Determination of the regional deformation rates of Shanghai and Kashima VLBI stations based on ITRF97

The vertical deformation rates (VDRs) and horizontal deformation rates (HDRs) of Shanghai VLBI station in China and Kashima and Kashima34 VLBI stations in Japan were re-analysed using the baseline length change rates from Shanghai to 13 global VLBI stations, and from Kashima to 27 stations and from Kashima34 to 12 stations, based on the NASA VLBI global solution glb1123 (Ma, 1999). The velocity vectors of the global VLBI stations were referred to the ITRF97 reference frame, and the Eulerian vectors of different models of plate motion were used for comparative solutions. The VDR of Shanghai station is estimated to be −1.91±0.56 mm/yr, and those of Kashima and Kashima34 stations, −3.72±0.74mm/yr and −8.81±0.84mm/yr, respectively. The difference between the last two was verified by further analysis. Similar estimates were also made for the Kokee, Kauai and MK_VLBA VLBI stations in mid-Pacific.     

A spectroscopic study of the peculiar galaxy UGC 5600

We present our observations of the galaxy UGS 5600 with a long-slit spectrograph (UAGS) and a multipupil field spectrograph (MPFS) attached to the 6-m Special Astrophysical Observatory telescope. Radial-velocity fields of the stellar and gaseous components were constructed for the central region and inner ring of the galaxy. We proved the existence of two nearly orthogonal kinematic subsystems and conclude that UGC 5600 is a galaxy with an inner polar ring. In the circumnuclear region, we detected noncircular stellar motions and suspected the existence of a minibar. The emission lines are shown to originate in H II regions. We estimated the metallicity from the intensity ratio of the [N II]λ6583 and Hα lines to be nearly solar, which rules out the possibility that the polar ring was produced by the accretion of gas from a dwarf companion.     

Planar deformation features and impact glass in inclusions from the Vredefort Granophyre,South Africa

Abstract— The Vredefort Granophyre represents impact melt that was injected downward into fractures in the floor of the Vredefort impact structure, South Africa. This unit contains inclusions of country rock that were derived from different locations within the impact structure and are predominantly composed of quartzite, feldspathic quartzite, arkose, and granitic material with minor proportions of shale and epidiorite. Two of the least recrystallized inclusions contain quartz with single or multiple sets of planar deformation features. Quartz grains in other inclusions display a vermicular texture, which is reminiscent of checkerboard feldspar. Feldspars range from large, twinned crystals in some inclusions to fine‐grained aggregates that apparently are the product of decomposition of larger primary crystals. In rare inclusions, a mafic mineral, probably biotite or amphibole, has been transformed to very fine‐grained aggregates of secondary phases that include small euhedral crystals of Fe‐rich spinel. These data indicate that inclusions within the Vredefort Granophyre were exposed to shock pressures ranging from <5 to 8–30 GPa. Many of these inclusions contain small, rounded melt pockets composed of a groundmass of devitrified or metamorphosed glass containing microlites of a variety of minerals, including K‐feldspar, quartz, augite, low‐Ca pyroxene, and magnetite. The composition of this devitrified glass varies from inclusion to inclusion, but is generally consistent with a mixture of quartz and feldspar with minor proportions of mafic minerals. In the case of granitoid inclusions, melt pockets commonly occur at the boundaries between feldspar and quartz grains. In metasedimentary inclusions, some of these melt pockets contain remnants of partially melted feldspar grains. These melt pockets may have formed by eutectic melting caused by inclusion of these fragments in the hot (650 to 1610 °C) impact melt that crystallized to form the Vredefort Granophyre.     

Subglacial and subaqueous processes near a glacier grounding line: sedimentological evidence from a former ice-dammed lake, Achnasheen Scotland

Subglacial and subaqueous sediments deposited near the margin of a Late-glacial ice-dammed lake near Achnasheen, northern Scotland, are described and interpreted. The subglacial sediments consist of deformation tills and glacitectonites derived from pre-existing glaciolacustrine deposits, and the subaqueous sediments consist of ice-proximal outwash and sediment flow deposits, and distal turbidites. Sediment was delivered from the glacier to the lake by two main processes: (1) subglacial till deformation, which fed debris flows at the grounding line; and (2) meltwater transport, which fed sediment-gravity flows on prograding outwash fans. Beyond the ice-marginal environment, deposition was from turbidity currents, ice-rafting and settling of suspended sediments. The exposures support the conclusion that the presence of a subglacial deforming layer can exert an important influence on sedimentation at the grounding lines of calving glaciers.     

Stochastic modelling of groundwater flow and solute transport in aquifers

This paper presents an introductory overview of recently developed stochastic theories for tackling spatial variability problems in predicting groundwater flow and solute transport. Advantages and limitations of the theories are discussed. Lastly, strategies based on the stochastic approaches to predict solute transport in aquifers are recommended.