摘要:

Stratotectonic and morphotectonic data from the two principal exposed domains (pre‐Adelaidean rocks) of the Gawler sub‐province are used to characterize the Proterozoic Olarian orogeny and to distinguish its effects from those of the later Phanerozoic Delamerian orogeny.

ISSN:0016-7614    

DOI:10.1080/00167617708728975

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

In the Lake Frome area of South Australia there is a sedimentary sequence of non‐marine (or possibly distant marginal marine) pale‐green to grey, fine elastics and carbonates (Namba Formation). The base of these deposits is Medial Miocene in age and they are overlain unconformably by Pleistocene (and ? Pliocene) sediments. The Miocene sequence is equivalent to the Etadunna Formation of the Lake Eyre Basin, and the clay mineralogy is similar.

ISSN:0016-7614    

DOI:10.1080/00167617708728976

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Secondary zeolites in the Jurassic dolerites of Tasmania are re‐interpreted as burial assemblages reflecting stages of unloading of the Jurassic land surface.

ISSN:0016-7614    

DOI:10.1080/00167617708728977

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0016-7614    

DOI:10.1080/00167617708728978

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The central part of the Murrumbidgee River meanders across an alluvial plain which is 1.5 km to 5 km wide, and confined between low hills composed of granite and folded lower Palaeozoic rocks. Deposition commenced under humid and reducing conditions during the Miocene, and continued during Pliocene time. Oligomict quartz‐sand and gravel beds are dominant in the sequence, and are interlayered with grey to black clay and silty clay, which contain a prolific pollen fauna. During Pleistocene time, a marked reduction in rainfall and consequent change in vegetation resulted in the deposition of a widespread coarse polymict poorly‐sorted gravel associated with yellow and brown clay and silt.

ISSN:0016-7614    

DOI:10.1080/00167617708728979

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The Newer Volcanics Province of Victoria and South Australia consists of a major region of mainly alkaline basalts within which are two restricted areas containing strongly differentiated flow‐rocks. Typical alkalic basalts from this widespread province have K‐Ar ages from 4.5 to 0.5 m.y. and initial87Sr/86Sr ratios from 0.7038 to 0.7045. Contrastingly, in the Macedon area of differentiated lavas, flow compositions range from limburgite to soda trachyte, with K‐Ar ages from 6.8 to 4.6 m.y. and initial87Sr/86Sr ratios from 0.7052 to 0.7127. These differentiated rocks therefore are older, and some of them may have been contaminated by reaction with more radiogenic basement rocks during differentiation. Alternatively, the variation in initial Sr‐isotope composition may have resulted from varying isotopic composition of partial melts from the immediate source rocks. The most felsic of the differentiated rocks, soda trachyte, is extremely enriched with Rb relative to Sr; one of the three restricted outcrops of this rock (Camel's Hump) yields a total‐rock Rb‐Sr isochron age of 6.3 ± 0.6 m.y. with an initial87Sr/86Sr ratio of 0.7127. K‐Ar sanidine ages reported for the three outcrops of trachyte are identical to each other and to the Rb‐Sr isochron result.

ISSN:0016-7614    

DOI:10.1080/00167617708728980

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

An ‘autochthon’ model for the tectonic development of Timor is suggested, based on observations of Palaeozoic‐Mesozoic relationships from a broad area of central East Timor, including:a.(a) ‘allochthonous’ Permian rocks unconformable on metamorphic rocksb.(b) ‘allochthonous’ Permian units interbedded with ‘autochthonous’ Permian units, andc.(c) ‘autochthonous’ Triassic sediments stratigraphically overlying ‘allochthonous’ Permian rocks.

ISSN:0016-7614    

DOI:10.1080/00167617708728981

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Evidence is presented to show that the Tumut ‘greenstone’ occurrence is unlikely to be an example of Palaeozoic oceanic crust. First, new rare‐earth element analyses are unlike those obtained from oceanic tholeiites. Second, the published major‐ and trace‐element analyses of the metabasalts are not definitive of an oceanic magma type. Third, the juxtaposition of mafic volcanic rocks and ultramafic intrusives is not considered to be diagnostic of an oceanic crustal section. Fourth, the sulphide mineralization is not similar to that found in typical ophiolites such as those at Troodos in Cyprus.

ISSN:0016-7614    

DOI:10.1080/00167617708728982

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Phosphate Hill is a small inlier of Ordovician rocks enclosed in an envelope of ?Lower Devonian quartzose sandstones and shales. Lithological layering (S0) within the Ordovician inlier shows tightB1folds with a second group of folds (B2) superimposed. The orientation and shape of theseB2folds are highly variable. The overall structure of the area falls naturally into two subareas: Subarea 1 comprises sub‐horizontal east‐westB1folds which are overturned to the north and show slides on their lower limbs;B2folds in this subarea are small‐scale features. Subarea 2 is dominated byB2folds and contains a large S‐shapedB2fold in its eastern part.

ISSN:0016-7614    

DOI:10.1080/00167617708728983

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Late Silurian batholiths were emplaced into the highs in the Lachlan Fold Belt during latitudinal crustal extension. Normal faulting and possibly related wrench‐faulting resulted from the extension. Thrust faulting and compressional wrench‐faulting were produced by later horizontal compressional events. The Berridale Wrench Fault, the master fault in the Berridale region, had its major movements after Middle Devonian times, possibly during latitudinal horizontal compression in the Tabberaberan deformation. Wrench‐ and thrust‐faulting are not related to theI‐S line,nor to any change in basement conditions across the line.

ISSN:0016-7614    

DOI:10.1080/00167617708728984

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor