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Analysis of scattered, or diffraction energy (the seismic response of small-scale objects) in the seismic data from Canterbury Basin, New Zealand reveals additional geological information about depositional patterns in sedimentary deposits. Diffrac- tion images from the seismic response for Canterbury Basin provide complementary interpretation tools to the conventional specular reflection images. To image diffrac- tions for a dataset from Canterbury Basin, I take the following steps: First, I attenuate multiples using a surface multiple prediction algorithm to predict multiples and apply regularized nonstationary regression to adaptively subtract the predicted multiples. Next, I separate diffractions using the plane-wave destruction method. The plane- wave destruction method removes conventional reflected energy in order to enhance the diffracted energy. I then apply a velocity continuation method on diffraction data to estimate migration velocities and then migrate the data using Kirchhoff migration in the dip-angle-gather domain. The resultant conventional and diffraction images are improved images suitable for geological interpretation of prograding sediment drifts. / text

The Canterbury Basin is located on a passive margin on the east coast of the South Island, developed by the rifting of the New Zealand continental fragment from Antarctica in the Late Cretaceous. Well cuttings produced during petroleum exploration in the offshore Canterbury Basin have been examined for secondary minerals and textures. Minerals and textures have been identified primarily from optical examination in reflected light, with a particular focus on producing high-resolution images. Additional identifications are made using thin sections, SEM, XRD and XRF analysis. The focus of this study is the Clipper-1 well in the Clipper sub-basin as it contains the most abundant mineralisation and covers the full depth of the Canterbury Basin sedimentary sequence. Examination of cuttings from this well has revealed intrusive igneous carbonates and native metals including iron, aluminium and copper. The trace element concentrations in the igneous carbonates indicates they are derived from crustal material. Textures indicating fluidisation and recrystallisation of sedimentary material are also present. The proposed mechanism for producing these unusual mineral assemblages is a late Pliocene or younger mafic intrusion into the schist basement of the Canterbury Basin. The igneous carbonates are inferred to be derived from melting of carbonates in the schist. The native metals have been produced from melt due to highly reducing conditions produced by interaction of the intrusion with coal and limestone. The combination of native metals and igneous carbonates with a conspicuous absence of typical silicate igneous rocks is inferred to represent a new type of intrusive environment that has not previously been described in the scientific literature.

High rates of Neogene sediment influx to the offshore Canterbury Basin resulted in preservation of a high-resolution record of seismically resolvable sequences (~0.1-0.54 my periods). Subsequent sequence development was strongly influenced by submarine currents. This study focuses on correlating seismically interpreted sequence boundaries and sediment drifts architectures beneath the modern shelf and slope with sediment facies observed in cores from shelf Site U1351 and slope Site U1352 drilled by Integrated Ocean Drilling Program (IODP) Expedition 317. A traveltime-depth conversion was created using sonic and density logs and is compared with two previous traveltime-depth conversions for the sites. Eleven large elongate drifts were interpreted prior to drilling. Two new small-scale plastered slope drifts in the vicinity of the IODP sites, together with sediment waves drilled at Site U1352, have been interpreted as part of this study. Lithologic discontinuity surfaces and transitions together with associated sediment packages form the basis of identifying sequences and sequence boundaries in the cores. Contacts and facies were characterized using shipboard core descriptions, emphasizing grain-size contrasts and the natures of the lower and upper contacts of sediment packages. Lithologic surfaces in cores from sites U1351- (surfaces S1-S8) and U1352- (surfaces S1-S6) correlate with early Pleistocene to recent seismic sequence boundaries U12-U19 and U14-U19, respectively. The limited depths achieved by downhole logging, in particular sonic and density logs, together with poor recovery in the deeper section did not allow correlation of older lithologic surfaces. Slope Site U1352 experienced a complex interplay of along-strike and downslope depositional processes and cores provide information about the principal facies forming sediment waves. The general facies are fine-grained mud rich sediment interbedded decimeter-centimeter thick sand and sandy mud. Core evidence for current activity is reinforced at larger scale by seismic interpretations of sediment waves and drifts. / text

Au cours des vingt dernières années, les études sur les sédiments marins profonds ont révélé la présence et l'activité de communautés microbiennes inattendues. Il est maintenant formellement établi que la biosphère profonde héberge de nombreux représentants des domaines des Archaea et des Bacteria. Cependant,les micro-eucaryotes et plus particulièrement les champignons n’ont été que très peu étudiés dans ces écosystèmes singuliers. Dans ce contexte, des approches moléculaire et culturale ont été utilisées afin de caractériser la diversité des communautés fongiques des sédiments marins profonds en utilisant le bassin de Canterbury comme modèle d’étude. Les résultats principaux obtenus lors de ce travail de thèse sont les suivants : (i) L’approche moléculaire basée sur l’ADN a fourni la preuve directe que les communautés fongiques peuvent persister jusqu’à la profondeur record de 1740 mètres sous la surface du plancher océanique. (ii) Des approches complémentaires ciblant les ARNr et les ARNm ont permis de préciser leur activité métabolique et d’obtenir de premiers indices sur les fonctions de ces champignons à 350m sous la surface du plancher océanique, principalement liées à la croissance, à l’adaptation aux contraintes environnementales in situ et aux interactions entre communautés microbiennes. (iii) L’approche culturale a permis de constituer une collection de culture de 183 isolats fongiques avec des caractéristiques écophysiologiques témoignant leur capacité d’adaptation aux conditions in situ. (iv) Le potentiel biotechnologique des isolats obtenus a été estimé via la recherche de gènes impliqués dans la synthèse de métabolites secondaires et a permis de positionner cette collection d’organismes originaux comme une ressource d’intérêt biotechnologique potentiel. Ce travail qui témoigne de la persistance et de l’activité des communautés fongiques dans les sédiments marins profonds élargit notre vision de la diversité microbienne dans ces milieux et soulève des hypothèses sur le rôle écologique des champignons au sein de la biosphère profonde. / Over the past two decades, investigations on deep marine sediments have revealed the occurrenceand activity of unexpected microbial communities. Many representatives of Archaea and Bacteria were reportedbut micro-eukaryotes and especially fungal communities are still poorly studied in this ecosystem. In this underexplored context, molecular- and culture-based approaches were used to characterize the diversityof fungal communities in deep subsurface sediments using the Canterbury Basin as a model system. The main results of this work are: (i) The molecular DNA-based approach provided direct evidence that the fungal communities persist until the record depth of 1,740 meters below sea floor. (ii) Supplementary approaches targeting rRNA and mRNA revealed their metabolic activity and highlighted first hints into the fungal functions at350 meters below sea floor, mainly related to growth, adaptation to in situ environmental constraints andmicrobial interactions. (iii) The culture based approach allowed establishing a culture collection of 183 fungal isolates with ecophysiological characteristics indicating their ability to adapt to in situ conditions. (iv) This culture collection seems to represent a reservoir of secondary metabolites as many genes involved in secondary metabolites pathways were revealed. The fungal collection established may be considered as an untapped resource to explore for biotechnological applications. This work demonstrating the persistence and activity of fungal communities in deep subsurface sediments (i)broadens our view of microbial diversity in these environments and (ii) raises hypotheses about the ecologicalroles of fungi in the deep biosphere