Metamorphic and metasomatic convergence of basic igneous rocks and lime‐magnesia sediments of the precambrian of North‐western Queensland*
作者:
K. R. Walker,
Germaine A. Joplin,
J. F. Lovering,
R. Green,
期刊:
Journal of the Geological Society of Australia
(Taylor Available online 1959)
卷期:
Volume 6,
issue 2
页码: 149-177
ISSN:0016-7614
年代: 1959
DOI:10.1080/00167615908728504
出版商: Taylor & Francis Group
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.
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