摘要:

From north to south, the sedimentary basins of Western Australia change from broad platforms of wholly marine strata that span the entire Phanerozoic (Bonaparte Gulf and Canning Basins) through the intermediate Carnarvon Basin to rifts of nonmarine Permian and Mesozoic strata (Perth Basin). These contrasts in age, facies, and structure reflect different positions of the basins in Gondwanaland: the Bonaparte Gulf and Canning Basins have lain at the continental margin facing an open ocean during the entire Phanerozoic, whereas the Perth Basin lay in the interior of Gondwanaland until India and Australia moved apart in the Cretaceous.

ISSN:0016-7614    

DOI:10.1080/00167617108728747

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Rb‐Sr and K‐Ar measurements have been made on five glauconite samples from the near basal Treuer Member of the Vaughan Springs Quartzite of the Ngalia Basin, Northern Territory, Australia. Comparison of results between and within the two groups of data demonstrates that variable losses of radiogenic strontium and argon have occurred, but allows a minimum age of 1280 m.y. to be calculated for the member. Sedimentation began in the Ngalia Basin shortly before the time of deposition of this member.

ISSN:0016-7614    

DOI:10.1080/00167617108728748

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Bauxite deposits in Gippsland are small, low in grade, and buried under a thick cover of Tertiary sands. Occurring at various stratigraphic levels in the Thorpdale volcanic sequence, they are also texturally and compositionally primitive and hence now presumably fossilised. Although broadly comparable with deposits in Tasmania and New England, they show few obvious analogies with other Australian bauxites. Profile studies reveal a somewhat erratic vertical mineralogical zonation which can, at least in part, be accounted for by assuming a degree of post‐bauxitisation planation so that some profiles are now truncated. Some profiles show gibbsite increasing with depth and at least in the Boolarra profile this has significant genetic implications. Here, during submergence of the lateritic surface, rising carbonated connate waters precipitated scarbroite and this, with subsequent renewed leaching, decomposed initially to form nordstrandite, and finally gibbsite.

ISSN:0016-7614    

DOI:10.1080/00167617108728749

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

An investigation of plagioclases from the Gosse Pile ultramafic layered intrusion has shown a negative correlation between strontium and anorthite content, irrespective of rock type or whether the plagioclases are cumulus or intercumulus. This general trend is regarded as reflecting the relative ease of entry of strontium into the plagioclase lattice with change in composition.

ISSN:0016-7614    

DOI:10.1080/00167617108728750

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The petrography and structure of three small areas, the Nussbaum Riegel and the north and south sides of the Garwood Valley in the “Dry Valleys” region of Victoria Land, Antarctica, are described and discussed. The rocks are mostly pure or impure marbles plus lesser quantities of amphibolite, schist and quartz‐feldspar rocks, and mineral assemblages indicate that they have been metamorphosed under conditions of the amphibolite fades, and possibly, locally under conditions transitional to the granulite facies. In general they have not suffered retrograde metamorphism.

ISSN:0016-7614    

DOI:10.1080/00167617108728751

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Two well‐defined sequences of earthquakes in South Australia were recorded in January and October 1969, these being associated with main shocks of magnitude ML 4.4 and 4.1 respectively. The events occurred in a region of little previous seismic activity, near the boundary of the Adelaide Geosyncline and the Willyama Block.

ISSN:0016-7614    

DOI:10.1080/00167617108728752

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

An X‐ray determinative curve has been produced for the rapid analysis of simple silver halides. Complete analyses of thirty‐two specimens of silver halides and examination of approximately fifty more by X‐ray diffraction show that they are, with very few exceptions, embolites with only a few percent of silver iodide present. Most of these fall within a small composition field and it is possible that there has been more than one period of halide formation which would account for specimens outside this field. All the pure silver iodides gave hexagonal diffraction patterns except those containing small amounts of copper, suggesting an excess of iodide ions in the solutions at the time of formation.

ISSN:0016-7614    

DOI:10.1080/00167617108728753

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The petrography of laterites in the Sydney district shows that source rocks range from shales—in which quartz grains are not common and average about 0.03 mm in diameter—to sandstones, with generally abundant quartz grains which may average up to 0.5 mm in diameter. Ferricretes or iron‐cemented duricrusts occur in rocks with coarser quartz grains, such as the Tertiary river gravels of the Maroota area. The porosity and permeability of these rocks have considerably influenced the nature and profiles of the laterites. Two possible sources of sesquioxides in the laterites appear to be the Wianamatta Shale and, perhaps more importantly, basic igneous rocks.

ISSN:0016-7614    

DOI:10.1080/00167617108728754

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The Beltana zinc‐lead deposit, the largest of several such small deposits in the Beltana area, owes its formation to intense localised marginal faulting and brecciation of Ajax Dolomite at its contact with the Beltana Diapir. Considerable frictional heat was generated by the upward movement of this diapir. The enormous stresses set up in it squeezed out hot interstitial saline mineralising fluids into the brecciated dolomite footwall to form initially a prominent lead arsenate‐rich horizon containing hedyphane, finnemanite, vanadinite and several minor components. Sporadic, but significant manganese mineralisation also occurred during this phase resulting in the precipitation of coronadite and hollandite. During the final and most prominent stage in the paragenetic sequence, the mineralising fluids became more siliceous and zinciferous leading to extensive replacement of earlier arsenates and precipitation of willemite. Late‐stage alteration is largely confined to the earlier arsenate‐rich zone, which has been carbonated and leached by meteoric waters.

ISSN:0016-7614    

DOI:10.1080/00167617108728755

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The Arltunga Nappe Complex trends east‐west along the northeastern margin of the Amadeus Basin, approximately in the centre of the Australian continent. The nappes formed in a stratigraphic sequence consisting of the crystalline Precambrian Arunta Complex overlain unconformably by Upper Proterozoic Heavitree Quartzite and carbonate rocks of the Bitter Springs Formation. The uppermost and largest nappe was transported at least 24 km across strike and developed by a combination of recumbent folding and overthrusting. The lower nappes formed by overthrusting alone. The nappes root to the north in a belt of crystalline rocks of the Arunta Complex, originally in the amphibolite facies, that are retrograded to the greenschist facies. North of the retrograded zone a belt of rocks belonging to the granulite facies and amphibolite facies is exposed.

ISSN:0016-7614    

DOI:10.1080/00167617108728756

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor