Lupinaster pentaphyllus and related species (Fabaceae)

The taxonomic analysis of Lupinaser pentaphyllus s. l. (Trifolium lupinaster s. l.) group is considered; typification for some taxa is proposed. The new species Lupinaster uralense and L. tundricum are described. The new combination Lupinaster angustifolius is given. An identification key for species of Lupinaser pentaphyllus s. l. group and maps of distribution some of them: Lupinaser spryginii, L. uralense, L. tundricum (northern part of the area), L. pentaphyllus s. str. (western flank of the area) are presented.

Deformation of the western flank of the Andes at ~20–22°S: a contribution to the quantification of crustal shortening

<p>The Andes are the case example of an active Cordilleran-type orogen. It is generally admitted that, in the Bolivian Orocline (Central Andes at ~20°S), mountain-building started ~50–60 Myr ago, close to the subduction margin, and then propagated eastward. Though suggested by some early geological cross-sections, the structures sustaining the uplift of the western flank of the Altiplano have often been dismissed, and the most common view theorizes that the Andes grow only by east-vergent deformation along its eastern margin. However, recent studies emphasize the significant contribution of the West Andean front to mountain-building and crustal thickening, in particular at the latitude of Santiago de Chile (~33.5°S), and question the contribution of similar structures elsewhere along the Andes.  Here, we focus on the western margin of the Altiplano at 20–22°S, in the Atacama desert of northern Chile. We present our results on the structure and kinematic evolution on two sites where the structures are well exposed. We combine mapping from high-resolution satellite images with field observations and numerical trishear forward modeling to provide quantitative constraints on the kinematic evolution of the western front of the Andes. Our results confirm two main structures: (1) a major west-vergent thrust placing Andean Paleozoic basement over Mesozoic strata, and (2) a west-vergent fold-and-thrust-belt deforming primarily Mesozoic units. Once restored, we estimate that both structures accommodate together at least ~6–9 km of shortening across the sole ~7–17 km-wide outcropping fold-and-thrust-belt. Further west, structures of this fold-and-thrust-belt are unconformably buried under much less deformed Cenozoic units, as revealed from seismic profiles. By comparing the scale of these buried structures to those investigated previously, we propose that the whole fold-and-thrust-belt has most probably absorbed at least ~15–20 km of shortening. The timing of the recorded main deformation can be bracketed sometime between ~68 and ~29 Ma – and possibly between ~68 and ~44 Ma – from dated deformed geological layers, with a subsequent significant slowing-down of shortening rates. This is in good agreement with preliminary modeling of apatite and zircon (U-Th)/He dates suggesting that basement exhumation by thrusting started by ~70–60 Ma, slowed down by ~50–40 Ma, and tended to cease by ~30–20 Ma. Minor shortening affecting the mid-late Cenozoic deposits indicates that deformation continued after ~29 Ma along the western Andean fold-and-thrust-belt, but remained limited compared to the more intense deformation that occured during the Paleogene. Altogether, the data presented here will provide a quantitative evaluation of the contribution of the western margin of the Altiplano plateau to mountain-building at this latitude, in particular at its earliest stages.</p>

Draft Genome Sequences of Idiomarina abyssalis Strain KJE, Marinobacter salarius Strain NP2017, and Marinobacter salarius Strain AT3901, Isolated from Deep-Sea Sediment near the Western Flank of the Mid-Atlantic Ridge

ABSTRACT We report the draft genomes of environmental cultures collected from shallow sediment from the western flank of the Mid-Atlantic Ridge. The isolates were most closely related to Idiomarina abyssalis strain KJE (100% complete), Marinobacter salarius strain NP2017 (97.6% complete), and Marinobacter salarius strain AT3901 (98.4% complete). Isolates identified as an Idiomarina species possess complete nitrite oxidation and reduction pathways, and isolates identified as a Marinobacter species possess complete dissimilatory nitrate reduction pathways.

