Acquisition of chemical remanent magnetization by synthetic iron oxide

Nature ◽  
1987 ◽  
Vol 327 (6123) ◽  
pp. 610-612 ◽  
Author(s):  
Laura B. Stokking ◽  
Lisa Tauxe
Keyword(s):  
Iron Oxide ◽  
Remanent Magnetization ◽  
Chemical Remanent Magnetization

Paleomagnetism and U–Pb geochronology of the Clarence Head dykes, Arctic Canada: orthogonal emplacement of mafic dykes in a large igneous province

2009 ◽  
Vol 46 (3) ◽  
pp. 155-167 ◽  
Author(s):  
Steven W. Denyszyn ◽  
Don W. Davis ◽  
Henry C. Halls
Keyword(s):  
Remanent Magnetization ◽  
High Arctic ◽  
Large Igneous Province ◽  
Dyke Swarm ◽  
Canadian High Arctic ◽  
The North ◽  
Igneous Province ◽  
The Difference ◽  
Age Range ◽  
Chemical Remanent Magnetization

The north–south-trending Clarence Head dyke swarm, located on Devon and Ellesmere Islands in the Canadian High Arctic, has a trend orthogonal to that of the Neoproterozoic Franklin swarm that surrounds it. The Clarence Head dykes are dated by the U–Pb method on baddeleyite to between 716 ± 1 and 713 ± 1 Ma, ages apparently younger than, but within the published age range of, the Franklin dykes. Alpha recoil in baddeleyite is considered as a possible explanation for the difference in ages, but a comparison of the U–Pb ages of grains of equal size from both swarms suggests that recoil distances in baddeleyite are lower than those in zircon and that the Clarence Head dykes are indeed a distinctly younger event within the period of Franklin magmatism. The Clarence Head dykes represent a large swarm tangential to, and cogenetic with, a giant radiating dyke swarm ∼800 km from the indicated source. The preferred mechanism for the emplacement of the Clarence Head dykes is the exploitation of concentric zones of extension around a depleting and collapsing plume source. While the paleomagnetism of most Clarence Head dykes agrees with that of the Franklin dykes, two dykes have anomalous remanence directions, interpreted to be a chemical remanent magnetization carried by pyrrhotite. The pyrrhotite was likely deposited from fluids mobilized southward from the Devonian Ellesmerian Orogeny to the north that used the interiors of the dykes as conduits and precipitated pyrrhotite en route.

Identifying and Dating the Destruction of Hydrocarbon Reservoirs Using Secondary Chemical Remanent Magnetization

2019 ◽  
Vol 46 (20) ◽  
pp. 11100-11108
Author(s):  
Yong Zhang ◽  
Adrian R. Muxworthy ◽  
Dong Jia ◽  
Guoqi Wei ◽  
Bin Xia ◽  
...  
Keyword(s):  
Remanent Magnetization ◽  
Hydrocarbon Reservoirs ◽  
Secondary Chemical ◽  
Chemical Remanent Magnetization

Redox chemical remanent magnetization—A new dimension in exploration for sulfide deposits in volcanic covered areas

Geophysics ◽  
1981 ◽  
Vol 46 (8) ◽  
pp. 1169-1181 ◽  
Author(s):  
Lloyal O. Bacon ◽  
Charles L. Elliot
Keyword(s):  
Remanent Magnetization ◽  
Field Tests ◽  
Massive Sulfide ◽  
Rock Properties ◽  
Sulfide Deposit ◽  
Magnetic Memory ◽  
Sulfide Deposits ◽  
Surface Redox ◽  
Chemical Remanent Magnetization

Redox chemical remanent magnetization (CRM) results from current flow associated with a redox potential cell. An active redox cell covered by later volcanics may continue in operation for a period of time, sufficiently long that the current flowing in the overlying volcanics will cause or assist in the remobilization of iron. The remobilization may be either in situ as an alteration of minerals or by actual migration as a ferrous hydroxide, with fixation at a higher Eh nearer the surface. Redox CRM will leave a characteristic pattern as a magnetic memory in the rocks. Measurement of the magnetic rock properties and interpretation of resulting patterns can be used to locate the ancient redox cell. Redox cells in nature are usually associated with oxidizing sulfide deposits. Under appropriate conditions, redox CRM can be utilized as an indirect method for sulfide exploration. Field results for two porphyry sulfide deposits and a massive sulfide deposit under approximately 400 m of post‐mineral volcanic cover demonstrate the feasibility of this technique. Field tests in nonsulfide areas indicate that pervasive occurrence of false redox CRM anomalies do not exist except in the presence of sulfides. Laboratory experiments in the simulation of the redox CRM concept give support to the theory.

scholarly journals Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors

2020 ◽  
Author(s):  
Anish Kumar Warrier ◽  
Joju George Sebastian ◽  
K. Amrutha ◽  
A. S. Yamuna Sali ◽  
B. S. Mahesh ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Grain Size ◽  
Magnetic Properties ◽  
Spatial Distribution ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Remanent Magnetization ◽  
Principal Component ◽  
East Antarctica ◽  
Schirmacher Oasis

Abstract Purpose We investigated the magnetic properties (abundance, grain size, and mineralogy) of iron oxides present in Lake L-55 sediments, Schirmacher Oasis, East Antarctica, with an aim to understand their spatial distribution and the underlying mechanisms that control their formation and distribution. Methods Twenty-five surficial sediments retrieved from different parts of Lake L-55 were subjected to the entire range of environmental magnetic (magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM)) measurements (at different field strengths). Inter-parametric ratios (χARM/SIRM, χARM/χlf, χARM/χfd, IRM20 mT/SIRM, IRM20 mT/ARM, S-ratio, L-ratio) provided insights into the magnetic properties (abundance, grain size, and mineralogy of iron oxides). Scanning electron microscopic-energy dispersive X-ray spectroscopic (SEM-EDS) analysis was performed on magnetic extracts from a few sediments. Besides, organic matter (%) was also calculated for the sediment samples. Principal component analysis was performed to gain information on the presence of different components and their relative dominance. Results The iron oxides are strongly magnetic (high values of concentration-dependent parameters). The principal iron oxide is magnetite (S-ratio > 0.90) which is coarse-grained (multi-domain (MD) and stable single-domain (SSD) grains), and there is no influence of authigenic greigite, bacterial magnetite, and anthropogenic magnetite. The mineralogy is confirmed by SEM-EDS data. The iron oxides are of different grain sizes, and their contribution is in the order of MD > SSD > SP as shown by the principal component analysis. Pedogenic iron oxide minerals seem to be present in the samples whose formation is due to the oxidation of magnetite into hematite. However, they are of SSD size and not SP, suggesting that the intensity of pedogenesis is not sufficient to form SP grains. Conclusion The iron oxide minerals are mainly terrigenous, and the biogenic activity within the lake is not sufficient to modify the ferrimagnetic minerals. Spatial distribution patterns suggest the non-uniform distribution of magnetite/titanomagnetite of varying sizes in the lake basin which is transported by both melt water streams and winds.

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