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A detailed palaeointensity study was performed using the modified Thellier method on 18 Quaternary and Neogene volcanic units, ages ranging from 0.08 to 5.98 Ma, in Central Anatolia, Turkey. Robust data, which were estimated from 12 lava units in the study area, significantly increase the database of palaeomagnetic data, directions and absolute palaeointensity for the Anatolian region covering the time window back to ∼6 Ma. Previous studies sensitively dated the samples, except for one site dated in this study. The palaeointensity (VDM) value from the upper Miocene site estimated as 48.6 ± 9.2 μT (10.1 × 1022 ± 1.9 Am2) fits well into the Neogene VDM range in the data archives. For Pliocene samples with an age of 4.7 Ma, the palaeointensity was calculated to be 21.0 ± 4.7 μT. For these samples, an inclination of +42.9° was determined, and together with the results of low palaeointensity and normal polarity, this corresponds to the Nunivak or Sidufjall subchrons. These are normal polarity chrons within the Gilbert Chron which predominantly has reversed polarity. Palaeodirectional data and field strength with age between 0.08 and 2.57 Ma clearly showed the Brunhes and Matuyama Chrons in the Pleistocene. Three new data with 25.0 ± 7.9 μT (age 1.84 Ma), 59.7 ± 8.2 μT (age 2.15 Ma) and 79.6 ± 19.3 μT (age 2.57 Ma) from the early Pleistocene period significantly contribute to global data archives, which lack palaeointensity data from similar latitude range. The average VDM values for nine Pleistocene sites were calculated to be 51.5 ± 16.4 μT (10.3 × 1022 ± 3.7 Am2). According to the comparison of our data with the palaeointensity database, field model record and previous studies of the Pleistocene, significantly high field strength obtained from Central Anatolia, located in the Northern Hemisphere, could have occurred due to asymmetry between the Northern and Southern Hemispheres during the Pleistocene. [ABSTRACT FROM AUTHOR]

The southern Alborz mountains of northern Iran are an integral part of the Arabia/Eurasia collision zone. A magnetostratigraphic and rock magnetic investigation of the Eyvanekey stratigraphic section in the southern Alborz mountains reveals the spatiotemporal character of sedimentary facies migration in the Alborz foreland basin. The section constitutes three coarsening upward units (units 1, 2, and 3), comprising the Upper Red and Hezardarreh formations. Our data reveal that the Upper Red Formation was deposited between 17.5 and 7.5 Ma, while the depositional age of the top of the Hezardarreh Formation can be extrapolated to ~6.2 Ma. Slow sediment accumulation rates correlate with sedimentary facies comprising prograding, coarsening-upward units. This is likely the result of intraforeland uplift (units 1 and 2) and basin inversion, probably associated with a growth syncline located in the proximal foreland (unit 3). In contrast, fine-grained strata at the bottom of each cycle are associated with faster sediment accumulation rates, testifying to enhanced flexural basin subsidence in the course of thrust loading. Progradation of coarse-grained facies also occurred during relatively fast sediment accumulation (top of unit 2), suggesting that the influx of coarse-grained sediment outpaced the storage capacity of the proximal foreland. Thus, despite an overall southward propagation of deformation into the southern Alborz foreland, the locus of active deformation must have migrated back and forth on a time scale of circa 0.7 to 2 Ma.

The determination of the natural remanent magnetization (NRM) of archaeological features can be used for magnetic modelling, joining of shards, archaeomagnetic dating or the investigation of the firing–cooling–collapsing order of ancient buildings. The measurement of NRM is normally conducted on cylindrical or cubic samples in the laboratory. Nevertheless, archaeological finds should preferably not be destroyed, and laboratory instruments are high in costs. Therefore, we propose a lightweight and portable measurement set‐up including already available field magnetometers (preferably caesium magnetometers) in which the archaeological sample of arbitrary shape, in our case a piece of daub, is mounted inside a gimbal to be rotated in all directions. The magnetic field of the sample is measured at a large number of rotational positions with the magnetometer kept at fixed position. In these measurements, the unknown direction of the NRM vector of the sample is rotated, whereas the average magnetic susceptibility of the sample and the ambient magnetic field are constant and known. Hence, the vector of NRM can be determined through least‐squares inversion. For the inversion computation, the sample volume is discretized either as voxel model or approximated as an equivalent sphere. Under certain conditions depending on sample–sensor distance, dipole moment and radius of the sample, the approximation by a sphere is valid without effect on the accuracy of results. Empirically determined functions quantifying these conditions for different sensor sensitivities and noise levels are provided. Validation with laboratory measurements on palaeomagnetic subsamples from the destroyed daub samples indicate that the NRM can be determined by our proposed method with a maximum error in inclination of 2°, in declination of 20° and in magnetization of ±0.6 A/m. This is accurate enough, for example, to determine from daub pieces of burnt house remains whether the building was burnt and cooled before or after it collapsed. [ABSTRACT FROM AUTHOR]

High-resolution geochemical, physical and pollen data from lake sediments in Italy and from a Mediterranean sediment core are presented. The lacustrine sequence extends to the past 102,000 years, and many features correspond well with the Greenland ice-core records. This shows that the influence of the ocean-atmosphere system of the Northern Hemisphere extended as far as the central Mediterranean region.

A high-resolution multiparameter stratigraphy allows the identification of late Quaternary glacial and interglacial cycles in a central Arctic Ocean sediment core. Distinct sandy layers in the upper part of the otherwise fine-grained sediment core from the Lomonosov Ridge (lat 87.5 [degrees] N) correlate to four major glacials since ca. 0.7 Ma. The composition of these ice-rafted terrigenous sediments points to a glaciated northern Siberia as the main source. In contrast, lithic carbonates derived from North America are also present in older sediments and indicate a northern North American glaciation since at least 2.8 Ma. We conclude that large-scale northern Siberian glaciation began much later than other Northern Hemisphere ice sheets.

High-resolution magnetostratigraphy and nannoplankton biostratigraphy yield the sediment rates and control the age determination of coccolith abundance patterns of long sediment cores. The cores are measured for natural remnant magnetization, magnetic volume susceptibility, species composition and coccolith abundance. The magnetic and nannofossil stratigraphic study results are combined to assign absolute ages to coccolith presence in sediment cores.

Arising from: G. Yancheva et al. Nature 445, 74-77 (2007) On the basis of the anti-correlation of their palaeoclimatic proxy for the strength of the East Asian winter monsoon from [...]