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The Paleocene submarine fans of the Central Graben represent important petroleum reservoir units recording the cyclic input of sand-rich turbidity flows into the post-rift basin. Provision of extensive seismic (a subset of ~l5000 km" of the PGS Central North Sea MegaSurvey), well (n = 549) and core (n = 28, totalling ~2760 feet/84l m) datasets by Shell UI Europe enabled a regional-scale re-evaluation of these deposits. This thesis presents new models illustrating the distribution and quality of the Maureen and Lista Formation sandstones and the syn- and post-depositional controls on these deposits. The Lista Formation sandstones occur within northwest (channelised, proximal, ~300 feet net) to southeast (sheet-like, distal, ~50 feet net) trending (axial) fans with western/eastern fairways and minor sidefan sedimentation (west/east). Four sand-rich to sand-poor facies are defined, with distinct grain size distributions. Mean grain size is the main control on porosity and permeability. Progradation occured between the Ll and L2 units with retrogradation in the L3. This variability, and internal porosity trends, is linked to global sea level change. Characterisation of the Maureen Formation sandstones is complicated by the presence of variable chalk facies derived from turbidite, debris flow and pelagic processes. However, these deposits can still be classified in a similar manner to the Lista Formation and exhibit similar spatial distributions, although the sandstones are thinner ~125 feet in the northwest to 25 feet in the southeast, suggesting that similar depositional controls were active. Sandstone quality is controlled by grain size (with calcitisation also important) although the porosity/permeability values are lower than in the Lista Formation. Progradation occured between the TlO and T20/30 sequences with retrogradation in the T35. The current MlIM2 divisions do not describe the complexity of this formation. The routing of the sandstones was defined by the relict graben structure with offset stacking an additional local control. Routing from the shelf to the basin was controlled by global sea level change. Although these systems are often labelled as basin floor fans they do not resemble classical examples, thanks to their confined nature.

The Saluda Formation, a lithologically distinct but spatially variable unit, is mappable in the subsurface. Lithologic characters such as dolomitic and laminated finegrained carbonates, paucity of fossils and terriginous detritus, birdseye structures, and intraclasts distinguish the formation and aid in interpreting the depositional environment. Similarities of features for modern and ancient carbonate tidal-flats and those of the Saluda suggest a tidal-flat environment of origin for the formation. Lateral and vertical lithologic relationships with contiguous formations record spatially variable but time transgressive subenvironments of deposition for the tidal-flat complex and surrounding sea.

The phosphatic chalks of the Anglo-Paris Basin are granular phosphorites of Santonian to early Campanian age. They were deposited in erosional cuvettes up to 1 km long, 250 m wide and 30 m deep, incised into white chalks. Most are situated in the Picardy region of northern France. Cuvettes are floored by strongly indurated and mineralized basal hardgrounds developed in intraclastic sediments. The hardgrounds are penetrated by prominent phosphatic-chalk filled Thalassinoides burrows and overlain by intraclast-pebble lags containing 'Terebella' phosphatica Leriche, Diblasus arborescens Parent and Lopha semiplana (J. Sowerby). Lithification occurred a few centimetres below the sediment/water interface in a sediment of increased permeability, and is geochemically discernible ~90 cm below the hardground surface. Glauconitization was restricted to replacement of clay minerals during the early development of the hardground, later phosphatization replacing carbonate. Actinocamax verus Miller occurs in basal phosphatic chalks and a bed of Gonioteuthis quadrata quadrata (Blainville) occurs at the summit. The Gonioteuthis Bed is commonly underlain by, but separated from, a bed of Offaster pilula (Lamarck). The proportion of faecal pellets, phosphatic ooliths, echinoderm fragments and benthonic foraminiferans decline above the basal hardgrounds as the phosphorites become finer-grained and less phosphatic. Inoceramid prisms or pelagic foraminiferans are the dominant component of poorer phosphatic chalks. Intraformational slump folds and hardground mélanges occur at the base of some successions. The palaeobiology of belemnites is considered in detail and it is concluded that the Gonioteuthis Beds were the products of massmortalities accompanying reproduction. Pelletal phosphate was formed by the replacement of carbonate during early diagenesis in an organic-rich, anoxic environment and water depths of <150 m. Current activity and subsurface anoxia were intermittent; colonization, bioturbation and winnowing alternating with quiescent, anoxic phases of mineralization. Phosphatic chalk cuvettes were eroded by a proto-Gulf Stream during a eustatic regression. Upwelling of this current was the main source of phosphate in the phosphatic chalks.

The East Kirkton Limestone outcrops in the Bathgate Hills area of central Scotland. The deposit is Visean (Lower Carboniferous) in age and is the site of a tropical freshwater lake set within a richly vegetated volcanic terrain. The succession consists of an unusual sequence of laminated, spherulitic and massive limestone beds, interbedded with thin mudstones, siltstones and abundant volcaniclastic horizons. This study investigates the palaeoenvironment of the East Kirkton lake, and for the first time presents convincing evidence for the presence of hot springs at East Kirkton. Two distinct mounds of massive limestone are located at the north end of the East Kirkton quarry and are interpreted as hot spring vent deposits. Calcite samples from the Lower Mound have light δ¹⁸O_PDB values consistent with precipitation at elevated temperatures ranging from 45°C to ˜80°C, whereas samples from the laminated lake sediments have heavier δ¹⁸O_PDB values, consistent with precipitation at lower temperatures. The East Kirkton Limestone is unique because it contains a variety of unusual radial fibrous calcite (RFC) precipitates, including mm-sized spherules, oncoids, and laminated botryoidal accretions. These are found within the laminated limestone and also within the Lower Mound of massive limestone, and many of them contained filamentous and cellular microbial remains and are within the definition of microbial carbonates. This study provides good evidence for a microbial involvement in the formation of the East Kirkton laminated accretions. A study of modern stromatolites from Lake Tasek Dayang Bunting, Malaysia highlights close similarities with the East Kirkton accretions in terms of morphology and microstructure. Both have a nodular growth morphology and laminated interior consisting of layers of radial fibrous carbonate botryoids interspersed with organic-rich micritic laminae. The modern stromatolites are covered by a microbial community comprising filamentous bacteria and cyanophytes, plus diatoms and associated mucilage, and microbes are thought to have played an essential role in the morphogenesis of both the modern and ancient examples.

The Calama and eastern Pampa del Tamarugal Basins are located between 22°S and 23°S within the forearc of northern Chile. They are filled by sediments deposited in alluvial braidplain, fluvial, playa sandflat, lacustrine and volcaniclastic environments under a semi-arid to hyper-arid climate. The nature of the alluvial braidplain depositional environment is unusual in that it combines elements of both alluvial fan and fluvial depositional systems, in contradiction to recently published models of alluvial fan sedimentation. Detailed sedimentary logging, magnetostratigraphy and dating of 14 volcanic interbeds by the ⁴⁰Ar/³⁹Ar laser fusion method has established a lithostratigraphic and chronostratigraphic framework for the 700 m thick basin-fill. Basin formation was investigated by regional subsidence during the Late Eocene or Early Oligocene, followed by widespread alluvial braidplain deposition during the Oligocene(?). A change to fluvial and playa sandflat deposition during the Early to Mid-Miocene is considered to be coincident with a decrease in active subsidence. Sedimentation ceased and thick (25 m) gypcrete deposits developed along the eastern margin of the basin during the Mid-Miocene as a response to an increasingly arid climate. Phases of minor lacustrine, fluvial and alluvial braidplain deposition during the Late Miocene-Early-Pliocene and the Late Pliocene(?) to Pleistocene were primarily controlled by small-scale fault movements and folding events, although climatic variations may have been important in some cases. A new lithostratigraphic division of the basin-fill is proposed here, which comprises 13 different formations. The previously defined El Loa Formation comprises a number of depositional units which are spatially and temporally discrete formations, and is therefore awarded group status.