This work focuses on the sedimentation and geomorphology of the Messenia and Eastern Lakonia Peninsulae (S Peloponnese, Greece) during the Pliocene-Quaternary (last ca. 5 Ma). Shallow-marine and subaerial sediments and landforms are described and interpreted in terms of tectonic and sea level controls. The S Peloponnese underwent regional uplift since the Middle Miocene. Normal faulting, in directions parallel and transverse to the Aegean Arc led to the formation of horsts and grabens on scales varying from <1 to >20 km. Sea level cyclicity resulted in deposition of shallow-marine to subaerial sequences separated by unconformities. Changing climatic conditions since the Middle-Late Miocene influenced subaerial erosion and sedimentation and also the facies/fauna of marine and marginal marine deposits. Pliocene-Quatemary landforms and sediments in the two areas studied reflect the interplay between the above controls. In both the Ntessenia and Eastern Lakonia Pensinsulae Late Tertiary surfaces of subaerial erosion and Quaternary marine sediments and terraces are present at progressively lower altitudes with decreasing age as a result of uplift and forced regression. Maximum numbers of terraces are present in fault-bounded areas of maximum Quaternary uplift, in the NW parts of each peninsula, where uplift rate since the early Pleistocene (last ca. l Ma) was 0.08-0.35 m/ka. Pliocene (only in the Messenia Peninsula) and Quaternary shallow-marine sediments (in both peninsulae) are subdivided into informal units, correlated with 3^rd or higher-order sea level cycles. The Pleistocene part of the stratigraphy, present in both peninsulae, is resolved into two 3^rd order sequences, of early and middle-late Pleistocene age, respectively. The middle-late Pleistocene sequence is further divided into Eutyrrhenian and Neotyrrhenian units, correlated with higher order late Pleistocene sea level cycles.

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Late Quaternary Climatic Oscillations are known to be intense, and in some cases too rapid to be resolved reliably using a radiocarbon chronology. Tephrochronology, the use of widespread and isochronous layers of volcanic ash is increasingly seen as a valuable tool in the inter-environmental correlation of proxy- palaeonclimatic indicators. A fundamental assumption that underpins tephrochronology in the North Atlantic is the acceptance that tephra horizons can be fingerprinted uniquely, by the major/minor element compositions of their vitric shards. This thesis concentrates on the analytical (Electron Probe Microanalysis) methodology required in the accurate and precise determination of this fingerprint, on factors which inhibit successful correlation using such fingerprints and on the application of geochemical signatures to the establishment of a meaningful regional tephrochronology. In addition, studies of tephra deposition and re-mobilisation have also been undertaken following the 1991 eruption of Hekla, with results indicating the need for caution in interpreting mass-loading and mapping of tephra isochrons. The principal tephrostratigraphy within this thesis relates to the Late Glacial and early Holocene, and is used in an attempt to achieve correlations between marine, terrestrial and ice-sheet environments. At least seven tephra isochrons are shown to be present in the North Atlantic region in the interval <I>ca. </I>14,000 <SUP>14</SUP>C yrs BP to <I>ca. </I>9,000 <SUP>14</SUP>C yrs BP, with one interpretation of evidence from the UK continental shelf suggestive of further horizons. Rigorous investigation of these tephras has revealed the potential inadequacies of major elements as unambiguous indices in the correlation and differentiation of Iceland-derived tephras. This is summarised by the term "geochemical equifinality", associated with higher eruption frequencies of known individual volcanic centres than previously recognised. It is apparent that, (i) geochemical data must be supplemented by more rigorous investigations of stratigraphical context; and (ii) new analytical techniques must be applied to the characterisation of potential trace elements signatures.

A facies analysis of Middle-Upper Jurassic boundary beds, i.e. Callovian-Oxfordian Stage boundary beds, has been carried out on numerous sections across Europe, with the aim of constructing relative sea-level curves for each geographic area. Accurate correlation of the various epeiric-sea, sedimentary successions has been achieved using ammonite zonations. The comparison of twelve relative sea-level curves has led to the recognition of regional sea-level events in Europe during the Callovian-Early Oxfordian interval. A regional sea-level rise occurred during the Middle and Late Callovian, reaching its greatest extent in the latest Callovian (lambert; Zone), and highstand conditions and incipient sea-level fall characterized the Early Oxfordian. A literature review of Callovian-Oxfordian boundary beds in six further regions from four other continents has shown that a Middle Callovian sea-level rise and Late Callovian-Early Oxfordian phase of high sea-level can be recognized on a global scale. The European regional sea-level changes are, therefore, considered to be eustatic in origin, and are a response to a third, or possibly second-order, eustatic cycle of 6-1 0 Ma. A "Norris eustatic curve" has been constructed and compared with two published eustatic curves. It differs markedly from that of Hallam (1988), also based on the facies analysis technique, but is very similar to that of Haq el al. (1987), based on sequence stratigraphic concepts. However, the systems tracts and coastal onlap curve of the Haq ct al. (1987) chart are at odds with the facies interpretations made in this study, reflecting the inadequacy of the sequence stratigraphy model in addressing the Jurassic epicontinental sea successions.

The Cretaceous Sidi as Sid Formation outcrops in the Jabal Nafusah Escarpment, northwest Libya. It is composed of two members; the lower Ain Tobi Member and the upper Yifran Member. The Yifran Member consists of marl, dolomitic limestone and gypsum. The Ain Tobi Member is composed entirely of dolomite and in this study is named the "Ain Tobi Dolostone Member". The Sidi as Sid Formation is part of an inner ramp sequence which graded from restricted ramp in the south and southwest into an open to semi-restricted ramp in the northeast. The entire succession is without biostratigraphic markers. Sedimentological, petrographic, geochemical and isotopic studies have led to the definition of five diagenetic dolomite types within the Ain Tobi dolostones; these reflect more than single diagenetic events which were involved in the formation of these dolomites. Type-1 dolomite is laminated, fine, subhedral, stoichiometric to nearly stoichiometric and poorly ordered. It is characterized by homogeneous luminescence, relatively high Sr and Na contents and low Fe and Mn, positive carbon isotope values and negative oxygen isotopic composition. It is suggested that Type-1 dolomite is formed near-surface by reflux dolomitization. Type-2 dolomite is calcian-rich, poorly to moderately ordered and very fine. It replaces packstone/grainstone facies and shows bright yellow luminescence. Type-2 dolomite is Sr-enriched and Fe, Mn, Na-depleted and possesses a similar isotopic composition as dolomite Type-1. Therefore, it is interpreted as a replacive dolomite formed at the near-surface under the influence of mixed water. Type-3 dolomite is a fine to medium dolomite, interbedded with quartz. It is calcian to nearly stoichiometric and moderately ordered. Type-3 dolomite is characterized by dirty orange luminescent cores and very thin bright luminescent rims, high Fe and Mn, but low Sr and Na contents. It has negative carbon and oxygen isotopic composition and is interpreted as dolomite formed in an intermediate stage probably post-compaction under the influence of mixed marine-meteoric water in shallow burial. Type-4 dolomites are calcian to nearly stoichiometric, well ordered, medium to coarse and have dirty orange luminescent cloudy cores and dull clean rims. Type-4 dolomites possess low trace element contents due to recrystallization from precursor dolomites. Type-4 dolomites have normal marine oxygen and carbon isotopic compositions. The Type-4 dolomites are interpreted as being formed by continuous dolomitization processes involving marine-meteoric pore-water mixing in shallow burial situations. Type-5 dolomite (saddle dolomite) is coarse to very coarse with orange luminescent cloudy cores and dull clean rims. It is calcian-rich, well ordered and posses low Fe, Mn and Sr contents and a relatively high Na concentration. Its isotopic composition is the lightest in oxygen and has a similar carbon composition compared to other dolomite types. Type-5 dolomite is interpreted as being formed at a late stage in deeper burial and elevated temperature environment. Two types of replacive calcite (dedolomite) are found to replace dolomite in the Ain Tobi sequence. The first, is found close to the unconformity surface. These calcites show replaced cores and thin unreplaced dolomite zones. These dedolomite crystals are characterized by complex luminescent zonation and are interpreted as an early replacement under the influence of marine-meteoric mixing water. The second type is observed in the upper part of the Ain Tobi sequence and is characterized by very coarse or blocky crystals with replaced rims and/or whole dolomite rhombs. This calcite is interpreted as a dolomite replacement formed at a late stage under the influence of freshwater as indicated by very light delta18O values.

This thesis integrates high-precision (<0.2%, 2σ) [superscript 206]Pb/[superscript 238]U dating of zircons from volcanic tuffs intercalated in key Late Eocene-Oligocene marine and terrestrial sedimentary successions, with high-resolution biostratigraphic and magnetostratigraphic data sets in order to critically examine the accuracy and precision of the numerical age calibration of the Eocene – Oligocene transition (EOT). Weighted mean [superscript 206]Pb/[superscript 238]U ages from the Italian Umbria-Marche and North American White River Group (WRG) sedimentary successions are 0.4-1.0 Myr younger than legacy [superscript 40]Ar/[superscript 39]Ar biotite and sanidine data from the same tuffs (calibrated relative to Fish Canyon sanidine at 28.201 Ma). [superscript 206]Pb/[superscript 238]U calibrated age-depth models were used to constrain the age of magnetic reversals between 26.5-36 Ma (C8r-C16n.2n). Interpolated magnetic reversal ages are consistent with relatively constant seafloor spreading rates, and provide a fully integrated and robust chronostratigraphic framework for the EOT, as shown by mutual consistency of chron boundary ages from the Umbria-Marche basin and the WRG between 31-36 Ma. These data effectively eliminate the discrepancies between astronomically tuned and radio-isotopically calibrated time scales of the EOT. An evaluation of the fidelity of planktonic foraminifer bioevent based chronostratigraphy across the EOT indicates that the last occurrence of hantkeninids and the last common occurrence of Chiloguembelina cubensis which mark the Eocene-Oligocene (34.090 ± 0.074 Ma) and Rupelian – Chattian (28.126 ± 0.175 Ma) boundaries are not timetransgressive across oceanic basins. However, other Oligocene planktonic foraminifer bioevents occur 0.4-0.8 Myr later in the western Tethys than in tropical and subtropical open ocean settings. In the WRG sedimentary succession, the first and last appearance datums of key Late Eocene mammal taxa show diachroneity of ca. 1 Myr over a distance of 400 km. Long-term aridification recorded by the WRG appears to be time-transgressive, and progressed gradually from west to east, while abrupt Early Oligocene cooling reported from WRG outcrops in NE Nebraska was synchronous with Early Oligocene glaciation of Antarctica.

