摘要:

In the high‐grade (granulite facies) metamorphic rocks at Broken Hill the foliation is deformed by two groups of folds. Group 1 folds have an axial‐plane schistosity and a sillimanite lineation parallel to their fold axes; the foliation has been transposed into the plane of the schistosity by these folds. Group 2 folds deform the schistosity and distort the sillimanite lineation so that it now lies in a plane. Both groups of folds are developed as large folds. The retrograde schist zones are zones in which new fold structures have formed. These structures deform Group 1 and Group 2 folds and are associated with the formation of a new schistosity and strain‐slip cleavage. The interface between ore and gneiss is folded about Group 1 axial planes but about axes different from those in the foliation in the gneiss. On the basis of this, the orebody could not have been parallel to the foliation prior to the first recognizable structural and metamorphic events at Broken Hill. The orebody has been deformed by Group 2 and later structures.

ISSN:0016-7614    

DOI:10.1080/00167616608728616

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Important Late Quaternary tectonic movements near Echuca initiated drainage diversions and modifications from which a detailed geomorphic sequence is established. In this sequence, the development of faults, lakes, lunettes and stream cycles may be placed in correct order and some inferences made about the conditions that caused them.

ISSN:0016-7614    

DOI:10.1080/00167616608728617

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Travel times from explosions fired on the continental shelf off the central coast of New South Wales were observed at permanent stations and spreads of seismic exploration instruments, and combined with existing results to give a seismic crustal profile across part of southeastern Australia. An intermediate layer, dipping to the southwest, underlies the surface rocks and has aPvelocity of about 6–52 km./sec. Beneath Sydney, its top may either be in contact with the basin sediments at a depth of about 5 km., or separated from them by a wedge of a few kilometres of 6 km./sec. material. The Mohorovičić discontinuity (M) is at a depth of 25 km., dips to the southwest at about 4 degrees, and the velocity under it is about 7.86 km./sec. The depth to the top of the intermediate layer under the Snowy Mountains is about 20 km., and the revised depth to M is about 42 km. M dips at about 2° to the southwest in this region, and the velocity at the top of the mantle is 8.1 km./sec.

ISSN:0016-7614    

DOI:10.1080/00167616608728618

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The Australian Permian bivalvesMegadesmus, Astartila, Pyramtis,andMyoniahave previously been grouped in either the Family Pachydomidae (Fischer, 1887) or the Family Edmondiidae (King, 1850). Because of similarities in their musculature (in addition to those in dentition, micro‐ornament, and to some extent, shape) they can now be included in the same family as the deep‐burrowing bivalveVacunella(previouslyChaenomya). Vacunellais closely related to the living genusPholadomyawhich has existed at least since the Mesozoic, and the two can be placed in the same family — Pholadomyidae (Fleming, 1828). Because of these similarities betweenPholadomya, Vacunella,and the “Pachydomidae” it seems likely that the middle and upper Palaeozoic edmondioid bivalves gave rise to the Mesozoic and Cainozoic pholadomyoids, and that these two groups together constitute a major division of the Class Bivalvia — a division that may have been relatively distinct since Ordovician time.

ISSN:0016-7614    

DOI:10.1080/00167616608728619

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

In the southwestern Bonaparte Gulf Basin, a pebbly sandstone and an overlying dolomite breccia (together called the Waggon Creek Breccia) mantle a partly exhumed late Tournaisian and early Viséan surface. The sandstone contains pebbles of metaquartzite and quartz, and the breccia consists of angular blocks of dolomite up to 30 ft (9 m.) long, and rounded pebbles and boulders of quartz and metaquartzite, in a sandy dolomite matrix. Marine fossils indicate a Visean age. The pebbly sandstone is probably beach rock, and the overlying brecciaisa littoral talus breccia probably formed by the isolating and undermining by the sea of beds of dolomite in the otherwise soft Cockatoo Formation. Many coarse breccias are related to the relief along faults, whether actual or postulated; the Waggon Creek Breccia probably owes its coarse texture to sedimentary and erosional processes only, and its description here may help in the recognition of similar deposits elsewhere.

ISSN:0016-7614    

DOI:10.1080/00167616608728620

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

A Devonian granite complex intrudes Precambrian and Silurian siltstones and sandstones as well as (?) Cambrian volcanics and dunite.

ISSN:0016-7614    

DOI:10.1080/00167616608728621

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Lower Palaeozoic sedimentary and volcanic rocks east of Queanbeyan, N.S.W., have undergone multiple deformation resulting in four systems of folds. The first of these consists of large isoclinal, recumbent folds (F1). The second generation folds (F2) are the most pronounced; they consist of flattened flexural‐slip folds with well developed axial‐plane slaty cleavage. Minor variants of this system are associated with meridionally‐trending faults. Third and fourth generation folds are minor kinksystems.

ISSN:0016-7614    

DOI:10.1080/00167616608728622

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Extremely fine‐grained pelagic oozes overlie basal basaltic lavas on Malaita Island, on the Pacific flank of the Solomon Islands group. These sediments contain upto 20%planktonic (but not benthonic) Foraminifera, but have less than5%acid‐insoluble clay and little or no terrigenous material. They are associated with radiolarian chert and with finely disseminated marine manganese. The Foraminifera include several species ofGlobotruncana,referred toG. arca, G. havanensis, G. lapparenti and G. tricarinata.The sediments accumulated in a low‐energy, deep‐water environment (exceeding 1,000 m.) during Late Cretaceous (Senonian) time, probably in the late Senonian. These sediments are the oldest in the Solomon group and older than any so far found in the outer part of the Melanesian re‐entrant. Their age supports the idea that the Solomon Islands began their geological history in the Cretaceous.

ISSN:0016-7614    

DOI:10.1080/00167616608728623

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The reported age of 1,100 ± 50 m.y. for the Albany Granite is taken as marking the waning stages of the main orogeny in the south coast of Western Australia. The high initial87Sr/86Sr for this granite, 0.7118 ± 0.0064, suggests an anatectic or rheomorphic origin which is consistent with petrographic evidence for the absence of a later metamorphism. Shales from the Stirling Range Beds indicate a metamorphic event at 1,150 ± 40 m.y. which is considered to be the time of upthrusting of rocks of higher metamorphic grade to their present position adjacent to the Stirling Range Beds. The minimum age of deposition for the Stirling Range Beds is postulated as 1,340 m.y.

ISSN:0016-7614    

DOI:10.1080/00167616608728624

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Rb‐Sr isotopic age measurements relate emplacement of the Pieman and Meredith Granites (356 ± 9 and 353±7 m.y., respectively), and the Bischoff and Renison Bell Porphyries (349 ±4 and 355 ± 4 m.y., respectively) to the Tabberabberan Orogeny. The genetic relationship of the Bischoff Porphyry to mineralization and the agreement between the age of this porphyry and the age of the adjacent Meredith Granite, strongly suggests that the Bischoff mineralization resulted from granite intrusion.

ISSN:0016-7614    

DOI:10.1080/00167616608728625

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor