摘要:

The Albany and Torbay Adamellites are composite plutons emplaced in Pre‐cambrian gneisses of the Albany‐Esperance Block in the vicinity of Albany, Western Australia. The gneissic country rocks have been metamorphosed to the lower granu‐lite facies at Albany and the upper amphibolite facies at Torbay. Granitized aureoles about 1 km wide, metasomatically enriched in SiO2, K2O, and various trace elements commonly including Rb, Ba, La, Pb, and Th, are developed in the gneisses around both plutons. Field relations suggest late‐kinematic magmatic emplacement of the Adamellites in the catazone. Both show chemical variation trends comparable with the trends normally associated with fractional crystallization of calc‐alkali magmas, and their normative compositions correspond with the thermal trough in the system An‐Ab‐Or‐Q‐H2O at 4–7 kb PH2o, suggesting an origin involving crystal‐liquid equilibria at a water vapour pressure of about this value. The initial87Sr/86Sr ratio of 0.7118 for the Albany Adamellite is consistent with derivation of the magma from crustal rocks. The late‐kinematic field characteristics of the plutons and the limited isotopic data available are compatible with emplacement and crystallization during the closing stages of orogeny and regional metamorphism. The magmas are believed to have been generated not at their present sites of emplacement, but in a deeper, higher‐temperature zone of the crust, with magma generated during an earlier phase of the orogeny.

ISSN:0016-7614    

DOI:10.1080/00167617408728848

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

During the Cainozoic there was widespread volcanism, mainly basaltic, in eastern New South Wales. Numerous new K‐Ar ages, together with previously published results, provide information on the age of virtually all the main volcanic provinces, and indicate that the volcanism started about 70 m.y. ago in the Late Cretaceous, and was continuous from about 60 m.y. ago (Palaeocene) until about 10 m.y. ago (middle Miocene). There has been no volcanic activity since 10 m.y. ago.

ISSN:0016-7614    

DOI:10.1080/00167617408728849

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

156 samples of naturally‐occurring molybdenite from 87 localities in Australia have been examined to determine the distribution of the hexagonal (2H1) and rhombohedral (3R) polytypes. 90% of the specimens examined are 2H1polytypes, the remainder being 3R and mixtures of 2H1and 3R polytypes. The 3R and mixed polytypes are more abundant in porphyry copper deposits or as disseminations, in veins, and in garnet‐quartz pipes in granite. 2H1polytypes are the sole modification observed in pegmatites, quart‐pegmatite pipes, simple quartz veins, and skarns.

ISSN:0016-7614    

DOI:10.1080/00167617408728850

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The recent sediments of Broken Bay (Australia) have been investigated to determine the environmental conditions prevailing in this estuary.

ISSN:0016-7614    

DOI:10.1080/00167617408728851

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A major west‐trending lineament marked by a wide belt of highly deformed rocks (the Redbank Zone), lies in the Arunta Complex, north of the Amadeus Basin. Along its southern margin the Zone has been progressively affected by, and is hence older than, migmatization and granite intrusion. The migmatization event yields a Rb‐Sr isochron age of 1076±50 m.y. Within the migmatite complex, relicts of a pre‐migmatite metasedimentary sequence around the Chewings Range yield a Rb‐Sr isochron age of 1620 ± 70 m.y. The migmatites are unconformably overlain by the basal unit of the Amadeus Basin sequence, the Heavitree Quartzite. The 1076 ± 50 m.y. date thus provides a maximum age for the start of sedimentation along the northern margin of the Basin. The existence of a major zone of weakness in the basement probably exerted a strong control on basement and cover deformation during the Palaeozoic Alice Springs Orogeny.

ISSN:0016-7614    

DOI:10.1080/00167617408728852

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

This paper is a summary of the present knowledge of the Tertiary stratigraphy of Western Australia. Also included is new information on the Cainozoic of the Carnarvon Basin, a result of petroleum exploration in the area.

ISSN:0016-7614    

DOI:10.1080/00167617408728853

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The Cape Hoskins volcanoes form part of the Quaternary volcanic island arc that extends from Rabaul in the east to the Schouten Islands in the west, and they overlie the northerly dipping New Britain Benioff Zone. The products of the volcanoes range in composition from basalt to rhyolite, and are normative in quartz and hypersthene. They contain phenocrysts of plagioclase and subordinate augite, hypersthene, and in most samples iron‐titanium oxides; some samples also contain olivine or quartz or both, and some pumice contains hornblende and, rarely, biotite.

ISSN:0016-7614    

DOI:10.1080/00167617408728854

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

When Tuluman volcano, in St Andrew Strait, northern Bismarck Sea, erupted between 1953 and 1957, it produced acid rocks similar in major element chemistry to those of three other islands in the Strait — Lou, Pam Lin, and Pam Mandian. These acid rocks — termed the TLP’ series — are thought to represent magmas, or to be derivatives of a parental magma, produced by melting of crust (about 25 km thick beneath St Andrew Strait). TLP rocks have agpaitic indices ranging between 0.86 and 0.96. Acid lava also makes up 3 of the 4 Fedarb Islands at the northern end of St Andrew Strait, but its composition appears to be unrelated to that of the TLP series, and its origin is uncertain.

ISSN:0016-7614    

DOI:10.1080/00167617408728855

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

On 24 March 1970 an earthquake of magnitude ML 6.7 took place in the eastern Canning Basin. The earthquake was unusual because it occurred in a region where no previous earthquake had been reported and where there was no evidence of recent tectonic activity. First motion results indicate a thrusting type focal mechanism with the pressure axis approximately northeast‐southwest and dipping about 24° to the southwest. The main shock was followed, over the next two years, by many earthquakes in a zone covering 140 km by 20 km. The longitudinal axis of this zone is approximately parallel to the north‐northwest striking nodal plane determined from the first motion results, and to the trend of intrabasin faulting.

ISSN:0016-7614    

DOI:10.1080/00167617408728856

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167617408728847

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor