The area is made up of Lower Dalradian metasedimentary rocks intruded by granite ("Younger Granite") and minor intermediate to basic igneous rocks, the order of intrusion being basic to acid. Although the succession of the metasediments cannot be proved, enough evidence exists to show that these rocks were folded to form two primary recumbent nappe structures, partially bound by slides0 The attitude of these structures is compatible with the general Caledonoid pat-tern and they are thought to belong to part of the hinge region of the Ben Lui Syncline. Intense smaller-scale folds in the metasediments are the products mainly of two subsequent deformations, the earlier producing "cross-folds", the later producing folds on Caledonoid axes. Both nappes, however, have a complicated history of deformation, this being borne out by petrofabric studies of the quartzite and granite intrusions of each nappe. The deformation fabric of the granite is often similar to that of the adjacent quartzite despite the fact that the granite appears in the field to post-date most of the folding The fabric of both rock-types corroborates other evidence that the general structure of the upper nappe is simpler than that of the lower. Metamorphic changes in the pelitic rocks can to some extent be correlated with the main phases of deformation. The rocks were firstly regionally metamorphosed, and then (in the area around and to the north-east of Braemar) thermally altered. The resulting zone of foliated horn-felses corresponds with the limit of granite intrusion around the margins of the Lochnagar Granite Complex. The "thermal" minerals are themselves affected by even later deformation - probably contemporaneous with the straining of the granite.

Volcanic rocks from Sao Miguel form two distinct alkaline (potassic) magma series. Recent eruptives comprise Ne-normative basalts and derivatives (Main Series). Older basalts associated with the extinct stratovolcano Povoacao are either Ne or Hy-normative (Povoacao Series ) and have lower P/Zr, Ba/Zr and Sr/Zr ratios. Faial volcanic rocks form a single series, basaltic compositions being Ne-normative. Differentiates on both islands range through intermediate compositions to metaluminous and peralkaline trachytes. The latter are strongly enriched in the incompatible elements (eg Th, Rb, Ta, Nb, Zr and the rare-earths) and are depleted in Mg, Ni, Cr, V, Ti, P, Sr, Eu and Ba. Fractional crystallization of the observed phenocryst assemblages can account for most chemical variations, incompatible element abundances indicating that the trachytes result from some 60--85% solidification of a parental basalt. Mixed-magma lavas occur on both Faial and Sao Miguel. They form two distinct groups. (1) M-type lavas. These have high Ni, Cr and MgO and low CaO, Sr, P₂ O₅, TiO₂ and V. Modelling suggests they are a mix of trachyte (70%) and MgO-rich basalt (30%). (2). AM-type lavas. They show similar geochemical features but also have high Ba and Eu and large K/Rb ratios. They are best modelled by mixing hawaiite, trachyte and alkali feldspar. AM-type lavas and geochemically heterogeneous pumice deposits suggest compositionally zoned (basalt-intermediate-trachyte) magma chambers beneath both islands. Compositional variations in recent pumice deposits from Agua de Pau volcano show temporal control. Trends up the succession include the depletion of Sr, Ba and Eu coupled with stepwise enrichment in the incompatible elements. These suggest the deposits represent successive samples of an evolving body of trachytic magma. The lack of similar variations in the Furnas pumice succession is attributed to a high magma viscosity, inhibiting crystal/liquid fractionation. Pre-eruptive temperatures for trachytic pumice deposits, from coexisting magnetite and ilmenite, ranged between 960°C--880°C. fO₂ varied between 10^-10.9--10^-13.4. Thermodynamic-based estimates of magnetic water contents were between 6.5--7.2 wt.%. These values are compatible with field data. Estimates of S₂, H₂S, SO₂, SO₃, H₂, CO₂, HCl and HF suggest they are several orders of magnitude less abundant than H₂O. Lastly, Azores basalts exhibit inter and intra-island compositional heterogeneity. Relative to N type m.o.r.b., they are characterized by high La/Yb, Ba/La, ⁸⁷Sr/⁸⁶Sr ratios and low ¹⁴³Nd/¹⁴⁴Nd, Zr/Nb, Zr/Ta and K/Rb ratios. Sao Miguel shows a systematic increase in ⁸⁷Sr/⁸⁶Sr ratios from west to east (up to 0.70522). Most of these features represent source characteristics and suggest a complexly heterogeneous mantle.

During Caledonian amphibolite grade metamorphism in the Fannich/Ullapool area of N.W. Scotland, high grade migmatitic gneisses were overthrust northwestward along the Sgurr Beag Slide, onto lower grade rocks. A minimum displacement of about 50km is indicated. Features associated with the slide include: the presence of slivers of Lewisian basement along the slide at Achnasheen; the intensification of strain in a 2km zone adjacent to the slide; differences in the early structural and metamorphic histories of the crustal blocks lying above and below the slide; and local inversion of isograds. The slide zone, and all peak metamorphic fabrics, were reworked by a set of major N-S trending, westward verging asymmetrical folds. Associated deformation fabrics intensify towards the Moine Thrust zone, culminating in the development of greenschist facies mylonites. Within 4km of the thrust, folds and fabrics of this generation become sub-parallel to banding and fold axes are rotated towards the movement direction of thrusting (i.e. the W.N.W.). Shear bands are developed in pelitic horizons whilst in psammitic lithologies, strong quartz c-axis girdle fabrics characterise mylonitic rocks. K-Ar dates on muscovite and biotite pairs from pelites (200-250um grain-size), along an 18km E-W traverse through the area indicate that the whole of the area cooled virtually simultaneously between 424Ma and 421Ma. However uplift possibly as early as 430Ma is indicated close to the thrust. During the same period an excess argon atmosphere was developed in a zone within 4km of the Moine Thrust. The K-Ar study reveals a relationship between age, reproducibility and grain-size. Fine grain-sizes (125-200um) give reproducible ages with a mean of 423.5Ma (muscovite) and 421.5Ma (biotite). Whereas coarser grain-sizes (250-500um)give unreproducible ages at around 433Ma, significantly older than the finer. Rb-Sr mica pairs of all grain-sizes give ages compatible with the K-Ar ages from the finest grain-sizes. It is suggested that the micas suffered a partial resetting event late in their cooling history. The major conclusion of the study is that the development of the Moine Thrust zone significantly post-dates peak metamorphism and movement upon the Sgurr Beag Slide. The slide zone is thought to have moved during peak metamorphic conditions around 460Ma whereas the Moine Thrust developed and moved between 430Ma and 420Ma.

A structural and metamorphic study of Moine rocks between Loch Eil and Loch Eilt, Inverness-shire. "Research between Loch Eil and Loch Eilt, Inverness-shire on rocks from all three Divisions of the Moine Succession within the Caledonian Orogen, above and to the east of the Moine thrust zone, has revealed that, within the area, all three Divisions share a common sequence of polyphase deformation and metamorphism. All three Divisions have been metamorphosed during Precambrian and Caledonian tectono-thermal events. The Ardgour granitic gneiss, a = 1000 Ma. pre-D₁ intrusion, sub-parallel but transgressing the junction between the central Glenfinnan and eastern Loch Eil Divisions, has undergone partial anatexis during D₁, unlike the adjacent migmatitic meta-sediments. Major folds have not been recognised. Grenvillian ( = 1000 Ma.) D₂ deformation and high grade metamorphism has almost completely transposed the D₁ granitic gneiss foliation but there is no unequivocal evidence for D₂ partial anatexis. F₂ major folds occur in the vicinity of the granitic gneiss but not elsewhere. Caledonian D₃ deformation has produced major F₃ sub-recumbent folds with curvilinear hinge lines, within the Glenfinnan and Loch Eil Divisions, above a flat lying major D₃ simple shear zone, the Sgurr Beag slide. Large scale WNW transport has carried these rocks over the underlying Morar Division rocks. Only at the highest levels of strain within the shear zone has the Grenville metamorphic assemblage re-equilibrated. Elsewhere the early isograds are folded during D₃. Post-D₃ microdiorite sheet intrusions have suffered medium grade (amphi-bolite facies) metamorphism during D₄ deformation. D₄ heterogeneous, horizontally directed pure shear deformation, possibly above a flat lying decollement plane such as the Moine Thrust, has produced major upright folds of the D₃ Sgurr Beag slide and rotated Glenfinnan Division F₃ sub-recumbent isoclines towards vertical, to form the D₄ "steep belt". D₅ deformation has produced sporadically distributed minor folds possibly related to regional warps of the earlier major structures.

The rocks exposed on the eastern part of the island of Seiland are the metasedimentary envelope to the large basic and ultrabasic plutons that make up the western part of the island and the neighbouring island of Stjernoy. These metasediments have been intensely deformed and metamorphosed, thus all sedimentary structures have been obliterated. The metasedimentary sequence is, therefore, a structural one. The lowest group is the psammitic Komagnes Group. This is followed by the Eidvageid Schist Group which is followed by the relatively thin psammitic Trollvann Group. Structurally above this is the pelitic Olderbugten Group and finally the dominantly psammitic Olderfjord Group. Broadly speaking two major fold-forming deformations have been recognised; F.1 and F.2. The latter part of the first phase, which was responsible for tight isoclinal folds and a penetrative schistosity, was accompanied by intrusion of sheets of basic material parallel to the axial planes of the early folds. During the static interval separating the two deformations the maximum grade of metamorphism was achieved, this, however, varies across the area and a sequence of metamorphic isograds have been recognised. The highest grade occurs in the west and is marked by a kyanite-sillimanite porphyroblastesis, migmatisation and intrusion of adamellitic sheets. The lowest grade in the east is characterised by albite, biotite, epidote, hornblende assemblages in the psammites of the Lower Komagnes Group. These isograds reflect a contemporaneous lateral change in metamorphic grade. Following the development of these high grade assemblages in the west, there was a phase of intense flattening leading to the development of mylonitic textures in the rocks. It is suggested that this deformation phase is related to a rising basic asthenolith. The majority of folds on the area are attributed to F.2.By the onset of F.2. the metamorphic grade appears to have waned to sub-garnet grade conditions. The folds have a very variable style. In the east, they have intensely attenuated long-limbs with a number of vertically-stacked folds in the short-limbs. In the west, the limbs are of more equal length. This change in style is related to the different states of competence of the rocks at the onset of F.2. A ubiquitous feature of F.2. folds on both the major and minor scale, is the curvature of their axial-lines. In the east a number of oblique boudins have been recorded which post-date F.2. They are closely associated with rotated tension-gashes and monoclinal folds. It is suggested that all these structures were formed in response to a progressive deformation sequence. This sequence was also responsible for the development of the late Caledonian thrusts on the mainland. In the north of the area there is a pronounced swing in strike. A number of open folds are associated with this swing. These folds have been designated F.3. Monoclinal warps have been recorded in the east of the area. Their temporal relationship to the F.3. folds in the north is not known. The final phase of movement in the area led to the development of joints, faults and locally kink-folds. The prevailing metamorphic grade during this phase of deformation, and indeed all the phases subsequent to F.2., was the Quartz-Albite-Muscovite-Chlorite Sub-facies of the Greenschist Facies.

The geology of a previously unmapped 170 square miles (440 sq. kms.) area of South Turkana, lying within the Kenya rift, is described. A contoured and coloured geological map is presented. The stratigraphical succession established which totals about 6000 feet (18OO m.) in thickness and consists largely of volcanic rocks, ranges in age from about 25 to 4 million years b.p. New potassium/argon age determinations on some of the lavas are presented and reinforce the established stratigraphy . Particular attention is paid to the Pliocene succession which consists of a thick, widespread basalt formation overlain by a number of trachyte volcanoes. The morphology of the multicentred trachyte volcanoes suggests that they are a type not described before. The potrography of the lavas of the Nasaken area is described in detail. Chemical analyses of rocks and minerals are presented and the petrogenesis of the Pliocene lavas is discussed withparticular reference to the relationship between the basalts and the voluminous trachytes and the origin of the chemical variation within the trachytes. The trace-element geochemistry of the Pliocene lavas is compared with the geochemistry of lavas from other areas within the East African rift system.

The study area lies within the marginal part of the Caledonian orogen of the Northwest Highlands of Scotland. The aim of the thesis was to attempt to correlate events from the marginal Moine thrust zone eastward into the Mobile Belt. The correlations included stratigraphy, structure and metamorphism. Stratigraphie correlations were restricted to Moine lithologies hitherto undifferentiated; they included rocks on the Sleat Peninsula of Skye, and in Eastern Knoydart. Structural and metamorphic events are closely related, and developed as a result of two distinct orogenic episodes. The earliest of these orogenic episodes occurred during the Pre-Cambrian and resulted in deformation on a regional scale producing tight, often flat lying structures. The metamorphic grade increased from west to east. Microfabric studies enabled a close correlation between the second phase of deformation and the advance of the meta-morphic front. The youngest orogenic event is the Caledonian event which produced open profile, upright structures, associated with a second metamorphic event, which also advanced from east to west. It has proved possible to correlate structural and metamorphic events over an area of some 1,100 sq.kms. within the Moine nappe. Further studies established that structural and metamorphic events recorded in the Moine nappe may be extended to include the underlying Tarskavaig nappe. Wider correlations were also attempted; firstly in immediately adjacent areas and subsequently on a more regional scale. The discussion of regional correlations includes data presented in the literature for areas both within the Moine thrust zone and within the Mobile Belt. Although the suggested correlations may be only tentative, there would appear to be some basis for regional correlation.

The thermal infrared portion of the electromagnetic spectrum has considerable potential for mineral and lithological mapping of the most abundant rock-forming silicates that do not display diagnostic features at visible and shortwave infrared wavelengths. Lithological mapping using visible and shortwave infrared hyperspectral data is well developed and established processing chains are available; however, there is a paucity of such methodologies for hyperspectral thermal infrared data. Here, a new fully automated processing chain for deriving lithological maps from hyperspectral thermal infrared data is presented; the processing chain is developed through testing of existing algorithms on synthetic hyperspectral data. The processing chain is then applied to the first ever airborne hyperspectral thermal data collected in the Antarctic. A combined airborne hyperspectral survey, targeted geological field mapping campaign and detailed mineralogical and geochemical datasets are applied to a small test site in West Antarctica where the geological relationships are typical of continental margin arcs. The challenging environmental conditions and cold temperatures in the Antarctic meant that the data have a significantly lower signal to noise ratio than is usually attained from airborne hyperspectral sensors. Preprocessing techniques were applied to improve the signal to noise ratio and convert the radiance images to ground leaving emissivity. Following preprocessing, the fully automated processing chain was applied to the hyperspectral imagery to generate a lithological map. The results show that the image processing chain was successful, despite the low signal to noise ratio of the imagery; the results are encouraging with the thermal imagery allowing clear distinction between granitoid types.

This thesis is an investigation of the magmatic processes that operated in the plumbing system of the Franklin Large Igneous Province (LIP). The Franklin LIP (~723-716 Ma) extends >2500 km across northern Canada and is superbly exposed in the Minto Inlier of Victoria Island. The exposed plumbing system is dominated by sills, with subordinate fault-guided feeder dykes. Locally, sills are characterised by olivine-enriched bases, with overlying doleritic gabbros. One example is the Lower Pyramid Sill. This sill was investigated in detail using petrography, whole-rock chemistry and in-situ mineral chemistry. Petrological and geochemical observations, combined with inverse melt modelling show that the olivine-enriched layer formed by olivine slurry replenishment into a resident gabbroic mush. In contrast, the overlying gabbros formed by in-situ differentiation. Intervening clinopyroxene-rich cumulates formed by a metasomatic reaction between different pore melts. The study emphasises that both slurry emplacement and in-situ differentiation played a role in the formation of cumulate layering in this sill. Sections examined through the same sill along strike, collectively termed the Fort Collinson Sill Complex, reveal that the olivine slurry propagated >50 km downstream. Radiogenic and stable isotope data support this interpretation. The geochemical consequences of cumulate remobilisation and mixing in the sill complex are demonstrated, as well as quantified, using Fe=Mg modelling. Additionally, the effects of dolostone assimilation are considered, which can potentially affect phase equilibria. This thesis also investigates the Ni-Cu-PGE potential of the Franklin LIP by studying the Southern Feeder Dyke Complex. This dyke complex was fault-guided and brecciated dykes contain microdoleritic microxenoliths that are impregnated by sulphides. Immiscible sulphide liquids formed when the magma became sulphur saturated due to the ingestion of local sulphur-rich wallrock. This study demonstrates the importance of external sulphur addition to magma in triggering sulphide mineralisation and highlights the economic potential of the Franklin LIP.

Hydraulic conductivity (K), porosity and cation exchange capacity (CEC) were determined at the laboratory scale on samples of the Wildmoor Sandstone and Kidderminster Formations of the Birmingham Triassic sandstone. The impact of the rock colour was considered in a semi-quantitative manner using the Munsell Colour System. SEM, flushing experiments and image analysis of thin-section photomicrographs were used to assess the role of rock fabric in the development of hydraulic and chemical properties. The image analysis was carried out on colour images using a custom-written code. XRD, point counting and geophysical methods were utilised to assess the mineralogical variation between samples, the presence of iron and manganese oxides within the sandstone was quantified. The study found significant negative correlations between porosity and CEC in all samples, while a correlation between K and CEC was only observed in samples with a lower colour saturation. A significant role for manganese oxides in the development of CEC in the Triassic Sandstone of Birmingham has been identified. The study has concluded that a significant part of the CEC within these rocks is due to the presence of a reducible phase. This has significant implications for migration of contaminants, particularly those entrained in a reducing plume.