Additional Paleomagnetic Data on the Baffin Diabase Dikes and a Revised Franklin Pole

1973 ◽  
Vol 10 (4) ◽  
pp. 576-581 ◽  
Author(s):  
W. F. Fahrig ◽  
E. J. Schwarz
Keyword(s):  
Coastal Area ◽  
Remanent Magnetization ◽  
Magnetic Mineral ◽  
Paleomagnetic Data ◽  
Published Data ◽  
Baffin Island ◽  
Thermomagnetic Curves ◽  
Representative Material

Paleomagnetic data were obtained from eleven additional sites on Baffin diabase dike intrusions (part of the Franklin diabases). The rock at four sites was found to be normally magnetized, at six sites reversely magnetized, and at one site the rock contained no primary remanent magnetization that could be isolated by alternating field (a.f.) demagnetization. Baffin Island is divisible into several zones within which the Baffin dikes are either normally or reversely magnetized. This may indicate that more than one reversal is represented. The ten sites yield a pole at 168 °E, 6 °N, α95 = 5°, and when combined with previously published data (total 46 sites) yield a revised Franklin diabase pole at 166 °E, 6 °N, α95 = 4°. At least 10 of the 11 new sites apparently lie outside the zone from within which Baffin dikes have yielded anomalous remanent magnetization directions. Thermomagnetic curves for representative material of the Baffin dikes indicate that the magnetic mineral of these rocks is almost pure magnetite. It does not explain the anomalous magnetization of the Franklin dikes that occur along the northeast coastal area.

Borden dykes of Baffin Island, Northwest Territories: a Franklin U-Pb baddeleyite age and a paleomagnetic reinterpretation

1999 ◽  
Vol 36 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Sally J Pehrsson ◽  
Kenneth L Buchan
Keyword(s):  
Northwest Territories ◽  
Remanent Magnetization ◽  
Paleomagnetic Data ◽  
Dyke Swarm ◽  
Baffin Island ◽  
Normal Faulting ◽  
Polar Wander ◽  
Baffin Bay ◽  
The North ◽  
Chemical Remanent Magnetization

U-Pb baddeleyite geochronology for two Borden diabase dykes of northern Baffin Island gives an intrusion age of ca. 720 Ma, coeval with the age established elsewhere for the Franklin igneous event. Thus, the Borden dykes belong to the Franklin dyke swarm, rather than forming a separate swarm that intruded at ca. 950-900 Ma, as has been suggested previously on the basis of paleomagnetism and K-Ar ages. As a result, the paleopole from the Borden dykes can no longer be utilized to help constrain the ca. 1050-850 Ma Grenville Loop of the North American polar wander path. Reevaluation of paleomagnetic data for the dykes of northern Baffin Island suggests that Borden dyke magnetizations resulted from superposition of a steeply directed component of chemical remanent magnetization on normal and reversed primary Franklin components. The overprint direction is consistent with a Cretaceous-Tertiary age and is likely related to normal faulting and graben development during the opening of Baffin Bay.

Linking cave sediments and soil magnetism in the Urșilor cave (Romania)

2021 ◽  
Author(s):  
Cristian George Panaiotu ◽  
Cristian Necula ◽  
Relu D. Roban ◽  
Alexandru Petculescu ◽  
Ionut-Cornel Mirea ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Frequency Dependence ◽  
Remanent Magnetization ◽  
Rock Magnetism ◽  
Magnetic Mineral ◽  
Magnetic Data ◽  
Sediment Samples ◽  
Superparamagnetic Particles ◽  
Susceptibility Data ◽  
Cave Sediments

<p>Cyclical changes in the magnetic mineral assemblages have been observed in numerous sedimentary records confirming the relationship between rock magnetism and past global change. Several studies have shown that the magnetic susceptibility data of cave sediments reflect both long- and short-term climatic oscillations. These magnetic susceptibility variations are attributed to changes in climate-controlled pedogenesis which influence the production of low coercivity magnetic mineral phases, magnetite, and maghemite outside the cave. These soils with climate-dependent magnetic properties are then washed, blown, or tracked into the cave where they accumulate, creating the changes observed in rock magnetic data. We present a rockmagnetism study of the sediments from the Urșilor cave and the soils above the cave. Our focus is the detailed characterization of the ferromagnetic mineralogy preserved in the cave sediments and its links with potential soil sources. In the cave, we sampled four sections (2-3 m high) consisting mainly of silts and clays, with some sand layers. The age of the sediments is older than 40 ka. At the surface, we sampled various types of soils from 9 sites. For all samples, we measured: variation of magnetic susceptibility with frequency (976 and 15616 Hz), the anisotropy of magnetic susceptibility, isothermal remanent magnetization, and anhysteretic remanent magnetization. Because soils are characterized by the presence of superparamagnetic magnetite produced by pedogenesis which can be detected by the frequency dependence of magnetic susceptibility, we also measured the frequency dependence of soils and selected cave sediment samples at 13 frequencies (between 128 and 512000 Hz). Multi-frequencies measurements of the magnetic susceptibility of recent soils show that all the sampled soils have a strong frequency dependence indicating the presence of superparamagnetic particles produced by pedogenesis. Most of the sediment samples have an important frequency dependence similar to the one observed in the recent soils. As a preliminary conclusion, we can state that most of the fine cave sediments contain superparamagnetic particles, which can be probably attributed to soils transported into the cave by erosion. These results suggest that during the deposition of high magnetic susceptibility sediments it was a climate favorable for intense pedogenesis. The interpretation of the intervals with lower values of magnetic susceptibility is still under investigation to decide if represents a climatic signal or a change in the dynamics of sediment transport. <strong>Acknowledgment:</strong> The research leading to these results has received funding from the EEA Grants 2014-2021, under Project contract no. EEA-RO-NO-2018-0126.</p>

Paleomagnetism of the 1180 Ma Grenvillian Umfraville gabbro, Ontario

1978 ◽  
Vol 15 (6) ◽  
pp. 956-962 ◽  
Author(s):  
D. T. A. Symons
Keyword(s):  
Remanent Magnetization ◽  
Pole Position ◽  
Paleomagnetic Data ◽  
Grenville Province ◽  
Thermal Demagnetization ◽  
Before And After ◽  
Primary Origin

The 1180 ± 20 Ma Umfraville gabbro is a slightly metamorphosed stock in the Grenville Province. It was sampled at 17 sites (183 specimens). After alternating field and thermal demagnetization the gabbro retains the same very stable remanent magnetization of primary origin both before and after screening. The screened AF direction from 10 sites (96 specimens) gives a pole position of 166°E, 11°S (δp = 7°, δm = 10°). This position is ≈ 13° southeast of that originally reported for the gabbro by Hood. This pole position either does not fit or necessitates modifications to the four hypotheses that have been invoked to explain Grenville paleomagnetic data.

scholarly journals POTENSI SUMBERDAYA ALAM PASIR BESIPANTAI ARAKAN KABUPATEN MINAHASA SELATAN

2011 ◽  
Vol 15 (1) ◽  
pp. 225
Author(s):  
Adey Tanauma ◽  
Ferdy Ferdy
Keyword(s):  
Natural Resources ◽  
Saturation Magnetization ◽  
Seed Size ◽  
Coastal Area ◽  
Magnetic Hysteresis ◽  
Magnetic Domain ◽  
Magnetic Mineral ◽  
North Sulawesi ◽  
Size Measure ◽  
Magnetic Seeds

