A geothermal method for detecting gas hydrates in the bottom sediments of water basins

We formulate the fundamentals of the geothermal method for determining the hydrate saturation of bottom sediments. According to laboratory experiments (A.A. Trofimuk Institute of Petroleum Geology and Geophysics, A.V. Nikolaev Institute of Inorganic Chemistry), detecting gas hydrates in bottom sediments requires measurement of thermal conductivity at least twice at one bottom site, using a cylindrical probe with different heater power values. Changing the latter permits controlling gas hydrate stability and instability. A low-power probe does not destroy gas hydrates and permits measuring the true thermal conductivity of the sediments. Increasing heater power destroys gas hydrates near the probe and drastically increases effective thermal conductivity. Comparison between true and effective thermal conductivity clearly shows the presence of gas hydrates in the sample or their absence from it. A technique was proposed for the quantitative interpretation of changes in the temperature field of a cylindrical probe. It permits quite a precise determination of the mass of gas hydrate that decomposed in the layer surrounding the probe over a certain period. Also, it permits a rough estimation of the gas hydrate content of the sediments. Thermal conductivity can be measured in the field with submersible multichannel thermoprobes, which are commonly used for studying the heat flow through the bottom of water basins. Now it is important to perform field experiments, so that we gain the necessary experience with the geothermal method.     

Transformations of pollutants in the river water-pore solution-solid phase of the bottom sediments system in small rivers (using the example of waterways in the Losinyi Ostrov (Elk Island) National Park)

The distribution of heavy metals has been examined in water and bottom sediments of small streams within the Losinyi Ostrov (Elk Island) National Park (Moscow) that are undergoing manmade impacts. We demonstrated that pollution caused by motor vehicles causes seasonal changes in the general composition of the river water and pore solutions in bottom sediments. The strongest pollution of water and sediments was found near the CMHW (Circum-Moscow Highway) (Zn, Pb, Cu). This is expressed in the growth of mobile forms of metals in sediments. We have shown, using Zn as an example, the pollution transformation in the snow-river water-suspension-bottom sediment system.     

Early Turonian global warming in the Atlantic and Indian Oceans according to the data of the Foraminifera analysis

In the article, my own data on the species composition of the shells of planktonic Foraminifera (PF) from the Early Turonian sediments of the Atlantic and Indian Ocean and from a number of the cross sections of Australia have been analyzed. In addition, literature materials on the epicontinental basins of the northern hemisphere were also studied. The foraminifera species (PF) are grouped, and four types of thanatocoenoses are distinguished according to their relationship. A climatic zonality map for the early Turonian was constructed on the basis of the spatial distribution of these types. The reconstruction obtained was compared with the climatic maps compiled earlier for the later time intervals of the Late Cretaceous. It was established that the Turonian was characterized by the warmest climate. The tendency for global warming was the most clearly manifested in the Early Turonian.     

Natural stability of vegetation in geosystems of southern Middle Siberia

We consider some theoretical and methodological issues relating to stability assessment of natural development of vegetation in geosystems. We have ascertained the evolutionary-genetic essentials of vegetation stability and presented the cartographic states of its assessment. The stability map for plant communities has been developed on a conjugate scale of predictive-cartographic products.     

Deep Structure and Folded-Block Structure of the Garhwal Himalayas (India): Results of Integrated Geological and Geophysical Study

Geotectonics - The geological and geophysical study of the representative segment of the Alpine-Himalayan mobile belt—the Central zone of the Garhwal Himalaya—was conducted. The results...     

Heat flow in the Altai-Sayan Area: new data

Eleven new estimates of heat flow (q) from the southern Altai-Sayan Folded Area (ASFA) have provided update to the heat flow map of Gorny Altai. Measured heat flow in the area varies from 33 to 90 mW/m², with abnormal values of >70 mW/m^q at four sites. The anomalies may have a deep source only at the Aryskan site in the East Sayan (q = 77 mW/m²) while high heat flows of 75–90 mW/m² obtained for the Mesozoic Belokurikha and Kalguty plutons appear rather to result from high radiogenic heat production in granite, which adds a 25–30 W/m² radiogenic component to a deep component of 50–60 mW/m². The latter value is consistent with heat flow estimates derived from helium isotope ratios (54 mW/m² in both plutons). Heat flow variations at other sites are in the range from 33 to 60 mW/m². The new data support the earlier inferences of a generally low heat flow over most of ASFA (average of 45–50 mW/m²) and of a “cold” Cenozoic orogeny in the area (except for southeastern ASFA), possibly driven by shear stresses associated with India indentation into Eurasia.