change in monsoonal climatic regions, thus providing an example of the evolution of a large scale geomorphic feature resulting from river-sea interaction.
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paleoenvironmental reconstruction of the radial sand ridge field in the south yellow sea east china since 45 ka using the sediment Magnetic properties and granulometry
Journal of Applied Geophysics, 2015Co-Authors: Longsheng Wang, Shouyun Hu, Ge Yu, Mengna LiaoAbstract:Abstract Sediments of radial sand ridge field are commonly represented by a set of flood plain, paleosol, and tidal sand ridge facies. In this paper, measurements of Magnetic properties and particle size were obtained from Core Y2 from the radial sand ridge field in the South Yellow Sea. The results show that each facies has specific Magnetic Minerals and particle size distributions. In the flood plain, sand and coarse silt are the main grain sizes, and magnetite and subordinate hematite comprise the Magnetic Minerals. The clay and fine silt are the main grain-size distributions of paleosol, the Magnetic Minerals are dominated by hematite, and the soft-Magnetic Mineral content is very low. In the tidal sand ridge facies, sand is the predominant grain-size distribution, and magnetite dominates the bulk Magnetic properties, with small amounts of hematite. The strong relationships between χ and the > 63-μm fraction suggest that magnetite is enriched in the coarse sand fraction. Based on the combined Mineral-Magnetic, particle size and loss-on-ignition data, the low χ value of paleosol mainly resulted from the decrease in the Magnetic Mineral inputs and post-depositional dissolution of the Magnetic Minerals. The results show that the Magnetic Minerals were controlled by changes in the climate and hydrodynamic environment. This study not only provides a basis for a radial sand ridge field paleoenvironmental reconstruction by integrating detailed logs of Magnetic properties and grain-size parameters, but it also provides constraints for exploring the land–sea interactions recorded in the sediment cores as a part of the earth system, and thus demonstrates the effectiveness of this approach.
Xiaohui Wang - One of the best experts on this subject based on the ideXlab platform.
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Magnetic characteristics of sediments from a radial sand ridge field in the south yellow sea eastern china and environmental implications during the mid to late holocene
Journal of Asian Earth Sciences, 2018Co-Authors: Longsheng Wang, Shouyun Hu, Mengna Liao, Liangtao Ye, Ge Yu, Zhenhua Zhang, Qing Wang, Xiaohui WangAbstract:Abstract Proxy records from radial sand ridge fields are essential for understanding sedimentary environmental changes forced by climate-driven coast and sea level variations that affect large river inlets. We conducted a systematic environmental Magnetic study on sediments from a radial sand ridge field in the South Yellow Sea, eastern China. From 41.6 to 0 m, the sediments of core YZ07 derive from river mouth, littoral and modern tidal flat environments. Magnetic measurements indicate that magnetite and hematite dominate the studied Magnetic Mineral assemblages. Magnetic Mineral contents are highest in the river mouth environment and lowest in the modern tidal flat environment. The Magnetic Minerals in the core YZ07 sediments can be attributed primarily to detrital inputs rather than biogenic sources. The highest χ and SIRM values and lowest χARM/SIRM and χARM/χ values reflect relatively warm and humid climate conditions respectively during the period ∼7000 to 2900 a B.P. (41.6–24.73 m). Compared with the period ∼7000 to 2900 a B.P. (41.6–24.73 m), the period between ∼2900 and 870 a B.P. (24.73–5.14 m) is characterized by lower χ, χARM and SIRM values and higher χARM/SIRM and χARM/χ values, which indicate cool and dry climatic conditions. Our results reconfirm known regional climatic events that demonstrate Holocene climatic instability. Gradual decreases in χ and SIRM and increases in χARM/SIRM, χARM/χ and χfd characterize the sediments after 870 a B.P. (5.14–0 m). As indicated in previous studies, these changes were influenced by diversion of the Yellow River. Additionally, spectral analysis of the χ and χARM/SIRM records reveals rapid climatic fluctuations on millennial and centennial scales that coincide with those recorded in marine sedimentary records from adjacent regional seas. These results are important for investigations into the interactions between regional systems and global change in monsoonal climatic regions, thus providing an example of the evolution of a large scale geomorphic feature resulting from river-sea interaction.