Evolution and distribution of pore pressure across the Taranaki Basin, New Zealand

The Taranaki Basin lies onshore and offshore in the central-west of New Zealand’s North Island. The polyphase nature of the basin has led to a complex pore pressure history, generating significant variations in the present-day vertical and lateral distribution of overpressures. Investigating pore pressure distributions at a basin scale can mask key details, so in this study eight new sub-basin areas and structural zones are designated, each displaying individual pore pressure trends defined by their stratigraphic architecture and structural development. Variations in the thickness and facies of Eocene-Oligocene stratigraphy both within and between sub-basins are shown to provide a first-order control on the magnitude, distribution and maintenance of overpressure across the Taranaki Basin. Fluid pressure compartmentalisation through sealing faults and stratigraphic architecture has been identified across the basin. Deep pore pressure transitions within Taranaki Basin are shown to be sealed by diagenetic, structural and stratigraphic mechanisms and generated by an increase in mudrock volume (reduced permeability) or gas generation. A series of one-dimensional basin models are used to investigate the phases of overpressure generation by disequilibrium compaction across the Taranaki Basin: initially driven by the formation and early filling of a foreland basin in the eastern basin margin from ∼22 Ma, and subsequently by loading due to the progradation of a succession of sedimentary wedges across the continental shelf from ∼10 Ma to the present day. The plotting of vertical effective stress against porosity from reservoirs across each stratigraphic interval and depositional facies within the Taranaki Basin, identifies no clear relationships, primarily due to the late and deep onset of abnormal pressures. Analyses focused on Palaeocene Farewell Formation and the F-Sands reservoirs, demonstrates that mechanical compaction is the principle porosity reducing mechanism during the first 3000m of burial. Dissolved CO2 in the pore fluids of the F-Sands and Farewell Formation are likely to have driven the dissolution of detrital grains, generating secondary porosity and enhancing permeability. Continued compaction of secondary porosity in the Farewell Formation has further reduced porosity towards maximum burial. The F-Sands and Farewell Formation can be characterised as geochemically closed systems, where dissolved solutes are being preferentially precipitated in fine-grained heterolithic siltstone beds. This research presents the pore pressure evolution and distribution of the Taranaki Basin within a tectonostratigraphic context, demonstrating how multiphase overpressure generation and subsequent maintenance are controlled by a combination of sediment loading, uplift, lithofacies variations, fault zone permeability and mechanical compaction. This research has important implications for both hydrocarbon exploration in tectonostratigraphically diverse regions and research into the evolution of polyphase sedimentary basins worldwide

USE OF DRINKING WATER TREATMENT RESIDUALS AS A SOIL AMENDMENT FOR STORMWATER NUTRIENT TREATMENT

Stormwater runoff has been implicated as a major source of excess nutrients to surface waters, contributing to the development of eutrophic conditions. Bioretention, a promising technology for urban stormwater pollution treatment, was investigated to determine if an aluminum-based water treatment residual (WTR) amended bioretention soil media (BSM) could adsorb phosphorus to produce discharge concentrations below 25 μg/L. Batch, small column, and vegetated column studies were employed to determine both the optimal BSM mixture and media performance. Media tests demonstrated P adsorption proportional to WTR addition. Final selected experimental media consisted of 75% sand, 10% silt, 5.8% clay, 5.2% WTR, and 3.4% bark mulch (air dry mass basis).This media showed excellent P removal relative to a non-WTR-amended media. Whereas the control media leached P (71.1% increase in mass), the experimental media adsorbed 85.7% of the P mass applied, displaying a cumulative effluent EMC of 16.1 μg/L, below the 25 μg/L goal

Testing Observational Techniques with 3D MHD Jets in Clusters

Observations of X-ray cavities formed by powerful jets from AGN in galaxy cluster cores are commonly used to estimate the mechanical luminosity of these sources. We test the reliability of observationally measuring this power with synthetic X-ray observations of 3-D MHD simulations of jets in a galaxy cluster environment. We address the role that factors such as jet intermittency and orientation of the jets on the sky have on the reliability of observational measurements of cavity enthalpy and age. An estimate of the errors in these quantities can be made by directly comparing ``observationally'' derived values with values from the simulations. In our tests, cavity enthalpy, age and mechanical luminosity derived from observations are within a factor of two of the simulation values.Comment: 4 pages, 3 figures; to appear in proceedings of The Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters (AIP conference series

Recurrent ~24 h Periods in RXTE ASM Data

Analysis of data from the Rossi X-ray Timing Explorer satellite's All Sky Monitor instrument for several X-ray binary sources has identified a recurrent \~24 h period. This period is sometimes highly significant, giving rise to the possibility of it being identified as an orbital or super-orbital period. Further analysis has revealed the same period in a number of other X-ray sources. As a result this period has been discounted as spurious, described variously as arising from daily variations in background levels and beating between the sampling period and long-term secular trends in the light curves. We present here an analysis of the spurious periods and show that the dominant mechanism is in fact spectral leakage of low-frequency power present in the light curves.Comment: 9 Pages, 10 figures, 1 table, submitted to PASA 20th December 2004. Added 1 page of text and 3 figures to clarify results and discussion. Resubmitted 16th May 2005. Accepted 25th June 200

The Howling Muse: Chasing Coyote Tales in Northwestern California

Coyote is a popular figure in the oral literature of North America, with a sweeping distribution in the stories, songs, and folktales devoted to this beloved character. Coyote, the familiar canine species, has inspired a huge body of oral narratives, with striking similarities in the tales that circulate from the Great Plains to the Southwest and the Pacific Coast (which is the focus of this article). For some groups, such as the Karuk, Coyote occupies a central place in myth, playing a key role even in the creation of the cosmos; for other groups, such as the neighboring Hupa and Yurok, Coyote is displaced by other myth figures, even where similar episodes circulate, instead becoming the secondary focus of everyday folklore. However, wherever Coyote appears, as the subject of oral literature, this beloved muse tends to occupy a liminal position between the sacred and the profane; between the ancient past and the present; and between nature and culture.Coyote est une figure populaire dans la littérature orale de l’Amérique du Nord, largement répandue dans les histoires, les chants et les contes que le personnage inspire. Ce canidé a inspiré un vaste corpus de pièces orales, avec des similarités frappantes entre les contes connus depuis les Grandes Plaines jusqu’au Sud‑Ouest ou à la côte pacifique (à laquelle cet article est consacré). Pour certains groupes, comme les Karuk, Coyote occupe une place centrale dans le mythe, où il joue un rôle jusque dans la création du cosmos ; dans des groupes voisins, tels les Hupa et les Yurok, le mythe le remplace par d’autres figures, même si certains épisodes restent semblables, tandis qu’il garde sa place dans le folklore quotidien. En tout cas, où qu’il apparaisse, Coyote, qui joue aussi le rôle de muse, est aux confins du sacré et du profane, du passé et du présent, de la nature et de la culture