The tectonic generation of the Limpopo Mobile Belt,and a definition of its western extremity     

R.M. Key  S.M. Hutton 《Precambrian Research》1976,3(1):79-90

A new mechanism is suggested for the generation of the interference fold pattern which characterizes the Limpopo Mobile Belt. The mechanism is directly related to shear movement along the Tuli-Sabi Shear Zone, renamed the Tuli-Sabi Straightening Zone. The mobile belt is regarded as a taphrogenic lineament (McConnell, 1974) and its generation is compatible with the tectonic environment active in Proterozoic times according to Sutton and Watson (1974). Field evidence shows that the Tuli-Sabi Straightening Zone dies out in Botswana at Moshakabela, and it is reasoned that the mobile belt as a whole also disappears in this vicinity. It does not extend into central and western Botswana beneath the Karroo and Kalahari cover. Detailed examination of ERTS-1 imagery of northeastern Botswana strengthens these deductions. The Tuli-Sabi Straightening Zone and the characteristic fold patterns of the mobile belt can be seen quite clearly on the satellite imagery. Furthermore, the Tuli-Sabi Straightening Zone appears to be displaced southwards at the international boundary between Botswana and Rhodesia. The existence of a fold belt trending about N150° superimposed on the Limpopo Mobile Belt in the west of the area is postulated which is not the Shashe Mobile Belt (Crockett, 1967).  相似文献   

Sodium exchange in a NaCl waste disposal case (Lobatse,Botswana): Implications to mineral water studies     

E. Mazor  B. Th. Verhagen  J. P. F. Sellschop  M. T. Jones  L. G. Hutton 《Environmental Geology》1981,3(4):195-199

In the reconstruction of the chemical evolution of mineral waters, sodium exchange for calcium and magnesium, upon contact with soil and rocks, is often suggested. Such a process has been observed to take place on a large (and rapid) scale in NaCl waste disposal: that infiltrated to the local groundwater at Lobatse, Botswana. The process was repeated in laboratory experiments. Visiting Scientist at the Nuclear Physics Research Unit, University of the Witwatersrand, Johannesburg, South Africa, during 1972.  相似文献   

Magnetic behavior of magnetite and rocks stressed to failure — Relation to earthquake prediction     

Jacques Revol  Ron Day  Michael D. Fuller 《Earth and Planetary Science Letters》1977,37(2):296-306

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A scaling law for the occurrence of aftershocks in southern California     

R. Lamoreaux  V.I. Keilis-Borok  L.K. Hutton 《Physics of the Earth and Planetary Interiors》1983,31(3):193-201

A scaling law for the occurrence of aftershocks in southern California is proposed which suggests that the number of aftershocks is independent of the magnitude of the mainshock if aftershocks are counted in the magnitude interval from (Mm ? Δ) to Mm.  相似文献   

NMR and EPR studies of the chemically intermediate plagioclase feldspars     

C. M. Scala  D. R. Hutton  A. C. McLaren 《Physics and Chemistry of Minerals》1978,3(1):33-44

The NMR spectra of ²⁷Al and ²³Na and the EPR spectra of Fe³⁺ and Mn²⁺ have been studied in a range of plagioclase feldspars, of intermediate composition. Many of these crystals have previously been investigated by TEM methods (McLaren and Marshall, 1974). The broad, central ²⁷Al signals observed in labradorites have been interpreted in terms of an overall order/disorder of the Al/Si distribution. Spin Hamiltonian parameters have been determined for the Fe³⁺ spectra observed in labradorites and bytownites; these spectra were similar and yielded evidence of disordering of the Al/Si distribution. The severe limitations imposed by the variety of sites, the complex microstructures and the disordering, limit the structural information available from the resonance methods.  相似文献   

Geography and the Social Sciences in Australia: an opportunity lost?1     

Ron Johnston 《The Australian geographer》2006,37(2):279-284

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Three-dimensional seismic reflection investigation of the upper crustal Winagami sill complex of northwestern Alberta, Canada     

J. Kim Welford  Ron M. Clowes 《Geophysical Journal International》2006,166(1):155-169

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RXTE spectroscopy of GRS 1915+105     

Jochen Greiner  Ed H. Morgan  Ron A. Remillard 《New Astronomy Reviews》1998,42(9-10)

The galactic superluminal motion source GRS 1915+105 has been extensively observed with the RXTE satellite over the last two years. More than 250 RXTE pointings have been performed until mid-May 1998 with more than 1.5 Msec exposure time on roughly a weekly basis. Here we report on first results of our spectral analysis of a major part of these pointed RXTE observations. We establish the existence of at least 5 spectral components and present the changes of these components over the last two years.  相似文献   

Evidence for a poleward meridional flow on the sun     

Ken Topka  Ron Moore  Barry J. LaBonte  Robert Howard 《Solar physics》1982,79(2):231-245

We define for observational study two subsets of all polar zone filaments, which we call polemost filaments and polar filament bands. The behavior of the mean latitude of both the polemost filaments and the polar filament bands is examined and compared with the evolution of the polar magnetic field over an activity cycle as recently distilled by Howard and LaBonte (1981) from the past 13 years of Mt. Wilson full-disk magnetograms. The magnetic data reveal that the polar magnetic fields are built up and maintained by the episodic arrival of discrete f-polarity regions that originate in active region latitudes and subsequently drift to the poles. After leaving the active-region latitudes, these unipolar f-polarity regions do not spread equatorward even though there is less net flux equatorward; this indicates that the f-polarity regions are carried poleward by a meridional flow, rather than by diffusion. The polar zone filaments are an independent tracer which confirms both the episodic polar field formation and the meridional flow. We find:

1. The mean latitude of the polemost filaments tracks the boundary of the polar field cap and undergoes an equatorward dip during each arrival of additional polar field.
2. Polar filament bands track the boundary latitudes of the unipolar regions, drifting poleward with the regions at about 10 m s^-1.
3. The Mt. Wilson magnetic data, combined with a simple model calculation, show that the filament drift expected from diffusion alone would be slower than observed, and in some cases would be equatorward rather than poleward.
4. The observation that filaments drift poleward along with the magnetic regions shows that fields of both polarities are carried by the meridional flow, as would be expected, rather than only the f-polarity flux which dominates the strength. This leads to the prediction that in the mid-latitudes during intervals between the passage of f-polarity regions, both polarities are present in nearly equal amounts. This prediction is confirmed by the magnetic data.

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Everywhere different? Globalisation and the impact of international migration on Sydney and Melbourne     

James Forrest  Michael Poulsen  Ron Johnston 《Geoforum》2003,34(4):499-510

Using a new approach to classifying migrant group concentrations, we test for evidence of the effects of globalisation, associated by some with ‘protopostmodernity’, on two Australian cities. Sydney is characterised as an emergent world city and a focus of ‘new economy’ activities. Melbourne is associated with ‘old economy’ activities, dominated by manufacturing. In the Australian context, the onset of globalisation also coincided with significant changes to immigration policy: the end of a ‘white Australia’ policy in the early 1970s in favour of a skills-based policy, regardless of race or ethnicity. We argue that the evidence of the spatial behaviour of ethnic groups for these two cities highlights the essential continuity of ethnic segregation and spatial assimilation processes in two cities where segregation levels and experience are fundamentally different from many overseas examples. We further argue for a need to recognise that context, and the ethnic experience, are everywhere different, both intra- and internationally.  相似文献