摘要:

K‐Ar measurements were carried out on 24 mineral concentrates, mostly biotite, from rocks in the Broken Hill district of New South Wales; Rb‐Sr measurements were carried out for comparison on eight of these. The results range from 430 to 1360 m.y. for K‐Ar, and from 460 to 550 m.y. for Rb‐Sr. They indicate that the last event of sufficient intensity to affect the biotites of this area occurred in the Lower Palaeozoic. This may be correlated, as a first hypothesis, with the event which caused emplacement of the secondary “Thackaringa‐type” lead deposits.

ISSN:0016-7614    

DOI:10.1080/00167616308728543

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

The rocks of the Birrimian Series in the Winneba District of Ghana have been progressively metamorphosed during the emplacement of the early and late orogenic granitic masses. The“Z”axial colours of the amphiboles generated in the hypabyssal and extrusive rocks of the Series can be broadly correlated with the grade of metamorphism as indicated by the mineral assemblages. A possible classification for amphibolites is discussed and the role of quartz indicated.

ISSN:0016-7614    

DOI:10.1080/00167616308728544

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

The Palmerville Fault in North Queensland is an important structure with a probable length of at least 600 miles, extending from Princess Charlotte Bay in the north to Townsville in the south, and controlling the configuration of the coast line of eastern Cape York and at Halifax Bay. The fault forms the western boundary of both the Palaeozoic Hodgkinson Basin (Tasman Geosyncline) and of the Mesozoic Laura Basin, and has been active at least four times since the Silurian. The latest movements took place during the late Cainozoic.

ISSN:0016-7614    

DOI:10.1080/00167616308728545

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

An analysis of joint patterns in the Grampians Group rocks o£ Western Victoria has established that the dominant directions are north‐north‐west, east‐north‐east, west‐north‐west, north‐north‐east and north. The master joints are steeply‐dipping structures which formed after the sediments were lithified and folded. The joint‐formation is not genetically related to the folding and post‐dates the emplacement of the igneous intrusions. Joint orientation is independent of lithology and the sediments have reacted as a uniform mass to an applied stress.

ISSN:0016-7614    

DOI:10.1080/00167616308728546

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Potassium‐argon measurements have been carried out on the separated micas of 27 samples, principally granites, from the Mount Isa‐Cloncurry region of north‐western Queensland. There is evidence for at least two tectonic periods within the “Lower Proterozoic” of the area. The first is represented only in the north‐western portion, with ages greater than 1,770 m.y. on the Ewen Granite, and on the granites of the Nicholson River area to the far north‐west. The second at 1,400–1,450 m.y. is manifested only to the south and east of the Kalkadoon‐Leichhardt complex, and including the Sybella Granite. The results may be further interpreted as lending support to the concept of a possible “metamorphic discontinuity” along the western flank of the Kalkadoon‐Leichhardt complex, postulated by Carter, Brooks and Walker; as suggesting possible contemporaneity of the Cliffdale Volcanics and the Argylla Formation; and as giving further evidence for the antiquity of stromatolites. Comparison with earlier work suggests that some deposits in this region may be contemporaneous with some of the Agicondian sediments of the Katherine‐Darwin area, and that the second tectonic period corresponds with the K‐Ar ages obtained on the Davenportian granites of Central Australia.

ISSN:0016-7614    

DOI:10.1080/00167616308728547

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

The results of potassium‐argon measurements are reported. Three samples from the southern end of the New England bathylith confirm its Permian age (240–245 m.y.). Two samples of the “pre‐Permian” granites are not younger than Lower Permian (Hillgrove, 270 m.y.; Barrington Tops, 260 m.y.). A sample of the analcite basalt from Spring Mountain gave an Oligocene age (34 m.y.) by measurements on two separate minerals.

ISSN:0016-7614    

DOI:10.1080/00167616308728548

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

K‐Ar age determinations on granites from Central Queensland support the conclusions of field mapping, that the intrusives of the Anakie High are generally older than the rocks of the Drummond Basin. Results on granites from the Bowen‐Collinsville region indicate that they pre‐date most of the Bowen Basin sediments. Four ages are reported for basement rock from bore‐cores in the Great Artesian Basin. They confirm Precambrian basement to the south of the Mt. Isa‐Cloncurry area, and suggest possible Precambrian in the Long‐reach Spur. Two samples from the Nebine Ridge give Lower Carboniferous results. A previous report of Permian basement in the Surat Basin has been shown to be incorrect.

ISSN:0016-7614    

DOI:10.1080/00167616308728549

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Fractionation of tholeiitic magma in the Red Hill intrusion produced a gradational series of rocks ranging from dolerite to granophyre (McDougall, 1962). Granophyres are enriched in Fe, Si and alkalies, and impoverished in Mg, Ca and Al. With fractionation the magma was depleted rapidly in Cr and Ni owing to their removal in early crystallizing pyroxene and iron oxides. Cobalt decreases gradually from chilled dolerite to silicic dolerite, followed by a significant maximum in the most Fe‐enriched rocks, and finally decreases markedly in the granophyres. Cobalt follows Fe2+ closely and shows no obvious relationship with Mg. Copper was progressively enriched in the magma during the main stages of fractionation until precipitation of sulphide occurred, which caused impoverishment of Cu in the final liquid. Copper also is present in the silicates, it substitutes for Na in the feldspars and Fe2+ in pyroxenes and iron oxides.

ISSN:0016-7614    

DOI:10.1080/00167616308728550

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Nepea narinosaWhitehouse, 1939, is as yet the only known species of the Nepeidae and Nepeacea. It is based on fragmentary material unsuitable for conclusive interpretation. The census of Nepeidae as yet unpublished includes five genera and twelve species, confined to the Middle and early Upper Cambrian of Australia. All nepeids have cedariform posterior sutures, free cheeks fused into a unit, a preglabellar boss, forked ocular ridges and a pustulose test.Nepea narinosais distinguished by its very long intergenal spines and pointed, falcate palpebral lobes provided with a doublure.

ISSN:0016-7614    

DOI:10.1080/00167616308728551

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

The pegmatite complex of epi‐Permian age at Bismuth near Torrington, N.S.W., consists of an elongated intrusion of a granitoid quartz‐topaz rock (silexite) together with a series of pegmatites of varying composition. The principal pegmatite consists of orthoclase, biotite, quartz and beryl with concentric zoning passing outwards into fine‐grained biotite‐beryl rock containing a number of ore minerals: arsenides of Co, Fe and Ni, wolframite, bismuth, bismuthinite, molybdenite, joseite, cassiterite, rutile, uraninite and monazite. Small pegmatite veins issuing from this main body contain, in addition to the silicate minerals, high temperature tetrahedrite, chalcopyrite and sphalerite. A second group is characterised by quartz, orthoclase and beryl with occasional patches of tourmaline.

ISSN:0016-7614    

DOI:10.1080/00167616308728552

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor