scholarly journals Mineralogy and Magnetic Behavior of Yellow to Red Xuanhua-Type Agate and Its Indication to the Forming Condition

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 877
Author(s):  
Danyi Zhou ◽  
Guanghai Shi ◽  
Suzhen Liu ◽  
Bailing Wu
Keyword(s):  
Raman Spectroscopy ◽  
Magnetic Susceptibility ◽  
Iron Oxides ◽  
Fluid Inclusions ◽  
Remanent Magnetization ◽  
Magnetic Behavior ◽  
Homogenization Temperature ◽  
Isothermal Remanent Magnetization ◽  
Magnetic Minerals ◽  
Forming Condition

Iron oxides/hydroxides are important magnetic minerals to provide information about changes in the forming environment. However, the magnetic behavior in agate has been rarely investigated. In this study, the magnetic behavior of the Xuanhua-type agate with intense yellow to red colors from the Xuanhua District (China) was investigated by temperature dependence of magnetic susceptibility, hysteresis loop, isothermal remanent magnetization and the analysis of remanent coercivity components from the gradient acquisition plot. Yellow goethite and red hematite can be quantitatively identified by XRD and Raman spectroscopy due to their relatively higher content. Results showed that the red, yellow and orange Xuanhua-type agate had different magnetic behavior, and magnetite existed in the yellow and orange ones. Fluid inclusions in such agate had the homogenization temperature of ~168 °C to 264 °C. All results suggested that the dehydration of goethite to form hematite was the main reason for the high remnant coercivity (above 1000 mT) of hematite in the red agate. The co-existence of magnetite and goethite in the yellow and orange agate reflects the transformation from Fe2+ to Fe3+, indicating the change in the redox property of the environment. Unique patterns mainly formed by hematite and goethite make it a popular gem-material with high research value.

Photo-induced magnetic behavior in the amorphous spin-glass material Co3(SbTe3)2

1994 ◽  
Vol 9 (4) ◽  
pp. 909-914 ◽  
Author(s):  
Biao Wu ◽  
Lianwei Ren ◽  
Charles J. O'Connor ◽  
Jinke Tang ◽  
Jin-Seung Jung ◽  
...  
Keyword(s):  
Spin Glass ◽  
Remanent Magnetization ◽  
Magnetic Behavior ◽  
Freezing Temperature ◽  
Specific Resistivity ◽  
Metathesis Reaction ◽  
Isothermal Remanent Magnetization ◽  
Magnetization Data ◽  
Magnetizing Field ◽  
Thermal Remanent Magnetization

A new ternary material Co3(SbTe3)2 was prepared by using a rapid precipitation metathesis reaction between the Zintl material K3SbTe3 and CoCl2 in aqueous solution. The dc specific resistivity of this material is in the region for metallic conductors (p = 2.75 × 10-3 Ω-cm). The dc magnetic susceptibility of Co3(SbTe3)2 is reported over a 2.2 K-300 K temperature region, and the material is characterized as a spin glass with a freezing temperature of about 5 K. Magnetization data are also reported as both thermal remanent magnetization and isothermal remanent magnetization as a function of magnetizing field and temperature. When cooled well below the glass freezing temperature, the frozen spin glass has been observed to exhibit photomagnetic effects consistent with a disruption of the spin-glass state caused by uv-radiation.

scholarly journals NEOGENE TECTONIC ROTATIONS IN THE VICINITY OF THE NORTH AEGEAN TROUGH: NEW PALAEOMAGNETIC EVIDENCE FROM ATHOS AND SAMOTHRAKI (GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 343 ◽  
Author(s):  
D. Kondopoulou ◽  
I. Zananiri ◽  
A. Michard ◽  
H. Feinberg ◽  
A. Atzemoglou ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Remanent Magnetization ◽  
Strike Slip ◽  
Isothermal Remanent Magnetization ◽  
Northern Greece ◽  
The North ◽  
Low Field ◽  
Palaeomagnetic Data ◽  
North Aegean ◽  
Major Strike

The present study focuses on two post-orogenic plutons, the Athos (Grigoriou) and Samothraki granites, as well as the Samothraki volcanics, located in the vicinity of the North Aegean Trough. A detailed palaeomagnetic study was carried out, with the aim of constraining the age and mechanism of tectonic rotations. In addition, anisotropy of low field magnetic susceptibility (AMS) was studied and isothermal remanent magnetization (IRM) and thermomagnetic analyses were performed. Finally, a radiometric age for the Athos granite was obtained (43.3 ± 1.0 Ma K/Ar biotite). The measured declinations indicate clockwise rotations of the Athos (16.6°) and Samothraki (36.3°) blocks. The age of rotation is constrained to be <18 Ma at Samothraki, whereas the much smaller rotation of the Athos block can only be dated as younger than Eocene. Comparing the new palaeomagnetic data to the published dataset for Northern Greece, we suggest that the palaeomagnetically determined rotations in the vicinity of the North Aegean Trough are dominantly of post-Early Miocene age, and are controlled by major strike-slip faults and distributed "small" or minor faults.

