Multidisciplinary Study of Burnt Deposits at Surungur, Fergana Valley, Southern Kyrgyzstan

Burnt deposits are an important source of information on ancient lifestyles, providing the possibility of reconstructing the size, intensity of use, and functions of fi replaces at prehistoric settlements, and to assess fuel sources. We outline the results of a multidisciplinary study of fi replaces and their contexts at Surungur—a stratifi ed site in the Fergana Valley, in southern Kyrgyzstan. Sixteen samples from ash lenses and intermediate deposits were studied by rock-magnetism, gas chromatography mass spectrometry (GC-MS), and X-ray fl uorescence (XRF). The rock-magnetic analysis suggests that the origin of all samples from ash lenses was anthropogenic. Types of fuel were reconstructed. At the initial stage (Early Holocene), the encompassing deposits likely resulted from short-term occupation, and fuel consisted of wood and grass/ dung. In the Middle Holocene, occupation became more long-term, as evidenced by maximal heating temperatures and high concentration of fi replaces. During the Late Holocene, habitation intensity on the platform under the stone ledge remained the same, but heating was less intense. Wood and grass/dung were used as fuel at all stages, suggesting that wood was available in the region throughout the Holocene.

Rock Magnetism of Late Cretaceous to Middle Eocene Strata in the Lesser Himalaya, Western Nepal: Inferences Regarding the Paleoenvironment

The growth of the southern piedmont of the Himalayan boundary and its depositional setting has changed since uplift of the Himalaya due to continental Indian-Eurasian collision, which has resulted in variation in magnetic minerals in marine- and terrestrial-facies sediments. In this paper, we utilize rock magnetism data from the late Cretaceous to middle Eocene strata, including the Amile and Bhainskati formations from the Lesser Himalaya (western Nepal), to understand the mechanism controlling magnetic susceptibility (χ). The active tectonics strongly influenced saturation isothermal remanent magnetization (SIRM), HIRM, and hysteresis loops, forming both low-coercivity minerals in sediments with low χ from the terrestrial facies (zones I, IIIA, and V) and high-coercivity minerals in the sediments with high χ from the marine facies (zones II, IIIB and IV). Thermomagnetic κ-T curves and frequency-dependent χ (χfd%) values show that sediments with low χ and high χ carry magnetite with coarse non-superparamagnetic (SP) grains and hematite with SP grains, respectively. Comparing the χ data with the lithologic, sedimentary environments, geomorphic features, and sea level data, we propose that low χ values were mainly produced by an increase in terrigenous detrital influx during the regression period of the Tethys Sea, while high χ values formed in marine sediments, which prompted the appearance of ferromagnetic-antiferromagnetic and paramagnetic minerals during the transgression of the Tethys Sea.

Rock magnetism and soil magnetic susceptibility

Information support of modern agriculture and ecology forms a demand for ever higher requirements for efficiency and density of the sampling network. This fact determines the spread of high-performance methods of soil research, among which are magnetometric ones. However, these methods have a number of limitations associated with the existence in soils of ferromagnets of non-pedogenic nature. The purpose of the study is to show the patterns of spatial and profile distribution of soils with high values of magnetic characteristics, inherited from parent rocks as a result of pedogenesis. The research used: determination of specific magnetic susceptibility using kappabridge KLY-2, determination of volumetric magnetic susceptibility with kappameter KT-5 and induction of magnetic field by proton magnetometer MP 203. The study was conducted at two objects located in the central part of the Ukrainian shield region. Studies have shown that soils developed on the weathering crust are characterized by certain features of their magnetic properties. First of all, it depends on the petromagnetic parameters of the source rocks. On magnetic rocks, the MS of soils is determined primarily by inherited magnetic minerals. The magnetic susceptibility of such soils has two maxima. The first is in the upper part of the profile, where it is determined by the sum of pedogenic and terrigenous magnets. The second is located in the lower part of the profile, which consists almost entirely of weathering products.

Kimmeridgian–Volgian ostracods of Samarskaya Luka: Paleoecological analysis and reflection of sedimentation conditions in rock magnetism

The analysis of the distribution of the Kimmeridgian–Volgian ostracods in the section near the village Valy made it possible to establish a sequence of eight communities, the change of which reflects changes in the ecological conditions in the basin. Changes in sea level fluctuations, the main physical and chemical parameters of the ostracod habitat – temperature, salinity of water, oxygen content in it, eutrophy and concentration of organic matter in sediment – are reconstructed. Information on the magnetic susceptibility and its increase after heating was obtained. Statistically significant relationships between the petromagnetic characteristics and some conditions of sedimentation were established. The conclusion about the relevance of continuing such studies at objects of different ages and genesis was made.

Magnetotactic Bacteria and Magnetosomes: Basic Properties and Applications

Magnetotactic bacteria (MTB) belong to several phyla. This class of microorganisms exhibits the ability of magneto-aerotaxis. MTB synthesize biominerals in organelle-like structures called magnetosomes, which contain single-domain crystals of magnetite (Fe3O4) or greigite (Fe3S4) characterized by a high degree of structural and compositional perfection. Magnetosomes from dead MTB could be preserved in sediments (called fossil magnetosomes or magnetofossils). Under certain conditions, magnetofossils are capable of retaining their remanence for millions of years. This accounts for the growing interest in MTB and magnetofossils in paleo- and rock magnetism and in a wider field of biogeoscience. At the same time, high biocompatibility of magnetosomes makes possible their potential use in biomedical applications, including magnetic resonance imaging, hyperthermia, magnetically guided drug delivery, and immunomagnetic analysis. In this review, we attempt to summarize the current state of the art in the field of MTB research and applications.