Late Quaternary marine terraces in the Mediterranean coastal area of Syria: Geochronology and neotectonics

In order to provide new data on the neotectonics and geodynamic properties of western Syria, studies of marine terraces have been carried out. The most attention was paid to the lower terraces in the range of 3–5 to 30–35 m above sea level, because they have more complete distributions along the shore. The lower terraces were examined along the coastal area from Tartus to Latakia, and along the carbonate cliff on Arwad Island. Seven ²³⁰Th/U dates for these terraces are in the range of 85–130 ka, suggesting the age interval of the last interglacial (MIS 5). New dates on the lower terraces provide a basis for stratigraphical and geomorphological interpretation as well as neotectonic reconstruction. According to the geomorphological data and lithological composition of those terraces, two main uplifted blocks can be established. One coincides with the Latakia block, and another corresponds to the western margin of the Banias volcanic plateau. These blocks are divided by a subsided structure corresponding to the Nahr el Kebir graben. The amplitude of neotectonic uplifting in the Latakia and Banias blocks reaches 15–20 m for the Late Pleistocene.     

Peculiarities of the primary production process in the Kara Sea at the end of the vegetation season

Research was implemented from September 15 through October 4, 2011 in the Kara Sea along transects located southeastwards Novaya Zemlya, in the St. Anna Trough, the Yenisei River estuary, and the adjacent shelf. The concentration of chlorophyll a was the highest in the photic zone (0.05–2.30 mg/m³, on average, 0.80 ± 0.37 mg/m³). The maximal concentration of Chl a at most of the stations located in the water layer of 7–30 m. Integral primary production in the water column varied from 3.0 to 151.0 mg C/m² per day, on average, 37.2 ± 36.6 mg C/m² per day. The maximal rate of primary production at most of the stations has been observed for the surface layer of the water column. Within the upper mixed water layer, relative primary production was from 31 to 100% (on average, 77 ± 20%). The most productive zone was the waters along Yenisei transect. In the estuary and at the adjacent shelf, primary production was 50 mg C/m² per day, exceeding the range observed for other areas by 1.5–2.0 times. The concentrations of silica and nitrogen together with light regime and water temperature were the major limiting factors affecting the primary production rate in the Kara Sea in autumn.     

Portlandia-dominated Communities in the Arctic: Taxonomic Composition and Structure along the Geographical Gradient

Doklady Earth Sciences - The species composition and structure of bottom communities with a predominance of bivalve mollusks of the Portlandia genus, which are widespread on the shelf of the...     

Quaternary tectonics of recent basins in northwestern Armenia

New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350–500 m in basins and 600–800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene (~1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.     

The first discovery of natural duralumin

The results of X-ray structural, electron-microscopic, and X-ray spectral microprobe studies of Al-based metal solid solutions that underwent nuclear disintegration and that were discovered in nature for the first time are presented. Based on the similarity to technical counterparts, it is suggested to recognize the previously unknown alloys as natural duralumin.     

Environments of the Russian Plain during the Middle Valdai Briansk Interstade (33,000–24,000 yr B.P.) Indicated by Fossil Mammals and Plants

Abundant mammal (45 localities) and plant (52 sections) fossil data collected from the Russian Plain deposits of the Middle Valdai Briansk Interstade indicate a period of noticeable warming. These materials were jointly analyzed. The data were organized in the database software PARADOX and then moved to the GIS program ARC/INFO. Mathematical methods as well as traditional research methods were used for the analysis. The reconstructed biogeographical provinces illustrate the specific environmental and climatic conditions of the Briansk Interstade. Analogues of modern natural zones did not exist at this time on the Russian Plain. The Briansk landscapes reflect the moderate-cool climate of this period, when the majority of northern subarctic plant and mammal species extended their ranges considerably to the south to the Central Russian Plain. At the same time, steppe species penetrated farther north and west. This combination shows that the continuous forest zone was destroyed during the Briansk Inter-stade. Five biogeographical provinces have been reconstructed from the north to the south for the Russian Plain during the Briansk warming on the basis of joint analysis of mammalian and botanical data.     

Paleogene-Neogene sediments of Bel’kov Island (New Siberian Islands): Characteristics of sedimentary cover in the eastern Laptev shelf

This work is aimed at characterizing the 40-m-thick Paleogene-Neogene sedimentary sequence of Bel’kov Island, which was accumulated in the marginal part of a fluvial plain. On the basis of the plant megafossils and spore-pollen data, the studied sediments were formed in the Late Eocene-Early Miocene with a probable sedimentation gap at the Eocene-Oligocene boundary. It was substantiated that the Paleogene-Neogene sediments were developed as a continuous cover over the entire area of Bel’kov Island. Later, they were eroded away from the island, but presumably preserved on the Bel’kov Horst and Zarya Strait. This suggests that the pre-Quaternary seismic complex, which continuously covers the Bel’kov Horst, also has Late Eocene-Early Miocene age. Selective dating of nonrounded detrital zircons from Lower Miocene conglomerates allowed us to substantiate the transportation of sediments from the Verkhoyansk-Kolyma Fold System along the Bel’kov-Svyatoi Nos Graben. The crystalline basement similar to the Ust’-Lena inlier was likely exposed on the East Laptev Horst and served as the source of metamorphic detritus, including zircons dated within 1850–2000 Ma.     

Depth-integrated and depth-resolved models of Kara Sea primary production

Primary production (PP) models of the Kara Sea are developed based on data collected on fall expeditions (September–October 1993, 2007, and 2011) and their precision assessment utilizes the dataset collected in September 2013. The algorithms for different model types (depth-integrated and depth-resolved) are compared. The depth-resolved model performs slightly better than the depth-integrated one (the rootmean- square-difference (RMSD) are 0.29 and 0.31, respectively). These algorithms utilize the daily assimilation number (DAN) and photosynthetic efficiency (ψ) as the model coefficients, and surface chlorophyll a (chl a) and photosynthetically active radiation (PAR) as input variables. These algorithms perform better than the models that use chl a alone. Our results suggest that an increase in the performance of the Kara Sea PP models depends on the input of the photophysiological characteristics of phytoplankton (DAN and ψ) and PAR. To a lesser extent, this concerns the advantages of the depth-resolved model over the depth-integrated one. The constructed region-specific Kara Sea PP models combined with satellite-derived chl a and PAR can be used to estimate annual values and long-term variation of PP in hydrologically and hydrochemically similar waters of the Arctic Ocean.