摘要:

The Taupo Volcanic Zone extends for approximately 300 km north-eastwards across the central North Island, New Zealand. Within the zone are five volcanic centres: Tongariro, which includes over 95% andesites; Taupo, Maroa, and Okataina, rhyolitic centres, each probably associated with multiple caldera collapse; and Rotorua, a simple collapse structure, sited on the western side of Taupo Volcanic Zone.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424173

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The morphology of the Wadati-Benioff zone in the Tonga-Kermadec island arc verified the existence of an intermediate aseismic gap in the recent subduction zone and its relation to active andesitic volcanism. The gap, interpreted as a partially melted zone, appears to be the source of primary magma for andesitic volcanoes. A clear correlation between the depth of penetration of the Wadati-Benioff zone and the major physiographic units of the ocean floor implies a nonuniform rate of subduction along the Tonga-Kermadec trench due to the hampering effect of the main structural features of the subducting Pacific plate.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424174

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Gravity and seismic refraction data are used to construct a geophysical section across the Canterbury Plains, along Ashburton River. The apparent Quaternary-Tertiary boundary deepens towards the coast. The Mesozoic basement profile shows vertical displacements of up to 1300 m and reaches a maximum depth of 3000 m below sea level at the Pacific coast.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424175

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Potassium-argon total-rock ages are presented for extrusive and hypabyssal volcanic rocks of Campbell Island Volcanics, which overlie Cretaceous-Oligocene pelagic marine (Campbell Island Group) and Upper Miocene volcaniclastic sediments (Shoal Point Formation). Ages of basalt, hawaiite, mugearite, and trachyte range from 11.1 to 6.5 Ma, but there is an important concentration at 7.0-7-4 Ma (Upper Miocene). The earliest basalt flows (11.1 Ma), seen only at Puiseux Peak, are overlain by about 300 m of hawaiite-mugearite-trachyte extrusives of alkali olivine basalt type (7.0-7.4 Ma). These in turn are capped by at least 100 m of similar but younger flows (6.5-6.7 Ma) that are best seen on the northern flanks of the island at Mt Faye.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424176

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The structurally complex rocks exposed throughout Waioeka Gorge are flysch-type redeposited volcaniclastic sedimentary rocks. The massive greywackes, thin-bedded alternating greywacke and argillite sequences, and massive argillites are inferred to have been deposited in a submarine fan-type environment by grain flow, turbidity current, and hemipelagic sedimentation mechanisms.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424177

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Sediments of the Caples terrane in the Thomson Mountains have been mapped in five units, namely Bold Peak, Kays Creek, Upper Peak, Momus Sandstone, and Mt Campbell Formations. Each unit has a distinctive clastic petrography and a diagnostic heavy mineral assemblage, as well as being sedimentologically distinct. The Caples terrane as a whole is quartz poor, and clastic assemblages are dominated by volcanic (andesitic) and plutonic (dioritic) detritus.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424178

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A zeolite-rich horizon containing calcic analcime and laumontite occurs directly above a thin grossular-bearing limestone within the Permian Wellar Coal Measures on Mt Fleming, South Victoria Land. The textural features of the zeolite-rich horizon strongly suggest that the analcime has been derived from a primary sedimentary analcimolite, even though the presence of grossular, prehnite, and laumontite indicates thermal metamorphism resulting from the intrusion of a thick Jurassic sill 146 m below. The zeolite horizon and associated thin limestones stratigraphically below appear to span the transition from an alluvial plain to a braided river environment. The analcimolite and limestones are regarded as evaporites formed in temporary lakes on an alluvial plain under arid conditions.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424179

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Collection details are summarised for two fossil turtles from New Zealand, one from the Teurian (Paleocene) Amuri Limestone, Marlborough, and the other from the Whaingaroan (Early Oligocene) McDonald Limestone, Otago. The identity of none of the other supposed reptiles recorded from the New Zealand Tertiary has been proven.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424180

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A new species ofPermophorus, P. obovatus, is described from early Triassic (Smithian) faunas of southern New Zealand, from the Takitimu foothills and Countess Range, near Eglinton Valley. Rocks with this species from Countess Range are referred to the newly proposed Retford Member, at the base of Snowdon Formation.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424181

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Poor Knights Islands, at the north-west extremity of an Upper Cenozoic chain of rhyolitic volcanoes, consist of tuffs and breccias with minor interbedded flows and sediments. Intense hydrothermal alteration has resulted in almost complete replacement of primary minerals by quartz, adularia and albite, minor sericite, cristobalite, pyrite, leucoxene and sphene, and retrograde smectite and kaolinite. The alteration took place at temperatures up to about 240°c and resulted in addition of silica and potash and the leaching of lime. Except for the near absence of calcium bearing minerals and the presence of retrograde minerals, the alteration is very similar to that occurring in the active thermal areas of Taupo Volcanic Zone today.

ISSN:0028-8306    

DOI:10.1080/00288306.1979.10424182

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor