摘要:

A re‐examination in the field of the lamproites of the Fitzroy Basin, Western Australia, shows that for the most part they occur in concentrically‐zoned plugs occupying diatremes. The zonal distribution of the lamproites in each plug is due to the different rates of cooling in different parts of the plug and the peculiar nature of the lamproite magma (high potash dominant over alumina, absence of soda, and abundance of titania, zirconia, baryta and fluorine) is ascribed to upward gas transfer of these constituents in the diatremes, the parental magma being of peridotitic character.

ISSN:0016-7614    

DOI:10.1080/00167615908728501

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

Point‐counter analyses include two errors, determined separately by count length and by sample area. The counting error has been studied by Chayes, and his latest results admit an estimate also of the sampling error. It is postulated that the sample size and the rock coarseness do not affect this error independently; instead, they combine to determine the effective number of grainsections sampled, and this in turn controls the sampling error. The estimate of the sampling error is compared with that for the counting error in selecting the best sample sizes and count lengths for projected work.

ISSN:0016-7614    

DOI:10.1080/00167615908728502

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

Slopes are the fundamental unit of the physiographic landscape. Yet the reasons for variations in their morphology and inferred mode of development are not well understood. The problem is complex, but the slope budget, which results primarily from the interplay of climatically induced factors and structure is significant: where the erosion of the upper slope elements surpasses that on the lower, parallel retreat prevails, but when the reverse is the case, slope decline is dominant. Complications are introduced by such factors as climatic change and fluctuations of baselevel, both local and general. But structural factors can and do override all others.

ISSN:0016-7614    

DOI:10.1080/00167615908728503

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

With increasing intensity of metamorphism, and particularly metasomatism, it becomes more and more difficult to separate amphibolites in North‐western Queensland into ortho‐ and para‐amphibolites, and a stage is reached at which the two are indistinguishable. Field evidence, carefully sought, has enabled the origin of some apparently identical rocks to be determined, and laboratory methods were applied to these rocks to see if grounds for the separation of amphibolites of unknown origin could be determined. None of the six methods tried — mineralogy (including feldspar twinning), chemical analysis (including TiO2 content), spectrography, rock magnetism — proved to be as successful as the field method in distinguishing the two rock groups; some methods used with apparent success elsewhere, such as feldspar twinning or chemical analyses, are found to be unsuccessful here, which suggests that though the problem is world‐wide, solutions are only of local validity.

ISSN:0016-7614    

DOI:10.1080/00167615908728504

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

The central nucleus of the Australian Precambrian shield lies in the western half of the continent and is characterized by striking similarities in structure and age over a vast area. Ages in the vicinity of 2,700 m.y. have been determined at many localities by the Rb/Sr and K/A methods.

ISSN:0016-7614    

DOI:10.1080/00167615908728505

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167615908728506

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167615908728507

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

F.L. Stillwell Anniversary Volume.Australian Institute of Mining and Metallurgy, Melbourne, 302 pages, many plates and figures. 1958.

ISSN:0016-7614    

DOI:10.1080/00167615908728508

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167615908728509

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167615908728510

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor