摘要:

The Kaikoura system of orogenesis, sedimentation, and volcanism reached a tectonic climax in Northland in the uppermost Oligocene with east-to-west gravity-slide emplacement of an internally disrupted plate of Upper Jurassic oceanic igneous rocks (Tangihua Volcanics) and Cretaceous-Oligocene sedimentary formations. Synorogenic and postorogenic epicontinental marine sedimentation (Waitemata, Otaua, and Parengarenga Groups) extended throughout the Waitakian, Otaian, and Altonian stages of the Lower Miocene. The sediments include distinctive facies derived by marginal collapse of the gravity-slide sheet (Onerahi Chaos-breccia) and by deep erosion of the Tangihua Volcanics (Albany Conglomerate); concurrent volcanic activity (Manukau Breccia, Wairakau Andesites, and Parahaki Volcanics) contributed calc-alkaline debris to the sedimentary basin. Volcanism and marine sedimentation terminated during a post-Altonian episode of profound block-faulting which marked the end of Kaikoura Orogeny in Northland and was followed by a sequence of Upper Tertiary Quaternary subaerial volcanic eruptions. The Mid-Tertiary tectonic timetable for northern New Zealand is similar to that of New Caledonia, New Hebrides, and New Guinea, and seems similarly to have been controlled by a sequence of subduction zones at the interface between the Indian and Pacific plates, and substantial dextral movement on a transform Alpine Fault system.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428473

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The Tertiary sequence at Naseby and Kyeburn consists of the Hogburn Formation, terrestrial quartzose sediments of probably Arnold age, overlain by the marine Naseby Greensand (Whaingaroan-Duntroonian) and succeeded by a further terrestrial suite, the Wedderburn Formation. This transgressive-regressive sequence is aggregated into the new Stranraer Group, and is overlain, probably unconformably, by the piedmont gravels of the Maori Bottom Formation. The Dansey Gravels Formation, formerly considered a transitional unit between the Wedderburn and Maori Bottom Formations is discredited as a valid unit.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428474

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A map of the Wairoa River-Mount Heslington area is presented, in which Garden Formation (new formation), Problematica Shellbed (new fomation name), Max Sandstone (new formation), Heslington Conglomerate (new formation), Mount Wellington Sandstone, and Richmondiana Shellbed (new formation name) are shown as formations within Richmond Group, Murihiku Supergroup. The formations comprise 610 m of siltstone, sandstone, conglomerate, shellbed, and tuff exposed in sections along Wairoa River and on the slopes of Mount Heslington. The succession is repeated in the limbs of the isoclinal Heslington Syncline which appears to be non-plunging. The syncline lies north-west of Eighty-eight Fault and is itself faulted. Faunas allow recognition of Oretian, Otamitan, and Warepan stages (Upper Triassic). Stages in the evolutionary development of athyridid and spiriferinide brachiopods and the occurrence of gregarious bivalves allow refined correlation with formational units in sequences in the Southland and Kawhia synclines. Heslington Syncline appears to have an extended sequence for part of late Otamitan time.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428475

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Detailed study of the Kaitorete barrier enclosing Lake Ellesmere suggests that barrier formation took place 6 000–7 000 years ago when sea level was still rising in this area. Relic cliffs and shore platforms west of Birdlings Flat date from the last interglacial or earlier. Barrier development has now ceased and shore-line erosion is extending eastwards across the barrier.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428476

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The oldest rocks in the Mt Arthur district, dominantly marble, shale, and phyllite of Cambrian to Devonian age, are divided into eight formations belonging to the Haupiri, Mt Arthur, and Baton River Groups. The Mt Arthur and Baton River Groups are intruded by basic rocks of the late Paleozoic Riwaka Complex and acidic rocks of the Mesozoic Separation Point Batholith. Unconformably overlying the rocks in the south and west of the district are Lower Tertiary coal measures and limestones belonging to the Westhaven Group.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428477

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Two iron-rich concretions from the Waikato Coal Measures are described. Each has a hard iron oxide shell with a weathered outer surface. In one case there is a solid siderite-rich interior; in the other the shell encloses a void which contains a clay rattle. Concentrations of Fe, Al, Ca, K, Si, P, S, Mn, Ti, Mo, Mg, and Cu, in various parts of the concretions have been measured and the dominant minerals in these parts have been determined. The concretions are considered to represent different stages in a process which begins when iron mobilised by decomposing organic matter is precipitated under reducing conditions as siderite in sediments. Subsequent oxidising conditions produce a series of “boxes” each with a dense ferric oxide shell. The shell thickens as the enclosed ferrous ions are oxidised and eventually a void is created within the concretion. The kaolin rattle represents the weathered remnant of the host sediment.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428478

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Before the installation of a seismograph on Campbell Island, the Campbell Plateau was regarded as aseismic. In the first six years of the instrument's operation, however, it recorded twelve local earthquakes, with magnitudes between 3½ and 5½. All these earthquakes are within 230 km of Campbell Island, and must have originated on the Campbell Plateau, but only one was large enough for its position to have been determined precisely. The earthquake occurred on 1971 Jun 26, near Cathedral Banks, an area of volcanic outcrops about 60 km south-east of Auckland Island. The best epicentre for this earthquake was obtained by assuming aP-wave velocity of 7.78 km/s across the Campbell Plateau, rather than that of 8.1 km/s which is appropriate beneath New Zealand. This earthquake, and others in the south of New Zealand that have been recorded at Campbell Island, show crustal phases which confirm that the structure of the Campbell Plateau is continental. The arrival times of these phases are consistent with the crustal thickness of about 20 km determined previously from dispersive-wave analysis.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428479

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Torlesse rocks in the northern Ben Ohau Range form steeply plunging north-facing structures with steep axial planes trending mostly NNE and NE. In a central belt of the range textural zone 2 (and some zone 3) schists have been developed, probably after the folding, by a mechanism including flattening across the schistosity plane. Fold axes have variable attitudes and plunge north in the non-schistose rocks. In the schists the axes are more strongly aligned and plunge south to give overturned structures and well developed lineations. Décollements with dextral vergence complicate the pattern of the main structure, the Bush Stream anticline, which is exposed along the crest of the range; they also affect the Whale Stream syncline to the east. Local south-facing folds in the non-schistose rocks of the eastern foothills may indicate earlier stages of structural development. Movement along the Great Groove Fault on the eastern edge of the schist has been complex, possibly changing from a system with a reverse component of slip to one with a normal component.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428480

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Recent mapping in the Tinui-Awatoitoi district has revealed a major unconformity in what was previously considered to be a continuous Cretaceous sequence. The rocks below the unconformity, mapped as the Torlesse Supergroup, are strongly folded, indurated greywacke and argillite, locally containing Upper Jurassic (Upper Tithonian) fossils. Overlying the unconformity are less indurated gently folded sediments of Clarence and Raukumara Series (Albian-Campanian) age mapped as the Mangapurupuru Group. The occurrence of an unconformity at a comparable stratigraphic position elsewhere on the east coast of New Zealand is discussed.

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428481

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Coals from oil and gas wells in the Gippsland Basin (Victoria, Australia) and in the Taranaki Basin (New Zealand) range up to high-volatile bituminous in rank and exhibit a wide range of coal type. Original depths of burial are estimated at up to 5000 m (17 000 ft); temperatures are estimated to have ranged up to 160°c(320°f).

ISSN:0028-8306    

DOI:10.1080/00288306.1974.10428482

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor