摘要:

From the results of this preliminary survey it would appear that the bathyliths of the southern belt of the Tasman Geosyncline represent a history of continuous tectonic activity from Middle Silurian through to Middle Devonian, with a gradual movement eastwards of the axis of the intrusions. The gneissic “Ordovician‐type” granite is dominant in the Upper Silurian, just preceding the foliated “Silurian‐type” plus massive types which are dominant in the Lower Devonian, but with significant overlap in time between them to the extent that “rock type” is not a safe determinant of age. It is therefore recommended that this terminology be no longer used. A few cases of Carboniferous intrusion have been observed. These generally are transgressive to the main trend. Later intrusions occurred to the east and north, ranging from Permian in New England to Mesozoic further north, in good agreement with expectation. Smaller Mesozoic instrusions in the southern coastal region have ages different from those anticipated.

ISSN:0016-7614    

DOI:10.1080/00167616208728514

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The igneous events of two geosynclines within the N.S.W. portion of the Tasman Orthogeosyncline are compared, not according to the actual ages of the igneous rocks, but on the basis of their position with respect to the development of the geosyncline. Thus, Cambrian volcanic rocks in one depositional area are compared with Lower Devonian in the other, Ordovician and Silurian with Middle Devonian‐Lower Carboniferous, and Devonian with Permian. Intrusive rocks are fitted into this scheme, and their ages discussed. Such a comparison reveals an apparent igneous cycle, and speculations on the cause of such a cycle are outlined.

ISSN:0016-7614    

DOI:10.1080/00167616208728515

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The small area surrounding Narooma provides an example of a departure from the ideal geometry of superposed fold systems. Three systems of folds are recognized, the second set being by far the best developed. Axial planes of these folds lack a preferred orientation so that the fold style is polyclinal and B‐axes are variable. Evidence of extension parallel to B is widespread. Some dynamic aspects of the second deformation are discussed.

ISSN:0016-7614    

DOI:10.1080/00167616208728516

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Umbrella‐shaped objects, presumably fossils, were collected from the Lower Proterozoic Noltenius Formation at two localities about 80 miles south of Darwin. Radial and concentric forms are described morphologically, and their probable mode of origin is discussed.

ISSN:0016-7614    

DOI:10.1080/00167616208728517

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Coober Pedy provides an example of slope development in an arid area. There are two plains separated by slopes which are the subject of this paper. The upper plain is duricrusted and this hard layer has an important protecting effect on the underlying rock. The slopes are gullied and water erosion was important in the formation of both the lower plain and the slopes. Both plains are covered by lag deposits of gibbers indicating considerable wind action. Landslides and desert gilgai are of minor importance. Many slopes take the form of “J” curves, with an upper straight section and a lower concave slope. There is a general parallelism of slopes, but there is variation in detail. Debris is nowhere more than a veneer, and accumulations of debris are not responsible for any slope elements. Slope development takes place largely by parallel retreat.

ISSN:0016-7614    

DOI:10.1080/00167616208728518

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167616208728513

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor