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Würzburg, Univ., Diss., 2009. / Zsfassung in dt. Sprache.

published_or_final_version / Earth Sciences / Master / Master of Philosophy

In unstable landscapes, modern pedological research explores the role of soils as products and indicators of geomorphologic change. Understanding the dynamics of hill slope pedogenesis is especially important in regions with limited, poor, or threatened soil resources. The island of Cyprus, situated in the eastern Mediterranean, is claimed by many authors to exhibit signs of severe soil degradation and is a prime site for comparative soil geomorphologic research. This study strove to 1) identify the controls of soil genesis and landscape stability within the Troodos Mountains of Cyprus using image and GIS analysis; 2) compare toposequence data to expected soil thickness trends from traditional models of xeric soil toposequences prevalent in current scientific literature; and 3) develop a predictive model for hillslope pedogenesis based on measured soil properties within the field area. Study soils within the Troodos are thin, weakly developed Lithic and Typic Xerorthents formed in colluvium derived from fractured, igneous bedrock. Soil thickness was measured at 368 sites in seven transects across three watersheds in the Troodos, using interpretations of field profiles and image analysis of digital soil-bedrock profiles in photographed road-cuts along forestry paths. Soil thickness was compared through GIS and statistical analysis to landscape attributes derived from a 25-m DEM and other map data. Results indicate that lithology is the only factor of several studied to have a significant relationship with the variability of soil-profile thickness in the Troodos, and that soil thickness does not vary in a predictable manner across toposequences. These results, combined with differences between measured soil data and values predicted by the landscape stability model SHALSTAB, suggest that soil genesis in the Troodos is best described only within the context of a weathering-limited geomorphological system. Short-term disruptive processes such as forest fires, land sliding, tree throw, and raindrop impact, combined with long-term processes such as tectonic uplift and stream incision, are the most likely driving forces behind the rapid erosion of hill slope sediments and the weak development of Troodos hill slope soils. These findings have important implications for DEM-based, predictive soil mapping in weathering-limited geomorphologic systems. / Graduation date: 2005

The Troodos ophiolite is a type example of ophiolite and has been studied for more than 50 years. Albeit numerous findings have been derived from previous investigations, some questions about the details of its formation processes are still outstanding. One of them concerns the origin of the pyroxenites in the mantle and the lower crustal section, and this is the main theme of this thesis. Integrated field, petrographical and geochemical work was conducted in this study. On the basis of distribution, the pyroxenites can be divided into two categories, crustal pyroxenites and mantle pyroxenite dykes. The results show that the layered or massive crustal pyroxenites can be distinguished by their magmatic features, and their formations have been controlled by a series of factors, including the melt composition, change of pressure, magma replenishment and magma mixing. The crystallization sequences of the crustal ultramafic unit samples are classified into two trends. Trend (i) olivine, orthopyroxene, clinopyroxene, plagioclase has been derived from tholeiitic-boninitic transitional melts, whereas trend (ii) olivine, clinopyroxene, plagioclase, orthopyroxene from depleted boninitic melts. Regarding the mantle section, the pyroxenite dykes have been formed by focused flow of melt during migration towards the crust. Data show that they are products of several processes, including melt-rock reactions and fractional crystallization. On the basis of modal composition, the pyroxenite dykes are divided into clinopyroxenites and orthopyroxenites. Geochemical compositions suggest that the clinopyroxenites have been derived from island arc tholeiitic melts, whereas the orthopyroxenites from boninitic melts. The important overlap of the tholeiitic and the boninitic series throughout the sections of the ophiolite, as well as the presence of lithologies with compositions transitional between the two series, suggests that the two magmatic suites existed together. A tectonic model of subduction initiation, during which the subducting slab rolled-back rapidly, triggering asthenospheric mantle flow into the mantle wedge, inducing partial melting at a shallow level of the mantle to generate a series of island arc tholeiitic magmas and at deeper level, a series of depleted boninitic magmas. The two magmatic series have possibly been mixed during migration in the mantle, producing transitional units of the two series. / published_or_final_version / Earth Sciences / Master / Master of Philosophy

Graduation date: 1997

The study investigates the water resources and aquifer dynamics of the igneous fractured aquifer-system of the Troodos Mountains in Cyprus, using a coupled, finite differences water balance and groundwater modelling approach. The numerical water balance modelling forms the quantitative framework by assessing groundwater recharge and evapotranspiration, which form input parameters for the groundwater flow models. High recharge areas are identified within the heavily fractured Gabbro and Sheeted Dyke formations in the upper Troodos Mountains, while the impervious Pillow Lava promontories - with low precipitation and high evapotranspiration - show unfavourable recharge conditions. Within the water balance studies, evapotranspiration is split into actual evapotranspiration and the so called secondary evapotranspiration, representing the water demand for open waters, moist and irrigated areas. By separating the evapotranspiration of open waters and moist areas from the one of irrigated areas, groundwater abstraction needs are quantified, allowing the simulation of single well abstraction rates in the groundwater flow models. Two sets of balanced groundwater models simulate the aquifer dynamics in the presented study: First, the basic groundwater percolation system is investigated using two-dimensional vertical flow models along geological cross-sections, depicting the entire Troodos Mountains up to a depth of several thousands of metres. The deeply percolating groundwater system starts in the high recharge areas of the upper Troodos, shows quasi stratiform flow in the Gabbro and Sheeted Dyke formations, and rises to the surface in the vicinity of the impervious Pillow Lava promontories. The residence times mostly yield less than 25 years, the ones of the deepest fluxes several hundreds of years. Moreover, inter basin flow and indirect recharge of the Circum Troodos Sedimentary Succession are identified. In a second step, the upper and most productive part of the fractured igneous aquifer-system is investigated in a regional, horizontal groundwater model, including management scenarios and inter catchment flow studies. In a natural scenario without groundwater abstractions, the recovery potential of the aquifer is tested. Predicted future water demand is simulated in an increased abstraction scenario. The results show a high sensitivity to well abstraction rate changes in the Pillow Lava and Basal Group promontories. The changes in groundwater heads range from a few tens of metres up to more than one hundred metres. The sensitivity in the more productive parts of the aquifer-system is lower. Inter-catchment flow studies indicate that - besides the dominant effluent conditions in the Troodos Mountains - single reaches show influent conditions and are sub-flown by groundwater. These fluxes influence the local water balance and generate inter catchment flow. The balanced groundwater models form thus a comprehensive modelling system, supplying future detail models with information concerning boundary conditions and inter-catchment flow, and allowing the simulation of impacts of landuse or climate change scenarios on the dynamics and water resources of the Troodos aquifer-system. / Die vorliegende Arbeit untersucht die Grundwasserressourcen und die hydraulische Dynamik des Troodos Kluftaquifersystems in Zypern mit Hilfe gekoppelter numerischer Wasserhaushalts- und Grundwasserströmungsmodelle auf Rasterbasis. Die Wasserhaushaltsmodelle quantifizieren die hydrologischen Rahmenparameter des Untersuchungsgebietes. Grundwasserneubildung und Evapotranspiration werden als Eingangsparameter der Grundwassermodelle weiterverarbeitet. Die Grundwasserneubildung ist in den niederschlagsreichen Regionen des höheren Troodos Gebirges, im Bereich der stark geklüfteten Gabbro und Sheeted Dyke Lithologien, am höchsten, nimmt zu den Vorgebirgen ab und erreicht dort ein Minimum in den gering durchlässigen Pillow Lava Sequenzen. Die Evapotranspiration zeigt einen umgekehrten Trend. Zusätzlich zur aktuellen Evapotranspiration wird eine sogenannten Sekundär-Evapotranspiration ermittelt, die sich – unabhängig von der Bodenfeuchte – aus der Verdunstung von Wasser-, Feucht- und Bewässerungsgebieten berechnet. Dieses Konzept erlaubt die Ermittlung der Verdunstungsmenge der bewässerten Flächen und somit die Abschätzung regionaler Grundwasserentnahmeraten, die als Brunnenentnahme in die Grundwassermodelle eingearbeitet werden. Mit zweidimensionalen, bilanzierten, vertikalen Grundwassermodellen, die entlang geologischer Schnitte durch das Untersuchungsgebiet verlaufen, wurde die Grundwasserströmung bis zu einer Tiefe von mehreren Kilometern hoch auflösend simuliert. Die generelle Strömungscharakteristik zeigt eine dominierende Vertikalkomponente in den Neubildungsgebieten des hohen Troodos, quasi stratiforme Strömung in den Mittelläufen im Bereich der Gabbros und Sheeted Dykes, und einen relativen Anstieg des Potentials und Grundwasserausfluss im Bereich der geringdurchlässigen Pillow Laven der Vorgebirge. Indirekte Neubildung durch Grundwasser aus dem Troodos kann in den überlagernden Sedimenten nachgewiesen werden, ebenso wie Lateralflüsse zwischen den Einzugsgebieten. Die Grundwasserverweildauer liegt meist bei wenigen Jahrzehnten. Ausnahmen bilden tiefe Strömungen aus dem hohen Troodos, die Verweilraten von mehreren Jahrhunderten erreichen. Der oberflächennahe, stark geklüftete und für die Wasserwirtschaft wichtige Teil des Aquifersystems wurde in einem horizontalen, den gesamten Troodos umfassenden Grundwassermodell nachgebildet. Bewirtschaftungsszenarien ohne bzw. mit gesteigerten Entnahmeraten simulieren die Dynamik dieses Aquifers. Die Ergebnisse zeigen, dass die Sensitivität auf die Änderung der Entnahmeraten regional sehr unterschiedlich ist. In den Entnahmegebieten des hohen und mittleren Troodos liegen die Spiegelschwankungen meist bei wenigen Metern bis Zehnermetern, während die Schwankungen in den gering durchlässigen und niederschlagsarmen Vorgebirgen teilweise mehr als hundert Meter betragen können. Das laterale Strömungsverhalten wird in einzelnen Test-Einzugsgebieten im Troodos untersucht. Während in den Untersuchungsgebieten generell effluente Grundwasserverhältnisse vorherrschen, gibt es Seitentäler, die vom Grundwasser unterströmt werden und die Grundwasser in benachbarte Einzugsgebiete abgeben. Diese Lateralflüsse können lokal die Wasserbilanz von Einzugsgebieten im Troodos beeinflussen. Die bilanzierten Grundwassermodelle illustrieren sowohl die Tiefenströmung mit hoher Auflösung als auch den oberflächennahen, wasserwirtschaftlich interessanteren Teil des Troodos - Kluftaquifersystems und zeigen die großflächigen Auswirkungen von Änderungen der Grundwasserentnahmerate. Die bilanzierten Grundwassermodelle stellen somit ein Übersichtsmodellsystem dar, mit dessen Hilfe Randbedingungen und Lateralflüsse für zukünftige Detailmodelle bestimmt, sowie Auswirkung künftiger Klima- bzw. Landnutzungsänderungen auf die Dynamik und die Grundwasserressourcen des Troodos Aquifersystems abgeschätzt werden können.

