摘要:

Group and phase velocities for Rayleigh waves, in the period range 15–100 s, were analysed for paths crossing the Coral and Tasman Seas. We used data from 14 earthquakes recorded at the 6 World Wide Standard Stations: CTA, HNR, PMG, RIV, TAU, and WEL. By fixing the S-wave velocities at 4.65 km/s from 220 to 400 km and at 5.0 km/s for greater depths, we modelled the upper 220 km. As previous workers have found for oceanic regions, it was necessary to incorporate a significant low-velocity layer (LVL), usually centred at about 150 km, in all models. Typically the lid above the LVL has an S-wave velocity of 4.50 km/s, and the LVL a velocity of 4.25 km/s.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427539

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Late Eocene-Oligocene sediments of the Te Kuiti Group represent a classical transgressive sequence from basal nonmarine coal measures to overlying shallow marine mudstones, sandstones, and limestones. Paleoenvironmental conditions in the South Auckland region during the Paleogene were such that basement Mesozoic sandstones and mudstones, the only local source rocks for terrigenous material, exerted a relatively subordinate role on the mineralogy of the Te Kuiti Group sediments accumulating in adjacent depocentres. Instead, the sediments include abundant transformed, authigenic, and biogenic mineral associations reflecting conditions pertaining in each of the pedogenetic, paludal, and temperate latitude, shallow marine environments. A kaolinite-quartz-siderite mineralogy dominates the nonmarine beds, and a low-Mg calcite-smectite-quartz-sodic plagioclase-glauconite mineralogy characterises the bulk of the marine deposits. The mineralogy bears the imprint of a complex set of factors in which the influences of climate, soil provenance, depositional environment, and diagenesis greatly dominate over the influences of tectonics and source-rock provenance.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427540

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Teurian (Paleocene) sequence at Te Kaukau Point, southeast Wairarapa, includes light green-grey, indurated, burrowed, slightly sandy calcilutite. These rocks are interbedded with laminated sandstone, mudstone, and siliceous limestone lithotypes, all of which are cut by intrusive sandstone. A variety of sedimentary structures, including burrows, indicate that the laminated sandstone was deposited conformably within the limestone sequence and is regarded as a turbidity current deposit, which later became overpressured to produce the intrusive sandstone.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427541

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Late Triassic greywacke and argillite from Titahi Bay, Wellington form part of the Torlesse Complex, interpreted as a subduction-related accretionary wedge. Several mesoscopic folds formed during tectonism, some with accompanying axial-surface cleavage, and others having cleavage oblique to the axial surface. At least two deformational events are clearly recognised. Upward-facing folds and a downward-facing fold, both with accompanying axial-surface cleavage, indicate that parts of the sequence were already overturned prior to formation of the downward-facing fold. The folds with oblique cleavage developed during the earlier event and thus are not transected folds. Groove casts were rotated to their predeformational orientation by unrolling the two fold generations. Based on the orientation of the groove casts and other sedimentary structures, the paleocurrent flowed from southwest to northeast, and reconstructions indicate that the sediment was transported longitudinally in the trench.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427542

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Two newin situfossil faunas are described from a melange terrane within Torlesse rocks in the southern Ruahine Range, North Island, New Zealand. T23/f7530 is an isolated, allochthonous limestone block containing foraminifera, brachiopods, gastropods, bivalves, ammonoid fragments, ostracods, conodonts, crinoids, echinoids, and fish remains. The bivalves includeHalobia lillieiMarwick of Oretian age (Late Triassic; Late Karnian-Early Norian). Locality T23/f3 is a massive argillite, probably of autochthonous origin, containingRetroceramus (Retroceramus) haasti(Hochstetter) of Ohauan age (Late Jurassic; Late Oxfordian-Kimmeridgian). Stratigraphic and structural relationships between the two localities are uncertain. The conodont fauna from T23/f7530 provide a possible new line of correlation between New Zealand Triassic sequences and the world standard for Late Karnian-Early Norian time.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427543

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Waipoapoa Landslide (February 1976) in Southern Hawke's Bay is a complex failure in Upper Miocene weak alternating sandstone and mudstone (flysch). The landslide extends over approximately 18 ha and forms a reactivated portion of a larger ancient landslide complex. The Waipoapoa Landslide has a calculated volume of 8.35 × 106m3.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427544

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Ponui Landslide (September 1976), in Southern Hawke's Bay, is a wedge failure in an Upper Miocene weak-rock alternating sandstone-mudstone and amalgamated sandstone succession. The planimetric area involved with failure covers 25 ha and represents the reactivation and enlargement of a previous landslide. The Ponui Landslide has a calculated volume of approximately 2.5 × 106m3.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427545

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Radiocarbon dates on corals taken from the upper landward and seaward surfaces of fringing reefs on the north coast of Viti Levu, Fiji (18°S, 178°E), indicate the probable course of Holocene sea-level change. Sea level apparently rose to c. 0.45 m above present level by 5300 years B.P. and has since declined at a constant rate. These observations are consistent with other data from Viti Levu.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427546

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The quartz-gold-stibnite-bearing Consolidated Lode at Nenthorn, eastern Otago, contains abundant prismatic quartz crystals and hydrothermal breccia. Fluid inclusion data imply that boiling occurred during mineral deposition at about 190°C at very shallow levels, possibly within 120 m of the surface. This type of vein system may be common in eastern Otago. Gold may be found beneath Sb and/or Hg deposits formed by similar near-surface hydrothermal activity.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427547

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Tarpaulin Metagranite (new name), a deformed, two-mica granitoid, crops out on The Neck, northeastern Stewart Island. It lies in fault contact with the Anglern Complex to the north, and the Paterson Group to the south.

ISSN:0028-8306    

DOI:10.1080/00288306.1987.10427548

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor