Characteristic of quaternary sedimentation on a shelf of the Laptev Sea according to the molecular composition of n-alkanes

The molecular composition and distribution of the concentration of n-alkanes are considered for sediments of boreholes drilled in the shallow part of the Laptev Sea, in the area of Buor Khaya Gulf. The diverse molecular composition of n-alkanes is dominated by long-chain odd homologs, which indicate terrigenous organic matter (OM). Heterogeneous distribution and burial of OM are shown under conditions of pulsating contribution of river and thermoabrasive material and multiple changes in them up to hiatuses in sedimentation.     

A climate shift in seasonal values of meteorological and hydrological parameters for Northeastern Asia

The well-known climate shift that occurred around 1976/1977 in the marine ecosystem of North Pacific Ocean was preceded by changes in the early 1970s over Northeastern Asia. In this paper long-term variability of Siberian High and Aleutian Low parameters, seasonal discharge of Siberian rivers and air temperature and precipitation regime in their watersheds are examined in data sets covering 1945–1995. It was found that the change in seasonal values of Siberian river discharges is a consequence of an atmospheric climatic shift that occurred in the early 1970s over North Asia. This shift was induced by a change in atmospheric circulation pattern in the Eurasian sector and Pacific sector of the Northern Hemisphere after 1970. It resulted in changes in position and intensity of the Siberian High and Aleutian Low before and after the 1970s, which induced a different pattern of precipitation in West and East Siberia. There was an increase in winter precipitation over West Siberia but a decrease over East Siberia. The period after 1970s is characterized by higher amplitude of all parameters and increases in the year-to-year variability.     

Ionic composition of pore water in shallow shelf deposits of the Laptev Sea

The cationic and anionic compositions of pore water in shallow deposits of Buor-Khaya Bay is studied. Significant concentration heterogeneity of the vertical ionic profile in the studied drill columns is shown. It is established that the vertical ionic profile of shelf deposits of the Laptev Sea is basically formed under the influence of thawing of underwater permafrost, hydrodynamic conditions, the water mass, and heat flows and depends on the lithological and granulometric types of the deposits. The highest concentrations of ions are registered in plant detritus represented by ground grass vegetation. A relationship between the ionic composition of pore water and cryogenic state of the sequence and its variability is demonstrated using the method of major components.     

The first ever application of electromagnetic sounding for mapping the submarine permafrost table on the Laptev Sea shelf

The inconsistency between the position of the submarine permafrost table in the East Arctic seas revealed by simulation and anomalies in the distribution of dissolved methane associated with ascending torchlike ejections of bubbling methane made it necessary to develop a representative geophysical express method, which allows the position of the submarine permafrost table to be determined. The method is based on sounding of the generated primary electromagnetic field in the near zone of the medium and measurement of the induced secondary EM field. The reliability of the method is confirmed by core drilling in the Laptev Sea.