Search results for "Magnetism"
showing 10 items of 1934 documents
The Ventian mammal age (Latest Miocene): present state
2013
[EN] The Ventian land mammal age includes most of the Spanish faunas assigned to the biochronologic unit MN 13. It is correlatable with the Messinian, although it may include, in its latest part, Early Pliocene faunas. We propose that the Ventian begins with the fi rst occurrence of the Muridae genus Stephanomys (7 Ma, paleomagnetic dating from El Bunker, Teruel basin), well recorded in Teruel basin, and ends with the appearance of Promimomys (ca. 5 Ma), also registered in the Teruel basin. We suggest a new reorganization of the Ventian. The first subdivision corresponds to the zone M (Dam et al., 2001). The second, zone N, is proposed here for the first time, being equivalent to the zone w…
Volcanological evolution of Pantelleria Island (Strait of Sicily) peralkaline volcano: a review
2022
International audience; Pantelleria volcano has a particularly intriguing evolutionary history intimately related to the peralkaline composition of its explosively erupted magmas. Due to the stratigraphic complexity, studies over the last two decades have explored either only the pre-Green Tuff ignimbrite volcanism or the post-Green Tuff activity. We here focus on the whole evolutionary history, detailing the achievements since the first pioneering studies, in order to illustrate how the adoption and integration of progressively more accurate methods (40 Ar/ 39 Ar, paleomagnetism, petrography, and detailed field study) have provided many important independent answers to unresolved questions…
Palaeomagnetic investigations in the Hercynian mountain belt of central Europe
1983
Abstract The palaeomagnetism of sediments and volcanics of Middle Devonian to Early Carboniferous age has been studied in the Hercynian realm of the Vosges, Harz and Franconian Forest (France and Germany). After appropriate cleaning, characteristic directions of natural remanent magnetization (NRM) have been determined, which are considered to be of pretectonic origin according to rock magnetic and structural geological evidence. A mean palaeopole for the Devonian rocks in the areas investigated was determined at — 29.7°N and 9.0°E. The site latitude derived from the Devonian rocks agrees very well with that observed in Great Britain and Britanny. The significant difference in longitude bet…
First Early Pliocene micromammal faunas from Venta del Moro (Cabriel Basin, Spain) : new data on the Messinian dispersal of Debruijnimys
2021
The localities of La Bullana 3 and LA Bullana 2B (Valencia, E Spain) have yielded remains of Apodemusgorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet. and Asoriculus cf. gibberodon the former, and Apodemusgorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet., Asoriculus cf. gibberodon, Castillomysgracilis, Occitanomysbrailloni, Occitanomys sp., Paraethomys meini, Ruscinomys sp., Eliomys intermedius, Debruijnimys cf. julii and Atlantoxerussp. the latter. Based on the study of these micromammal assemblages, we propose an Early Pliocene age (MN14) for both sites. The pres-ence a gerbilid related to De…
Chemostratigraphy, magnetostratigraphy, chronology, palaeoenvironments and correlations.
2013
4 pages
Palaeomagnetic results from the late Precambrian Chela Group of southwest Angola
1992
Abstract Palaeomagnetic results from fourteen sites (56 samples) in the late Precambrian Chela Group of southwest Angola are reported. After alternating field demagnetization eight of the sites have mean directions closely grouped around D = 123°, I = −44 1 2 ° ; the dispersion of these directions increases substantially after tectonic corrections suggesting magnetic overprinting. Intensive thermal demagnetization proved more effective than alternating field demagnetization in resolving magnetic components. After removal of viscous components, samples from five sites (Group I) show a single component, similar to that observed after alternating field demagnetization. At four more sites (Grou…
Unprecedented layered coordination polymers of dithiolene group 10 metals: Magnetic and electrical properties
2016
One-pot reactions between Ni(ii), Pd(ii) or Pt(ii) salts and 3,6-dichloro-1,2-benzenedithiol (HSC6H2Cl2SH) in KOH medium under argon lead to a series of bis-dithiolene coordination polymers. X-ray analysis shows the presence of a common square planar complex [M(SC6H2Cl2S)2]2- linked to potassium cations forming either a two-dimensional coordination polymer network for {[K2(μ-H2O)2(μ-thf)(thf)2][M(SC6H2Cl2S)2]}n [M = Ni (1) and Pd (2)] or a one-dimensional coordination polymer for {[K2(μ-H2O)2(thf)6][Pt(SC6H2Cl2S)2]}n (3). In 3 the coordination environment of the potassium ions may slightly change leading to the two-dimensional coordination polymer {[K2(μ-H2O)(μ-thf)2][Pt(SC6H2Cl2S)2]}n (4) …
Cesi, an early Middle Pleistocene site in the Colfiorito Basin (Umbro-Marchean Apennine), central Italy
1997
Near the village of Cesi, at the head of the Chienti River, in the Colfiorito Basin (Umbro-Marchean Apennines, central Italy), fluvio-lacustrine deposits have yielded mammal fossil remains. The results of a multidisciplinary investigation indicate that the vertebrate-bearing sediments date about 700 ka and accordingly provide a fossil assemblage for the Middle–Late Galerian. Palynological investigations carried out from sediments underlying the fossiliferous level suggest predominantly cold and dry conditions, whereas the fauna suggests a slight climatic amelioration towards cool and moist conditions in the uppermost part of the sequence. © 1997 John Wiley & Sons, Ltd.
Polarized neutron diffraction and Mössbauer spectral study of short-range magnetic correlations in the ferrimagnetic layered compounds(PPh4)[FeIIFeII…
2002
Short-range antiferromagnetic correlations have been studied in the layered compounds (PPh 4 ) [Fe I I Fe I I I (ox) 3 ] and (NBu 4 ) [Fe I I Fe I I I (ox) 3 ] by neutron polarization analysis and Mossbauer spectroscopy. Polarized neutron diffraction profiles obtained between 2 and 50 K on (d 2 0 -PPh 4 ) [Fe I I Fe I I I (ox) 3 ] show no magnetic Bragg scattering; the lack of such scattering indicates the absence of long-range magnetic order. However, a broad asymmetric feature observed at a Q of ca. 0.8 A - 1 is attributed to two-dimensional short-range magnetic correlations, which are described by a Warren function. The correlation length is ca. 50 A between 2 and 30 K and then decreases…
Effect of cation disorder on the magnetic properties ofSr2Fe1−xGaxReO6(0<x<0.7)double perovskites
2007
The effect of diamagnetic dilution of the Fe sublattice on the structural and magnetic properties of the double perovskite Sr{sub 2}Fe{sub 1-x}Ga{sub x}ReO{sub 6} (0 =}0.4 is detected by x-ray structural analysis accompanied by the observation of a magnetically ordered and a paramagnetic phase in the corresponding Moessbauer spectra. Below 20% Ga content, Ga statistically dilutes the -Fe-O-Re-O-Fe- double-exchange pathways. Phase separation begins at 20% Ga substitution; between 20% and 40% ofmore » Ga content, the paramagnetic Ga-based phase does not contain any Fe. The Fe-containing, paramagnetic cubic phases which can be detected by Moessbauer spectroscopy first appear for x=0.4.« less