Showing papers in "Australian Journal of Earth Sciences in 1968"
TL;DR: The relationship of the shoshonite association to the tholeiite, alkali basalt, calcal-kaline and carbonatite associations is examined in this paper.
Abstract: The absarokite‐shoshonite‐banakite series described from Yellowstone Park by Iddings and the ciminite‐toscanite series described from western Italy by Washington are compared. In both regions these rocks are associated with leucite‐bearing rocks, potassium‐rich trachytes and with andesitic rocks with above average potassium. A similar association of rock‐types is described from Indonesia and several other regions including the Rift Valley of Africa where, at Bufumbira, Holmes & Harwood have described members of the absarokite‐shoshonite‐banakite, potassium trachytes and leucite rocks. It is concluded that the absarokite‐shoshonite‐banakite series and the ciminite‐toscanite series are parts of a single rock association here called the shoshonite association. Intrusive members, such as monzonites, are also briefly discussed. The relation of the shoshonite association to the tholeiite, alkali basalt, calcal‐kaline and carbonatite associations are examined and an attempt is made to relate these to te...
114 citations
TL;DR: The Baldwin Formation consists of interbedded greywackes and mudstones deposited in the New England Eugeosyncline during Late Devonian times as mentioned in this paper and they may be termed volcanic greywacks.
Abstract: The Baldwin Formation consists of interbedded greywackes and mudstones deposited in the New England Eugeosyncline during Late Devonian times. The greywackes consist essentially of andesitic detritus and they may be termed volcanic greywackes. They contain very little detrital quartz or sedimentary rock fragments. Chemical analyses of ten greywackes are presented. These show that the greywackes have an andesitic composition, differing only in their relatively high sodium contents. The high sodium values may be due to reaction between the detritus and sea water. Burial metamorphism of the greywackes has produced minerals characteristic of the prehnite‐pumpellyite metagreywacke facies. Secondary minerals include albite, chlorite, calcite, prehnite, pumpellyite and epidote.
49 citations
TL;DR: In this paper, a systematic study of Carboniferous spores from New South Wales, Australia, fifteen species (all but one of them new) are formally described and are distributed among eight established genera and two new genera (Rattiganispora, a distally annulate trilete form, and Psomospora, an inaperturate or proximally hilate form).
Abstract: In this initial systematic study of Carboniferous spores from New South Wales, Australia, fifteen species (all but one of them new) are formally described and are distributed among eight established genera and two new genera (Rattiganispora, a distally annulate trilete form, and Psomospora, an inaperturate or proximally hilate form). The species were selected as being the most characteristic and distinctive forms found in the Italia Road Formation at its well‐exposed type section in the Hunter Valley, east‐central New South Wales. The formation is a cyclical non‐marine unit, over 300 metres (1,000 ft) thick, consisting of lithic arenites together with carbonaceous shales, claystones, and siltstones; its age is regarded as West‐phalian‐Stephanian. The microfiora is compared with those known from sediments of similar age elsewhere and its place in the Australian Palaeozoic palynostratigraphic record is discussed. New specific institutions are as follows: Punctatisporites lucidulus, P. sub‐tritus, V...
47 citations
TL;DR: When a tsunami wave series approaches and interacts with a coast, the consequent passage shorewards of great volumes of water and their invasion of the land, especially within bays and up river valleys, results in the disturbance of existing sediment and the removal seawards of land debris and coastal and shallow-water marine sediments as mentioned in this paper.
Abstract: When a tsunami wave series approaches and interacts with a coast, the consequent passage shorewards of great volumes of water and their invasion of the land, especially within bays and up river valleys, results in the disturbance of existing sediment and the removal seawards of land debris and coastal and shallow‐water marine sediments. Tsunami action builds up sequences of peculiar sediments in shallow water; it at least assists in the formation and maintenance of submarine canyons and, through them, produces turbidity currents of a particularly powerful kind. Tsunami action may explain many puzzling sedimentary phenomena, for example, sudden and drastic changes in near‐shore bathymetry; the formation of chaotic sediments such as some paraconglomerates and edgewise conglomerates. It offers solutions to problems arising from the study of turbiditic sequences, both modern and ancient.
45 citations
TL;DR: In this article, travel time from explosions fired on the continental shelf round the Cape York Peninsula was recorded by a number of mobile seismic recording crews and seismic observatories, and the results from various groups of shots indicated upper crustal velocities between 5.82 km/sec and 5.94 cm/sec.
Abstract: Travel‐time from explosions fired on the continental shelf round the Cape York Peninsula were recorded by a number of mobile seismic recording crews and seismic observatories. Least squares analysis of the results from various groups of shots indicated upper crustal velocities between 5.82 km/sec and 5.94 km/sec, lower crustal velocities between 6.62 km/sec and 6.83 km/sec, and upper mantle velocities between 7.84 km/sec and 8.09 km/sec. Subsequent time‐term analysis of the results gave depths to the intermediate refractor of 10 km at the continental margins increasing to 25 km in the Gilbert River region of Cape York. The Mohorovicic “Discontinuity” (M) dips at an average of 3° from depths of 25 km at the edge of the continent to 45 km in Central Cape York and the regions northwest of Charters Towers.
26 citations
TL;DR: Neutron activation analyses for rhenium and non-radiogenic osmium abundances in molybdenites and other sulphide minerals, mostly from Tasmanian localities, indicate that the non-radioactive osmia content in these minerals is very low and is less than 0#lb005 ppm as mentioned in this paper.
Abstract: Neutron activation analyses for rhenium and non‐radiogenic osmium abundances in molybdenites and other sulphide minerals, mostly from Tasmanian localities, indicate that the non‐radiogenic osmium content in these minerals is very low and is less than 0#lb005 ppm. When compared with other recently published data, the rhenium abundances in molybdenites from Tasmania are significantly lower than those occurring within the rocks of the Tasman Geosyncline in Victoria, New South Wales and Queensland. In both Tasmania and the Australian mainland the rhenium abundances are log‐normally distributed. Within Tasmania, at least, molybdenites with relatively high rhenium contents do not seem to be necessarily associated with copper mineralisation as Riley (1967) has suggested.
22 citations
TL;DR: In this article, seven glaciated pavements of late Precambrian age in the Kimberley region of Western Australia are described, and the pavements provide further direct and unequivocal evidence of late-precambrian glaciation in northwestern Australia, and as a corollary, strengthen the case for a late pre-glacial glaciation of probable global extent.
Abstract: Seven glaciated pavements of late Precambrian age in the Kimberley region of Western Australia are described. They are of special interest because of the rarity of glaciated pavements of comparable age in other parts of the world. The pavements provide further direct and unequivocal evidence of late Precambrian glaciation in northwestern Australia, and as a corollary, strengthen the case for a late Precambrian glaciation of probable global extent.
19 citations
TL;DR: In this paper, chemical analyses of olivine analcimites and olivines nephelinite are presented and discussed, showing that these are alkaline, transitional to olivinite tholeiite and are associated with the Piebald Basalt.
Abstract: Over most of the area, the McLean Basalt, southwest of Cooktown, and the Piebald Basalt, north of Cooktown, were erupted on to a land surface generally similar to that of the present day. The basalts form horizontal flows, and a number of vents have been identified. In the main, the lavas consist of olivine basalt; these are shown by chemical analysis to be alkaline, transitional to olivine tholeiite. In the McLean Basalt, several flows consisting of olivine analcimite have been discovered. An olivine nephelinite flow is associated with the Piebald Basalt. Chemical analyses of olivine analcimites and the olivine nephelinite are presented and discussed.
13 citations
TL;DR: In the Palaeozoic geosynclinal sediments of the Mossman and Cooktown areas, the sediments have been strongly folded in four phases, and are now characterised by widespread steep dips and steeply plunging folds as discussed by the authors.
Abstract: The Palaeozoic geosynclinal sediments of the Mossman and Cooktown areas consist of shallow‐water shelf sediments in the west, subdivided into two formations, overlain by a thick pile of deep‐water turbidites occupying the remainder of the Palaeozoic outcrop and constituting one formation. The sediments have been strongly folded in four phases, and are now characterised by widespread steep dips and steeply plunging folds.The first folds (B1) were acute folds with steeply dipping axial planes striking north or northnorthwest, and with almost horizontal axes. Broad open B2 folds, with steep axial planes of various trends, were superimposed on the steeply dipping beds of the B1 folds. Few minor structures are associated with either of these phases of folding. The third phase of folding (B3) resulted in tight, almost isoclinal, folds with steep axial planes trending between north and northwest, and with steep plunges. These folds were accompanied by a strongly developed axial plane slaty cleavage which, in many areas, led to a progressive transposition of the original sedimentary bedding into a new lamination. The final period of folding (B4) was a minor one, affecting only a limited area in which the slaty cleavage of the B3 folds is the dominant planar element. The cleavage is folded into sharp‐angled chevron folds with almost horizontal axes and gently dipping axial planes.
12 citations
TL;DR: A systematic appraisal of the seismicity of the Sydney Basin was not possible until a network of seismograph stations was established there in 1958-1959 as discussed by the authors, by means of this network, 181 tremors have been located in and around the Basin between 1959 and 1967, including the 1961 Robertson-Bowral earthquake and 33 aftershocks.
Abstract: Minor earthquakes have been felt in the Sydney Basin since the foundation of the colony in 1788, but a systematic appraisal of the seismicity of the area was not possible until a network of seismograph stations was established there in 1958–1959. By means of this network, 181 tremors have been located in and around the Basin between 1959 and 1967, including the 1961 Robertson‐Bowral earthquake and 33 aftershocks. Many epicentres lie near the western boundary of the Sydney Basin, and some others appear to be associated with structures at the western edge of the inner Cumberland Basin. The epicentres of the Robertson‐Bowral sequence suggest a fault system trending to the northwest in that area. A number of events were located near the edge of the continental shelf, and it is possible that these may delineate the eastern edge of the Sydney Basin.
12 citations
TL;DR: The lead-zinc ore veins of the Zeehan field have long been accepted as excellent examples of hydrothermal zoning centred around the Heemskirk Granite stock, despite several anomalies apparent in earlier descriptions and a general lack of detailed information about the distribution and textural relationships of the ore and gangue minerals as discussed by the authors.
Abstract: The lead‐zinc ore veins of the Zeehan field have long been accepted as excellent examples of hydrothermal zoning centred around the Heemskirk Granite stock, despite several anomalies apparent in earlier descriptions and a general lack of detailed information about the distribution and textural relationships of the ore and gangue minerals. Mineralogical studies show that the zoning can be substantiated, and the apparent anomalies have arisen as a consequence of the combined effects of multiple mineralisation and post‐mineralisation faulting. When allowance is made for these effects, the zoning is seen to be manifested by progressive changes, with increasing distance from the parent stcok, in ore and gangue mineralogy. Although the changes are mostly transitional, they can be conveniently described in terms of four successive zones, namely, 1. Cassiteritic; 2. Pyritic; 3. Sidero‐pyritic; and 4. Sideritic. In general the zonal sequence closely parallels the paragenetic sequence, as determined from d...
TL;DR: In this paper, the authors examined the layering adjacent to the orebody in the Zinc Corporation, New Broken Hill Consolidated, and Broken Hill South mine workings and leases and found that much of the deformation observed in contact with the lode is a direct result of deformation and metamorphism.
Abstract: Examination of the layering adjacent to the orebody in the Zinc Corporation, New Broken Hill Consolidated, and Broken Hill South mine workings and leases suggests that much of the layering observed in contact with the lode is a direct result of deformation and metamorphism. The layering in the “pelitic” gneisses is described and its stratigraphic significance is discussed. The contacts of the orebody are broadly concordant with the layerings described and the geometry of the layering and the orebody shape define two southward‐plunging folds. These folds are equivalent to the Group 2 folds defined by Hobbs (1966) for the northern end of the orebody. The plunge reversals in the orebody folds are attributed to subsequent deformational movements associated with a retrogressive phase of metamorphism.
TL;DR: The meandu creek bentonite as discussed by the authors is a type of bentonite that is similar to the meandugu bentonite, and it can be traced back to the early 1800s.
Abstract: (1968). The meandu creek bentonite—a reply. Journal of the Geological Society of Australia: Vol. 15, No. 2, pp. 347-350.
TL;DR: In this article, the lead-zinc ores of the Zeehan field in Tasmania have been investigated and the lead mineralogical zoning in the ZEEHAN field has been discussed.
Abstract: (1968). Mineralogical zoning in the lead‐zinc ores of the Zeehan field, Tasmania. Journal of the Geological Society of Australia: Vol. 15, No. 2, pp. 217-244.
TL;DR: The Eulogie Park Gabbro as discussed by the authors consists of 65 saucer-shaped layers consisting of olivine gabbros, ferrigabbros and leucogabbros.
Abstract: The Eulogie Park Gabbro comprises approximately 65 saucer‐shaped layers consisting of olivine gabbros, ferrigabbros, troctolites, leucogabbros, gabbros and magnetite‐rich rocks. The intrusion is divisible into three main parts: a lower portion consisting mainly of ferrigabbros and magnetite‐rich layers, a middle portion composed of troctolites and olivine gabbros, and an upper portion consisting mainly of olivine gabbros and leucogabbros. The minimum stratigraphic thickness is 3,000 ft (900 m). Modal compositions and textures exhibit marked changes across the boundaries of the layers. Mineral compositions vary irregularly with height in the layered sequence, and small oscillations are common. Compositional data suggest that temperature increased during the first half of the crystallisation period, and then remained fairly constant. Chemical and petrographie studies of the iron‐titanium oxides indicate that the primary phase was an ulvospinel‐magnetite solid solution. Subsolidus oxidation resulted...
TL;DR: The shell of Subansiria sp. is composed of two distinct layers, the primary or outer layer is approximately 0#lb 1 mm thick and appears to consist of a granular outer part and an inner portion in which small crystals are oriented normal to the surface of the layer.
Abstract: The shell of Subansiria sp. is composed of two distinct layers. The primary or outer layer is approximately 0#lb1 mm thick and appears to consist of a granular outer part and an inner portion in which small crystals are oriented normal to the surface of the layer. The secondary or inner layer of the shell comprises elongate fibres inclined obliquely forwards at a low angle from the exterior to the interior of the shell. Transverse sections show the cross‐sectional outlines of the fibres of the secondary layer. The characteristic spatulate outline of the end of each secondary layer fibre on the internal surface of the shell is produced by the overlap of successive fibres. In radial section the fibres of the secondary layer underlying the area of attachment of the muscles in the pedicle valve are similar to those in other parts of the layer except that they are several times larger. The shell is punctate and around each puncta the fibres of the secondary layer are deflected towards the external surface of the shell.
TL;DR: Triphormic clay minerals from the Permian sediments of the Lower Hunter Valley fall into two categories (mixed layer mica-montmorillonite and montmorillonites) as discussed by the authors.
Abstract: Triphormic clay minerals from the Permian sediments of the Lower Hunter Valley fall into two categories—mixed‐layer mica‐montmorillonites and mont‐morillonites The montmorillonites from epiclastic sedimentary environments contain appreciable interlayer potassium and show “abnormal” (mica‐like) layer characteristics The mixed layer minerals have mica‐montmorillonite ratios ranging from about 8:2 to 1:1 These structures are also mica‐like, but are usually richer in interlayer K+ and show more extensive tetrahedral Al for Si substitution than the fully expandable types A common mica parentage is implied for these mixed‐layer and abnormal montmorillonite species Mixed‐layer minerals from the coarser rock types invariably show more highly‐ordered interstratification than those from the lutites The trend in ordering is toward maximum alternation and predominance of ABABAB type regularity Strongest development is generally observed in the medium‐grained arenites It is concluded that the o
TL;DR: The valid names for two species of spiriferids with multi‐ribbed valve flanks in the Berriedale Limestone in Tasmania are now considered to be Trigonotreta stokesi Koenig, 1825 and "Spirifer” tasmaniensis Morris, 1845.
Abstract: Three names are available for two species of spiriferids with multi‐ribbed valve flanks in the Berriedale Limestone in Tasmania. The valid names for the species are now considered to be Trigonotreta stokesi Koenig, 1825 and "Spirifer” tasmaniensis Morris, 1845; the other available name, Grantonia hobartensis, 1953, is a synonym of Trigonotreta stokesi. Grantonia Brown, 1953 (type species, Grantonia hobartensis) is therefore a synonym of Trigonotreta Koenig, 1825 (type species, Trigonotreta stokesi).