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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic fabric analysis of the Plio-Pleistocene sedimentary formations of the Coastal Range of Taiwan
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 98 (1990), S. 23-32 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(90)90085-C
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    Paper (German National Licenses)
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  • 2
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    Magnetic properties of sedimentary greigite (Fe3S4): An update (2011)
    Wiley
    Details
    Publication Date: 2011-01-29
    Description: Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a collinear ferrimagnet with antiferromagnetic coupling between iron in octahedral and tetrahedral sites. The crystallographic c axis is the easy axis of magnetization, with magnetic properties dominated by magnetocrystalline anisotropy. Robust empirical estimates of the saturation magnetization, anisotropy constant, and exchange constant for greigite have been obtained recently for the first time, and the first robust estimate of the low-field magnetic susceptibility is reported here. The Curie temperature of greigite remains unknown but must exceed 350°C. Greigite lacks a low-temperature magnetic transition. On the basis of preliminary micromagnetic modeling, the size range for stable single domain behavior is 17–200 nm for cubic crystals and 17–500 nm for octahedral crystals. Gradual variation in magnetic properties is observed through the pseudo-single-domain size range. We systematically document the known magnetic properties of greigite (at high, ambient, and low temperatures and with alternating and direct fields) and illustrate how grain size variations affect magnetic properties. Recognition of this range of magnetic properties will aid identification and constrain interpretation of magnetic signals carried by greigite, which is increasingly proving to be environmentally important and responsible for complex paleomagnetic records, including widespread remagnetizations.
    Print ISSN: 8755-1209
    Topics: Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Ferromagnetic resonance characterization of greigite (Fe3S4), monoclinic pyrrhotite (Fe7S8), and non-interacting titanomagnetite (Fe3-xTixO4) (2012)
    Wiley
    Details
    Publication Date: 2012-05-19
    Description: Ferromagnetic resonance (FMR) spectroscopy has become an increasingly useful tool for studying the magnetic properties of natural samples. Magnetite (Fe3O4) is the only magnetic mineral that has been well characterized using FMR. This limits the wider use of FMR in rock magnetism and paleomagnetism. In this study, we applied FMR analysis to a range of magnetic minerals, including greigite (Fe3S4), monoclinic pyrrhotite (Fe7S8), magnetically non-interacting titanomagnetite (Fe3-xTixO4), and synthetic magnetite chains to constrain interpretation of FMR analysis of natural samples and to explore applications of FMR spectroscopy. We measured the FMR signatures of a wide range of well-characterized samples at the X- and Q-bands. FMR spectra were also simulated numerically to compare with experimental results. The effects of magnetic anisotropy, mineralogy, domain state, and magnetostatic interactions on the FMR spectra are discussed for all studied minerals. Our experimental and theoretical analyses of magnetically non-interacting tuff samples and magnetically interacting chains enable quantitative assessment of contributions of magnetostatic interactions and magnetic anisotropy to the FMR spectra. Our results also indicate that intact magnetosomes are a unique system with distinct FMR signatures. While FMR analysis is useful for characterizing magnetic properties of natural samples, care is needed when making interpretations because of overlaps in a range of FMR signatures of different magnetic minerals with different magnetic properties. Our analyses will help to constrain such interpretations in rock magnetic studies.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
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    Ferrimagnetic Iron Sulfide Formation and Methane Venting Across the Paleocene-Eocene Thermal Maximum in Shallow Marine Sediments, Ancient West Siberian Sea (2017)
    Wiley
    Details
    Publication Date: 2017-12-05
    Description: Authigenesis of ferrimagnetic iron sulfide minerals (greigite and monoclinic pyrrhotite) occurred across the Paleocene-Eocene Thermal Maximum (PETM) within the Bakchar oolitic ironstone in southeastern Western Siberia. Co-occurrence of these minerals is associated with diagenetic environments that support anaerobic oxidation of methane, which has been validated by methane fluid inclusion analysis in the studied sediments. In modern settings, such ferrimagnetic iron sulfide formation is linked to upward methane diffusion in the presence of minor dissolved sulfide ions. The PETM was the most extreme Cenozoic global warming event and massive methane mobilization has been proposed as a major contributor to the globally observed warming and carbon isotope excursion associated with the PETM. The studied sediments provide rare direct evidence for methane mobilization during the PETM. Magnetic iron sulfide formation associated with methanogenesis in the studied sediments can be explained by enhanced local carbon burial across the PETM. While there is no strong evidence to link local methane venting with more widespread methane mobilization and global warming, the magnetic, petrographic, and geochemical approach used here is applicable to identifying authigenic minerals that provide telltale signatures of methane mobility that can be used to assess methane formation and mobilization through the PETM and other hyperthermal climatic events.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
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    Pyrrhotite as a tracer for denudation of the Taiwan orogen (2012)
    Wiley
    Details
    Publication Date: 2012-08-03
    Description: The use of pyrrhotite as an index mineral to delineate metamorphic isograds has long been proposed. However, details of the occurrence of pyrrhotite in different metamorphic facies and its implications have rarely been explored. Here, by simple characterization of magnetic properties and mineral identification, we demonstrate that pyrrhotite is widely distributed in low-grade metamorphic terranes of Taiwan's Central Range and in sediments derived therefrom. By coupling the distribution of pyrrhotite in rocks with that in dated sediment strata, we have studied the denudation history of Taiwan's orogen from a source-to-sink perspective. We suggest that pyrrhotite is a potential tracer for studying surface processes in orogens with high denudation rates similar to that in Taiwan.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
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    Relating sulfate and methane dynamics to geology: The accretionary prism offshore SW Taiwan (2013)
    Wiley
    Details
    Publication Date: 2013-05-14
    Description: [1] Geochemical data (CH 4 , SO 4 2– , I – , Cl – , particulate organic carbon (POC), δ 13 C–CH 4 and δ 13 C–CO 2 ) are presented from the upper 30 m of marine sediment on a tectonic submarine accretionary wedge offshore southwest Taiwan. The sampling stations covered three ridges (Tai–Nan, Yung–An and Good Weather), each characterized by bottom simulating reflectors, acoustic turbidity and different types of faulting and anticlines. Sulfate and iodide concentrations varied little from seawater-like values in the upper 1-3 m of sediment at all stations; a feature which is consistent with irrigation of seawater by gas bubbles rising through the soft surface sediments. Below this depth, sulfate was rapidly consumed within 5 to 10 m by anaerobic oxidation of methane (AOM) at the sulfate-methane transition. Carbon isotopic data imply a mainly biogenic methane source. A numerical transport-reaction model was used to identify the supply pathways of methane and estimate turnover rates at the three ridges. Methane gas ascending from deep layers, facilitated by thrusts and faults, was by far the dominant term in the methane budget at all sites. Differences in the proximity of the sampling sites to the faults and anticlines mainly accounted for the variability in gas fluxes and AOM rates. By comparison, methane produced in situ by POC degradation within the modeled sediment column was unimportant. This study demonstrates that the geochemical trends in the continental margins offshore SW Taiwan are closely related to the different geological settings.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 7
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    Magnetic fabric analysis of the Plio-Pleistocene sedimentary formations of the Coastal Range of Taiwan (1990)
    Elsevier
    Details
    Publication Date: 1990-04-01
    Print ISSN: 0012-821X
    Electronic ISSN: 1385-013X
    Topics: Geosciences , Physics
    Published by Elsevier
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  • 8
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    (Table T1) Magnetic properties of MORB from ODP Leg 187 sites (2004)
    PANGAEA
    In:  Supplement to: Shau, Yen-Hong; Torii, Masayuki; Horng, Chorng-Shern; Liang, Wen-Tzong (2004): Magnetic properties of mid-ocean-ridge basalts from Ocean Drilling Program Leg 187. In: Pedersen, RB; Christie, DM; Miller, DJ (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 187, 1-25, https://doi.org/10.2973/odp.proc.sr.187.204.2004
    Details
    Publication Date: 2024-01-09
    Description: The core samples of mid-ocean-ridge basalts (including Indian and Pacific type) recovered from the Southeast Indian Ridge (SEIR) area near the Australian Antarctic Discordance during Ocean Drilling Program Leg 187 were studied using rock magnetism, mineralogy, and petrography methods. On the basis of thermomagnetic analyses and low-temperature magnetometry, the dominant magnetic carrier in most of the basalt samples (pillow basalts) is characterized as titanomaghemite, which presumably formed by low-temperature oxidation of primary titanomagnetite. Some samples from unaltered massive basalts contain nearly unoxidized titanomagnetite as the main magnetic mineral. A metadiabase sample showing greenschist facies metamorphism contains magnetic minerals dominated by magnetite. The pillow basalts contain titanomaghemite ranging from stable single-domain to pseudosingle-domain (PSD) grains, and the majority are characterized by a single stable component of remanence. The massive basalts show hysteresis features of larger PSD grains and contain a very low coercivity remanence. The values of natural remanent magnetization (NRM) of the samples in this SEIR area are on the same order as those of other oceanic ridge basalts. They show a general decreasing trend of NRM with increasing crust age. However, the values of NRM show no correlation either with the tectonic zonations (Zone A vs. Zone B) or with the mantle provinces (Pacific vs. Indian types).
    Keywords: 187-1152A; 187-1152B; 187-1153A; 187-1154A; 187-1155A; 187-1155B; 187-1156A; 187-1156B; 187-1157A; 187-1157B; 187-1158A; 187-1158B; 187-1158C; 187-1159A; 187-1160A; 187-1160B; 187-1161A; 187-1161B; 187-1162A; 187-1162B; 187-1163A; 187-1164A; 187-1164B; Bartington MS2 magnetic susceptibility meter; Coercive force; Coercivity of remanence; Coercivity of remanence/coercive force; Curie temperature; Depth, relative; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; Hysteresis, saturation magnetization, per unit volume; Hysteresis, saturation magnetization/ saturation remanence; Hysteresis, saturation remanence, per unit volume; Indian Ocean; Joides Resolution; Leg187; MAG; Magnetic susceptibility, volume; Magnetometer; Magnetometer, spinner (SMD-88); NRM, Intensity; Ocean Drilling Program; ODP; Sample code/label; Sample comment; Sample ID
    Type: Dataset
    Format: text/tab-separated-values, 1411 data points
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  • 9
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    Spectrum gamma ray borehole logging of sediment core TCDP-A (2023)
    PANGAEA
    Details
    Publication Date: 2024-06-12
    Keywords: Core wireline system; CWS; Cyclostratigraphy; DEPTH, sediment/rock; Foreland basin; Natural gamma ray; Paleoclimate; Sedimentology; TCDP-A
    Type: Dataset
    Format: text/tab-separated-values, 81401 data points
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  • 10
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    R script for time-series and astrochronological analyses (2023)
    PANGAEA
    Details
    Publication Date: 2024-06-12
    Keywords: Core wireline system; CWS; Cyclostratigraphy; Foreland basin; Paleoclimate; Sedimentology; TCDP-A
    Type: Dataset
    Format: text/plain, 3.1 kBytes
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