Geological structure of the forearc basin in central Hawke’s Bay, eastern North Island

Central Hawke’s Bay lies within an extensive forearc basin in eastern North Island that developed during the Late Miocene to Pleistocene. The onshore structural elements of Hawke’s Bay can be classified into four structural domains, each reflecting differing styles and scales of deformation. These domains are from west to east, the axial range domain, the range front con¬tractional domain, the central forearc basin domain, and the eastern contractional domain. Some degree of the oblique-interaction of the Australia and Pacific plates on the subduction thrust is inferred to be partitioned across the four structural domains and to be expressed dominantly as oblique-(dextral) slip on faults bordering the axial ranges, and as short¬ening on reverse faults and folds in more eastern parts of the forearc. The axial range domain involves the eastern parts of the North Island axial ranges where there is marked oblique-slip displacement on major faults. Some dextral offest is accommodated in the range front contractional domain, although dip-slip displacement is more significant. The central forearc basin domain is comparatively undeformed with only minor reverse faulting and (fault-force driven) folding. By comparison, the ad¬jacent eastern contractional domain, which comprises an accretionary wedge, is characterised by imbricate reverse and thrust faulting and associated folding. A small degree of dextral-slip is also accommodated in this domain. The uppermost parts of the inboard margin of the accretionary wedge, particularly the part onshore, is currently undergoing gravitationally-driven collapse expressed as deep-seated landslides and normal faulting. Many folds in the basin are fault-cored, several of which have been targeted in recent years by petroleum exploration companies (e.g. Hukarere-, Whakatu-and Kereru-). Most deformation of the forearc basin fill in central Hawke’s Bay is post early Nukumaruan (2.4 Ma) and much of this has occurred since the early Pleistocene (.8 Ma). Dextral-slip on Mohaka and Ruahine Faults since the Early Pliocene is likely to be less than 0 km. Significant unconformities in the basin fill reflect early phases of development of oblique-slip faults in the axial ranges. New dextral oblique-slip faults are developing in the basin fill to the east of the main oblique-slip faults bordering the ranges

Stratigraphy and development of the Late Miocene-Early Pleistocene Hawke’s Bay forearc basin

A Late Miocene-Early Pleistocene mixed carbonate-siliciclastic sedimentary succession about 2 500 m thick in the Hawke’s Bay forearc basin is the focus of a basin analysis. The area under investigation covers 3 500 km2 of western and central Hawke’s Bay. The stratigraphy of Hawke’s Bay Basin is characterised by dramatic vertical and lateral facies changes and significant fluxes of siliciclastic sediment through the Late Miocene and Pliocene. This project aims to better understand the character and origin of the sedimentary succession in the basin. Geological mapping has been undertaken at a scale of 1:25000, with data managed in an ARCINFO geodatabase, following the database model employed in the IGNS QMap programme. Along the western margin of the basin there is progressive southward onlap of late Cenozoic strata on to basement. The oldest units are of Late Miocene (Tongaporutuan) age and the youngest onlap units are of latest Pliocene (Nukumaruan) age. Geological mapping of the basin fill places constraints on the magnitude (about 10 km) and timing (Pleistocene) of most of the offset on the North Island Shear Belt. Lithofacies have been described and interpreted representing fluvial, estuarine, shoreface and inner- to outer-shelf environments. Conglomerate facies are representative of sediment-saturated prograding fluvial braidplains and river deltas. These units are dominated by greywacke gravels and record the erosion of the Kaweka-Ahimanawa Ranges. Sandstone facies typically comprise very well sorted, clean non-cemented units of 10-50 m thickness that accumulated in innershelf environments. Siltstone facies probably accumulated in relatively quiet, middle- to outer-shelf water depths, and comprise well-sorted, firm non-cemented units with occasional tephra interbeds. Limestone facies represent examples of continent-attached cool-water carbonate systems that developed in response to strong tidal currents and a high nutrient flux during the Pliocene. These facies are examples of mixed siliciclastic-bioclastic sedimentary systems. Of these facies the widespread distribution and thickness of sandstone and limestone units present the most potential for hydrocarbon reservoirs. Similarly, the distribution of siltstone and mudstone beds provides adequate seal rocks. Mangapanian limestone facies have already been targeted as potential petroleum reservoirs (e.g. Kereru-1). Geological mapping suggests that potential hydrocarbon reservoir and seal rocks occur extensively in the subsurface

Systematic lithostratigraphy of the Neogene succession exposed in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand

This report presents a systematic lithostratigraphy for the Neogene (Miocene–Recent) sedimentary succession in central parts of Hawke’s Bay Basin in eastern North Island, New Zealand. It has been built up chiefly from strata exposed in outcrop, but petroleum exploration drill hole data have also been incorporated to produce this stratigraphic synthesis. Most of the strata exposed in this part of the basin are of Late Miocene (Tongaporutuan, local New Zealand Stage) to Recent age, and the majority of this report focuses on these starta, with brief description of Middle and Early Miocene formations. A companion PR report (Kamp et al. 2007) contains stratigraphic columns for sections through the Neogene succession described in this report

Late Miocene – Early Pleistocene paleogeography of the onshore central Hawke’s Bay sector of the forearc basin, eastern North Island, New Zealand, and some implications for hydrocarbon prospectivity

The timing of trap formation in relation to the timing of source rock burial and maturation are important considerations in evaluating the hydrocarbon prospectivity of onshore parts of the forearc basin in central Hawke’s Bay. We describe here aspects of the Late Miocene to Early Pleistocene paleogeography for the area based on detailed field mapping and lithofacies analysis, to help constrain petroleum systems evaluations. Key conclusions are: • Most deformation of the forearc basin fill appears to be relatively young (i.e. post-2 Ma). This deformation has occurred after a major phase of Late Miocene to Pliocene sediment accumulation, and is particularly significant along the northwestern and southeastern margins of the basin. • The axis of the forearc basin in central Hawke’s Bay appears to have undergone little structural deformation. Gentle force and reverse faults in the subsurface may be suitable traps. • The most widespread potential reservoir beds are Miocene sandstone beds. • Potential hydrocarbon source rocks are mostly absent from western parts of the basin due to significant Neogene uplift and erosion. They are, however, probably still widely preserved beneath central parts of the basin where uplift and erosion have been much less pronounced. • Miocene structures within the axis of the basin, buried by the Late Miocene to Pleistocene siliciclastic succession, are likely exploration targets. The forearc basin has been substantially inverted along its western side since the latest Pliocene, resulting in erosion of older sediments, including potential source rocks, down to basement in ranges flanking its western side. The stratigraphy along the eastern margin of the forearc basin, and particularly the outcrop pattern of westward-younging Plio-Pleistocene limestones, records the development of faulting and folding associated with the elevation and growth of the inboard part of the accretionary wedge. Parts of the forearc basin succession have become involved in the accretionary wedge, which has migrated westward through time. Uplift of the inboard margin of the accretionary wedge since the latest Miocene helped to cause an interior seaway to develop to the west during the Pliocene. Distinctive coarse-grained bioclastic carbonate sediments of the Te Aute lithofacies were deposited along both margins of the seaway, which was most extensive during the Late Pliocene (Mangapanian). Although significant volumes of siliciclastic sediment were supplied to the basin during the Pliocene, strong tidal currents periodically swept much of these sediments northeastward. Tidal connections existed during the Pliocene into Wanganui Basin in the vicinity of Kuripapango and Manawatu Gorge. By the latest Pliocene (lower Nukumaruan), the interior seaway became closed in the south with uplift of the Mount Bruce block in northern Wairarapa. Potential reservoirs within the map area include both shelf and redeposited sandstone beds in the Miocene to Early Pliocene Tolaga Group. Thick, coarse-grained, variably cemented Plio-Pleistocene limestone lithofacies in the Mangaheia Group are widespread along the margins of the basin, and have been the targets for several past exploration programmes. However, drilling has shown that the attractiveness of the Pliocene limestone facies as reservoir beds is limited because they quickly pass laterally into siliciclastic mudstone away from the margins of the basin

Analysis of the central Hawke's Bay sector of the Late Neogene forearc basin, Hikurangi margin, New Zealand

Hawke's Bay province lies within an extensive forearc basin in eastern North Island, New Zealand, that developed during the Late Miocene to present. An area of about 5 700 kmsup2; in central Hawke's Bay has been geologically mapped at 1:50 000 scale as part of an analysis of the Late Miocene-Early Pleistocene basin fill. A substantially revised lithostratigraphic nomenclature is proposed for the Neogene succession, particularly for the latest Miocene-Early Pleistocene part (Mangaheia Group). The Tolaga Group is extended into central Hawke's Bay from the north, and incorporates the Early Miocene-Early Pliocene succession. It is proposed that the Hawke's Bay, Petane, Napier, and Poporangi Groups be abolished, and incorporated into a geographically expanded Mangaheia Group. The Petane Group is demoted to Petane Formation. Most formations within the group are now redefined as members, with the exceptions of the Esk Mudstone and Kaiwaka Formations, which are retained as separate formations. An age model has been developed for the basin fill, chiefly using molluscan biostratigraphy. The Tongaporutuan-Kapitean boundary occurs in the Waitere Formation, and the Kapitean-Opoitian boundary occurs within the Mokonui Sandstone. The Opoitian-Waipipian boundary probably occurs in the Titiokura Formation, and the Waipipian-Mangapanian boundary in the Te Waka and Pohue Formations. The Mangapanian-Nukumaruan boundary has been identified at many localities, and occurs in several stratigraphic units, including the Papakiri Member (Matahorua Formation) and Sentry Box Formation. Geochemical analysis of glass shards in the Hikuroa Pumice Member (Petane Formation) suggests a correlation to tephra in the ODP 1124 record, and an inferred age of c. 2.15 Ma is suggested for this unit. The Plio-Pleistocene boundary is located in the Waipatiki Limestone Member (Petane Formation), and the top of the Olduvai paleomagnetic subchron occurs in the overlying Devils Elbow Mudstone Member. The geological structure of the basin is classified into four structural domains. The axial range domain involves the eastern parts of the North Island axial ranges and there is marked oblique-slip displacement on major faults within it. Some oblique-slip is accommodated in the adjacent range front contractional domain, although dip-slip displacement is more significant. The more easterly central forearc basin domain is comparatively undeformed with only minor reverse faulting and associated folding. The eastern contractional domain comprises the inboard margin of the accretionary wedge, and is characterised by imbricate reverse and thrust faults, and associated folding. The uppermost parts of the accretionary wedge are currently undergoing gravitationally-induced collapse, expressed as deep-seated landslides and normal faulting. While significant unconformities in the Neogene succession possibly reflect early phases in the development of the major faults in the North Island Shear Belt, most deformation of the basin fill is relatively young (post-lowermost Nukumaruan, c. 2.4 Ma), and much of this has occurred since the Early Pleistocene (c. 1.8 Ma), when deformation apparently intensified. This intensification coincides with the initiation of volcanism and rifting in the Taupo Volcanic Zone. The amount of Pliocene-Recent dextral-slip on the Ruahine Fault is likely to be less than 10 km, and there is probably less than 1 km of dextral-slip on the Mohaka Fault. New dextral-slip faults are developing in the basin fill east of the main oblique-slip faults, possibly due to dextral rotation of eastern North Island and the Hikurangi margin. Forty-one lithofacies within the Late Miocene-Early Pleistocene sedimentary succession have been identified and grouped into six lithofacies assemblages. Each assemblage generally corresponds to a broad depositional environment. Siltstone lithofacies (inner to outer shelf) dominate the succession, followed by sandstone (shoreface-inner shelf), bioclastic (inner to middle shelf), mixed siliciclastic-bioclastic (nearshore to middle shelf), conglomerate (non-marine to shoreface), and volcaniclastic (non-marine to outer shelf) facies in decreasing abundance. In addition, thirty molluscan biofacies associations and sub-associations have been identified, representing both in situ and transported assemblages, and paleoenvironments ranging from estuarine to outer shelf settings. Vail-type sequences, typically 20-80 m thick, are best developed in quote;middlequote; Pliocene to Early Pleistocene strata. These sequences are dominated by coarsening-upward packages of siliciclastic-dominated sediments, although bioclastic facies increase in prominence in Upper Nukumaruan cycles. Sequences are typically stacked in a strongly aggradational pattern, and although some periods of accelerated subsidence are recorded in the stratigraphic record, the aggradational nature of the succession shows that basin subsidence mostly kept pace with sediment flux during the Mangapanian to Upper Nukumaruan. Transgressive systems tracts (TSTs) typically comprise a combination of bioclastic and siliciclastic lithofacies. Highstand systems tracts (HSTs) are dominated by fine-grained siliciclastic-dominated facies. Regressive systems tracts (RSTs) may be either siliciclastic or bioclastic-dominated, although siliciclastic-dominated RSTs are most common. Lowstand systems tracts (LSTs) are mostly characterised by non-marine greywacke conglomerate beds. They sharply overlie shallow-marine rocks, and were deposited when high-bedload river systems prograded across a low-gradient coastal plain and exposed continental shelf. Eight sequence motifs have been developed, each representing different positions across a paleoshelf. While these motifs share some similarities, unique combinations of subsidence, sediment flux, and sediment provenance have combined to differentiate them. An idealised quote;shoreline to slopequote; two-dimensional sequence model has been produced for the Nukumaruan part of the basin succession using the motifs. The model sequence illustrates the idealised distribution across a paleoshelf of the various lithofacies, macrofaunal associations, and sequence stratigraphic surfaces. The Neogene geological history of central Hawke's Bay can be usefully subdivided into three major phases, each represented by one of the three lithostratigraphic groups documented. The Early Miocene-Early Pliocene (Otaian-Lower Opoitian) phase is represented by the Tolaga Group. This group comprises four deepening-upward bathyal-dominated packages with shelfal beds at their base. This succession is overlain by a thick sandstone (Mokonui Sandstone). Mokonui Sandstone is unconformably overlain by the Mangaheia Group (Upper Kapitean-Upper Nukumaruan), characterised by shelfal deposits with some cyclothemic intervals. Occasional upper bathyal beds occur, but appear to represent short-lived depositional phases. The uppermost Neogene phase is represented by the Middle Pleistocene (Castlecliffian) Kidnappers Group, characterised by thick non- to marginal-marine greywacke conglomerates. The basin has been substantially inverted along its western side, involving movement on faults of the North Island Shear Belt. The stratigraphic record along the eastern margin of the forearc basin records the development of faulting and folding associated with the growth of the inboard part of the accretionary wedge, such that parts of the forearc basin succession have become involved in the accretionary wedge. The outcrop pattern of westward-younging Pliocene limestones demonstrates that the inboard margin of the accretionary wedge has migrated toward the centre of the basin over time. Younger limestone beds (e.g. Mason Ridge Formation) presently crop out close to the forearc basin axis and at lower elevations compared with older Pliocene limestone beds (e.g. Kairakau Limestone) located along the eastern margins of the basin. Uplift of the accretionary wedge resulted in the development of a Pliocene interior seaway, which was most extensive during the Mangapanian and characterised by the development of prominent limestone formations (Te Aute lithofacies) along both margins. Although large volumes of siliciclastic sediment were entering the basin, strong tidal currents periodically swept the sea floor of siliciclastic sediment, allowing extensive continent-attached carbonate banks to develop along the western side of the basin. Thick continent-detached limestone beds developed along the eastern side of the basin due to the elevated positions of accretionary ridges. Breaches in the seaway were present at times in the areas of Kuripapango and the Manawatu Gorge. By the Lower Nukumaruan, the interior seaway became permanently closed to the south with uplift of the Mount Bruce block in northern Wairarapa. The most important influence on the stratigraphic architecture of the Neogene succession has been the tectonic factor. In comparison with the well developed cyclothemic record in the adjacent Wanganui Basin, the cyclothemic record in the Hawke's Bay area is incomplete and poorly developed. In most parts of the succession, tectonic influences have overprinted glacio-eustatic sea-level fluctuations. Only a limited correlation can be achieved between rocks in the Mangaheia Group and the elta;sup18;O record contained in deep-sea records, as the sequences are not well enough developed in general to allow for cycle-by-cycle correlations

Structure of the Hawke’s Bay Forearc Basin and North Island Shear Belt, eastern North Island, New Zealand

This report describes the broad structure of the forearc basin in Central Hawke’s Bay, provides descriptive details about many of the faults and folds and interprets the timing of formation of these structures. The structures are illustrated on 1: 50 000 geological maps (Bland and Kamp 2014) and four regional cross-sections (Enclosure 1). The North Island Shear Belt (NISB) encompasses a series of sub-parallel reverse and oblique-slip faults lying along the western margin of the basin. We infer no more than 10 km dextral offset on Ruahine Fault and a few hundred metres on Mohaka Fault, and their formation during the Late Pliocene (3.0 – 2.6 Ma). This was preceded by regional tilting along the western basin margin from c. 4.7 Ma. The southeastern margin of the basin has been offset by dip-slip reverse faults and uplifted through growth of the inboard margin of the accretionary wedge formed within the Hikurangi margin

Hawke’s Bay forearc basin (eastern North Island, New Zealand): Stratigraphy, biostratigraphy, chronology, geological maps and paleogeography

This report documents the results of analysis of the late Neogene forearc basin in central Hawke’s Bay, eastern North Island (Hikurangi subduction margin), New Zealand. This analysis is based on new 1:50,000-scale geological maps of the succession exposed in outcrop in central Hawke’s Bay, which are reproduced here as six sheets (Enclosures 3 & 4). The analysis builds on detailed stratigraphic and facies descriptions of the Late Miocene (Tongaporutuan) to Pleistocene (Castlecliffian) basin fill (see also Bland et al. 2007; Kamp et al. 2008), its biostratigraphy and chronology, which are integrated here. The history of Late Neogene basin development is summarised in a series of paleogeographic maps

Megasequence architecture of Taranaki, Wanganui, and King Country basins and Neogene progradation of two continental margin wedges across western New Zealand.

Taranaki, Wanganui and King Country basins (formerly North Wanganui Basin) have been regarded as discrete basins, but they contain a very similar Neogene sedimentary succession and much of their geological history is held in common. Analysis of the stratigraphic architecture of the fill of each basin reveals the occurrence of four 2nd order megasequences of tectonic origin. The oldest is the early-early Miocene (Otaian Stage) Mahoenui Group/megasequence, followed by the late-early Miocene (Altonian Stage) Mokau Group/megasequence (King Country Basin), both of which correspond to the lower part of the Manganui Formation in Taranaki Basin. The third is the middle to late Miocene Whangamomona Group/megasequence, and the fourth is the latest Miocene-Pleistocene Rangitikei Supergroup/megasequence, both represented in the three basins. Higher order sequences (4th, 5th, 6th), having a eustatic origin, are evident in the Whangamomona and Rangitikei megasequences, particularly those of 5th order with 41 ka periodicity. The distribution of the megasequences are shown in a series of cross-section panels built-up from well -to-well correlations, complemented by time-stratigraphic cross-sections. The base of each megasequence is marked by marine flooding and represents a discrete phase in basin development. For the first megasequence this corresponded to rapid subsidence of the King Country Basin in a compressional setting and basement overthrusting on the Taranaki Fault, with the rapid introduction of terrigenous sediment during transgression. The Mahoenui megasequence accumulated mostly at bathyal depths; no regressive deposits are evident, having been eroded during subsequent uplift. The second (Mokau) megasequence accumulated during reverse movement on the Ohura Fault, formation of the Tarata Thrust Zone, and onlap of the basement block between the Taranaki Fault and the Patea-Tongaporutu-Herangi High (PTH). The Whangamomona megasequence accumulated during extensive reflooding of King Country Basin, onlap of the PTH High and of basement in the Wanganui Basin. This is an assymetrical sequence with a thin transgressive part (Otunui Formation) and a thick regressive part (Mount Messenger to Matemateaonga Formations). It represents the northward progradation of a continental margin wedge with bottom-set, slope-set and top-set components through Wanganui and King Country basins, with minor progradation over the PTH High and into Taranaki Basin. The Rangitikei megasequence is marked by extensive flooding at its base (Tangahoe Mudstone) and reflects the pull-down of the main Wanganui Basin depocentre. This megasequence comprises a second progradational margin wedge, which migrated on two fronts, one northward through Wanganui Basin and into King Country Basin, and a second west of the PTH High, through the Toru Trough and into the Central and Northern Grabens of Taranaki Basin and on to the Western Platform as the Giant Foresets Formation, thereby building up the modern shelf and slope. Fifth and 6th order sequences are well expressed in the shelf deposits (top-sets) of the upper parts of the Whangamomona and Rangitikei megasequences. They typically have a distinctive sequence architecture comprising shellbed (TST), siltstone (HST) and sandstone (RST) beds. Manutahi-1, which was continuously cored, provides calibration of this sequence architecture to wireline log character, thereby enabling shelf deposits to be mapped widely in the subsurface via the wireline data for hydrocarbon exploration holes. Similar characterization of slope-sets and bottom-sets is work ongoing. The higher order (eustatic) sequences profoundly influenced the local reservoir architecture and seal properties of formations, whereas the megasequence progradation has been responsible for the regional hydrocarbon maturation and migration. Major late tilting, uplift and erosion affected all three basins and created a regional high along the eastern Margin of Taranaki Basin, thereby influencing the migration paths of hydrocarbons sourced deeper in the basin and allowing late charge of structural and possibly stratigraphic traps

Neogene stratigraphic architecture and tectonic evolution of Wanganui, King Country, and eastern Taranaki Basins, New Zealand

