Testing continuity of the Hadean-Eoarchean geodynamo with zircon paleomagnetism

2020 ◽  
Author(s):  
John Tarduno ◽  
Rory Cottrell ◽  
Axel Hofmann
Keyword(s):  
Electron Microscope ◽  
Detrital Zircons ◽  
Test Results ◽  
Eastern India ◽  
Technical Challenge ◽  
First Order ◽  
Jack Hills ◽  
Magnetic Inclusions ◽  
Field Strengths

<p>Understanding the pre-Paleoarchean geodynamo is arguably the greatest technical challenge for paleomagnetism: only silicate crystals bearing magnetic inclusions now found in younger sedimentary units may have escaped the metamorphism that otherwise excludes extant Paleoarchean to Hadean whole rocks from consideration. The recent optical and electron microscope documentation of primary magnetite inclusions in Jack Hills zircons (Tarduno et al., <em>PNAS</em>, 2020), previously predicted by paleomagnetic unblocking temperatures, together with microconglomerate test results, Pb-Pb radiometric age data and Li-diffusion constraints, support a geodynamo as old as 4.2 billion-years-old. While the available record is to first-order consistent with a continuous geodynamo since the Hadean, there are several 50-100 m.y. gaps in the record. Herein we examine these gaps and further test the paleointensity history derived from Jack Hills zircons through study of Paleoarchean and older detrital zircons of the Singhbum craton of eastern India. Preliminary paleomagnetic and paleointensity data suggest the presence of a primary magnetism, magnetite inclusion carriers and field strengths similar to those of the Jack Hills record.</p>

scholarly journals Secondary magnetic inclusions in detrital zircons from the Jack Hills, Western Australia, and implications for the origin of the geodynamo

Geology ◽  
2018 ◽  
Vol 46 (5) ◽  
pp. 427-430 ◽  
Author(s):  
Benjamin P. Weiss ◽  
Roger R. Fu ◽  
Joshua F. Einsle ◽  
David. R. Glenn ◽  
Pauli Kehayias ◽  
...  
Keyword(s):  
Western Australia ◽  
Detrital Zircons ◽  
Jack Hills ◽  
Magnetic Inclusions

Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2

1995 ◽  
Vol 30 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Deng Nansheng ◽  
Tian Shizhong ◽  
Xia Mei
Keyword(s):  
Photochemical Reaction ◽  
Uv Light ◽  
Reactive Dyes ◽  
Solar Light ◽  
Rate Equations ◽  
Oh Radical ◽  
Test Results ◽  
Dye Molecules ◽  
First Order ◽  
Dye Solutions

Abstract Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed. The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.

scholarly journals Secondary magnetite in ancient zircon precludes analysis of a Hadean geodynamo

2018 ◽  
Vol 116 (2) ◽  
pp. 407-412 ◽  
Author(s):  
Fengzai Tang ◽  
Richard J. M. Taylor ◽  
Josh F. Einsle ◽  
Cauê S. Borlina ◽  
Roger R. Fu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Remanent Magnetization ◽  
Diffusion Mechanism ◽  
Aqueous Fluid ◽  
Pipe Diffusion ◽  
Transmission Electron ◽  
Igneous Zircon ◽  
Jack Hills ◽  
Magnetic Inclusions

Zircon crystals from the Jack Hills, Western Australia, are one of the few surviving mineralogical records of Earth’s first 500 million years and have been proposed to contain a paleomagnetic record of the Hadean geodynamo. A prerequisite for the preservation of Hadean magnetization is the presence of primary magnetic inclusions within pristine igneous zircon. To date no images of the magnetic recorders within ancient zircon have been presented. Here we use high-resolution transmission electron microscopy to demonstrate that all observed inclusions are secondary features formed via two distinct mechanisms. Magnetite is produced via a pipe-diffusion mechanism whereby iron diffuses into radiation-damaged zircon along the cores of dislocations and is precipitated inside nanopores and also during low-temperature recrystallization of radiation-damaged zircon in the presence of an aqueous fluid. Although these magnetites can be recognized as secondary using transmission electron microscopy, they otherwise occur in regions that are indistinguishable from pristine igneous zircon and carry remanent magnetization that postdates the crystallization age by at least several hundred million years. Without microscopic evidence ruling out secondary magnetite, the paleomagnetic case for a Hadean–Eoarchean geodynamo cannot yet been made.