scholarly journals Application of the pseudo-Thellier technique to a paleomagnetic record from lake El Trébol (Patagonia, Argentina)

2008 ◽  
Vol 47 (4) ◽  
pp. 319-327
Author(s):  
C. S. G. Gogorza ◽  
S. Torcida ◽  
A. M. Sinito ◽  
M. A. E. Chaparro
Keyword(s):  
Magnetic Susceptibility ◽  
Error Estimates ◽  
Sediment Core ◽  
Standard Method ◽  
Remanent Magnetization ◽  
Reasonable Agreement ◽  
Natural Remanent Magnetization ◽  
Isothermal Remanent Magnetization ◽  
Low Field ◽  
Relative Paleointensity

The pseudo-Thellier technique was applied to obtain relative paleointensity determinations using a sediment core from Lake El Tre?bol (Patagonia, Argentina). Measurements of intensity of natural remanent magnetization left (NRMleft) after AF demagnetization versus intensity of anhysteric remanent magnetization gained (ARMgained) at the same peak were carried out on a set of samples. Two versions of a jackknife resampling scheme were used to get error estimates on the paleointensity. The pseudo-Thellier paleointensity records were compared with the authors previous results where the remanent magne- tization at 20mT (NRM20mT) has been normalized using the anhysteric remanent magnetization at 20mT (ARM20mT), the satu- ration of the isothermal remanent magnetization at 20mT (SIRM20mT) and the low field magnetic susceptibility (k) (Gogorza et al., 2006). The pseudo-Thellier record shows a reasonable agreement with the standard method of normalization (NRM20mT/ ARM20mT).

Late Holocene Changes in Precipitation and Hydrography Recorded in Marine Sediments from the Northeastern Caribbean Sea

2001 ◽  
Vol 56 (1) ◽  
pp. 87-102 ◽  
Author(s):  
Johan Nyberg ◽  
Antoon Kuijpers ◽  
Björn A. Malmgren ◽  
Helmar Kunzendorf
Keyword(s):  
Magnetic Susceptibility ◽  
Puerto Rico ◽  
North Atlantic ◽  
Remanent Magnetization ◽  
Caribbean Sea ◽  
Isothermal Remanent Magnetization ◽  
Low Latitude ◽  
Saturation Isothermal Remanent Magnetization ◽  
Magnetic Parameters ◽  
Mineral Magnetic

AbstractWe present a record of climate variability spanning the last 2000 years obtained from sediment cores retrieved south and west of Puerto Rico in the northeastern Caribbean Sea. The records include lithological and mineral magnetic parameters as well as planktonic foraminifer data. For chronostratigraphic control, AMS 14C and 210Pb/137Cs measurements were made. Harmonic analysis of the values of the mineral magnetic parameters “saturation isothermal remanent magnetization” (SIRM), “anhysteric remanent magnetization divided by magnetic susceptibility” (ARM/χ), and “saturation isothermal remanent magnetization divided by magnetic susceptibility” (SIRM/χ) indicate the existence of a ∼200-year-long climate cycle in the northeastern Caribbean during the last 2000 years. The detected cycle may reflect changes in precipitation patterns over the low-latitude North Atlantic Ocean and surrounding continental areas. Higher organic carbon contents appear in the sediments both off southern and western Puerto Rico before and at the onset of the Little Ice Age around A.D. 1300 to 1500. This is indicative of increased run off and/or enhanced surface productivity possibly associated with more intense wind-induced upwelling. Major changes in the geochemical and mineral magnetic records around A.D. 850–1000 concur with changes in other records from the Caribbean and North African regions indicating a shift toward a more humid climate over the low-latitude North Atlantic.

Distinguishing barren and auriferous veins in the Sigma Mine, Val-d'Or, Quebec

1993 ◽  
Vol 30 (3) ◽  
pp. 413-419 ◽  
Author(s):  
Ross L. Sherlock ◽  
E. Craig Jowett ◽  
Brian D. Smith ◽  
Donald E. Irish
Keyword(s):  
Raman Spectroscopy ◽  
Fluid Inclusions ◽  
Homogenization Temperature ◽  
Lode Gold ◽  
Quartz Veins ◽  
Melting Temperatures ◽  
Abitibi Greenstone Belt ◽  
Significant Difference ◽  
Lode Gold Deposit ◽  
Exploration Tool

The Sigma Mine is an Archean lode gold deposit located in the Abitibi greenstone belt, Quebec. Barren quartz veins occur subparallel to auriferous veins within the mine and also occur north of the mine. The quartz and auriferous veins exhibit a similar mineralogy and alteration and are indistinguishable except for the presence or absence of gold. This study determines differences between (i) a vein that may be auriferous but lacks gold at that location and (ii) a barren vein that formed from fluids that never had the capability of carrying gold. Microthermometry distinguishes two distinct salinities within aqueous inclusions in the barren veins, compared to high salinities only reported in the auriferous veins. The CO2–H2O fluid inclusions within barren veins are remarkably similar to their counterparts in auriferous veins in composition, homogenization temperature, and CO2 effervescence. The most significant difference between the two vein types, and a potential exploration tool, is observed in the CO2-rich inclusions. Tight clustering of first melting temperatures between −57.4 and −56.4 °C and Raman spectroscopy indicate the presence of only CO2 in the barren veins. These results contrast sharply with the −62.5 to −56.0 °C range of first melting temperatures and the presence of H2S indicated by Raman spectroscopy in auriferous veins. Lack of CH4 and H2S gases in the barren CO2-rich inclusions reflects the oxidation state of the fluids, which was too high to permit transport of gold as a reduced complex.

Magnetic susceptibility and isothermal remanent magnetization in human tissues: a study case

BioMetals ◽  
2015 ◽  
Vol 28 (6) ◽  
pp. 951-958 ◽  
Author(s):  
H. Sant’Ovaia ◽  
G. Marques ◽  
A. Santos ◽  
C. Gomes ◽  
A. Rocha
Keyword(s):  
Magnetic Susceptibility ◽  
Remanent Magnetization ◽  
Human Tissues ◽  
Isothermal Remanent Magnetization ◽  
Study Case

scholarly journals Large field impressed anisotropy of magnetic susceptibility (AMS) in metamorphic volcanoclastic rocks from the western Central Pamir with ilmeno-hematite as the main magnetic carrier.

2020 ◽  
Author(s):  
Pierrick Roperch ◽  
Jovid Aminov ◽  
Guillaume Dupont-Nivet ◽  
Stéphane Guillot ◽  
France Lagroix
Keyword(s):  
Magnetic Susceptibility ◽  
Remanent Magnetization ◽  
Strong Field ◽  
Large Field ◽  
Magnetic Characteristics ◽  
Magnetic Carrier ◽  
Isothermal Remanent Magnetization ◽  
Clastic Rocks ◽  
Magnetic Fabrics ◽  
Degree Of Anisotropy

&lt;p&gt;Field impressed AMS fabric, although it has been recognized for a very long time, has been the subject of very few publications in the paleomagnetic literature. This effect has been mainly described in samples with magnetite as a main magnetic carrier. This fabric is usually of low magnitude and observed mainly in nearly isotropic rock after application of static AF demagnetization or after acquisition of an isothermal remanent magnetization (IRM).&amp;#160;Forty four paleomagnetic sites have been sampled in a &gt;2 km thick sequence of Cretaceous volcano-clastic rocks from the western Central Pamir mountain (Tadjikistan).&amp;#160;These rocks present a medium grade level of metamorphism characterized by fine grained recrystallisation of biotite.&amp;#160;The magnetic properties are very homogeneous across the sequence. Bulk magnetic susceptibilities vary between 150-250 &amp;#956; SI. The AMS magnetic fabrics correspond to triaxial tensors with a well defined foliation plane and a steeply dipping magnetic lineation. The degree of anisotropy varies between 1.03 and 1.2. This fabric was likely acquired during the deformation associated with the emplacement of Middle Miocene gneiss domes.&amp;#160;SEM/EDS data indicate that the main iron oxide mineral is hematite with up to 15% of ilmenite in solid solutions. This is in agreement with unblocking temperatures of SIRM around 630 &amp;#176;C, lower than the one of pure hematite.&amp;#160;One of the most surprising magnetic characteristics of these rocks is the effect of strong-field remanent magnetizations upon the AMS. During the acquisition of an Isothermal Remanent Magnetization (IRM), the initial AMS is progressively obliterated by a new AMS fabric. The field-impressed AMS is characterized by a decrease of the magnetic susceptibility along the direction of the IRM and an increase in magnetic susceptibility in the orthogonal plane. The field-impressed AMS is thus mainly oblate with a degree of anisotropy usually between 1.2 and 1.4. As far as we know, such a strong effect has never been reported. In sandstone with detrital hematite as the main carrier, the degree of the induced AMS fabric is less than 1.02 suggesting that the ilmenite content in the metamorphic hematite is the main cause of the large observed field induced fabric in these rocks.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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