摘要:

The slaty cleavage in the sigmoidal Adelaide Fold Belt of South Australia is a predominantly planar fabric with only a weak down‐dip lineation. However, in a gradation towards the Rapid Bay area of south‐west Fleurieu Peninsula, the linear element of the slaty cleavage becomes more pronounced. This increase in fabric linearity is accompanied by a progressive change in fold axis orientation, from approximately horizontal fold axes pitching at a high angle to the mineral lineation (which is typical for the fold belt) to reclined folds with axes at a low angle to the lineation. The variation in fold axis orientation is similar to that calculated by Sanderson (1973) for increasing X:Y strain.

ISSN:0016-7614    

DOI:10.1080/00167618108729139

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

New chemical, X‐ray and cell dimension data are presented for ferrian tourmaline in quartz‐tourmaline rock at three localities near Bungonia, New South Wales. The tourmaline is fine‐grained, normally euhedral, and forms up to 90% of the rock. It shows restricted solid solution between dravite and ferridravite, although some grains are zoned and others have an irregular, bipartite chemical variation. Tourma‐linisation is interpreted as being.related to late‐stage volatile emanations from the Marulan Batholith.

ISSN:0016-7614    

DOI:10.1080/00167618108729140

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The concept that spacing geometry of volcanoes reflects crustal or lithospheric thickness can be extended to granite plutons. Various factors may control pluton spacing, and the influence of faulting and erosion level is discussed. In southern New South Wales pluton spacing appears to have been largely controlled by a 6 to 10 km thick ‘brittle’ upper layer, but pluton clusters and batholiths are spaced wider, suggesting that the magma was derived from 12 to 25 km within the crust—a figure in accord with available mineral barometric data. S‐ and I‐type, granites have similar spacing geometries; the boundary between their source layers cannot be specifically determined, but is inferred to have been at about 20 km. A possible crustal thickness of 35 km is inferred from the spacing of granites in Victoria and Silurian volcanic centres.

ISSN:0016-7614    

DOI:10.1080/00167618108729141

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The partly eroded remains of a Miocene compound shield volcano crop out near Orange, central New South Wales. A cluster of conical and domical landforms occupies the central elevated core of the volcano, and they are usually surrounded by flows of more basic lava that radiate out from this centre. At the present level of erosion, trachyte, and in particular ferroaugite trachyte, is the most abundant type of rock in the core of the complex, whereas hawaiite is the dominant type of rock in the outer part. Other rocks in the central area include mugearites, benmoreites, comendites, and a wide variety of pyroclastic rocks. The pyroxenes in the hawaiite‐trachyte suite range from Mg‐rich augite to ferrohedenbergite. Arfvedsonite is the characteristic mafic phase in the comendites. All the rocks of the complex are part of a single comagmatic suite. It is proposed that the magmas that formed most of the mugearites, benmoreites, trachytes and comendites evolved at relatively low pressures in a large compositionally zoned body of magma, in which the main processes of differentiation were crystal‐settling and volatile‐transfer.

ISSN:0016-7614    

DOI:10.1080/00167618108729142

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Most strata are inverted in the Rockvale Block, northern N.S.W., which is completely deformed and contains at least three recognisable deformations (D1, D2, D3). A deformation, Do, has been invoked to explain the existence of inverted strata over a large region. The intensities of the mesoscopic deformations increase eastwards, the W being dominated by D1. D2and D3features become progressively more common eastwards and are eventually observed in regional metamorphic rocks of amphibolite facies grade. D1produced upright folds on the previously inverted strata. Planar structures vary from an axial‐surface slaty cleavage in the W to a schistosity in the E. The predominant E‐W strike of S1in the W has been rotated to a N‐S orientation in the E. A macroscopic F1fold, the Rockvale Anticlinal Synform, plunges steeply to the E with its axial surface parallel to the regional strike of the slaty cleavage. The F1folds were produced by buckling modified by relatively homogeneous strain. F2folds vary considerably in style from gentle warps, through kink bands and tight chevron folds in the low‐grade slates, to isoclinal folds in the high‐grade schists. Rotation of S3from NE‐SW in the W to NNW‐SSE in the E has occurred. D3is manifest only as gentle warps observed in S2.

ISSN:0016-7614    

DOI:10.1080/00167618108729143

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The chemistry and. mineralogy of calcretes and associated calcareous fine earth from the lower River Murray Basin and Yorke Peninsula in South Australia suggest that the carbonate material was deposited as a continuous unit and subsequently modified. At each site examined the Ca/Mg ratio progressively decreases with increasing depth, and where data are available, a similar decrease in the Ca/Sr ratio is observed. This sequence is independent of the hardness or physical condition of the carbonate. In some places the carbonate from the lowest horizons is nearly pure dolomite. The change in Ca/Mg ratio with depth is considered to be due to leaching, probably during periods of the past when the climate was less arid and the rainfall penetrated to about 2 m.

ISSN:0016-7614    

DOI:10.1080/00167618108729144

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A system of parallel arcuate ridges dominates the present‐day topography of the Billa Kalina area, South Australia; facies relationships indicate that they are silicified strandlines of a Miocene lake, etched out by later erosion. Clays and dolomites of the Miocene Mirikata Formation (Billa Kalina Clay and Millers Creek Dolomite Members) were deposited in the distal portion of the lake, which at its peak was over 100 km wide.

ISSN:0016-7614    

DOI:10.1080/00167618108729145

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167618108729146

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167618108729147

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167618108729148

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor