Geological interpretation of a deep seismic‐reflection transect across the boundary between the Delamerian and Lachlan Orogens,in the vicinity of the Grampians,western Victoria

A deep seismic‐reflection transect in western Victoria was designed to provide insights into the structural relationship between the Lachlan and the Delamerian Orogens. Three seismic lines were acquired to provide images of the subsurface from west of the Grampians Range to east of the Stawell‐Ararat Fault Zone. The boundary between the Delamerian and Lachlan Orogens is now generally considered to be the Moyston Fault. In the vicinity of the seismic survey, this fault is intruded by a near‐surface granite, but at depth the fault dips to the east, confirming recent field mapping. East of the Moyston Fault, the uppermost crust is very weakly reflective, consisting of short, non‐continuous, west‐dipping reflections. These weak reflections represent rocks of the Lachlan Orogen and are typical of the reflective character seen on other seismic images from elsewhere in the Lachlan Orogen. Within the Lachlan Orogen, the Pleasant Creek Fault is also east dipping and approximately parallel to the Moyston Fault in the plane of the seismic section. Rocks of the Delamerian Orogen in the vicinity of the seismic line occur below surficial cover to the west of the Moyston Fault. Generally, the upper crust is only weakly reflective, but subhorizontal reflections at shallow depths (up to 3 km) represent the Grampians Group. The Escondida Fault appears to stop below the Grampians Group, and has an apparent gentle dip to the east. Farther east, the Golton and Mehuse Faults are also east dipping. The middle to lower crust below the Delamerian Orogen is strongly reflective, with several major antiformal structures in the middle crust. The Moho is a slightly undulating horizon at the base of the highly reflective middle to lower crust at 11–12 s TWT (approximately 35 km depth). Tectonically, the western margin of the Lachlan Orogen has been thrust over the Delamerian Orogen for a distance of at least 25 km, and possibly over 40 km.     

Some thermodynamical and microphysical aspects of monsoon clouds

The thermodynamical and microphysical characteristics of monsoon clouds in the Poona, Bombay and Rihand regions were investigated using extensive aircraft in-cloud observations. The number of clouds sampled at Poona, Bombay and Rihand is 2199, 169 and 104 respectively. The temperatures inside the cloud are colder than its environment at Poona and Rihand. The maximum difference is about 3°C at the cloud base level and the difference decreased with height. At Bombay the difference is less than 1°C and at some levels the temperatures inside the cloud are warmer than its environment. The lapse rates of temperatures inside the cloud are slightly less than those in the immediate environment of the cloud. The environmental lapse rates are nearly equal to the saturated adiabatic value. The positive increments in liquid water content (LWC) are associated with the increments in temperature inside the cloud. Similarly positive increments in temperatures inside the cloud are associated with the increments in temperature of its immediate environment at the same level or the layer immediately above. The maximum cloud lengths observed at Poona and Bombay respectively are 14 and 3 km. The horizontal cross-section of LWC showed a maximum number of 13 peaks in clouds at Poona while only 7 peaks were observed at Bombay. The location of maximum LWC in the horizontal cross-section is more or less at the centre of the cloud. The LWC profile showed an increase with height from the base of the cloud at Poona and Bombay. There is no marked variation of LWC with height at Rihand. The total droplet concentration at different altitudes at Poona and Bombay is in the range 28–82 cm^?3. The size distribution of cloud droplets experienced a broadening effect with increase in height from the cloud base at Poona. The broadening effect at Bombay is not as marked as that at Poona.     

Using Quantitative Textural Analysis to Understand the Emplacement of Shallow-Level Rhyolitic Laccoliths--a Case Study from the Halle Volcanic Complex, Germany

In qualitatively homogeneous magmatic bodies, quantitative texturalanalysis—such as crystal size distribution, modal abundance,and spatial distribution pattern analyses—allows theirinternal heterogeneity to be measured and interpreted. In thisstudy, these methods are applied to samples from a 300 m drillcore through one of the porphyritic rhyolitic laccoliths (Petersbergunit) of the     

TRANSFORMATION OF THE LINE LENGTHS OF CARTOGRAPHIC MODELS IN ACCORDANCE WITH FUNCTIONAL UNITS

A paper devoted to the transformation of cartographic images based on nontraditional systems of scaling (travel time, transport effort, cost, etc.) describes the results of work to develop a more effective algorithm for such transformations, i.e., one which the authors claim provides for the more accurate determination of “transformed” line lengths than possible with earlier methods. Translated from: Izvestiya AN SSSR, seriya geograficheskaya, 1987, No. 4, pp. 105-111.     

