The minerals potential of Nepal

Historically, Nepal has relied on its agricultural sector to sustain economic development. However, given rapid population growth, the nation may find it necessary to develop its mineral base in order to promote economic growth and stability. This paper presents a mineral resource assessment of Nepal and its five development regions, primarily to make an estimate based on geology of the range of minerals that may exist in Nepal. Resource estimates for each development region were obtained by way of geologic comparisons with the 50 US states. It is concluded that Nepal may be well-endowed in non-fuel and energy minerals.     

The development of India's mining industry

This paper evaluates the development of India's mining industry, its present status and future outlook. Despite its growth, the contribution of India's mining industry to GDP has remained relatively stable since 1970. At present the nation is a leading world producer of 11 major mineral and energy commodities, including bauxite, chromite, coal, iron ore and manganese. Recent economic reforms have stimulated industrial expansion in India; however, problems, including a restricted private sector role in resource development and ineffective government mineral strategies, may limit future growth in output. Capital investment levels in India's mining industry are examined in the paper to assess possible long-term expansion levels.     

Field measurements of shear strength of an underconsolidated marine clay

This paper presents the observations of cone penetration testing (CPT), in situ vane shear testing and undrained triaxial testing of underconsolidated marine clay in the Craney Island Dredged Material Management Area (CIDMMA), Norfolk, VA. Comparison of vane shear measurements, taken during 1981–1983, to CPT measurements, taken during 1993, indicates a change in undrained shear strength. Both the vane shear and cone penetration resistances are lowest at the mid-heights of the clay layers and the excess pore water pressures are highest at the mid-height of the clay layers, indicating that the clay layer is underconsolidated.     

A contribution to Pleistocene chronology in southeast Essex,England

Parallel to the Essex coast north of the mouth of the Thames, a series of gravel spreads ranging in altitude from near sea level westward to more than 200 ft O.D. (mean sea level) proved to be the remnants of an abandoned Thames/Medway terrace system, rather than a series of “raised” beaches, as their location had suggested. The seaward side of the ancient river valley has subsequently been “captured” by subsidence.Evidence is given for five terraces, with surface levels between 5 and 75 ft O.D. Because of subsidence of the Essex coast, the terrace levels are not easily correlatable with either the Thames or Medway terrace levels. Temporal placement is attempted on the basis of one site in the 25 ft Barling terrace, which yielded a Middle Acheulian archaeological assemblage associated with a cool temperate fauna including an early form of mammoth. An ice wedge cast in the Barling terrace was filled with floodloam which weathered to a parabraunerde soil during an interglacial climate warmer than now. For these reasons man is thought to have lived on the floodplain of the Barling terrace either at the onset of the Wolstonian (Riss) glacial or during an interstadial of that stage. The question of possible linkages between Swanscombe and Clacton terraces is discussed.     

New insights into volcanic processes from deep mining of the southern diatreme within the Argyle lamproite pipe,Western Australia

Underground mining and deep drilling of the richly diamondiferous ~1.2 Ga Argyle lamproite in Western Australia has prompted a re-evaluation of the geology of the pipe. Argyle is considered to be a composite pipe that formed by the coalescence of several diatremes and has been offset and elongated by post-emplacement faulting. Recent geological studies have recognised at least five distinct volcaniclastic lamproite lithofacies with differing diamond grades. The new data suggest that the centre of the southern (main) diatreme is occupied by well-bedded, olivine lamproite lapilli tuff with very high diamond grades (>10 ct/t). Characteristic features include a clast-supported fabric and high modal abundance of densely packed lamproite lapilli and coarse-grained, likely mantle-derived olivine now replaced by serpentine and/or talc. The persistence of small-scale graded and cross-bedding in this lithofacies to depths of ~1.5 km below the original surface prior to erosion suggests phreatomagmatic volcanism forming the diatreme was syn-eruptively accompanied by subsidence of the tephra, maintaining a steep-walled diatreme in the water-saturated country rock sediments.

     

Climatic and environmental variability during the termination of the Last Glacial Stage in coastal eastern Australia: a review

By comparison with the Northern Hemisphere, there is a paucity of high-resolution, continuous records extending into the Last Glacial Maximum from the Southern Hemisphere. With specific reference to coastal eastern Australia, there are long records of paleoclimatic and paleoenvironmental variability available from the tropical north and temperate south. However, there are significant spatial gaps between such records: in particular, until relatively recently, little attention had been paid to the subtropics. This review paper summarises understanding of regional paleoenvironmental and paleoclimatic variability in coastal eastern Australia during the termination of the Last Glacial Stage, with the aim of highlighting gaps in the current state of knowledge. Recommendations for future research are prioritised to answer knowledge gaps in understanding climate variability in eastern Australia between ca 33–18 kyr BP.     

