Strong Medieval Earthquake in the Northern Issyk-Kul Lake Region (Tien Shan): Results of Paleoseismological and Archeoseismological Studies

A number of archeological monuments in the northern Issyk-Kul Lake region (Tien Shan) in the basins of the Chet-Koysuu and Chon-Koysuu rivers are studied. All monuments have undergone significant seismogenic deformations and destructions. A cromlech (7th century BC to 8th centuries AD) was displaced along the sinistral strike-slip fault. A kurgan (7th–13th centuries AD) was deformed in a front of the reverse fault scarp. A fortress (14th–15th centuries AD) was submerged beneath the lake water during the catastrophic subsidence of the coastal zone. We identify a zone of the seismogenic rupture. It is located along the Kultor border fault, which separates the Issyk-Kul depression and its surrounding mountains (Kungey Ala-Too Range). During the earthquake, the seismogenic reverse fault scarp was formed. A total of 1.6 m was offset along the rupture, which corresponds to an earthquake with М _S ≥ 7 and seismic intensity of I ₀ ≥ IX. Judging by numerous radiocarbon datings of submerged wood, which was used in building the fortress (end of 14th to the beginning of 15th centuries AD), the earthquake occurred in the 16th century AD and could have caused the decline of the Mogul civilization in the northern Issyk-Kul Lake region.     

Middle Triassic age of metarhyolite of the Bondikha Formation,Argun Continental Massif,Central Asian Fold Belt

Research works carried out for the first time made it possible to determine the age of one of the key geological complexes in the Argun Continental Massif (Central Asian Fold Belt). It has been found that the metarhyolite of the Bondikha Formation is not Middle–Late Riphean, as previously thought, but is of Middle Triassic age (242 ± 6 Ma). Based upon the geochemical characteristics of the volcanics and regional geology of the Bondikha Formation, it can be assumed that they formed during one of the stages of subduction processes in the history of the Mongol–Okhotsk Fold Belt.     

Provenance sources of Upper Proterozoic and Lower Paleozoic clastic deposits of the Lesser Khingan terrane,Central Asian fold belt: U–Pb (LA–ICP–MS) geochronological results

Doklady Earth Sciences - The ages of detrital zircons from sandstones and silty sandstones from conditionally Upper Proterozoic–Cambrian rocks have been obtained for the first time. These...     

40Ar/39Ar Age of the Burinda Gold–Silver Deposit and Its Relationship to Magmatism (Northeastern Part of the Argun Superterrane)

Doklady Earth Sciences - Our investigations have made it possible to estimate the age of hydrothermal ore metasomatic rocks at the Burinda Au–Ag deposit, one of the best known in East Asia,...     

Age and Sources of Lower Mesozoic Metasedimentary Rocks of the Un’ya-Bom Terrane in the Mongol–Okhotsk Fold Belt: Results of U–Pb Geochronological (LA-ICP-MS) and Sm–Nd Isotope Studies

Doklady Earth Sciences - The results of U–Th–Pb geochronological study indicate that the youngest peaks on the relative probability curves of the age obtained for the Un’ya-Bom...     

Granitoids of the Pozdnestanovoy Complex of the Dzhugdzhur–Stanovoy Superterrane,Central Asia Fold Belt: Age,Tectonic Setting,and Sources

The geochemistry, geochronology, and isotope geochemical systematics (Nd, Sr, Hf, and Pb) of the granitoids of the Pozdnestanovoy complex of the Dzhugdzhur–Stanovoy superterrane of the Central Asia fold belt were investigated. It was shown that their age is Mesozoic (142–138 Ma) rather than Early Precambrian, as was previously supposed. The main sources of parental melts for these granitoids were the Neoarchean and Paleoproterozoic rocks of the lower continental crust of the Dzhugdzhur–Stanovoy superterrane and the rocks of the Late Paleozoic–Early Mesozoic continental crust of the Amur microplate. They were formed at depths of >40 km and temperatures of 700–800°C, most likely through the melting of mafic feldspar granulites under the conditions of aqueous fluid infiltration without any significant contribution from a juvenile heat source. The granitoids of the Pozdnestanovoy complex were emplaced during the closure of the eastern segment of the Mongolia–Okhotsk Ocean owing to the collision of the Siberian and Sino-Korean continents.     

Spatial and seasonal patterns of European short-snouted seahorse Hippocampus hippocampus distribution in island coastal environments

This study represents the first report on seahorses in the Macaronesian islands (North-East Atlantic), determining the spatial and seasonal abundance, population structure and physical appearance of European short-snouted seahorse Hippocampus hippocampus. Animals were surveyed off Gran Canaria Island in two bays, Melenara and Sardina del Norte, within three habitats: rocky bottom, artificial substrata and seagrass. Populations were monitored over a 5-year period (spring 2006–winter 2011) using 15-minute visual fast count (VFC) surveys. Seahorses were characterised by low abundances, small proportions of subadults and roughly equal sex ratios at each site. We aimed to determine whether environmental conditions and geographical position could explain differences in seahorse abundance and population structure between the study sites. Melenara Bay (mean sighting rate = 0.44 individuals VFC–¹; SD 0.72) offered protected environments where seahorse distribution varied with substratum type, irrespective of season. Strong hydrodynamic forces in winter affected abundance and size at exposed locations in Sardina del Norte Bay (mean sighting rate=0.21 individuals VFC^?1; SD 0.52). Our findings contribute to the scarce available knowledge about this Data Deficient species (IUCN Red List), helping to establish future conservation strategies and management recommendations for the preservation of H. hippocampus populations around Gran Canaria Island and other localities with similar coastal environments.