Chalk

The foraminiferal fauna from twenty-seven sections of Campanian and Maastrichtian chalk from both the onshore and offshore United Kingdom have been studied. In total, 160 species and subspecies belonging to 54 genera have been recorded and a complete revision of their systematics, with full synonomies and descriptions, has been given. The detailed stratigraphic distribution of these species has been studied, and 65 species and subspecies of prime stratigraphic importance have been recognised and employed in the definition of a tripartite biozonal scheme based on planktonic foraminifera, Bolivinoides lineages and faunal assemblages respectively. This biozonal scheme has been accurately related to local rock units as well as to current macrofossil zonations. Correlation of all sections studied has been achieved by use of the proposed biozonal scheme.
            Broad similarities have been noted between the British foraminiferal faunas of the Upper Cretaceous and those of wide areas of northern Europe, clearly placing Britain within the Transitional biogeoprovince. Palaeoecological study has indicated that marine conditions with normal salinities prevailed throughout the Campanian and Maastrichtian. Palaeotemperatures appear to have gradually declined throughout this time, with a short-lived warm phase in the latest Maastrichtian. Depths of deposition of the chalk are interpreted as having been between 150 - 250m., though greater depths probably prevailed in the North Sea basins. A transgressive phase is indicated for the Upper Campanian and a regressive phase for the Maastrichtian.

To ensure rice food security, the target outputs of future rice breeding programmes should focus on developing climate-resilient rice varieties with emphasis on increased head rice yield coupled with superior grain quality. This challenge is made greater by a world that is increasingly becoming warmer. Such environmental changes dramatically impact head rice and milling yield as well as increasing chalkiness because of impairment in starch accumulation and other storage biosynthetic pathways in the grain. This review highlights the knowledge gained through gene discovery via quantitative trait locus (QTL) cloning and structural–functional genomic strategies to reduce chalk, increase head rice yield, and develop stable lines with optimum grain quality in challenging environments. The newly discovered genes and the knowledge gained on the influence of specific alleles related to stability of grain quality attributes provide a robust platform for marker-assisted selection in breeding to design heat-tolerant rice varieties with superior grain quality. Using the chalkiness trait in rice as a case study, we demonstrate here that the emerging field of systems genetics can help fast-track the identification of novel alleles and gene targets that can be pyramided for the development of environmentally robust rice varieties that possess improved grain quality.

The construction of port Solent Marina involved the removal. of alluvial silt to expose a Iayer of reworked chalk which acted as the foundation for a land reclamation project utilizing 564,000m3 of Ports Down chalk as fill, up to 5m thick. In order to prevent deterioration of the reworked chalk and to continue working throughout the winter with the minimal of delay, a "thick layer" compaction specification was developed to preserve the lump structure of the chalk and avoid instability. Following a literature search on the use of chalk as fill, initial site trials were used to develop a specification for 450mm and 500mm thick layers. Construction was monitored by chalk classification tests, in-situ density tests, trial pitting and full-sized foundation Ioading tests, one of which involved cycling of the groundwater Ievel. Careful methods of working produced a successful fill which could support a foundation pressure of 167kPa with less than 10mm settlement. Settlement of the underlying natural ground was shown to be virtually complete by the end of the filling operation. No measurable effects of groundwater movement were detected.

The lithological composition of the Cretaceous Chalk of the North Sea Basin is homogenous and consists mainly of fine-grained calcareous plankton, with only locally admixtures of clays and coarser bioclasts. Traditionally, exploration strategy in these homogenous rocks was guided by acoustic impedance volumes that showed the location of high porosity units. With increased maturation of fields and the search for remaining hydrocarbon occurrences, it is now essential to better understand the high resolution stratigraphic architecture and the tectonic context to identify new play types. In this presentation we will present evidence for basin inversion, and pay particular attention to the rich pallet of seismic geomorphological features that characterises this tectonically active period.
This study focussed on the Danish Central Graben and benefitted from a recently re-processed, regional 3D seismic dataset (6000 km²) combined with well-log and biostratigraphic information. Advanced seismic geomodel interpretation technology was applied to construct a seismic Relative Geological Time (RGT) model. Standard seismic attributes, displayed upon horizons from a 3D RGT model, are very effective in the illustration and interpretation of complex chalk depositional features. The evolution from a post-rift phase into a dramatic inversion phase and its impact on sediment distribution is documented at the basin scale. In uplifted areas local erosion and long phases of non-deposition occurred, whereas in areas of subsidence thick packages of chalk accumulated. The stratigraphic heterogeneity this created is captured in chronostratigraphic schemes. Along the newly created highs, mass waste deposition took place at the 10 km scale. Several different mass waste complexes have been documented in 3D, illustrating a number of typical features such as sediment creep, slumping, debris avalanches, olistoliths, debris flows and mudflows. Also traction current sedimentary features had a prominent role in the depositional system and left several thalwegs of different aspect ratios. Together these features present a very dynamic picture of chalk sedimentation.
This integrated, regional 3D seismic geomorphological approach allows for interpretation of previously poorly understood seismic features in the context of the geological evolution of the area, and helps to redefine plays based on a better understanding and prediction of the porosity and permeability distribution in the chalk.

Laboratory test results on compacted chalk from Tersephanou Cyprus are presented in the paper. The tests were performed in a large-size direct shear device with circular section. The particular chalk in-situ constitutes a rock mass of poor to medium quality which upon contact with water or mechanical straining, like that induced by compaction, yields a material of soil-like behaviour. The shear strength, volume changes and coefficient of earth pressure at rest and its evolution with vertical stress and unloading-reloading cycles were measured and are presented in the paper.

Four continuously cored boreholes and 82 observation shafts were drilled over an area of c. 45 km² at Mundford, Norfolk in 1966-67 as part of a geological and geotechnical investigation of for a large (2.4 km diameter) proton accelerator and attendant experimental target areas that was to be commissioned by the Committé Européan pour Recherche Nucleaire (CERN). The site is a low-relief area underlain by Middle Chalk and the oldest part of the Upper Chalk in a region where the stratigraphy of the Chalk was poorly known prior to the investigation. The shafts enabled the unweathered succession to be examined in detail, both vertically and laterally, and proved numerous lithological marker beds, mostly flint bands and marl seams. Some were restricted to the site area; others remained unchanged over a much larger area. Penecontemporaneous erosion channels in the Middle Chalk that probably resulted from minor tectonic activity locally cut out some of the marker beds. The Mundford succession falls within the northern part of the Transitional Chalk Province. A few of the marker beds, notably the thicker marl seams, have been correlated with marker beds in the Southern and Northern Provinces. Some of the on-site names for marker beds were used to illustrate the geological succession and structure in the geotechnical report on the proposed site. As a result, the site subsequently became the de facto standard for the Middle Chalk stratigraphy of the region. A description of the full succession is included here for the first time.