Stellar Dynamo Waves: Asymptotic Configurations

We investigate the parameter space of a Parker dynamo with a simple alpha quenching nonlinearity, taking as governing parameters the dynamo number D (D<0) and the ratio of diffusion times in the radial and latitudinal directions in the convective zone. The latter parameter, μ, is connected with the aspect ratio (dimensionless thickness) of the convective zone. We isolate two asymptotic configuration of the dynamo waves excited by the Parker dynamo in the limiting case of strong generation. Apart from the standard case with the solar type dynamo wave travelling from mid-latitudes to the equator, we describe a form of dynamo activity which is basically an anharmonic standing wave. The first situation occurs when μ increases with |D|. With μ fixed and |D| increasing, the second asymptotic configuration occurs. We discuss possibilities of identifying these asymptotic configurations with various types of stellar activity as traced by stellar CaII data.     

Long‐term Holocene groundwater fluctuations in a chalk catchment: evidence from Rock‐Eval pyrolysis of riparian peats

The depositional history of peat‐dominated wetlands can be used to understand palaeoclimate and palaeohydrology and also constrain the impacts of future climate change. However, in chalkland valleys, seasonal water table fluctuations and a high alkalinity have diminished key environment indicators such as pollen, and there is a need for alternative investigative techniques. The method of Rock‐Eval pyrolysis can track changes in organic matter source and degradation, potentially relating to historic changes in vegetation cover. This is the first Rock‐Eval on cores from a groundwater‐dependent riparian chalk valley wetland combined with radiocarbon dating. The dating showed that the cores represented approximately 4000 years of depositional history. Changes in hydrocarbon chemistry including normal alkane composition of the peat indicated shifts of around 500 to 1000 years between terrestrial and more aquatic species, relating to periods of climate wetness. These climatic shifts are broadly consistent with other evidence from ombrotrophic peatland and lacustrine sediments across northwest Europe. However, the connection between climate wetness and groundwater dependent chalkland wetlands is complicated by external anthropogenically driven factors relating to land use and vegetation cover changes in the catchment. Nonetheless, this study suggests that Rock‐Eval pyrolysis is a useful and cost‐effective tool that can provide evidence for long‐term Holocene groundwater fluctuations. Copyright © 2016 British Geological Survey.     

The α-β phase transition in AlPO4 cristobalite: Symmetry analysis,domain structure and transition dynamics

Despite their crystallographic differences, the mechanisms of the α-β phase transitions in the cristobalite phases of SiO₂ and AlPO₄ are very similar. The β→α transition in AlPO₄ cristobalite is from cubic ( $\left( {F\bar 43m} \right)$ ) to orthorhombic (C222₁), whereas that in SiO₂ cristobalite is from cubic ( $\left( {Fd\bar 3m} \right)$ ) to tetragonal (P4₃2₁2 or P4₁2₁2). These crystallographic differences stem from the fact that there are two distinct cation positions in AlPO₄ cristobalite as opposed to one in SiO₂ cristobalite and the ordered (Al,P) distribution is retained through the phase transition. As a result, there are significant differences in their crystal structures, domain configurations resulting from the phase transition and Landau free energy expressions. A symmetry analysis of the “improper ferroelastic” transition from $F\bar 43m \to C222_1$ in AlPO₄ cristobalite has been carried out based on the Landau formalism and the projection operator methods. The six-component order parameter, η driving the phase transition transforms as the X₅ representation of $F\bar 43m$ and corresponds to the simultaneous translation and rotation of the [AlO₄] and [PO₄] tetrahedra coupled along 110. The Landau free energy expression contains a third order invariant, the minimization of which requires a first-order transition, consistent with experimental results. The tetrahedral configurations of twelve α phase domains resulting from the β→α transition in AlPO₄ cristobalite are of two types: (1) transformation twins from a loss of the 3-fold axis, and (2) antiphase domains from the loss of the translation vectors 1/2[101] and 1/2[011] (F→C). In contrast to α-SiO₂ cristobalite, the α-AlPO₄ cristobalite (C222₁) does not have chiral elements (4₃, 4₁) and hence, enantiomorphous domains are absent. These transformation domains are essentially macroscopic and static in the α phase and microscopic and dynamic in the β phase. The order parameter, η couples with the strain components, which initiates the structural fluctuations causing the domain configurations to dynamically interchange in the β phase. An analysis of the MAS NMR data (²⁹Si, ¹⁷O, ²⁷Al) on the α α-β transitions in SiO₂ and AlPO₄ cristobalites (Spearing et al. 1992, Phillips et al. 1993) essentially confirms the dynamical model proposed earlier for SiO₂ cristobalite (Hatch and Ghose 1991) and yields a detailed picture of the transition dynamics. In both cases, small atomic clusters with the configuration of the low temperature α phase persist considerably above the transition temperature, T₀. The NMR data on the β phases above T₀ cannot be explained by a softening of the tetrahedral rotational and translational modes alone, but require the onset of an order-disorder mechanism resulting in a dynamic averaging due to rapidly changing domain configurations considerably below T₀.