STRONG SEISMIC EVENTS on the SOUTH-WESTERN FLANK of the BAIKAL RIFT in 2014: November 1, 2014, Кp=13.6, Mw=4.6, I0=7–8 URIK EARTHQUAKE and December 5, 2014, Кp=13.9, Mw=4.9, I0=7–8 HOVSGOL EARTHQUAKE

We consider two earthquakes occurred at the south-western flank of the Baikal rift zone (BRZ): Urik, November 1, 2014 (Mwreg=4.6) and Hovsgol, December 5, 2014 (Mwreg=4.9). First of them is localized within the area of the Main Sayan fault, the second one is located at the north of the Hovsgol Lake. Seismic moment tensors (focal mechanisms, scalar seismic moments, moment magnitudes and hypocentral depths) of the study seismic events were calculated based on surface wave amplitude spectra. Earthquake hypocenters were found to be situated in the middle crust (h=14–21 km). Both events occurred under the strike-slip stress-strain field. The strike-slip was combined with a normal fault component in the source of the Urik earthquake and with a thrust fault component in the source of the Hovsgol earthquake. In both cases, shaking intensity in the nearest settlements (=42–124 km) was less than 4–5. Analysis of historical seismicity, seismological data on the Urik and Hovsgol earthquakes and the tectonic position of their sources demonstrates that the considered events are typical for the south-western flank of the BRZ and confirms the existence of the transition zone from rift structures at the central parts of the BRZ to regional compression structures in Northern Mongolia.

Sukhoy log gold deposit and possible prospecting for ores on its flanks

Background. Experimental exploitation of ores from the Sukhoi Log deposit has shown that its geology and structure requires elucidation.Aim. To study the geology and structure of the Sukhoi Log deposit and to determine the main mineralisation patterns in the plan, on the flanks and at depth. This information can be useful when mining gold both directly at the deposit and when prospecting new deposits on its flanks.Materials and methods. The existing maps, diagrams, sketches and block diagrams describing ore bodies and their behaviour in plan and at depth were used. A new structural layout of mineralisation at the Sukhoi Log deposit, both on its flanks and at depth was built.Results. The gold mineralisation in the Sukholozhskaya and Verninsko-Nevskaya ore-bearing areas is controlled by various elements of the fracture structure. At the same time, in the Sukholozhskaya area, the mineralisation is confined to a thick zone of a sublatitudinal shingled thrust-fault zone, in places accommodating a narrow strip of small faults, slip planes and fracturing in the northwestern direction. The fracture strip intersects sub-latitudinally laying Riphean argillaceous-shale rocks of the Khomolkhin formation approximately in the middle part of the field. The shingled thrust-fault zone accommodates the fissure faults, which open during mineralisation of the north-west extension, and flattens out. Its thickness in some places reaches 130 m. In the curved and flattened thrust interval, an ore gold-arsenopyrite-pyrite-quartz formation is localised, morphologically resembling a “thick pillow” with a thickness of 130 m. It bends and gently plunges in the north-north-east direction. The bulk of gold reserves is contained in this ore formation. The ores of the vein-disseminated type, veinlet and vein formations are the richest formations. Between them, the dissemination of gold-bearing pyrite and subordinate arsenopyrite is always manifested. The boundary of industrial mineralisation is determined by the density of the interveinous ore.On the western flank of the deposit, within the bounds of another — Ugakhan — deposit, vein and vein gold-quartz-pyrrhotite ores are found at a deeper level. Here, the search for Sukholozhsky pyrite-quartz ores (if they even existed) is not promising, since they were eroded long time ago, and the liberated gold was concentrated in placers. Prospecting is promising only along the Bezymyanny ore-controlling fault, which directly limits the western flank of the Sukholozhskoye deposit.The mineralisation of the Verninsk-Nevsky area is controlled by the Verninsky Fault of the east–north-east extension and separated by a series of single feathering ore-bearing overthrust zones of the east-west extension. To the east, this mineralisation gradually decreases. The search for the Sukholozhsk type ores is more promising on the eastern side of the Nyrli river, 2 km east of the fault of the same name and 7 km north of the Verninskoye deposit near a small, poorly explored area with commercial gold mineralization, marked on the deposit map with a sign TM.Conclusion. The main geological and structural laws of the localisation of gold ores were determined, which could be useful when conducting exploration works on the flanks of the deposit.