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.

scholarly journals Studying the dynamics of cosmic dust flux on the earth’s surface from peat deposits

2019 ◽  
pp. 150-160 ◽  
Author(s):  
A. Yu. Kurazhkovskii ◽  
A. Yu. Kazansky ◽  
A. A. Shchetnikov ◽  
T. A. Blyakharchuk ◽  
D. A. Philippov
Keyword(s):  
Remanent Magnetization ◽  
Cosmic Dust ◽  
Isothermal Remanent Magnetization ◽  
Climatic Zones ◽  
Saturation Isothermal Remanent Magnetization ◽  
Peat Deposits ◽  
Dust Flux ◽  
Order Of Magnitude

Peat cores sampled from different climatic zones are studied. The  petromagnetic and microprobe methods are used to find peat layers enriched with cosmic dust. It is established that the behavior of saturation isothermal remanent magnetization (SIRM) of peat deposits from the zones where the aeolian transfer of terrigenous particles is negligible can be used for studying the dynamics of the fall of cosmic matter on the Earth’s surface. The cosmic dust flux can be conditionally divided into the background and burst components. Here, the background flux of cosmic dust varies cyclically. The characteristic times of these cycles are about 100 years. The cyclicity in the background flux of cosmic material most clearly manifested itself in the interval of 1200 to 500 years ago. The most significant burst in the influx of cosmic material (by an order of magnitude above the background) is revealed in the layer that was formed about 5000 years ago. The microprobe studies established that the mineralogical content of cosmic dust differs between the background and burst fluxes.

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).

The Effect of Microtopography and Vegetation on the Catchment of Airborne Particles Measured by Remanent Magnetism

1979 ◽  
Vol 12 (3) ◽  
pp. 326-332 ◽  
Author(s):  
Frank Oldfield ◽  
Ann Brown ◽  
Roy Thompson
Keyword(s):  
Remanent Magnetization ◽  
Airborne Particles ◽  
Small Scale ◽  
Pollen Deposition ◽  
Isothermal Remanent Magnetization ◽  
Remanent Magnetism ◽  
Saturation Isothermal Remanent Magnetization ◽  
Raised Bogs ◽  
Spatial Changes ◽  
Order Of Magnitude

Measurements of saturation isothermal remanent magnetization (SIRM) for recent ombrotrophic peats show that the rate of deposition of magnetic particulates from the atmosphere varies strongly in response to the persistent, small-scale, spatial changes in vegetation and microtopography characteristic of many raised bogs. Hummock environments may trap over an order of magnitude more magnetic particulates than do Sphagnum lawns and pools. These results, thought to reflect the interception of subhorizontally moving particles by the hummock forming plants, have potentially important implications for studies of pollen deposition (“influx”) rates in peat.

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.

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

Paleomagnetism of the Eocene Kamloops Group and the cratonization of Terrane I of the Canadian Cordillera

1989 ◽  
Vol 26 (4) ◽  
pp. 821-828 ◽  
Author(s):  
D. T. A. Symons ◽  
M. R. Wellings
Keyword(s):  
North American ◽  
Remanent Magnetization ◽  
Middle Eocene ◽  
Pole Position ◽  
Canadian Cordillera ◽  
Isothermal Remanent Magnetization ◽  
Clockwise Rotation ◽  
Saturation Isothermal Remanent Magnetization ◽  
The North ◽  
North American Craton

The lower Middle Eocene (49.4 ± 2.4 Ma) Kamloops Group is exposed in the middle of the Quesnellia subterrane of Terrane I. The group consists of the siliciclastic Tranquille Beds and the overlying Dewdrop Flats plateau basalts and andesites. Detailed alternating field (AF) and thermal step demagnetization was carried out on 282 specimens from 26 flow sites and one conglomerate site, and saturation isothermal remanent magnetization (SIRM) tests were performed to examine the remanence carriers. The petrology of the gently dipping flows, the presence of antiparallel normal and reverse remanence, the conglomerate test, and the fold test all indicate that a primary remanence has been isolated. It resides in both magnetite and hematite over a broad range of AF coercivities, blocking temperatures, and domain sizes. Its mean direction of 355.0°, 73.4 °(α95 = 6.9°) gives a pole position of 138.4°W, 81.4°N (dp = 11.0°, dm = 12.3°) that is statistically indistinguishable from the 50 Ma reference pole for the North American craton. This indicates that the cratonization of Terrane I was complete by the Middle Eocene after it had undergone ~1300 km of northward translation and ~45 °of clockwise rotation since the mid-Cretaceous.

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