The Carboniferous Limestone outcrop of Derbyshire forms the southernmost section of the Pennines. It is part of the main waterdivide of Northern England and glaciation has played a crucial role in its Pleistocene development. Throughout the whole epoch, the Derbyshire upland was never of sufficient altitude to generate its own ice sheet and the limestone lay in the shadow of higher Millstone Grit to the north. Derbyshire was therefore subject to external influences. Of the seven cold stages established in the East Anglian sequence, only the last three were cold enough to generate glacial advances. The Anglian and Wolstonian ice sheets certainly crossed Derbyshire, but in the Devensian, the last stage, there is little evidence of glacial debris on the limestone. No interglacial deposits have been found on the plateau surface. In addition to the first detailed mapping and classification of the superficial sediments, geochemical, mineralogical and physical analyses have been made. Using computer analysis of the data for verification, a Pleistocene sequence of events has been established for the area. Problems of dating and distinguishing specific glacial deposits associated with Pleistocene stages have been partly solved by employing a variety of different techniques: emission spectroscopy, X-ray diffraction, scanning electron microscopy, weathering ratio and particle size analysis. Different superficial deposits, till, loess, 'silty drift', insoluble residue, solifluction deposits and erratic content have been compared with each other and limited cave sediments in order to elucidate the former glacial episodes no longer identifiable as distinct deposits on the surface. The analytical results from five important sections point to the existence of two tills on the plateau surface, a northern weathered till in deep limestone joints and over the Tertiary sandpits and a second occurring later within an established drainage system. All are covered indiscriminately by loess, a Devensian product. Surface tills are only preserved in favourable locations and within extensive cave systems. The development of the drainage pattern and stripping of the shale cover play key roles in this association. The investigations provide a framework for the Pleistocene history of north Derbyshire which illuminates the Pleistocene sequence of events throughout the Midlands.

Graptolites, extinct macrozooplankton of the phylum Hemichordata were a major element of the Early Palaeozoic seas. They are here investigated from Wales, Scotland and Northern Ireland and their use beyond biostratigraphy is considered. The leptotheca and convolutus biozones (Aeronian; Silurian) are characterized and correlated across Wales, Scotland and Northern Ireland, and in Scotland subdivision of the convolutus Biozone was possible through identification of Cephalograptus cometa extrema. In the Irish successions, previously unrecognized morphological intermediates within the established Petalolithus-Cephalograptus lineage were recognised and in Wales and Scotland, ‘pre-maxiculus’ morphotypes of Coronograptus are suggested. At all three localities Campograptus lobiferus is the dominant species with intraspecific variation recorded; the type material of this species from Scotland is shown to be unusually large. Use of X-ray images has enhanced biostratigraphy by enabling more specimens and taxa to be recorded, shown how graptolite number varies microstratigraphically and demonstrated that rhabdosomes are systematically aligned. The number and thickness of Aeronian ‘anoxic’ units varies within Wales, and between the Welsh and Scottish successions, indicating diachroneity of anoxia. A schema of microfacies types is constructed for the leptotheca Biozone anoxic unit in Wales and is applied to the Welsh convolutus Biozone anoxic units and to the gregarius to convolutus Biozone strata in Scotland. Facies with less clastic input and no burrows are associated with the best preserved graptolites, with pyrite formation being influenced by variations in palaeoproductivity and clastic input. Levels with well-preserved graptolites are not geochemically distinct, but differences in the major elements indicate provenance differences between the leptotheca and convolutus biozones. A reproducible &delta ^{13}C signal is obtainable from small amounts of carbon from graptolite periderm and periderm &delta^{13}C is different but not consistently so to whole-rock &delta^{13}C. Initial results suggest that periderm &delta^{13}C is not affected by physiology, life habit or metamorphic grade and that for chemostratigraphic study little regard is needed for species composition.

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No description available.