摘要:

The Tari‐Koroba district is at an altitude of about 1,500 m in the Southern Highlands of Papua in an imbricate province in which uplift and faulting occurred in Pliocene times. In the southeast of the area Miocene limestones are overlain by volcanic rocks erupted about 0.85 m.y. ago, as determined from K‐Ar measurements. These middle Pleistocene flows crossed the course of the Tagari River, damming its waters to form Lake Haibuga. Sediments accumulated in this and neighbouring basins. At one site near Pureni, diprotodontid remains were found; wood associated with the deposit gave a14C age of 32,700 yrs B.P. Pollen from this fossiliferous horizon and from another section nearby (14C age of 38,600 yrs B.P.) indicate that the climate was cooler than at present and perhaps equivalent to that experienced at about 600 m higher elevation today. Pollen from stratigraphically lower samples indicate still colder conditions and may reflect a glacial phase in the highlands earlier than the last glaciation.

ISSN:0016-7614    

DOI:10.1080/00167617208728772

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The main features of climate and geology relevant to a discussion of the soils and landscapes of Western Australia are briefly reviewed. The pattern of drainage is described in terms of six drainage divisions, each with characteristic physiography and soils. In the interior, this involves a reconstruction of an ancient drainage system, based on the maps of the Atlas of Australian Soils. It is shown, on a continental scale, that the major divides are characterised not only by deep, chemically weathered, often lateritic profiles, but also by extensive sandy deposits derived from these preweathered materials.

ISSN:0016-7614    

DOI:10.1080/00167617208728773

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The nature of the valley forms, and associated superficial deposits and soils of the South‐West Drainage Division of Western Australia are described. All the major rivers tap interior palaeo‐drainage lines associated with chains of salt lakes; thereafter, downstream, there is a succession of valley forms which are progressively more sharply incised and of steeper gradient. It is shown that this succession is repeated in all major rivers. The main palaeo‐drainage systems are named for the first time, and their catchments delineated. The changes in valley form which occur downstream of the palaeo‐drainage lines are interpreted as stages in rejuvenation of drainage of the epeiro‐genically uplifted Old Plateau of Western Australia. The relationship between the valley forms and patterns of distribution of soils, deeply weathered profiles and superficial deposits is described, and its agricultural, geochemical and hydrological significance briefly discussed.

ISSN:0016-7614    

DOI:10.1080/00167617208728774

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

‘Pressure shadow’ type structures, referred to here as ‘mica beards’ (Ransom, 1965), are described from a sequence of deformed Ordovician greywackes. The beards are very numerous and constitute a major fabric element in definition of an axial‐plane foliation. They consist of fine, polygonal grains of quartz and of layer silicates which are aligned approximately perpendicular to the surface of the host grain with which they are associated. Three possible explanations are offered for the formation of the structures and their relative merits are discussed briefly.

ISSN:0016-7614    

DOI:10.1080/00167617208728775

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The western Musgrave Ranges are broadly divided into three groups of metamorphic rocks. A central granulite‐facies core is bounded on the north by rocks of amphibolite grade and on the south by rocks transitional between the granulite and amphibolite facies. Faults trending east‐west separate the three groups of rocks.

ISSN:0016-7614    

DOI:10.1080/00167617208728776

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Structures previously described as umbrella‐shaped probable fossils are shown to be tectonically deformed cylindrical to conical sand volcanoes. They occur in the upper parts of greywacke beds in the middle Precambrian Pine Creek Geosyncline. The anisotropy caused by the occurrence of the volcanoes resulted in the localization of stresses during the deformation of the geosynclinal sequence, causing the formation of radial and concentric fractures in each of the volcanoes.

ISSN:0016-7614    

DOI:10.1080/00167617208728777

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Potassium‐argon ages on alkali feldspar phenocrysts from trachyte lavas and on trachyandesites of the Cape Hillsborough Beds, which crop out north of Mackay, Queensland, yield concordant ages of 32.5±0.4 m.y. This age is Early Oligocene and by correlation provides much firmer control than previously available on the age of the sediments deposited in the Hillsborough Basin. Isotopic ages on an altered biotite and on alkali feldspar from the Mount Jukes Syenite Complex, to the southwest of Cape Hillsborough, are indistinguishable from those measured on the Cape Hillsborough Beds, suggesting a possible genetic relationship between the lavas and the syenite intrusions. Present evidence indicates that Cainozoic volcanism in Queensland occurred in two main eruptive episodes. The earlier episode covered much of the Oligocene and its products are widespread in the southern half of the State. After a long hiatus of little or no volcanism there followed a later episode of volcanism in the Pliocene and Quaternary when widespread basaltic eruptions occurred, mainly in North Queensland.

ISSN:0016-7614    

DOI:10.1080/00167617208728778

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Australites in an excellent state of preservation are common (up to 1 specimen per 300 m2) in lag gravels flooring corridors between seif dunes in the Motpena and Myrtle Springs areas of the Lake Torrens plain, South Australia. A study of the Quaternary stratigraphy of the region indicates that late Wisconsinan relict dunes (Lake Torrens Formation) are the most likely source of the australites. Radiocarbon dating indicates that the Lake Torrens Formation was deposited between about 24,000 and 16,000 years B.P. As the excellent preservation of most of the australites indicates that they have undergone negligible transport since their infall, it is concluded that the australites fell into the dune field sometime between about 24,000 and 16,000 years B.P.

ISSN:0016-7614    

DOI:10.1080/00167617208728779

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

It is suggested that an explanation of the observed metastable formation of cristobalite and tridymite in the stability field of quartz lies in the topology of these silica polymorphs and the resulting energies at the time of formation.

ISSN:0016-7614    

DOI:10.1080/00167617208728780

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167617208728781

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor