摘要:

Quantitative studies of the variation of the arenite‐lutite ratio, and of bedding thickness for outcrops across the Siluro‐Devonian sediments in the Seymour East Syncline, indicate these significant features:

ISSN:0016-7614    

DOI:10.1080/00167616408728556

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Rocks of Upper Precambrian age near Adelaide show evidence of two or more phases of deformation. The first phase has resulted in concentric and similar folds with an associated slaty cleavage. Structures of this phase are overprinted by folds with associated crenulation cleavage. Minor occurrences of later kink folds are also observed. The hypothesis that the first phase folds overprint very large folds not observable in the field is examined. The observed variation in the attitude of first phase folds could also have resulted from large scale inhomogeneities of strain.

ISSN:0016-7614    

DOI:10.1080/00167616408728557

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Granitic rocks from the Wilson's Downfall‐Maryland area of northern New South Wales provide examples of albite and myrmekite of the intergranular and rim types. Following the views of Schwantke (1909), Spencer (1945), and Tuttle (1952), it is suggested that the process involved in the formation of secondary albite and myrmekite is one of unmixing of certain phases from an originally high temperature K–Na–(Ca) feldspar. The presence or absence of myrmekite is thought to be directly dependent on the original Ca content of the alkali‐feldspar.

ISSN:0016-7614    

DOI:10.1080/00167616408728558

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Bindheimite has been identified in specimens from the Lvov Lease, N.W. Queensland. Chemical, microscopic and X‐ray data are given for the mineral which was found to possess a cubic lattice with a unit cell dimension of 10–427 A.

ISSN:0016-7614    

DOI:10.1080/00167616408728559

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

A study has been made of the red‐beds in the Narrabeen Group in the central and southern portions of the Sydney Basin and it is concluded that the sediments were deposited in a piedmont environment. Siltstone is the dominant rock type although all gradations between claystone and fine sandstone occur. Clay minerals predominate in the red‐beds of the southern sector including those exposed in the Collaroy‐Newport area whereas, north of the Hawkesbury River, the rocks are characterised by abundant quartz and significant amounts of feldspar. In the western sector the composition of the red‐beds is not appreciably different from that of the shales in the succeeding Hawkesbury Sandstone and Wianamatta Group. The Bald Hill Claystone has the features of a re‐sorted laterite but the mineralogy of the red‐beds north of the Hawkesbury River appears incompatible with such an origin. More information on the entire sedimentation within the Sydney Basin will be necessary before the problem of the origin of the red‐beds is settled.

ISSN:0016-7614    

DOI:10.1080/00167616408728560

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Extensive and well‐developed pediments and pediplains in western New South Wales have hitherto received less than due attention in the literature. This paper records the details of instrumental survey and of excavation at The Pinnacles, near Broken Hill. It presents observation and analysis of slope, rock‐type, structure, and surficial cover, and discusses the significance of a peripediment which contains multiple soil profiles.

ISSN:0016-7614    

DOI:10.1080/00167616408728561

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Forty‐four tremors which occurred in the Snowy Mountains of New South Wales during the years 1958–1962 have been accurately located, using a network of seismic stations operating in that area. The largest of these were a tremor of magnitude 5 north of Berridale in May, 1959, and one of magnitude 4 near Rock Flat in September, 1958. Fault plane analysis suggests that the former was caused by a high‐angle thrust movement along the plane of the Crackenback Fault, while the latter may be associated with the Murrumbidgee Fault. These conclusions are supported by macroseismic data.

ISSN:0016-7614    

DOI:10.1080/00167616408728562

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The Great Lake dolerite sheet, which is up to 2,000 feet thick, was emplaced during the Jurassic in an essentially flat‐lying sequence of Permian and Triassic sedimentary rocks. The intrusion is markedly transgressive in the west, and becomes sill‐like to the east. The dolerite is tholeiitic, and chemical and micrometric analyses show that differentiation is marked. Above the floor of the intrusion a Mg‐rich zone is found, which passes upward into progressively more silicic dolerites. An elongated, lenticular body of granophyre, which crops out adjacent to Great Lake, appears to have been concentrated in a structural high in the roof of the intrusion. The granophyre passes gradationally into dolerite vertically and laterally and was formed by differentiation. The silicic dolerites and the granophyre are enriched in iron, silica and alkalies, and impoverished in CaO and MgO. Differentiation has taken place by fractional crystallization and the movement of phases under gravity. The fractionation trend is similar to that found in other Jurassic dolerite intrusions in Tasmania.

ISSN:0016-7614    

DOI:10.1080/00167616408728563

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The value of density measurements in the study of differentiated dolerite sills is discussed. It is shown that density measurements correspond closely with the results of chemical and modal analyses. There is a considerable statistical fluctuation in measured values of the density from relatively close specimens, and a similar fluctuation is to be expected in the results of chemical or modal analyses. Because of their speed, it is possible to make a large number of density measurements and take mean values over fifty foot intervals to indicate trends.

ISSN:0016-7614    

DOI:10.1080/00167616408728564

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Nuclear explosions in South Australia at Maralinga in 1956 and 1957, and at Emu in 1953, provided unique opportunities for determining accurately seismic velocities in the crust and upper mantle. Stations south and south‐east of Maralinga towards Adelaide gave P velocities of 3.4 km/sec in thin sediments, 5.8 km/sec in the upper 1–2 km of “granitic” material just below the sediments, and 6.3 km/sec (P1) for deeper granitic material which probably makes up much of the crust. S1 (Lg) velocity was 3.59 (±0–01) km/sec, Pn in the upper mantle was 8.05 (±0.04) km/sec, appreciably lower than previously found west of Maralinga, and Sn 4.61 (±0.04) km/sec.

ISSN:0016-7614    

DOI:10.1080/00167616408728565

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor