The New Massadou Diamondiferous Kimberlite Field in Guinea

Geology of Ore Deposits - A new Massadou kimberlite field, was discovered in southeastern Guinea, near the town of Macenta. It consists of 16 poorly diamondiferous kimberlite dikes, ~1 m thick on...     

Estimation of vegetation structure and its anthropogenic transformation by processing QuickBird images: A case study of the Novosibirsk Akademgorodok

A new method for forest mapping utilizing high-resolution satellite images has been developed by a case study of the Novosibirsk Akademgorodok. Guided classifications of summer and fall QuickBird images, overlay operations, and grid density analysis form the background for this method. This method was used to construct maps of forest density and quantitative ratios of softwood to hardwood tree species. A comparison with the traditional geobotanical mapping has demonstrated several advantages of the remote sensing approach (including the precise definition of boundaries as well as high accuracy of estimation of the canopy density and the ratio of soft- to hardwood tree species) and shortcomings. The proposed method is not intended to replace but rather supplement and quantitatively improve the traditional approach. Matching the integral forest map and the corresponding geological-geomorphological map makes it possible to reveal the correlations between specific geomorphological features of the area, the composition of surface deposits, and the forest stand structure and thus estimate the degree of anthropogenic transformation in the natural forest ecosystems. In turn, this may be useful when organizing ecosystem monitoring.     

Unknown large ancient earthquakes along the Kurai fault zone (Gorny Altai): new results of palaeoseismological and archaeoseismological studies

Palaeoseismological and archaeoseismological studies in the Kurai fault zone, along which the Kurai Range is thrust onto Cenozoic deposits of the Chuya intramontane basin, led to the identification of a long reverse fault scarp 8.0 m high. The scarp segments are primary seismic deformations of large ancient earthquakes. The scarp’s morphology, results of trenching investigations, and deformations of Neogene deposits indicate a thrusting of the piedmont plain onto the Kurai Range, which is unique for the Gorny Altai. Similarly for Northern Tien Shan, we explain this by the formation of both a thrust transporting the mountain range onto the depression and a branching thrust dislocation that forms the detected fault scarp. In a trench made in one of the scarp segments, we identified the parameters of the seismogenic fault – a thrust with a 30° dipping plane. The reconstructed displacement along the fault plane is 4.8 m and the vertical displacement is 2.4 m, which indicates a 7.2–7.6 magnitude of the ancient earthquake. The ¹⁴C age of the humus-rich loamy sand from the lower part of the colluvial wedge constrains the age of the earthquake at 3403–3059 years BP. Younger than 2500 years seismogenic displacements along the fault scarp are indicated by deformations of cairn structures of the Turalu–Dzhyurt-III burial mound, which was previously dated as iron age between the second half of I BC and I AD.     

Seismites in Quaternary sediments of southeastern Altai

We study earthquake-induced soft-sediment deformation (seismites) in reference Quaternary sections of southeastern Altai. Sediments in the sections bear signature of liquefaction and fluidization and deformation is localized in thin (few centimeters to 0.5–1.0 m) continuously striking and frequently repeated layers sandwiched between undeformed sediments. The soft-sediment deformation records coseismic motion of different slip geometries. Seismic origin is also inferred for layers and lenses of coarse colluvium slid into the lake bottom from the slopes, which intrude plane-bedded silt and sand and vary in thickness from a few centimeters to one meter. The occurrence of seismic soft-sediment deformation at different stratigraphic levels of the Quaternary and in the Upper Pliocene Beken Formation confirms the high seismicity of southeastern Altai in Quaternary time.     

Age of the Chibit Glaciation in Gornyi Altai

Doklady Earth Sciences - New results of Optically-Stimulated Luminescence (OSL) dating that make it possible to clarify the age of the Chibitskii glaciation in the Altai Mountains are reported....     

Traces of paleoearthquakes in the Quaternary deposits of intermontane basins in central Gorny Altai

Study of the sections of Neopleistocene–Holocene deposits filling the basins in central Gorny Altai has revealed earthquake-induced soft-sediment deformation (seismites). They formed as a result of the brittle deformation of deposits and liquefaction of loose water-saturated sediments under vibration seismic impact. The paleoearthquakes resulting in such seismites had the minimum intensity I = 6 and magnitude M = 5–6. Hence, the study region underwent strong earthquakes in the Neopleistocene–Holocene.     

Detailed Geological Mapping of the Olon-Ovoot Gold Ore Cluster (Southern Mongolia) Based on the Interpretation of Satellite Images of Medium and High Spatial Resolution

Izvestiya, Atmospheric and Oceanic Physics - This article presents the results of an interpretation of the territory of the Olon-Ovoot ore cluster using medium and high spatial resolution satellite...     

Age of Glacial and Fluvioglacial Deposits of the Chibit Glaciocomplex in Gornyi Altai

Doklady Earth Sciences - The aerial stratotype of the Chibit Glaciation in a stratigraphic chart of Quaternary deposits of the Altai–Sayan Mountains, which corresponds to the Last Glacial...