POTENSI SUMBERDAYA ALAM PASIR BESIPANTAI ARAKAN  KABUPATEN MINAHASA SELATAN Adey Tanauma1) dan Ferdy1) 1)Program Studi Fisika FMIPA Universitas Sam Ratulangi, Manado 95115 ABSTRAK Pasir besi merupakan salah satu sumberdaya alam di Sulawesi Utara yang belum dimanfaatkan secara optimal. Salah satu lokasi yang cukup potensial untuk mendapatkan endapan pasir besi ini adalah pesisir pantai Arakan. Penelitian ini bertujuan untuk menentukan sifat-sifat magnetik endapan pasir besi yang terdapat di pesisir Pantai Arakan kabupaten Minahasa Selatan Provinsi Sulawesi Utara. Suseptibilitas magnetik dan magnetisasi saturasi sampel pasir besi Arakan mengindikasikan bahwa kandungan mineral magnetik yang dominan adalah magnetite. Ukuran bulir dari mineral magnetik terutama magnetite didominasi oleh bulir-bulir magnetik berukuran besar atau bulir magnetik dengan domain magnetik antara pseudosingle domain dan multi domain. Tingginya kandungan mineral magnetik berdasarkan nilai karakterisasinya, terutama nilai suseptibilitas magnetik memberikan peluang untuk pemanfaatan lebih lanjut dari sumberdaya alam ini. Kata kunci: histeresis magnetik, pasir besi, suseptibilitas THE POTENTIAL OF NATURAL RESOURCES OF IRON SAND IN ARAKAN COASTAL SUBPROVINCE OF SOUTH MINAHASA ABSTRACT Iron sand represent one of the natural resources in North Sulawesi which not yet been exploited in optimally. One of the location which quite potential to get this iron sand sediment is coastal area of Arakan. This research aim to determine the nature of magnetic of iron sand sediment which there are in coastal area of Arakan, Sub-province of South Minahasa, Province of   North Sulawesi. Magnetic suseptibility and saturation magnetization of iron sand sampel of Arakan  indicated that dominant magnetic mineral is magnetite. Seed size measure of magnetic mineral especially magnetite predominated by big sized magnetic seeds or magnetic seed with magnetic domain between domain pseudosingle and multi domain. The height content of magnetic mineral based on characteristic value, especially  magnetic suseptibility give the opportunity for furthermore exploiting of this natural resources. Keywords : magnetic hysteresis, iron sand, suseptibility

Detrital remanent magnetization of single-crystal silicates with magnetic inclusions: constraints from deposition experiments

2020 ◽  
Vol 224 (3) ◽  
pp. 2001-2015
Author(s):  
Liao Chang ◽  
Hoabin Hong ◽  
Fan Bai ◽  
Shishun Wang ◽  
Zhaowen Pei ◽  
...  
Keyword(s):  
Field Dependence ◽  
Remanent Magnetization ◽  
Magnetic Moments ◽  
Magnetic Mineral ◽  
Simple Explanation ◽  
Rolling Ball ◽  
Mineral Inclusions ◽  
Recording Efficiency ◽  
Inclination Shallowing ◽  
Linear Field

SUMMARY Quasi-linear field-dependence of remanence provides the foundation for sedimentary relative palaeointensity studies that have been widely used to understand past geomagnetic field behaviour and to date sedimentary sequences. Flocculation models are often called upon to explain this field dependence and the lower palaeomagnetic recording efficiency of sediments. Several recent studies have demonstrated that magnetic-mineral inclusions embedded within larger non-magnetic host silicates are abundant in sedimentary records, and that they can potentially provide another simple explanation for the quasi-linear field dependence. In order to understand how magnetic inclusion-rich detrital particles acquire sedimentary remanence, we carried out depositional remanent magnetization (DRM) experiments on controlled magnetic inclusion-bearing silicate particles (10–50 μm in size) prepared from gabbro and mid-ocean ridge basalt samples. Deposition experiments confirm that the studied large silicate host particles with magnetic mineral inclusions can acquire a DRM with accurate recording of declination. We observe a silicate size-dependent inclination shallowing, whereby larger silicate grains exhibit less inclination shallowing. The studied sized silicate samples do not have distinct populations of spherical or platy particles, so the observed size-dependence inclination shallowing could be explained by a ‘rolling ball’ model whereby larger silicate particles rotate less after depositional settling. We also observe non-linear field-dependent DRM acquisition in Earth-like magnetic fields with DRM behaviour depending strongly on silicate particle size, which could be explained by variable magnetic moments and silicate sizes. Our results provide direct evidence for a potentially widespread mechanism that could contribute to the observed variable recording efficiency and inclination shallowing of sedimentary remanences.

δ13C stratigraphy of the Proterozoic Bylot Supergroup, Baffin Island, Canada: implications for regional lithostratigraphic correlations

1999 ◽  
Vol 36 (3) ◽  
pp. 313-332 ◽  
Author(s):  
Linda C Kah ◽  
Anne G Sherman ◽  
Guy M Narbonne ◽  
Andrew H Knoll ◽  
Alan J Kaufman
Keyword(s):  
Carbon Isotope ◽  
Record Values ◽  
Time Correlation ◽  
Published Data ◽  
Baffin Island ◽  
Isotopic Data ◽  
Carbon Isotopic ◽  
Somerset Island ◽  
Interval Comparison

The Bylot Supergroup, northern Baffin Island, contains >1500 m of platform, shelf, and slope carbonates deposited between ~ 1270 and ~ 723 Ma. Limited chronostratigraphic data have led to the broad correlation of the Bylot Supergroup with predominantly Neoproterozoic successions in northern and western Laurentia; yet, detailed correlation has been impossible given biostratigraphic and lithostratigraphic limitations. Carbon-isotope chemostratigraphy represents a potential dataset to constrain such interregional correlations. Carbon isotopic data from the Bylot Supergroup and broadly coeval successions from Somerset Island and northwest Greenland reveal distinct stratigraphic trends in δ13C, with intervals of moderate 13C enrichment (+3.5 ± 1‰) punctuated by excursions to slightly negative values (-1.0 ± 1‰). Although the scale of the observed variation is muted relative to Neoproterozoic standards, the dissimilarity of values to those recorded in northwestern Laurentia suggests that these strata delineate a discrete depositional interval. Comparison of isotopic values with published data indicates that δ13C values between approximately -1.0 and +4.0‰ are characteristic of the interval between ~ 1300 and ~ 800 Ma. This pattern is distinct from that of younger Neoproterozoic successions, which typically record values >+5‰, and older Mesoproterozoic successions, which record values near 0‰, and suggests that these moderately positive values may be useful for broad time correlation. Compilation of new and published data permits the tentative reconstruction of a global Mesoproterozoic carbon isotopic curve.

scholarly journals Upper Devonian (Frasnian stage) of the north-western part of the Russian Platform: paleomagnetic data

2020 ◽  
Vol 15 (4) ◽  
Author(s):  
A.G. Iosifidi ◽  
◽  
V.V. Popov ◽  
A.V. Zhuravlev ◽  
◽  
...  
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Upper Devonian ◽  
Paleomagnetic Data ◽  
Magnetic Minerals ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Pole ◽  
Frasnian Stage ◽  
Main Devonian Field

Paleomagnetic determinations for the Devonian strata of the Main Devonian Field, available in the international paleomagnetic data base, do not make it possible to construct both detailed magnetostratigraphic scales and reliable trajectories of the apparent polar wander path of the paleomagnetic pole. This is primarily due to the insufficient amount of data that determine modern reliability criteria. Obtaining more complete series of reliable paleomagnetic determinations is one of the important tasks of paleomagnetic studies. The paper presents new paleomagnetic determinations from a collection of rocks of the Frasnian stage of the Upper Devonian (Ilmen and Bureg Beds of the Semiluky Formation), sampled on the southern shore of Lake Ilmen, east of the village. Korostyn in 2009. Magnetomineralogical studies were carried out to determine the magnetic minerals of carriers of natural remanent magnetization. Three characteristic components of natural remanent magnetization have been identified. Two components correspond to the Late Paleozoic magnetization reversal (in the Carboniferous and Permian times). The third, bipolar component of the Frasnian age passes the reverse polarity test of the geomagnetic field.. The obtained position of the paleomagnetic pole by the bipolar component of the natural remanent magnetization is consistent with the available data on the section of the Late Upper Devonian of the Main Devonian Field.

Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

1993 ◽  
Vol 51 ◽  
pp. 1038-1039 ◽  
Author(s):  
G.A. Bertero ◽  
R. Sinclair
Keyword(s):  
Remanent Magnetization ◽  
Strong Influence ◽  
Uniaxial Anisotropy ◽  
Magnetic Coupling ◽  
Recording Media ◽  
Magnetic Media ◽  
Signal To Noise ◽  
Out Of Plane ◽  
Longitudinal Recording ◽  
The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

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