摘要:

The effectiveness of freezing and thawing as a means of reducing the mean particle size of fine-grained sediments has been investigated. It is shown that the amount of size reduction which takes place depends on the structure of the clay mineral. Where bonding between the basal planes of component sheets of the clay mineral is strong there is little size reduction by congelifraction. Where the bonding is weak expansion of ice produced from water entering between the basal planes causes rapid comminution.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422079

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Manganese ore in New Zealand can be divided into: (a) manganese gangue in auriferous quartz lodes; (b) manganese pockets or masses associated with contemporaneous “Red Rocks” in Permian–Cretaceous sediments; and (c) manganese pockets or lenses associated with metamorphosed “Red Rocks” in regionally metamorphosed schists. All the manganese mined has come from Permian–Jurassic rocks in (b), the characteristic features of the deposits being their patchiness and their close association with “Red Rocks” that are intercalated as scattered subordinate masses in the dominant greywackes and argillites. The “Red Rocks” consist of spilitic lavas, jaspers, cherts, volcanic argillites and carbonate, and the manganese is considered to have been precipitated during the submarine volcanism.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422080

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

A north–west striking belt of metasediments occurs within biotite granites in the Mt Radiant area. Copper and molybdenum mineralisation occurs in the vicinity of the granite-metasediment contact. The lodes are approximately parallel to the two major joint directions, which are parallel and at right angles, respectively, to the granite-metasediment contacts. It is considered that the ore deposits are genetically related to the emplacement of the granites.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422081

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Progressive movement resulting in displacements that can be resolved into horizontal and vertical components is recorded in the fault–displacement of flights of river terraces, the oldest terraces showing the greatest displacements. No unique interpretation of the sequence of events is possible, as illustrated from a hypothetical example, but the vertical and horizontal components of individual movements can be deduced according to a stated rule. In associating fault movement and river downcutting, the heights of the terraces on the lower side of the fault scarp should be used, not those on the higher side. As a result it is concluded that at the Wairau River downcutting and faulting do not show the linear relation deduced by Wellman; as a preferred interpretation, the rate of faulting is supposed to have been substantially uniform while the rate of downcutting has diminished, since the formation of the highest, depositional, surface in the flight. The depositional surface is typical of the highest in many terrace flights, and where these are the principal outwash aggradational surfaces of Last Glaciation age, or their correlatives, 20,000 years is thought a closer estimate of age than the 10,000 years used previously; previous estimates of the rates of fault movement are correspondingly halved.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422082

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The current application of S32/S34measurements in ore genesis studies is examined and it is suggested that, in emphasising fractionation processes, most investigators have made insufficient allowance for the possible influence of source variation, hybrdisation, migrational contamination and post–depositional homogenisation in the final development of S32/S34ratios in different sulphide ores.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422083

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The Calyptraeidae appear to have been present in New Zealand by late Cretaceous times. By mid–Eocene, the genusSigapatellaLesson had appeared and from such Eocene forms there have been two main evolutionary lines∶ one leading to the Recent S.superstesFleming; the second to the other Recent sigapatelloids. Analysis of sympatric and synchronous upper Oligocene populations showed variation in shell form fromSigapatellaLesson toZegalerusFinlay. The systematic position of some Calyptraeidae is discussed.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422084

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Beach and dune deposits on the south coast of Southland were sampled and the minerals of specific gravity greater than 2.9 were extracted, magnetically separated and counted for radioactivity; the percentages of heavy minerals are estimated and the predominant minerals noted. Total quantities of beach sands west of Orepuki are estimated. The predominant heavy mineral throughout is a green amphibole. No commercially attractive quantities of ore minerals are indicated.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422085

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The results from a number of observations of the currents in Cook Strait, made by various methods, are recorded. One of the methods of measurement enabled estimates of the current a few inches from the sea bottom to be made. The information presented deals mainly with the tidal currents, because in most of the measurements, the drift current effects were masked by the strong tidal currents.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422086

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Five periods of moraine building and aggradation in the Wanaka–Hawea basin and upper Clutha Valley are due to glaciations, called in this paper, the Hawea, Albert Town, Luggate, Lindis and Clyde Advances, in order of increasing age. The deposits of the Hawea advance have been examined in some detail in natural and artificial exposures near the site of the Lake Hawea Control Dam, and a peat section, the base of which has given a radio-carbon date of 15,100 ± 200 years, shows a flora sequence over the later part of the time since the Hawea Advance.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422087

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

During transcurrent faulting arcuate fold trends are produced and the regional stress is resolved into a series of oblique, lower order, stress systems which enable cross folds to develop without any necessary changes to the direction of the regional stress.

ISSN:0028-8306    

DOI:10.1080/00288306.1960.10422088

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor