摘要:

A major phreatic eruption occurred in Ruapehu Crater Lake, North Island, New Zealand, at 1975 April 24d, 03h59m, N.Z.S.T. Only nine minutes of volcanic-seismic activity preceded the eruption, but crater dilation had been measured by a geodetic survey two weeks earlier. Bad weather prevented observation of the eruption.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424215

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424216

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

White Island volcano erupted fresh andesite during March 1977, in the first emission of new lava bombs and blocks recorded in historic time. Preliminary analytical data indicate that the new lava differs petrographically and chemically from all other analysed White Island lavas. The eruption commenced with ejection of accessory ash derived from crater floor debris, overlying a shallow magma intrusion which has been causing inflation of the crater floor since 1973.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424217

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The Torlesse rocks of Kakahu, South Canterbury, New Zealand, consist of metasiltstone, metagreywacke, conglomerate, chert, metavolcanics, and marble. These rocks belong to textural zones 1 & 2A and the prehnite-pumpellyite metamorphic facies. Laminated, often graded, bedding occurs, but the rocks are generally devoid of sedimentary structures. Conglomerate is uncommon and was found at only three localities. Thirteen occurrences of chert up to 160 m thick are recorded, and radiolaria are provisionally identified in some chert thin sections. Two adjacent lithologies of intercalated metavolcanics and marble outcrop in the lower Kakahu gorge. The westernmost lithology is a 140–m–thick sequence of sixteen bedded units of metatuff, grey marble, and metasiltstone. The second lithology which lies directly to the east of the former is 90 m of intercalated poorly schistose hematitic metavolcanics and white marble. The Kakahu marble is a 30–m–thick grey marble which has yielded a fauna of upper Carboniferous conodonts. Conodonts of similar age have also been obtained from the grey marble which is interbedded with metatuff and metasiltstone in the lower Kakahu gorge.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424218

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The Mount Somers Volcanics of mid Canterbury in eastern South Island are a high-K calcalkaline andesite–dacite–rhyolite suite erupted subaerially approximately 95 Ma ago during the long Late Cretaceous episode of normal geomagnetic field. Thermoremanent magnetic directions at 46 sites, corrected for post–eruption tectonic tilt, are stable and group well (a95= 3·8°, K = 31·7) with a very steep mean inclination (I = –85°, D = 354°). The resulting paleomagnetic South Pole position is at 52° S 174° E, indicating that Canterbury was within 10° of the South Pole 95 Ma ago, and that little finite rotation of Canterbury relative to the South Pole has occurred since.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424219

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Opencast mining at Waikato North Head, Franklin County, South Auckland, New Zealand, has exposed the sedimentary structures in Late Quaternary titanomagnetite ironsands of two units of the Kaihu Group: the Waiuku Blacksand Member (Hood Formation) and the Entrican Dune Member (Mitiwai Formation).

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424220

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Geological, geochemical, and ore microscopy studies were undertaken on the Endeavour Inlet antimony–gold prospect, Marlborough Sounds, New Zealand.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424221

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Two examples of natural bridges cut in basalt lavas are described. Upstream of both examples is a gorge and a dry waterfall. Strearnwater bypasses the waterfall via enlarged joints in the flow. These features seem to have been initiated by collapse and extension of lava tube systems and the arches represent stronger sections of tube roof that have survived. Erosion and enlargement of joint planes has been important in developing these features and presently this may be the major erosional process in these valleys.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424222

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The extent of lateral inhomogeneity in the uppermost mantle beneath New Zealand has been studied by mapping the variation of Pn and Sn velocities. Ten regions of constant structure were required to model the distribution of velocities, which range from 7·4 km/s and 3· 95 km/s for Pn and Sn respectively, beneath the central North Island, to 8· 7 km/s and 4· 8 krn/s beneath Nelson. It is suggested that the regions partition the uppermost mantle according to whether its constituents are ultramafic or mafic and according to the concentrations of open cracks and melt.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424223

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Examination of mean sea levels during three of the most damaging storms on the New Zealand coast in the past decade reveals the storm surges produced had maximum elevations of only 0·6 m. Departures from isostatic equilibrium in mean sea level are common, however; a consequence of New Zealand's windy climate. The associated alongshore flows, on the west coast at least, are large compared to the steady state flow on the continental shelf under calm conditions. These flows may have a strong influence an the dispersion of material that is set in motion by the windgenerated waves.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424224

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor