78 research outputs found

    Eastern Taranaki Basin field guide.

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    Linking the onshore and offshore parts of Eastern Taranaki Basin: Insights to stratigraphic architecture, sedimentary facies, sequence stratigraphy, paleogeography and hydrocarbon exploration from the on land record

    The Late Miocene Southern and Central Taranaki Inversion Phase (SCTIP) and related sequence stratigraphy and paleogeography

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    We present a new sequence stratigraphic scheme for Taranaki Basin that identifies four 3rd order duration (3 - 4 m.y.) sequences of Middle Miocene to Pleistocene age. These include: (i) the late-Middle Miocene (upper Lillburnian to uppermost Waiauan) Otunui Sequence; (ii) the Late Miocene (lower and lowermost-upper Tongaporutuan) Mt Messenger Sequence; (iii) the latest Miocene (uppermost-upper Tongaporutuan) to Early Pliocene (lower Opoitian) Matemateaonga Sequence, and (iv), the Late Pliocene (upper Opoitian) to Late Pleistocene (Castlecliffian) Rangitikei Sequence, which includes the Giant Foresets Formation offshore in northern Taranaki Basin. Full sequence development can be observed in the parts of these four sequences exposed on land in eastern Taranaki Basin and in Wanganui Basin, including the sequence boundaries and component systems tracts; the character of the various depositional systems and their linkage to correlatives in subsurface parts of Taranaki Basin can be reasonably inferred, although we do not develop the detail here. Our sequence framework, with its independent age control, is integrated with established evidence for the timing of Late Miocene structure development in southern Taranaki (the Southern Inversion Zone of King & Thrasher (1996)) and new evidence presented here for the extent of Late Miocene unconformity development in central Taranaki. This shows that the Mt Messenger Sequence, particularly its regressive systems tract, results from a major phase of tectonism in the plate boundary zone, the crustal shortening then extending into the basin at c. 8.5 Ma and differentially exhuming parts of the sequence and underlying units in southern and central Taranaki Basin. This Southern and Central Taranaki Inversion Phase (SCTIP) peaked at around 7.5 Ma (mid-upper Tongaporutuan). At that time it extended across the whole of the area presently covered by Wanganui Basin, all of southern Taranaki Basin (Southern Inversion Zone), west to the Whitiki and Kahurangi Faults, and across southern parts of Taranaki Peninsula. We have also identified in outcrop sections, wireline logs for Peninsula exploration holes, and selected seismic reflection profiles, the occurrence of forced regressive deposits of the Mt Messenger Sequence. These deposits are mainly preserved beneath distal parts of the unconformity and basinward of it in central Taranaki Peninsula and west to the Tui Field, and need to be distinguished from the much younger Giant Forests Formation within the 3rd-order Rangitikei Sequence, which also shows clinoform development. The new sequence framework with its inferred stratal patterns also helps clarify understanding of the lithostratigraphic nomenclature for Late Miocene – Pliocene units beneath Taranaki Peninsula

    Late Miocene-Early Pliocene Matemateaonga Formation in eastern Taranaki Peninsula: A new 1:50,000 geological map and stratigraphic framework

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    In recent years the Matemateaonga Formation has become an additional exploration play in Taranaki Basin. Exploration interest has been stimulated by the success of Swift Energy Company in the Rimu/Kauri prospect (38719), located near south Taranaki Coast. At this location, sandstone lithofacies, commonly termed “Manutahi Sandstone” in the lower parts of the Matemateaonga Formation have been intersected by the Kauri-A2 and Kauri-A3 wells at depths of ~1100-1200 m and are yielding commercial quantities of oil. As part of a FRST-funded sedimentary basins research programme, we have geologically mapped in detail Matemateaonga Formation within an 1800 km2 area of the eastern peninsula region (Fig. 1), incorporating license areas 38739, 38718, 38753, 38138, 38139, 38141, 38140, 38716, 38758, 38728 and 38760. Mapping at 1:50,000 scale has revealed an ~1100 m-thick succession of cyclothemic, unconformity bounded shelfal strata of Late Miocene-Early Pliocene (Late Kapitean to Early Opoitian) age (c.5.5-4.7 Ma). This succession formed as a result of the interplay between climatically-driven 6th-order (41 k.y.) eustatic sea-level changes, high rates of basin subsidence and a substantial southerly-derived sediment flux. Individual sequences or groups of sequences are the fundamental mapping entities. The mapping area sits astride the southward-plunging Whangamomona Anticline, which has deformed the Late Neogene succession, producing a regional dip on its western flank of 2 to 4 degrees to the southwest. Northeast-southwest trending normal faults are relatively common and offset Matemateaonga Formation strata with throws of 2-50 m. This improved knowledge of Matemateaonga Formation stratigraphy enhances the understanding of the distribution and geometry of potential reservoir sandstone units and associated mudstone seal units in the region

    Constraints on the evolution of Taranaki Fault from thermochronology and basin analysis: Implications for the Taranaki Fault play

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    Taranaki Fault is the major structure defining the eastern margin of Taranaki Basin and marks the juxtaposition of basement with the Late Cretaceous-Paleogene succession in the basin. Although the timing of the basement over-thrusting on Taranaki Fault and subsequent marine onlap on to the basement block are well constrained as having occurred during the Early Miocene, the age of formation of this major structure, its character, displacement history and associated regional vertical movement during the Late Cretaceous- Recent are otherwise poorly known. Here we have applied (i) apatite fission track thermochronology to Mesozoic basement encountered in exploration holes and in outcrop to constrain the amount and timing of Late Cretaceous-Eocene exhumation of the eastern side of the fault, (ii) basin analysis of the Oligocene and Miocene succession east of the fault to establish the late-Early Miocene - Early Pliocene subsidence history, and (iii), regional porosity-bulk density trends in Neogene mudstone to establish the late uplift and tilting of eastern Taranaki Basin margin, which may have been associated with the main period of charge of the underlying Taranaki Fault play. We make the following conclusions that may be useful in assessing the viability of the Taranaki Fault play. (1) Mid-Cretaceous Taniwha Formation, intersected in Te Ranga-1 was formerly extensive across the western half of the Kawhia Syncline between Port Waikato and Awakino. (2) Taranaki Fault first formed as a normalfault during the Late Cretaceous around 85±10 Ma, and formed the eastern boundary of the Taranaki Rift-Transform basin. (3) Manganui Fault, located onshore north of Awakino, formed as a steeply east dipping reverse fault and accommodated about four km of displacement during the mid-Cretaceous. (4) Uplift and erosion, involving inversion of Early Oligocene deposits, occurred along the Herangi High during the Late Oligocene. This may have been associated with initial reverse movement on Taranaki Fault. (5) During the Early Miocene (Otaian Stage) the Taranaki and Manganui Faults accommodated the westward transport of Murihiku basement into the eastern margin of Taranaki Basin, but the amount of topography generated over the Herangi High can only have been a few hundred metres in elevation. (6) The Altonian (19-16 Ma) marked the start of the collapse of the eastern margin of Taranaki Basin that lead during the Middle Miocene to the eastward retrogradation of the continental margin wedge into the King Country region. During the Late Miocene, from about 11 Ma, a thick shelf-slope continental margin wedge prograded northward into the King Country region and infilled it (Mt Messenger, Urenui, Kiore and Matemateaonga Formations). (7) During the Pliocene and Pleistocene the whole of central New Zealand, including the eastern margin of Taranaki Basin, became involved in long wavelength up-doming with 1-2 km erosion of much of the Neogene succession in the King Country region. This regionally elevated the Taranaki Fault play into which hydrocarbons may have migrated from the Northern Graben region

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

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    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.

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    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

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

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    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

    Semantic and lexical features of words dissimilarly affected by non-fluent, logopenic, and semantic primary progressive aphasia

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    OBJECTIVE: To determine the effect of three psycholinguistic variables-lexical frequency, age of acquisition (AoA), and neighborhood density (ND)-on lexical-semantic processing in individuals with non-fluent (nfvPPA), logopenic (lvPPA), and semantic primary progressive aphasia (svPPA). Identifying the scope and independence of these features can provide valuable information about the organization of words in our mind and brain. METHOD: We administered a lexical decision task-with words carefully selected to permit distinguishing lexical frequency, AoA, and orthographic ND effects-to 41 individuals with PPA (13 nfvPPA, 14 lvPPA, 14 svPPA) and 25 controls. RESULTS: Of the psycholinguistic variables studied, lexical frequency had the largest influence on lexical-semantic processing, but AoA and ND also played an independent role. The results reflect a brain-language relationship with different proportional effects of frequency, AoA, and ND in the PPA variants, in a pattern that is consistent with the organization of the mental lexicon. Individuals with nfvPPA and lvPPA experienced an ND effect consistent with the role of inferior frontal and temporoparietal regions in lexical analysis and word form processing. By contrast, individuals with svPPA experienced an AoA effect consistent with the role of the anterior temporal lobe in semantic processing. CONCLUSIONS: The findings are in line with a hierarchical mental lexicon structure with a conceptual (semantic) and a lexeme (word-form) level, such that a selective deficit at one of these levels of the mental lexicon manifests differently in lexical-semantic processing performance, consistent with the affected language-specific brain region in each PPA variant

    Polygenic prediction of educational attainment within and between families from genome-wide association analyses in 3 million individuals

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    We conduct a genome-wide association study (GWAS) of educational attainment (EA) in a sample of ~3 million individuals and identify 3,952 approximately uncorrelated genome-wide-significant single-nucleotide polymorphisms (SNPs). A genome-wide polygenic predictor, or polygenic index (PGI), explains 12-16% of EA variance and contributes to risk prediction for ten diseases. Direct effects (i.e., controlling for parental PGIs) explain roughly half the PGI's magnitude of association with EA and other phenotypes. The correlation between mate-pair PGIs is far too large to be consistent with phenotypic assortment alone, implying additional assortment on PGI-associated factors. In an additional GWAS of dominance deviations from the additive model, we identify no genome-wide-significant SNPs, and a separate X-chromosome additive GWAS identifies 57

    Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

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    BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
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