The Kuta Formation is mainly a limestone deposit which crops out on the flanks of the Kubor Anticline in the Central Highlands of Papua New Guinea. It has been variously regarded as Cainozoic, Permian and Permo-Triassic in age, but is now positively dated as late Norian or Rhaetian (Late Triassic) on the basic of conodonts, molluscs and brachiopods. The Kuta Formation is thus the youngest known Triassic formation in Papua New Guinea. Interpretation of the local stratigraphy is simplified by this dating. It is now apparent that the marine Triassic sedimentation in Papua New Guinea commenced no later than the Anisian (Middle Triassic) and continued, probably uninterrupted, until Rhaetian time. The fossils identified and described include the conodont Misikella posthernsteini Kozur and Mock, 1974, the ammonite Arcestes (Arcestes) cf. sundaicus, Welter, 1914, and some bivalves. The brachiopods Clavigera, Zugmeyerella, Sinucosta, Robinsonella, ?Hagabirhynchia are equally important in dating the assemblage, but will be described in detail separately. All the more closely identified fossils have a Tethyan Provincial aspect except Clavigera which was previously known only from New Zealand and New Caledonia.

Thermal waters in Matupi Harbour and Sulphur Creek, Rabaul caldera have D/H and O18/O16 ratios that are indicative of a mixed source. They are the result of mixing of local meteoric waters with hot water of marine origin. The stable isotope data are grouped into distinct areas close to the meteoric water line. They suggest that the thermal systems away from the shoreline are dominated by meteoric water and that warmed sea water only enters the springs at the shoreline. Low temperature (100°C) fumarolic exhalations from Tavurvur and Rabalankaia volcanoes consist largely of recycled meteoric water. These conclusions conflict in part with those drawn from anion ratio and trace metal contents which were inferred by previous authors to be consistent with an hypothesis of modified sea water origin. We suggest that the chemistry of these acid, mineralised geothermal waters is a reflection of their later, near surface, history and does not necessarily give a correct picture of their ultimate origin. The enhanced Fe, Mn, and Zn values of the Matupi springs are a function of the leaching potential of geothermal fluids at elevated temperatures, and of the chemistry of the porous and chemically reactive rocks through which they pass.

Chemically analysed lavas from Bagana, an active andesitic volcano on Bougainville Island, can be assigned to one of three age groups - pre-1943, 1943-53, or 1959-75. Lavas of the oldest group are chemically the most fractionated, whereas those of the 1943-53 group are the most mafic. The rocks of the youngest group, although intermediate in degree of fractionation have K2O, Rb, and Ba abundances similar to, or lower than, the rocks of the 1943-53 group. The three groups appear to represent distinct batches of magma that were successively erupted from Bagana, possibly from a high-level reservoir that was periodically emptied and refilled. The andesites are regarded as fractionates of mantle-derived mafic magmas. Most of the crystal fractionation probably took place during ascent from the mantle source region, and before entry into the reservoir beneath the volcano. An average chemical composition of the analysed Bagana andesites has major-element values close to those of the mean for more than 800 analysed late Cainozoic volcanic rocks from Papua New Guinea, and is proposed as a reference andesite composition for comparative studies.

Geochemical data are presented for a sequence of spilitic pillow basalts (Tumu River basalts) associated with peridotites and gabbros of the Marum ophiolite complex in northern mainland Papua New Guinea. The basalts are strongly differentiated from relatively magnesian types (Mg-value = 70) to ferrobasalts (Mg-value = 30) characterised by high levels of Fe, Ti, Zr, Nb, Y. The Tumu River basalts are enriched in large ion lithophile elements such as REE, Zr, Hf, Nb, P2O5, and compare with tholeiites from oceanic islands. Major and trace elements suggest extensive fractionation involving olivine, pyroxene, and plagioclase, followed by pyroxene, plagioclase, titanomagnetite, and ilmenite. Trace-element plots are used to examine fractionation processes and to estimate abundances in the parent magma. The calculated initial concentrations are compared with abundances and abundance ratios in least fractionated enriched and depleted tholeiites. The abundances in the parent magma are used to calculate source abundances for large (20-30%) degrees of partial melting. The levels range from 2-3 times chrondites for HREE, Ti, Y, Zr, Sc, and P2O5, to 3.5-5.5 times for LREE, and are similar to those inferred for other LREE-enriched tholeiites from both oceanic and continental areas. The chemistry of the basalts therefore reflects the mantle-source composition rather than a particular tectonic setting within an ocean basin.