Cyprus comprises three tectono-stratigraphic terranes: first, the Troodos Massif made up of Late Cretaceous oceanic lithosphere and its sedimentary cover in the centre of the island; secondly, the Mamonia Complex (and Moni Melange) a passive margin lithological assemblage in the west (and south) and thirdly, the Kyrenia Range, an active margin lithological assemblage in the north. This study focuses on the sedimentary cover of the Troodos Ophiolite in W Cyprus, the Triassic-Cretaceous sedimentary rocks of the Mamonia Complex and Late Cretaceous-Miocene igneous and sedimentary rocks in the Kyrenia Range, mainly based on combined sedimentology, geochemistry and geochronological dating. The Late Triassic-Early Cretaceous Mamonia Complex, SW Cyprus (and the Moni Melange, S Cyprus) represent parts of the emplaced passive continental margin of the S Neotethys. Late Triassic sandstones are characterised by a predominantly felsic source, with a subordinate mafic contribution. Jurassic-Early Cretaceous sandstones have a polycyclic felsic origin. Geochemical analyses are suggestive of progressive weathering and sediment recycling/sorting. The dominance of Ediacaran-Cryogenian and Tonian-Stenian-aged detrital zircon populations is suggestive of an ultimate north Gondwana source, probably recycled from Palaeozoic siliciclastic sedimentary rocks within Anatolia to the north. Similar detrital zircon populations characterise Early Cretaceous deltaic sandstone of the Moni Melange, S Cyprus. Sporadic Late Cretaceous subduction-related magmatism, represented by a Campanian volcaniclastic sequence (80.44±1.0 Ma) inWCyprus and a Late Campanian felsic volcanogenic sequence (72.9±1.0 Ma) in N Cyprus, represents early and more advanced stages of northward subduction during closure of the S Neotethys. Specifically, the Kannaviou Formation in W Cyprus (up to 750 m thick) is made up of deep-marine volcaniclastic sandstones that were mostly deposited by gravity flows and as air-fall tuff, interbedded with clay and radiolarian mudstones. Petrographic and geochemical analyses are indicative of a volcanic arc source, with deposition in a fore-arc basin. Petrographic evidence of terrigenous input (e.g. muscovite, muscovite schist, polycrystalline quartz) points to a subordinate continental source. Mineral chemistry is consistent with a volcanic arc origin. Elevated trace-element ratios in undevitrified volcanic glass (e.g. Th/Nb, Th/La) are indicative of involvement of continental crust or subducted terrigenous sediments in source-arc melting. Felsic volcanogenic rocks (Fourkovouno (Selvilitepe) Formation) in the Kyrenia Range, N Cyprus, occur as an up to 400 m-thick sequence of felsic tuffs, felsic debris-flowdeposits and rhyolitic lava flows. Geochemical analyses are indicative of evolved high-K and shoshonitic compositions, similar to those of the Andean active continental margin. Subduction continued to affect the northern continental margin of the S Neotethys in the Kyrenia Range during the Maastrichtian. This lead to the accumulation of Late Cretaceous sandstone turbidites and related basaltic volcanics, possibly in a back-arc setting. The volcanism took place in two phases (Late Cretaceous and Palaeogene-Early Eocene) during pelagic carbonate accumulation. These lavas have within-plate affinities, but with a variable subduction influence in some areas (e.g. western Kyrenia Range), which may be contemporaneous or inherited from previous subduction. The sedimentary sequences in the Kyrenia Range, N Cyprus, document diachronous closure of the S Neotethys. Late Cretaceous and Eocene sandstone turbidites, and the lower part of the overlying Oligocene-Miocene succession exhibit enrichment in ultramafic components that was probably sourced from ophiolite-related rocks in the Taurides to the north. In contrast, Miocene sandstone turbidites higher in the sequence show an increasing input of continent-derived siliciclastic material (and sorting effects). The terrigenous-influenced sediments are likely to represent erosion of thrust sheets that were emplaced from the S Neotethys onto the Arabian foreland in SE Turkey related to continental collision. Ediacaran-Cryogenian and Tonian-Stenian-aged zircons dominate the Late Cretaceous and Eocene sandstone turbidites, consistent with derivation from the Tauride micro-continent to the north and/or NE. Overlying Miocene sandstones include minor populations of Neoproterozoic-aged zircons, suggestive of reworking from source rocks of ultimately Gondwanan origin (e.g. NE Africa/Arabian-Nubian Shield). In summary, the thesis results exemplify the interaction of tectonic processes associated with the evolution of the S Neotethys Ocean. This began in the area studied with passive margin development (Triassic-Cretaceous), and was followed by multi-stage subduction-related volcanism and sedimentation (Late Cretaceous-Miocene). Final closure of the S Neotethys in this area took place during the Late Miocene-Recent.

This dissertation combines mineralogical data and petrographic and field observations with geochemical analysis (major, trace and isotope) to provide new insights into the hydrology and geochemistry of mid-ocean ridge hydrothermal systems. Two study areas were chosen to study two different aspects of hydrothermal circulation: high-temperature on-axis hydrothermal systems were studied using samples from the Hess Deep Rift (Cocos Plate, Equatorial Pacific) and low-temperature off-axis hydrothermal systems were studied at the Troodos Ophiolite in Cyprus. Significant findings include the documentation of a previously unknown warm fluid that pervades the lavas leaching Li from newly formed crust. This finding corroborates a model of broad hydrothermal discharge in the sheeted dikes. In the off-axis low-temperature regime, lateral flow of warm fluid is documented in the lavas, advecting heat from the oceanic lithosphere, with minor geochemical changes to the lavas. The sedimentary cover was found to influence alteration in two ways. The longer an area remains unsedimented allowing the free ingress and egress of seawater, the deeper the enrichment of alkali metals is observed. The maximum enrichment in alkali metals (K, Rb, Cs) however, is similar in both locations. The sedimentary cover can also modify the seawater before it becomes impermeable to fluid flow; early metaliferrous oxide sediments react with seawater, creating a fluid that mobilizes and fractionates the REEs and Y. The fractionation results in negative Ce anomalies, positive Eu anomalies, and negative Y anomalies. Basalts altered under these conditions also lack the ubiquitous Fe-oxides and Fe-oxyhydroxides that are commonly associated with alkali metal uptake. In situ trace element analysis of alteration minerals formed at low-temperature confirmed that secondary phyllosilicates are strongly enriched in alkali metals (K, Rb, Cs and Li), Ba is found in adularia and zeolites, Sr is hosted in carbonates, and no phases were found to be enriched in U. The concentrations of K2O, Rb, Cs (as well as B) are highest in celadonites, whereas Li concentrations are highest in smectites (saponite, Al-saponite, beidellite) and smectite-chlorite mixtures, and much higher than previously reported. Alkalis are also taken up into palagonite, with Li having the highest concentrations, over 1000 ppm in one analysis. Crystal chemical factors were found to be the dominant control on trace element uptake, and for the phyllosilicates no correlation was found between the temperature, age of the crust, texture of the phyllosilicates. In phyllosilicates the K, Rb and Cs are adsorbed as exchange cations, with enrichment (Cs > Rb > K) increasing with decreasing hydration energy, whereas the uptake of Li and B does not correlate with the hydration energy. Lithium concentrations also do not correlate with the Mg content, suggesting substitution of Li for Mg is not the only mechanism of Li uptake into phyllosilicates as has been suggested. / Graduate

La mesure systématique dans les plans striés et leur traitement statistique par la méthode des dièdres droits ont permis de mettre en évidence, dans la région de Bourg-d'Oisans, 3 épisodes d'extension, antérieurs aux phénomènes alpins. Des critères stratigraphiques permettent de préciser leur âge, soit : • au Trias, direction d'extension N-S, • au Lias inférieur p.p., direction d'extension NE-SW, • au Lias supérieur, direction d'extension W.NW-E.SE. Ces faits sont à relier à la structuration de la marge européenne de la Téthys ligure, le bassin de Bourg d'Oisans étant considéré comme la couverture sédimentaire d'un bloc basculé décakilométrique. Le paléochamp de contraintes au Lias inférieur peut-être considéré comme le résultat d'une déviation de la contrainte générale en régime décrochant, du fait de l'existence d'accidents antérieurs hérités des phases tardi-hercyniennes. Les émissions de basaltes subalcalins (spilites) du sommet du Trias ont déjà été contrôlées par cette tectonique décrochante. Selon cette interprétation, le changement tectonique entre le sommet du Trias-Lias inférieur et le Lias supérieur s'est effectué par une simple permutation des contraintes D1 et D2 ; la contrainte minimale D3 étant restée constante en direction durant ces 2 épisodes. Ceci nous conduit à considérer que la réorganisation tectonique principale se situe au sommet du Trias et correspond donc au début du rifting dans cette région. L'évolution géodynamique de la région de Bourg-d'Oisans durant le Mésozoïque est similaire à celle d'autres systèmes de rift, comme le fossé rhénan et le Golfe de Suez. Les phases compressives alpines ont aussi été caractérisées. Leurs effets ont été fortement influencés par les structures héritées des épisodes distensifs mésozoïques. L'étude des structures syn-ophiolitiques dans le massif du Troodos à Chypre a permis d'individualiser une phase d'extension syn-ophiolitique dirigée W.NW-E.SE et des épisodes de déformation post-ophiolitiques (compression N160 et extensions récentes) fortement influencés par les structures antérieures.