Interaction of Waves With a Moored Semisubmersible

1984 ◽  
Vol 106 (4) ◽  
pp. 419-425 ◽  
Author(s):  
S. K. Chakrabarti ◽  
D. C. Cotter
Keyword(s):  
Diffraction Theory ◽  
Nonlinear Damping ◽  
Irregular Waves ◽  
Test Results ◽  
Regular Waves ◽  
Mooring Lines ◽  
Wave Groups ◽  
First Order ◽  
Oscillating Motion ◽  
Theoretical Results

A semisubmersible moored in waves experiences a steady offset and two types of motion—a first-order motion at frequencies corresponding to the incident wave frequencies and a slowly oscillating motion near the natural frequency of the semisubmersible/mooring system. An extensive wave tank testing of a semisubmersible model was undertaken in which the motions of the semisubmersible and the loads in the mooring lines were measured. The semisubmersible was tested in the tank in a head sea as well as a beam sea heading in a series of regular waves, regular wave groups and irregular waves. The test results of the steady offset and first-order and slowly oscillating motions are presented for each heading and for each of these wave series as functions of the wave period. The experimental results are correlated with theoretical results based on a 3-D diffraction theory which takes into account the appropriate first and second-order terms. It is found that the nonlinear damping terms are quite important in explaining the behavior of the moored semisubmersible in waves and that the steady drift loads in wave groups can be determined from results based on regular waves.

Criteria for Analysis-Test Correlation of Structural Dynamic Systems

1975 ◽  
Vol 42 (2) ◽  
pp. 471-477 ◽  
Author(s):  
J. C. Chen ◽  
B. K. Wada
Keyword(s):  
Dynamic Systems ◽  
Analytical Procedure ◽  
Perturbation Technique ◽  
Order Perturbation ◽  
Test Results ◽  
Matrix Perturbation ◽  
Structural Dynamic ◽  
First Order ◽  
Periodic Loading ◽  
Test Correlation

A rational criterion for structural dynamic analysis-test correlation has been established by using a matrix perturbation technique. This criterion can be used for the verification of an analytical model by the test results. Also, the same technique can be applied to update the analytical results by using the test results without repeating the entire analytical procedure. A sample problem has been used to demonstrate this technique. Very satisfactory results are obtained with only the first-order perturbation solution included for transient loading. For periodic loading, higher-order perturbation solutions are needed to achieve the same accuracy.

Experimental Study on Tire Non-Steady State Slip Properties

2013 ◽  
Vol 753-755 ◽  
pp. 1736-1744
Author(s):  
Jie Liu ◽  
Xiao Ling Jia
Keyword(s):  
Linear System ◽  
Dynamic Performance ◽  
Lateral Force ◽  
Slip Angle ◽  
Test Results ◽  
Relaxation Length ◽  
Side Slip Angle ◽  
First Order ◽  
Depth Analysis ◽  
Yaw Angle

As for the two typical inputs of pure side slip angle and pure yaw angle, this paper presents the in-depth analysis of lateral force, aligning torque and relaxation length respectively within the domains of distance and spacial frequency, and also explains the test results by theoretical model. Within the small side slip angle, tire is a first-order linear system. Relaxation length is equivalent to the time constant of linear system, which decreases as slip angle increases. It indicates the dynamic performance of tire system.

An Off-Resonance Synchronous Vibration Based Method for Rotor System Damage Detections

2005 ◽  
Author(s):  
Huageng Luo ◽  
Hector Rodriguez ◽  
Darren Hallman ◽  
Dennis Corbly
Keyword(s):  
Final Section ◽  
State Of The Art ◽  
Detection System ◽  
Detection Algorithm ◽  
Integrated System ◽  
Test Results ◽  
Test Rig ◽  
Test Setup ◽  
First Order ◽  
Vibration Detection

This paper presents a methodology of detecting rotor imbalances, such as mass imbalance and crack-induced imbalance, using shaft synchronous vibrations. A vibration detection algorithm is derived based on the first order nonresonant synchronous vibration response. A detection system is integrated by using state-of-the-art commercial analysis equipment. A laboratory rotor test rig with controlled mass imbalances was used to verify the integrated system. The system is then deployed to an engine sub-assembly test setup. Four specimens were used in the subassembly test and the test results are reported in the final section.

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