A co-operative survey between the Soviet Academy of Sciences and the Australian Bureau of Mineral Resources during 1979 successfully measured the acceleration due to gravity using an absolute apparatus at Sydney, Hobart, Alice Springs, Darwin, and Perth in Australia, and at Port Moresby in Papua New Guinea. The measurements have a precision of about 6 micro Gal and an accuracy of about 15 microGal. Gravity ties to earlier stations allow comparisms with GAG-2 gravity meters, OVM pendulums and IGSN71 results. Gravity differences between cities are generally not significant at the 95 percent confidence level. Gravity differences at individual cities are also not significantly different from zero. The mean difference for all cities could be interpreted as having a component of secular variation of +3.3 ± 1.2 microGal/yr.

Longitudinal Cross Section

This series of maps covers the whole of Papua New Guinea at a scale of 1:250 000 (1cm on a map represents 2.5km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150km from east to west and 110km from north to south. There are more than 50 special maps in the series and these maps cover a non-standard area some also include imagery and additional narrative information. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Some maps are supplemented by relief shading. Coverage: Upon completion of revision the series will cover the whole of Australia with 513 maps. Currency: From 1995 to 2007. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, (GDA94 compliant at this stage). Projection: Lambert Conformal Conic. Medium: Paper, flat and folded copies.

Interpretation of seismic refraction data from the southwestern coast of the Papuan Peninsula and the northwest Coral Sea gives consistent results using several inversion techniques. Sediments over the Papuan Plateau are 5 km thick; to the west and northwest they thicken to 10 km along the axes of the Moresby and southern Aure Troughs. Farther out into the Coral Sea, over the Eastern Plateau, they are 1 to 2 km thick. Beneath the sediments, a layer with a P-wave velocity of 6.07 km s^-1 was inferred over the region. It is underlain along the southern coastline of the peninsula by a lower crustal layer with a velocity of 6.9 km s^-1, which is probably also present under the Eastern Plateau. We cannot say whether the lower crustal layer also occurs offshore under the Moresby Trough, but it is not present under the Aure Trough in the north. Intervals where the velocity increases with depth are likely in the lower crust (> 17 km) under the peninsula, but we have insufficient data to say if they are present offshore. The Moho is 27 to 29 km deep along the southwestern coast of the peninsula. It shallows to 19 km under the Moresby Trough and deepens to 25 km under the Eastern Plateau. The crust is therefore continental under the Papuan Peninsula and Eastern Plateau and, excluding the sediments, oceanic under the Moresby Trough. We have examined several tectonic models for the region that imply different stress patterns at the time of formation of the Moresby Trough. We favour one in which northern Australia, the Eastern and Papuan Plateaus and the Papuan Peninsula once formed a continuous, continental crust. With the opening of the Coral Sea Basin, crustal thinning extended northwards along the axis of the Moresby Trough, probably into the Aure Trough. This model implies a regional tensional stress pattern at the time of formation.

This series of maps covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent.

This series of maps covers the whole of Papua New Guinea at a scale of 1:250 000 (1cm on a map represents 2.5km on the ground). Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150km from east to west and 110km from north to south. There are more than 50 special maps in the series and these maps cover a non-standard area some also include imagery and additional narrative information. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Some maps are supplemented by relief shading.