Analysis of the stratigraphic architecture of the fills of Wanganui, King Country, and eastern Taranaki Basins reveals the occurrence of five 2nd order Late Paleocene and Neogene sequences of tectonic origin. The oldest is the late Eocene-Oligocene Te Kuiti Sequence, followed by the early-early Miocene (Otaian) Mahoenui Sequence, followed by the late-early Miocene (Altonian) Mokau Sequence, all three in King Country Basin. The fourth is the middle Miocene to early Pliocene Whangamomona Sequence, and the fifth is the middle Pliocene-Pleistocene Rangitikei Sequence, both represented in the three basins. Higher order sequences (4th, 5th, 6th) with a eustatic origin occur particularly within the Whangamomona and Rangitikei Sequences, particularly those of 6th order with 41 000 yr periodicity

Megasequence architecture of Taranaki, Wanganui, and King Country basins and Neogene progradation of two continental margin wedges across western New Zealand.

Taranaki, Wanganui and King Country basins (formerly North Wanganui Basin) have been regarded as discrete basins, but they contain a very similar Neogene sedimentary succession and much of their geological history is held in common. Analysis of the stratigraphic architecture of the fill of each basin reveals the occurrence of four 2nd order megasequences of tectonic origin. The oldest is the early-early Miocene (Otaian Stage) Mahoenui Group/megasequence, followed by the late-early Miocene (Altonian Stage) Mokau Group/megasequence (King Country Basin), both of which correspond to the lower part of the Manganui Formation in Taranaki Basin. The third is the middle to late Miocene Whangamomona Group/megasequence, and the fourth is the latest Miocene-Pleistocene Rangitikei Supergroup/megasequence, both represented in the three basins. Higher order sequences (4th, 5th, 6th), having a eustatic origin, are evident in the Whangamomona and Rangitikei megasequences, particularly those of 5th order with 41 ka periodicity. The distribution of the megasequences are shown in a series of cross-section panels built-up from well -to-well correlations, complemented by time-stratigraphic cross-sections. The base of each megasequence is marked by marine flooding and represents a discrete phase in basin development. For the first megasequence this corresponded to rapid subsidence of the King Country Basin in a compressional setting and basement overthrusting on the Taranaki Fault, with the rapid introduction of terrigenous sediment during transgression. The Mahoenui megasequence accumulated mostly at bathyal depths; no regressive deposits are evident, having been eroded during subsequent uplift. The second (Mokau) megasequence accumulated during reverse movement on the Ohura Fault, formation of the Tarata Thrust Zone, and onlap of the basement block between the Taranaki Fault and the Patea-Tongaporutu-Herangi High (PTH). The Whangamomona megasequence accumulated during extensive reflooding of King Country Basin, onlap of the PTH High and of basement in the Wanganui Basin. This is an assymetrical sequence with a thin transgressive part (Otunui Formation) and a thick regressive part (Mount Messenger to Matemateaonga Formations). It represents the northward progradation of a continental margin wedge with bottom-set, slope-set and top-set components through Wanganui and King Country basins, with minor progradation over the PTH High and into Taranaki Basin. The Rangitikei megasequence is marked by extensive flooding at its base (Tangahoe Mudstone) and reflects the pull-down of the main Wanganui Basin depocentre. This megasequence comprises a second progradational margin wedge, which migrated on two fronts, one northward through Wanganui Basin and into King Country Basin, and a second west of the PTH High, through the Toru Trough and into the Central and Northern Grabens of Taranaki Basin and on to the Western Platform as the Giant Foresets Formation, thereby building up the modern shelf and slope. Fifth and 6th order sequences are well expressed in the shelf deposits (top-sets) of the upper parts of the Whangamomona and Rangitikei megasequences. They typically have a distinctive sequence architecture comprising shellbed (TST), siltstone (HST) and sandstone (RST) beds. Manutahi-1, which was continuously cored, provides calibration of this sequence architecture to wireline log character, thereby enabling shelf deposits to be mapped widely in the subsurface via the wireline data for hydrocarbon exploration holes. Similar characterization of slope-sets and bottom-sets is work ongoing. The higher order (eustatic) sequences profoundly influenced the local reservoir architecture and seal properties of formations, whereas the megasequence progradation has been responsible for the regional hydrocarbon maturation and migration. Major late tilting, uplift and erosion affected all three basins and created a regional high along the eastern Margin of Taranaki Basin, thereby influencing the migration paths of hydrocarbons sourced deeper in the basin and allowing late charge of structural and possibly stratigraphic traps