S.S. Vasiliev

A tree-ring and C-14 chronology of the key Sayan-Altai monuments

We present a radiocarbon chronology of key Sayan-Altai monuments from the Scythian period, based on a statistical analysis of dates produced in the 1980s and now supplemented with new dates. These new (super 14) C dates were produced for samples from the Tuekta-1 barrows (burial mounds) and were measured both in St. Petersburg and Groningen. These tree-ring samples were fitted to the calibration curve. Chronologies were established for the Arzhan, Tuekta-1 and Pazyryk-5 barrows. The time of the construction of the Arzhan and Pazyryk-5 barrows is the 9th and late 5th-4th centuries BC, respectively, and agrees with archaeology. According to new data obtained, the time of the Tuekta-1 barrow construction is some years older than has been accepted thus far by archaeologists.

The Sun, Climate Change and the Expansion of the Scythian Culture After 850 BC

The climate shift towards wetter conditions at the transition from Subboreal to Subatlantic in NW-Europe (ca 850 cal. yrs BC; caused by a decline of solar activity), is also evident in South Siberia. Areas that initially were hostile semi-deserts changed into attractive steppe landscapes with a high biomass production, and therefore high carrying capacity. We focus on south-central Siberia where an acceleration of cultural development and an increase in the density of nomadic Scythian populations took place shortly after 850 BC. We hypothesize a causal relationship between the Scythian expansion and migration, and the early Subatlantic shift towards increased humidity.

Chronology of key belonging to different stages of the Scythian period in Tuva (Arzhan-1 and Arzhan-2 barrows)

This paper focuses on the chronological study of 2 Scythian period monuments that are the key to the chronology of the entire Eurasian Scythian culture. These are the unique monuments of Arzhan-1 and Arzhan-2 in Central Asia (Tuva Republic). The dating of both these monuments began immediately after their discovery, but discussion about their chronological position is still current. Both monuments contained considerable wooden material from their construction suitable for dendrochronology and radiocarbon dating. The first results for the Arzhan-1 barrow were obtained by wiggle-matching in 20042005, while the Arzhan-2 barrow was first dated in 2003. It is now possible to compare the chronological position of these barrows using the same methods. As postulated earlier, Arzhan-1 is the oldest Scythian period monument and is dated to the boundary of the 89th centuries BC. The position of the Arzhan-2 monument stretches to the middle of the 7th century BC. d13C values for annual tree rings in logs from both barrows were also determined to gain a better understanding of the climatic conditions at the time of barrow construction.

Impact of the geomagnetic field and solar radiation on climate change

Recent studies have shown that, in addition to the role of solar variability, past climate changes may have been connected with variations in the Earth’s magnetic field elements at various timescales. An analysis of variations in geomagnetic field elements, such as field intensity, reversals, and excursions, allowed us to establish a link between climate changes at various timescales over the last millennia. Of particular interest are sharp changes in the geomagnetic field intensity and short reversals of the magnetic poles (excursions). The beginning and termination of the examined geomagnetic excursions can be attributed to periods of climate change. In this study, we analyzed the possible link between short-term geomagnetic variability (jerks) and climate change, as well as the accelerated drift of the north magnetic pole and surface temperature variations.The results do not rule out the possibility that geomagnetic field variations which modulate the cosmic ray flux could have played a major role in climate change in addition to previously induced by solar radiation.

Long-term variations in the flux of cosmogenic isotope 10Be over the last 10000 years: Variations in the geomagnetic field and climate

A spectral analysis of data on the flux of cosmogenic 10Be in ice core samples from the Central Greenland (project GRIP) over the last 10 thousand years have been carried out. It has been shown that the 10Be flux varies cyclically; the most significant cycle is of about 2300 years. Variations in the position of the virtual geomagnetic pole over 8000 years have been analyzed. Significant components, pointing to the cyclic variation in the position of the geomagnetic pole with a period of about 2300 years, have been revealed in a periodogram of the virtual geomagnetic pole longitude. In addition to the nearly 2300-year-long cycle, some lines are observable in the 10Be flux periodogram, which can be considered as a manifestation of the 1000-year-long cycle of the 10Be deposition rate on the ice surface. The relationship between the cyclicity of the geomagnetic pole position and the 10Be flux is discussed.

Comparison of cyclic variations in the flux of the solar wind and the global temperature of the Earth

The Earth’s global temperature is treated as indicator of climate changes. Relatively reliable assessments of temperature variations are obtained on the basis of results from instrumental observations performed only since the middle of the 19th century. It is significant that the temperature series are nonstationary, a consequence of global climate changes. Empirical mode decomposition (EMD) is used for temperature series pretreatment, allowing us to eliminate a long-term component and a linear trend. Along with expansion in the EMD series, analysis of the amplitudes of significance is used to eliminate noise. The resulting refined quasistationary series of data on the Earth’s surface temperature is studied via spectral analysis to identify the cyclic component.

Migration of the Earth’s north magnetic pole, increases in the concentration of CO2, and climate change in the twentieth century

Short-term temperature variations on Earth (∼21 years) are analyzed along with long-term variations (tens of years). The global nature of short-term temperature variations indicates a possible relation between this phenomenon and the modulating effect of the Sun’s activity on cosmic rays. Mechanisms of long-term climate change on Earth (increased concentrations of carbon dioxide in the atmosphere and variation of the planet’s north magnetic pole) are discussed.

The connection between cosmic rays and changes in the geomagnetic field and the Earth’s climate

The possible influence of changes in cosmic ray fluxes on climate variability has been the subject of wide speculation in recent years. New studies show that the interrelation between the parameters of the geomagnetic field and climate can also be followed on time scales of different lengths. We present our analysis of data on cosmic rays and changes in climate and the geomagnetic field obtained from different natural archives.

Dating of the Tashtyk Cultural Remains from the Oglakhty Burial Ground (Southern Siberia)

The present research is focused on the dating of the Oglakhty burial ground, the key site of stage I of the Tashtyk culture. Despite the numerous well-preserved burials of that type investigated at the Oglakhty complexes, their chronological position has remained unclear. From the early 20th century until the present, 2 different time periods had been identified for the Tashtyk burials: (1) from the 1st century BC until the 1st century AD and (2) from the 1st until the 2nd century AD. New data obtained in the 1990s suggested a different age for Tashtyk burials, namely the 3rd-4th centuries AD. This considerable shift in chronology needed to be checked with independent data. The chronological position of one of the Oglakhty burials, tomb 4, has been investigated with the use of wiggle-matching, applied to wooden logs used in the construction of tomb 4. The resulting dates for this burial strongly suggest its age as being limited to the 3rd-4th centuries AD, which is corroborated by the archaeological dates of the imported artifacts found in the grave and which is in agreement with the chronological position of the Oglakhty site, as proposed by previous investigations.