Sugarloaf mountains (inselbergs) are steep-sided, dome-shaped mountains often standing in isolation from the surrounding plains. Although principally recognised in Africa and Australia, the geological and geomorphological development of Brazilian sugarloaf mountains along the eastern Atlantic margin is poorly understood. The contemporaneous relationship of these landforms with the highly threatened Mata Atlantica rainforest, reduced to ~11% of its original distribution due to deforestation, provides a unique setting for multi-scale dynamic landscape research. This thesis determines the geological controls on sugarloaf mountain evolution, standardises geomorphometric inselberg landscape descriptors to improve the understanding of landform evolution through automated mapping retrieval, and assesses the environmental significance of these landscapes as refugia through measures of allometric biomass (AGB) across rainforest fragments in Pancas, eastern Brazil. Geological structural analyses reveal a five stage deformational history, with the granite gneiss sugarloaf basement encompassing both Neoproterozoic ductile shear and Cenozoic brittle extension. These structures, exploited during exhumation through the Eocene and Miocene, exert a strong control on the fragmentation of the plateau and morphology of the mountains revealing a “multi-stage etched” evolution of the current passive margin landscape. Geomorphological landscape analyses identify four novel types of sugarloaf morphometric classes: Summit, Slope, Collar, and Valley Floor. These features, defined by height, slope, minimum curvature and Topographic Profile Index in a Shuttle Radar Topography Mission dataset are used to develop an automated mapping program addressing issues in landscape feature extraction of extreme terrains, standardising descriptions of inselberg morphology and enabling evolutionary stages of inselberg landforms to be recognised. Measures of AGB across remnant forest fragments and analysis of their spatial distribution using Advanced Spaceborne Thermal Emission Reflectance (ASTER) imagery reveal that sugarloaf landscapes concentrate biomass in lowland topographic regions threatened by anthropogenic destruction. Therefore the environmental understanding of sugarloaves as refugia must be readdressed to inform future conservation efforts.

Mountains form where the Earth's plates collide; during this upheaval rocks are deformed by massive forces. The Himalayan orogen represents the ideal natural laboratory to decode the record of the deformational processes encrypted in the rocks. In the eastern region of Sikkim, a unique series of 'time windows' are exposed by doming of a major ductile fault, revealing the inner workings of one of the major mountain-building structures that accommodated the India-Asia collision. The temporal and thermal evolution of the complex zone of deformation associated with this structure, the Main Central Thrust (MCT), was investigated using a combination of whole rock geochemistry (ENd), geochronology (U-Pb and 4°Arl9Ar), accessory and major phase geochemistry, and pressure-temperature modelling. The results demonstrate that: (1) isotope geochemistry can distinguish rock packages that have been juxtaposed over many hundreds of kilometres in complex ductile shear zones; (2) during prolonged ductile deformation of the MCT zone from ~21-9 Ma there was progressively downwards-penetrating deformation and accretion of colder original footwall material to the hotter hanging wall; (3) the associated zone of inverted Barrovian metamorphism documents a sequence of 'paleo-thrusts' that evolved as the thrust-zone deformed rocks at successively lower pressure and temperature conditions «500 to >650°C and 8 to 10 kbar); (4) during the Miocene thrusting progressed at a rate of ~10 mm yr-1 followed by moderately rapid cooling at a rate of ~50-70°C Ma-1 These findings are consistent with a tectonic model where rocks were accreted to a partially-molten mid-crustal channel of ductilely deforming material along the MCT. This study provides new insight into how deformation is accommodated along major thrust faults during mountain building and has implications for how geological tools such as linked geochronology-geochemistry and P-T modelling are used to aid the interpretation of rock deformation in the cores of evolving mountain belts.

The geomorphological behaviour of steep jointed rock slopes has been studied using distinct element computer models. In order to model steep slopes effectively, methodologies need to be combined from the studies of environmental modellers, geomorphologists and engineers. The distinct element method is ideal for the study of the development of jointed rock masses, where the failure is controlled by the nature of the discontinuities. Theoretical modelling identified that block size is a key control affecting the deformation of rock masses. Deformation of rock masses with smaller block assemblages is greater than for rock masses composed of larger block sizes. This is due to the increased magnitude of joint normal closure. Catastrophic failure is less likely in slopes with smaller block sizes because the shear strength is greater in a closely jointed rock mass. These slopes are more likely to undergo gradual deformations. Block-size effects are also responsible for influencing the failure mechanism of rock masses. As block size decreases, the magnitude of block rotation increases and the failure mechanism changes from sliding to toppling. The effect of slope scale on the deformation properties of the rock masses has also been investigated. Two field locations, the Picos de Europa mountains, northern Spain and Wadi Rum, southern Jordan, have been chosen to provide a link between the theoretical modelling and classic rock landforms which are controlled by the discontinuity geometry. Given the sporadic and infrequent occurrence of failure events at the field sites, a computer modelling approach has been adopted to analyse slope behaviour. In the Picos de Europa, slope deformations are deep-seated, with sliding and toppling being the dominant modes of failure. Much of the slope deformation in these mountains is a result of post-glacial rock-slope deformation. The sandstone inselbergs of Jordan show a range of morphologies from rounded hills to vertical cliffs. The morphology of the inselbergs is related to the intact rock strength; stronger Red lshrin sandstone forms vertical slopes, whereas the weaker Disi sandstone forms rounded domes. Jointing in the area is sub-vertical with horizontal bedding and computer simulations have shown that toppling is the dominant mode of failure in these inselbergs. Comparison of computer model output suggests that different failure mechanisms have distinct failure signatures. Catastrophic, deep-seated failures are characterised by a long period of acceleration as the failure propagates through the rock mass and infinite velocity is reached. Non-catastrophic slope movements, such as self-stabilising topples, are characterised by short periods of acceleration followed by small creep movements at a constant velocity. Computer modelling has indicated that scale effects do exist in the modelled rock masses from the Picos de Europa and particularly Wadi Rum. In areas where jointing is constant, the relative block size of the rock mass decreases as slope scale increases. The greater numbers of blocks along with greater in situ stresses influence the failure of the slope. Cosmogenic dating was used to temporally constrain UDEC model output and provide a better understanding of rock slope failure mechanisms in the Picos de Europa and Wadi Rum. Dating indicated delayed paraglacial adjustment was the triggering mechanism for slope failure in the Picos de Europa, whereas failures in Wadi Rum appeared to be closely linked with wetter climatic conditions.

An area of c. 50 km² within the Altkristallin Sheet (Upper East Alpine Sheet sensu lato) south of the Tauern Window has been mapped at a scale of 1:10,000. The rocks have been tilted southwards by uplift of the Hohe Tauern area, and the mapped area represents a section from deep tectonic levels characterised by early Alpine (80 my) K-Ar mineral ages, through to higher levels with Hercynian (220-300 My) ages. The rocks are mainly metasediments with minor amounts of metamorphosed igneous material. Three principal schist types are distinguished. (i) in the south: phyllitic garnet-muscovite and quartzose schists. (Kreuzeck Schists). (ii) in the north: medium- to coarse-grained mica-schists and para-gneisses (Polinik Schists). (iii) in a central zone: schists intermediate in character between the above (intermediate Schists). The tectonic sequence in the map area has been determined by structural analysis and correlation, and the K-Ar mineral age provinces correlated with episodes of mineral growth. The area underwent a major Hercynian deformation and metamorphic event (F₁ and M₁) of amphibolite facies, with pelitic assemblages dominated by muscovite and garnet, now preserved in the Kreuzeck Schists. Mineral textures indicate syntectonic growth. Relict eclogites in the Polinik Schists are also assigned to this phase. An F₂ deformation increases northwards (i.e. downwards in the Altkristallin Sheet) in both intensity and ductile nature. F₂ structure has been synthesised across the map area largely by minor fold correlation. Early Alpine metamorphic recrystallisation also increases downwards, obliterating M₁ textures and defining a new foliation, axial-planar to F₂ folds. Although mineral growth is post-tectonic, it is suggested that M₂ and F₂ are part of the same tectonic event. An F₃ deformation, involving microfolding, flexuring and local chevron-folding, was followed by late Alpine retrogression (M₃) which is patchily distributed over most of the area, but more uniformly developed in greenschist facies in the basal kilometer of the Altkristallin Sheet. The Altkristallin Sheet is broken up into blocks by shear zones of (at least) two generations, distinguished on lithological grounds. Strain in quartz fabrics is related to late structures, probably to late arching of the Altkristallin Sheet (F₄), and locally to the development of shear zones. Petrograhic mapping revealed the progressive overprint of M₁ by M₂ assemblages in the Kreuzeck and Intermediate Schists, with the following features in approximate order of appearance, south to north: (i) growth of biotite and plagioclase porphyroblasts; (ii) gradual increase in muscovite fabric recrystallisation; (iii) growth of staurolite and breakdown of old garnet; (iv) breakdown of M₂ staurolite and growth of Al-silicates (sillimanite, andalusite and kyanite). Three isograds may be constructed in the Intermediate Schists: (i) an isograd marking the first appearance of M₂ staurolite; (ii) an andalusite-sillimanite isograd; (iii) a garnet-Al silicate-biotite isograd. Isograds (ii) and (iii) have been mapped over an outcrop length of 8 km and a vertical relief of c. 1 km, and are approximately parallel to the M₂ regional foliation and the compositional banding. The Polinik schists lie within the stability field of staurolite + quartz, but entirely within the kyanite field, indicating that there are two distinct areas of differing thermal gradient during M₂.

Results are reported of laboratory simulated weathering processes on a range of sedimentary rocks and the investigation of the deterioration of rock masses as observed on engineered and quarried rockslopes. The simulated weathering processes include freeze-thaw, wetting and drying, salt weathering and slaking. It is found that the rock properties of pore volume, saturation coefficient and microporosity exert greatest influence on susceptibility to breakdown. For stronger rocks it is found that durability correlates well with high strength and elasticity. A range of rock flaws visible in hand specimen are described and their influence on rock deterioration assessed. Linear flaws such as laminations and stylolites are more likely to be associated with breakdown, and the role of structural weaknesses is most evident in stronger rocks. Rock breakdown mode due to experimental weathering is found to closely resemble material weathering of source slopes in the field. A range of rock breakdown mechanisms are inferred from changes in pore microstructure and rock strength. There are indications of a progression from deterioration which is invisible and involves modification of the existing pore structure, to macro deterioration resulting from generation of new void space and microcracks. After field investigation of more than two hundred rockslopes deterioration is found to be widespread, and there is little evidence of a systematic approach to its assessment or mitigation. Fracture spacing, rock strength and lithology are found to be the most influential factors in rockslope deterioration and these are used to define a characteristic range of rock mass types. A range of morphological forms attributed to deterioration are defined and described. An engineering classification of deterioration modes is presented, based on constituent material size, velocity of movement and frequency of occurrence. Deterioration modes correlate well with rock mass type. A new rock mass classification, called Rockslope Deterioration Assessment (RDA) is proposed, dealing specifically with shallow, weathering and erosion-related rockslope processes. RDA is divided into three stages; a ratings assessment of deterioration risk, a qualitative review of the likely deterioration hazard, and guidance on appropriate mitigation. The findings of the experimental work are incorporated into stage one of RDA where appropriate. Notable in this respect is the emphasis in RDA on evaluation of fracture spacing on the basis of all fractures present, whether open or incipient, and whether natural, or induced by blasting, weathering or stress release. RDA is applied to the slopes investigated in the fieldwork and shows that certain types of rock mass are associated with higher risk of failure. There is also an element of predictability in the occurrence of deterioration modes. Correlation between stage one of RDA and Rock Mass Rating is examined and it is shown that, although there are some similarities, a fundamental difference relates to the basis upon which fracture spacing is assessed.

Slope channel systems represent significant but highly variable deep-water stratigraphic features and reservoir targets. Variations in architecture and component facies can take place along strike, depositional dip and stratigraphically. A better understanding of these variations permits improved sedimentological and architectural models. By integrating two outcrops (San Clemente, California and Baja California, Mexico) and one subsurface example (offshore Nile Delta), this study provides an opportunity to investigate cross-channel asymmetry, stratigraphic evolution and variability, vertical facies trends, and controls of slope channel systems. This study demonstrates that cross-channel asymmetry in facies and architecture is a lithology- and scale-independent feature, and preferentially occurs at channel bends and in the upper part of slope channel systems. Facies and architectural asymmetry are generally expressed as amalgamated, coarser-grained deposits displaced to the steeper channel edge (outer bend), and finer-grained deposits dominate towards the gentler channel edge (inner bend). A comparison of the systems exposed in Mexico and buried in the subsurface reveals a similar evolutionary trend, from initial sediment erosion/bypass, through early-stage laterally amalgamated channels, late-stage sinuous channels with levees/terraces, and final abandonment. However, pronounced variations exist in the late stage (e.g., presence or absence of lobes), and abandonment stage (e.g., presence or absence of MTDs plugging and channel avulsion). Additionally, for the first time, this study quantitatively demonstrates that early-stage and late-stage architectural elements are characterized by distinct patterns in preferred vertical facies transitions, based on Markov chain analysis of vertical successions. This study also suggests that both extrabasinal factors (e.g., relative sea-level) induced flow energy cycles and intrabasinal factors (e.g., folding and faulting, MTDs, channel bends) can exert a significant control on the architecture and/or evolution of slope channel systems.

Θεματικός πυρήνας της συγκεκριμένης εργασίας είναι η αναγνώριση, ιεράρχηση και ερμηνεία των παραμορφωτικών χαρακτηριστικών ενός τμήματος του καλύμματος της Όχης, που καταλαμβάνει τα υψηλότερα τεκτονοστρωματογραφικά επίπεδα της ενότητας κυανοσχιστολίθων Εύβοιας (EBU). Μολονότι θεματικό πυρήνα της εργασίας αποτελεί η τεκτονική ανάλυση τμήματος του καλύμματος της Όχης, έμφαση δίνεται και στους μηχανισμούς που έχουν προταθεί για τον εκταφιασμό λιθοτεκτονικών ενοτήτων που έχουν υποστεί συνθήκες υψηλών και υπερ - υψηλών πιέσεων. Καταληκτικά, εκτίθενται επίσης τεκτονοστρωματογραφικά δεδομένα, τεκτονικά δεδομένα και πετρολογικά δεδομένα απο την ευρύτερο τμήμα της Νοτίου Ευβοίας δίνοντας έμφαση στην μεταμορφική πληροφορία που εσωκλείουν τα πετρώματα που υπέστησαν τις συνθήκες ενός καναλιού καταβύθισης. / The core subject of the present study is the recognition, relative dating and structural interpretation of the deformational characterestics of a part of the Ochi nappe. The Ochi nappe possess the highest tectonostratigraphic levels between the stacked nappes which constitute the Evia Bluschist Unit (EBU). Emphasis in this study is given to the mechanisms which have been proposed that contribute to the exhumation of (U)HP metamorphic terranes. In general, this study expose the to date published information about the stratigraphy, structural geology and metamorphic petrology of Southern Evia blueschist belt.