摘要:

The Early Carboniferous brachiopod zones of eastern Australia are defined from reference sections in New South Wales. The zones include theTulcumbella tenuistriata, Spirifer sol, Schellwienellacf.burlingtonensis, Orthotetes australis, Delepinea aspinosa,andRhipidomella fortimusculaZones. Two contain subzones: thePustula gracilisSubzone is recognized in the upper part of theSchellwienellacf.burlingtonensisZone in the Rouchel district, New South Wales; and theInflatia elegansandGigantoproductus tenuirugosusSubzones are recognized in the lower and upper portions respectively of theDelepinea aspinosaZone.

ISSN:0016-7614    

DOI:10.1080/00167617408728871

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Compositional relationships, textures, and patterns in the distribution of minerals which include garnet, rhodonite, bustamite, wollastonite, hedenbergite, knebelite, and sphalerite in metamorphosed sulphide ores have been interpreted in terms of variation in fco2and some function of fs2on the scale of the mine during prograde regional metamorphism. In general, rocks which were originally within carbonate and sulphur‐rich ore layers equilibrated at higher gas fugacities than the borders, or structurally disturbed parts of the lodes. The rather constant FeS content of sphalerite in all but the more Fe‐poor rocks indicates that it is in equilibrium with pyrrhotite, which is present in significant amounts only at the south end of the mine. At the other extreme, garnet is commonly out of equilibrium with closely associated minerals. These differences and others indicate significant variations in the size of equilibrium subsystems in the mine. Some mineral zoning patterns and associations of incompatible minerals indicate that many of the rocks have changed bulk composition during mineral growth. The effects of retrograde metamorphism include the formation of andradite and exsolution of hedenbergite from bustamite.

ISSN:0016-7614    

DOI:10.1080/00167617408728872

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Four hundred and thirty‐two gravity stations have been established at intervals of about 1 km in the Uralla‐Kingstown district. The Bouguer gravity anomaly map shows close correlation with the surface geology. There are gravity lows over the granitic intrusions; this is to be expected, because the surrounding sedimentary rock is 0.06 g/cm3denser than the granite.

ISSN:0016-7614    

DOI:10.1080/00167617408728873

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Major tsunamigenic earthquakes occurred on 14 July and 26 July 1971 about 100 km apart in the north Solomon Sea. The second earthquake is not considered to be an aftershock of the first: aftershock patterns and fault‐plane solutions indicate that both were the result of movements along two separate parts of a major arcuate fault surface. The first earthquake caused movement along the part of the fault that extends south‐southeast, the second in the part that extends west‐southwest, from southernmost New Ireland.

ISSN:0016-7614    

DOI:10.1080/00167617408728874

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Evidence from seismic reflection profiles across the southeast Australian continental margin indicates that in some areas eustatism has not influenced the shelf‐break zone. Where this is the case, insufficient sediment has accumulated along the rifted continental margin since the opening of the Tasman Sea to compensate for subsidence and to raise the sea floor to within reach of wave‐base erosive influences during low sea levels. In some instances there is no evidence of outbuilding, and the sediments are draped over basement structures; thus the change of slope at the shelf break is the surface expression of basement relief and changes in the depth of the shelf break are related to changes in depth of basement. Erosion during times of low sea level has played no part in the development of the shelf break and therefore it is not necessary to invoke neotectonism to explain variations in its depth.

ISSN:0016-7614    

DOI:10.1080/00167617408728875

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Often in nature and sometimes in flumes, asymmetrical sand ripples do not form when considerations of hydraulic variables and grainsize indicate that they should. This paper reports experimental inhibition of ripple formation by allowing small waves, generated from sources both at the surface and on the bed, to pass upstream along a flume. If ripples do not appear on a bed, form drag is greatly reduced and equilibria between flows and particles consequently differ from those existing if ripples are present.

ISSN:0016-7614    

DOI:10.1080/00167617408728876

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The Coolac ultramafic belt in southern New South Wales consists largely of partly to completely serpentinized harzburgite. The rocks contain a diverse assemblage of sparsely disseminated oxide, sulphide, and metallic minerals, of which magnetite, ‘ferritchromit’, heazlewoodite, pentlandite, and awaruite predominate. Other than ‘ferritchromit’, which occurs as rims on primary chromian spinel grains, the opaque minerals are enclosed in serpentine minerals and minor brucite, talc, chlorite, and tremolite, and do not occur in contact with primary olivine, orthopyroxene, clinopyroxene, and chromian spinel. The least serpentinized harzburgite contains only trace amounts of opaque minerals, whereas in almost completely serpentinized rocks, disseminated opaque minerals are common. Textural and chemical data are interpreted as indicating that the opaque mineral assemblage formed during the serpentinization processs, the metals being derived from the primary minerals, and oxygen and sulphur from the fluids responsible for serpentinization. Differing mineral assemblages occurring in the variably serpentinized rocks are interpreted as resulting from rising, although possibly fluctuating, gradients of oxygen and sulphur fugacity during progressive serpentinization.

ISSN:0016-7614    

DOI:10.1080/00167617408728877

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167617408728878

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Palaeozoic greenstones lying at the base of stratigraphic sequences or in fault blocks in the Tasman Geosyncline are compared with the Penrose Conference definnition of an ophiolite by using tabulated petrological, structural, and metallogenic data. Of 45 occurrences, only 9 are recognizably ophiolites: 4 are in rift zones adjoining Precambrian continental crust at the ends of the geosyncline; and away from the margins, in that part of the geosyncline most typically of West Pacific‐type, only 5 of the 33 greenstone occurrences are recognizably ophiolites. Ophiolites are rare in the Tasman Geosyncline, in contrast to several Atlantic‐type geosynclines. This may be a characteristic of West Pacific‐type geosynclines in general.

ISSN:0016-7614    

DOI:10.1080/00167617408728879

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

TheAssociation of Australasian Palaeontologistsis a Specialist Group of the Geological Society of Australia. It was constituted in Hobart in February 1974. Its main functions are to promote palaeontology and biostratigraphy, to arrange conferences and symposia, and to publish the Association's new journalAlcheringa.

ISSN:0016-7614    

DOI:10.1080/00167617408728880

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor