Friedrich Heller

Magnetic record of industrial pollution in forest soils of Upper Silesia, Poland

The organic top horizons of forest soils in the vicinity of industrial centers in Upper Silesia, Poland, are characterized by remarkably high magnetic susceptibility. The unusually strong soil susceptibility does not result from weathering or pedogenesis or from deposition of natural detrital ferrimagnetic minerals but is due rather to the influx of anthropogenic magnetic particles contained in industrial dusts and fly ashes. The magnetic particles are iron oxide spherules which originate during the combustion of fossil fuels (brown and hard coals) and during iron or steel production. Heavy metals, such as zinc, lead, or cadmium which stem from the same pollution sources, are often associated with the magnetic and other dust particles and cause soil contamination, which is potentially hazardous for plants, animals, and humans. Because the regional magnetic susceptibility distribution pattern is closely correlated to measured dust fall and largely parallels the distribution of heavy metals, measurements of magnetic susceptibility, which can be conducted easily both in the laboratory and in the field, can be used as a fast and sensitive tool to trace and monitor soil contamination in industrialized regions.

Magnetic material in the human hippocampus

Magnetic analyses of hippocampal material from deceased normal and epileptic subjects, and from the surgically removed epileptogenic zone of a living patient have been carried out. All had magnetic characteristics similar to those reported for other parts of the brain [6]. These characteristics along with low temperature analysis indicate that the magnetic material is present in a wide range of grain sizes. The low temperature analysis also revealed the presence of magnetite through manifestation of its low temperature transition. The wide range of grain sizes is similar to magnetite produced extracellularly by the GS-15 strain of bacteria and unlike that found in magnetotactic bacteria MV-1, which has a restricted grain size range. Optical microscopy of slices revealed rare 5-10 micron clusters of finer opaque particles, which were demonstrated with Magnetic Force Microscopy to be magnetic. One of these was shown with EDAX to contain AI, Ca, Fe, and K, with approximate weight percentages of 55, 19, 19, and 5, respectively.

Late Permian to Early Triassic magnetostratigraphy

Abstract A Late Permian to Early Triassic magnetostratigraphic reference section is presented. The Lower Triassic part is based on results from marine limestone sections in South China published earlier [1,2]. Reliable new Permian data are added here which have been collected in the Nammal gorge (Salt Range, Northwest Pakistan) where marine sediments have been deposited quasi-continuously with occasional minor hiatuses during the late Palaeozoic to early Mesozoic. About 50% of the Permian samples from the Nammal section contain, hidden beneath a strong recent or Tertiary overprint, a characteristic remanent magnetization (ChRM) which is very likely of Permian age. This component, which was imprinted on the southern hemisphere, has normal as well as reversed polarity with a normal mean direction (Decl. = 289.3°, Incl. = −50.3°,α95 = 4.3°,N = 113) which is in close agreement with the palaeofield direction expected for a site belonging to the Indian plate as part of Gondwanaland during the Permian. In the lower Upper Permian several normal polarity zones are recognized. This contradicts the current assumption that rocks of this age belong to the long, reversely polarized Kiaman hyperzone. The Kiaman interval must end and the Illawarra hyperzone of mixed polarity must begin in or prior to the lowermost Upper Permian. The Permian/Triassic boundary at Nammal as well as in the Chinese sections is situated very close to a transition from a reversed to a normal polarity zone. The Upper Permian at Nammal together with the Lower Triassic South China sections is estimated to cover about 20 Ma. Nearly 30 polarity changes are observed which result in an average reversal frequency very similar to that observed during the early Tertiary. The reversal rate after the end of the long-lasting reversed Kiaman hyperchron apparently increases in a manner similar to that after the end of the Cretaceous Long Normal Superchron. Only a few polarity zones are found in the lower Upper Permian, while progressively more frequent reversals follow in the Lower Triassic.

10Be and magnetic susceptibility in Chinese loess

10Be and magnetic susceptibility have been measured in the top 12 m of a loess profile from Luochuan, Central China. Comparison of the 10Be concentration record with the SPECMAP δ18O profile of the last 130 ka (Imbrie et al., 1984] results in a new time scale which is in good agreement with that of Kukla et al. [1990]. The calculated loess accumulation rates can be compared with existing records of dust falls in Pacific deep sea sediments and Antarctic ice cores. A simple model for the 10Be dust flux demonstrates that a significant part of the magnetic susceptibility signal in palaeosol horizons is due to in situ pedogenic production. During times of high loess accumulation (cold palaeoclimate) this contribution is negligible.

Paleomagnetic evidence for clockwise rotation of the Simao region since the Cretaceous: A consequence of India-Asia collision

Samples were collected for paleomagnetic analysis from 36 sites from six formations west of the Red River Fault in southwestern Yunnan Province, China on the Simao block (23.4°N, 100.8°E) in an attempt to examine the effects of the India-Asia collision on the Asian continent. Paleomagnetic results from rocks ranging from Cretaceous to Miocene in age indicate a large clockwise rotation of these sites with respect to stable Eurasia since the Late Cretaceous. The tectonic-corrected data from Cretaceous samples (mean direction of two formations) are D = 112.6°, I = 34.7°, α95 = 7.5°, k = 9.1, n = 45, for Eocene samples the data are D = 84.7°, I = 38.9°, α95 = 7.6°, k = 12.0, n = 32, and for Miocene samples they are D = 21.1°, I = 35.5°, α95 = 7.1°, k = 15.3, n = 29. The samples from the Paleocene and Pliocene are either remagnetized or too weak to provide stable directions. The Cretaceous sites were sampled from folded beds and these sites pass the fold test. The amount of rotation seen in this study (R = 86.1 ± 9.9° as a mean value for the Cretaceous, R = 76.8 ± 11° for the Eocene, and R = 14.7 ± 10.0° for the Miocene) is significantly larger than that documented in previous studies from the Lower Cretaceous of northwestern and central Yunnan Province and may indicate that differential rotation has taken place in the region. This rotation can be explained by the northward motion and collision of India with Asia in the Paleocene, which caused continuous deformation of southwestern China in the form of strike-slip faulting and clockwise rotation. It is concluded that the rotation and deformation resulting from this collision probably continued from the Paleocene until at least the Miocene.

Magnetostratigraphy of the Permo-Triassic boundary section at Shangsi (Guangyuan, Sichuan Province, China)

Continous marine sedimentation characterizes many Late Permian to Early Triassic sections on the Yangtze terrane in South China. The Permo-Triassic (P/Tr) boundary section at Shangsi (Sichuan Province) consists of limestones intercalated with clays and mudstones which belong to the Wuchiapingian and Changxingian (Upper Permian) and the Griesbachian and Dienerian (Lower Triassic) stages. The P/Tr boundary is formed by a clay horizon with an unusually high iridium concentration. The intensity of natural remanent magnetization is very low with a mean of 0.15 mA m−1. About 40% of the samples contain secondary or unstable magnetization components only, whereas the remaining samples carry a characteristic remanent magnetization thought to reflect the polarity of the geomagnetic field during deposition with sufficient accuracy. Normal and reversed polarity of the characteristic magnetization constitute a pattern of at least six polarity zones, the P/Tr boundary being situated very close to the transition from a reversed to a normal polarity zone. The Shangsi polarity sequence represents part of the Illawarra interval of mixed polarity, the exact beginning of which has still to be determined.

Permian-Triassic magnetostratigraphy—new results from South China

Abstract Continuous marine sediments of Permian to Triassic age are widely distributed over large areas in Southern China. They offer the potential for developing magnetostratigraphic columns to investigate the polarity status of the palaeomagnetic field. Three carbonate sections on the Yangtze platform, which represent mainly the Upper Permian but also parts of the Lower Triassic and possibly parts of the uppermost Lower Permian, contain a long-term main R-N-R-N-R polarity succession throughout the Permian. This signal is hidden under strong overprint magnetizations of variable origin and can be mostly obtained only from directional trends of the natural remanent magnetization during demagnetization rather than from clear stable end-point directions. The new Chinese polarity sequences are in accord with magnetostratigraphic records from the former USSR and Pakistan. Depending on stratigraphic assignment of the lithological formations studied, either they include the boundary between the Lower and Upper Permian and give evidence that the Kiaman reversed polarity superchron had ended before the Upper Permian, or the formations all belong stratigraphically to the Upper Permian, with the oldest reversed interval to be correlated with the reversed zone in the Midian stage of the palaeontologically well-dated Nammal section in Pakistan. This zone is preceded by at least one normal polarity zone at Nammal so that the end of the Kiaman superchron would not be observed in the new Chinese sections.

Widespread Neogene remagnetization in Jurassic limestones of the South-Iberian palaeomargin (Western Betics, Gibraltar Arc)

Abstract Palaeomagnetic investigations in Upper Jurassic carbonate rocks from the Western Subbetics (Betic Cordillera, Southern Spain) testify to a widespread Neogene remagnetization. Progressive thermal and alternating field demagnetization analyses reveal the presence of two stable components of the natural remanent magnetization (NRM). The NRM is dominated by a pervasive Neogene overprint, which always shows normal polarity and maximum unblocking temperatures of 450°C throughout the whole region studied. The primary Jurassic component, however, can also be isolated in many outcrops. This component has low intensity values and maximum unblocking temperatures of about 550°C, showing both normal and reversed polarities. Palaeomagnetic and rock magnetic analyses indicate that both primary Jurassic and secondary Neogene components are carried by magnetite. The incremental fold test performed in all sampling localities demonstrates that the remagnetization occurred during some stage of the Neogene deformation of the Subbetics, being pre-, syn- or post-folding in the various folds studied.

Analysis of magnetic material in the human heart, spleen and liver

Isothermal remanent magnetization (IRM) acquisition and alternating field (A.F.) demagnetization analyses were performed on human heart, spleen and liver samples resected from cadavers. The magnetic properties of the samples were measured both at 77K and at 273K. A.F. demagnetization was performed at 273K. Results from the analyses of the tissue indicate the presence of ferromagnetic, fine-grained, magnetically interacting particles which, due primarily to magnetic properties, are thought to be magnetite and/or maghemite. The presence of superparamagnetic particles can be inferred from the increase in saturation IRM values when measured at 77K compared with measurements at 273K and the decay of remanent magnetization upon warming from 77K. The concentration of magnetic material (assuming it is magnetite or maghemite) in the samples varies from 13.7 ng g-1 to 343 ng g-1, with the heart tissue generally having the highest concentration. The presence of magnetic material in these organs may have implications for the function of biogenic magnetite in the human body.

Pedosedimentary division, rock magnetism and chronology of the loess/palaeosol sequence at Roxolany (Ukraine)

Abstract The loess mantle of the VIII Dniestre terrace at Roxolany in the Black Sea area of Ukraine is subdivided into six units, which encompass the following palaeosol taxons: pedocomplexes (PK) with evidence for several soil-forming and sedimentary episodes; incipient monogenetic palaeosols; and horizons of carbonate concretions. These cyclical loess-palaeosol units provide a depositional record from the end of the Matuyama chron through the Holocene. The detailed pedosedimentary subdivision of loesses at Roxolany is generally consistent with magnetic susceptibility depth functions and seems to reflect global climatic variations. Earlier chronologies [Guidebook of the International Geological Congress. XXVII Session, 1984] are re-estimated on the basis of a revised position of the Matuyama–Brunhes boundary and by detailed rock magnetic and micromorphological studies. The strongly developed chernosem of PK 4 at approximately 22 m depth, showing features of rubefication and the highest magnetic susceptibility value, is viewed as a good stratigraphic marker of the Late Cromerian and seems to represent the climatic optimum of the Brunhes chron (oxygen isotope stage 13?). The uppermost PK 2 is represented in the lower part by a chernosem analogous to surface soils of the area and is argued to be no younger than the Last Interglacial (oxygen isotope stage 5e). The poor preservation of PK 2 seems to result from processes of soil degradation and deflation at the time of interglacial–glacial transition. The closely spaced palaeosols between PK 2 and PK 4 seem to relate to three independent interglacials. Highest resolution of the palaeoclimatic record is found at the final Matuyama chron from PK 9 to PK 8 and in incipient soils that contain either humic horizons with enhanced magnetic susceptibility or only horizons of large carbonate concretions.