Geodetic uses of lunar laser ranging

A recent improvement in measuring accuracy together with the development of new techniques suggests that geodetic point coordination to 1 part in 10⁸ will become a reality in the near future. As a first step, however, the reference frame in which the points are to be coordinated, must be refined. Lunar Laser Ranging offers a means of solving both of these problems. The necessary equations are developed and the shortcomings of the method are analysed.     

Transmission electron microscope texture and crystal chemistry of coexisting ortho- and clinopyroxene in the Antarctic ureilite Frontier Mountain 90054: Implications for thermal history

Abstract— Frontier Mountain (FRO) 90054, from Antarctica, is a rare clino- and orthopyroxene-bearing ureilite with a coarse equigranular oriented texture (grains up to 3 mm); it is classified as a low-shock Ca-rich type. The crystal chemistry of its clinopyroxene (Wo_39.3En_54.6Fs_6.1), orthopyroxene (En_{84 2}Fs₁₁Wo_4.8) and olivine (Fa_12.6Fo_86.9) was investigated by single-crystal x-ray structural refinements and transmission electron microscope (TEM) observations to obtain data on the evolutionary history of the parent body. The M1 octahedron and unit cell volumes of the orthopyroxene and clinopyroxene are consistent with low-pressure crystallization. The closure temperatures for intracrystalline Mg-Fe²⁺ ordering yielded values of 674 °C and 804 °C for opx and 596 °C for cpx, which indicate high-temperature equilibration and fast cooling. Trasmission electron microscope investigations were performed on clinopyroxene, orthopyroxene and pigeonite. The (100) twin lamellae in the clinopyroxene and intergrowth of clino- and orthoenstatite lamellae in orthopyroxene most probably originated by deformation. Exsolution was not observed in any of the phases, which suggests rapid cooling. Analysis by TEM also revealed interstitial Na-rich glass and pigeonite with sharp h + k odd reflections and rare stacking faults parallel to (100). Textural and crystal chemical data, obtained by TEM, indicated rapid cooling that was probably due to fast radiative heat loss as a result of the disintegration of the parent body into small fragments, which subsequently reassembled into a larger body. One or more collisional events caused fine-scale stacking faults and partial melting.     

Equation of state of Fe3+-bearing phase-X

We investigated the high-pressure behaviour of Fe³⁺-bearing hydrous phase-X, (K_1.307Na_0.015)(Mg_1.504Fe _0.373 ³⁺ Al_0.053Ti _0.004 ⁴⁺ )Si₂O₇H_0.36, up to 34?GPa at room temperature by synchrotron X-ray powder diffraction. The lattice parameters behave anisotropically, with the [001] direction stiffer than [100]. In the 10^?4 to 22?GPa pressure range, the axial bulk moduli are K _0a ?=?112(3) GPa and K′?=?4, and K _0c ?=?158(2) GPa and K′?=?4, and the anisotropy of the lattice parameters is β_0c :β_0a ?=?0.71:1. The cell volumes are fitted by a second-order Birch–Murnaghan equation of state giving a bulk modulus of K ₀?=?127(1) GPa and K′?=?4 in the same pressure range. After 22?GPa, a discontinuity in volume and lattice parameters can be recognized. Sample did not become amorphous up to 34?GPa. The coupled substitution K?+?Mg?=?[]?+?Fe³⁺ has only a limited influence on the bulk modulus and structural stability of phase-X.     

Bemerkungen zu Sonders Arbeit: „Zur Theorie und Klassifikation der eruptiven vulkanischen Vorgänge“

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