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- Institut für Geowissenschaften (24) (remove)
Rainfall, snow-, and glacial melt throughout the Himalaya control river discharge, which is vital for maintaining agriculture, drinking water and hydropower generation. However, the spatiotemporal contribution of these discharge components to Himalayan rivers is not well understood, mainly because of the scarcity of ground-based observations. Consequently, there is also little known about the triggers and sources of peak sediment flux events, which account for extensive hydropower reservoir filling and turbine abrasion. We therefore lack basic information on the distribution of water resources and controls of erosion processes. In this thesis, I employ various methods to assess and quantify general characteristics of and links between precipitation, river discharge, and sediment flux in the Sutlej Valley. First, I analyze daily precipitation data (1998-2007) from 80 weather stations in the western Himalaya, to decipher the distribution of rain- and snowfall. Rainfall magnitude frequency analyses indicate that 40% of the summer rainfall budget is attributed to monsoonal rainstorms, which show higher variability in the orogenic interior than in frontal regions. Combined analysis of rainstorms and sediment flux data of a major Sutlej River tributary indicate that monsoonal rainfall has a first order control on erosion processes in the orogenic interior, despite the dominance of snowfall in this region. Second, I examine the contribution of rainfall, snow and glacial melt to river discharge in the Sutlej Valley (s55,000 km2), based on a distributed hydrological model, which covers the period 2000-2008. To achieve high spatial and daily resolution despite limited ground-based observations the hydrological model is forced by daily remote sensing data, which I adjusted and calibrated with ground station data. The calibration shows that the Tropical Rainfall Measuring Mission (TRMM) 3B42 rainfall product systematically overestimates rainfall in semi-arid and arid regions, increasing with aridity. The model results indicate that snowmelt-derived discharge (74%) is most important during the pre-monsoon season (April to June) whereas rainfall (56%) and glacial melt (17%) dominate the monsoon season (July-September). Therefore, climate change most likely causes a reduction in river discharge during the pre-monsoon season, which especially affects the orogenic interior. Third, I investigate the controls on suspended sediment flux in different parts of the Sutlej catchments, based on daily gauging data from the past decade. In conjunction with meteorological data, earthquake records, and rock strength measurements I find that rainstorms are the most frequent trigger of high-discharge events with peaks in suspended sediment concentrations (SSC) that account for the bulk of the suspended sediment flux. The suspended sediment flux increases downstream, mainly due to increases in runoff. Pronounced erosion along the Himalayan Front occurs throughout the monsoon season, whereas efficient erosion of the orogenic interior is confined to single extreme events. The results of this thesis highlight the importance of snow and glacially derived melt waters in the western Himalaya, where extensive regions receive only limited amounts of monsoonal rainfall. These regions are therefore particularly susceptible to global warming with major implications on the hydrological cycle. However, the sediment discharge data show that infrequent monsoonal rainstorms that pass the orographic barrier of the Higher Himalaya are still the primary trigger of the highest-impact erosion events, despite being subordinate to snow and glacially–derived discharge. These findings may help to predict peak sediment flux events and could underpin the strategic development of preventative measures for hydropower infrastructures.
The impact of global warming on human water resources is attracting increasing attention. No other region in this world is so strongly affected by changes in water supply than the tropics. Especially in Africa, the availability and access to water is more crucial to existence (basic livelihoods and economic growth) than anywhere else on Earth. In East Africa, rainfall is mainly influenced by the migration of the Inter-Tropical Convergence Zone (ITCZ) and by the El Niño Southern Oscillation (ENSO) with more rain and floods during El Niño and severe droughts during La Niña. The forecasting of East African rainfall in a warming world requires a better understanding of the response of ENSO-driven variability to mean climate. Unfortunately, existing meteorological data sets are too short or incomplete to establish a precise evaluation of future climate. From Lake Challa near Mount Kilimanjaro, we report records from a laminated lake sediment core spanning the last 25,000 years. Analyzing a monthly cleared sediment trap confirms the annual origin of the laminations and demonstrates that the varve-thicknesses are strongly linked to the duration and strength of the windy season. Given the modern control of seasonal ITCZ location on wind and rain in this region and the inverse relation between the two, thicker varves represent windier and thus drier years. El Niño (La Niña) events are associated with wetter (drier) conditions in east Africa and decreased (increased) surface wind speeds. Based on this fact, the thickness of the varves can be used as a tool to reconstruct a) annual rainfall b) wind season strength, and c) ENSO variability. Within this thesis, I found evidence for centennialscale changes in ENSO-related rainfall variability during the last three millennia, abrupt changes in variability during the Medieval Climate Anomaly and the Little Ice Age, and an overall reduction in East African rainfall and its variability during the Last Glacial period. Climate model simulations support forward extrapolation from these lake-sediment data, indicating that a future Indian Ocean warming will enhance East Africa’s hydrological cycle and its interannual variability in rainfall. Furthermore, I compared geochemical analyses from the sediment trap samples with a broad range of limnological, meteorological, and geological parameters to characterize the impact of sedimentation processes from the in-situ rocks to the deposited sediments. As a result an excellent calibration for existing μXRF data from Lake Challa over the entire 25,000 year long profile was provided. The climate development during the last 25,000 years as reconstructed from the Lake Challa sediments is in good agreement with other studies and highlights the complex interactions between long-term orbital forcing, atmosphere, ocean and land surface conditions. My findings help to understand how abrupt climate changes occur and how these changes correlate with climate changes elsewhere on Earth.
Spatial and temporal temperature and moisture patterns across the Tibetan Plateau are very complex. The onset and magnitude of the Holocene climate optimum in the Asian monsoon realm, in particular, is a subject of considerable debate as this time period is often used as an analogue for recent global warming. In the light of contradictory inferences regarding past climate and environmental change on the Tibetan Plateau, I have attempted to explain mismatches in the timing and magnitude of change. Therefore, I analysed the temporal variation of fossil pollen and diatom spectra and the geochemical record from palaeo-ecological records covering different time scales (late Quaternary and the last 200 years) from two core regions in the NE and SE Tibetan Plateau. For interpretation purposes I combined my data with other available palaeo-ecological data to set up corresponding aquatic and terrestrial proxy data sets of two lake pairs and two sets of sites. I focused on the direct comparison of proxies representing lacustrine response to climate signals (e.g., diatoms, ostracods, geochemical record) and proxies representing changes in the terrestrial environment (i.e., terrestrial pollen), in order to asses whether the lake and its catchments respond at similar times and magnitudes to environmental changes. Therefore, I introduced the established numerical technique procrustes rotation as a new approach in palaeoecology to quantitatively compare raw data of any two sedimentary records of interest in order to assess their degree of concordance. Focusing on the late Quaternary, sediment cores from two lakes (Kuhai Lake 35.3°N; 99.2°E; 4150 m asl; and Koucha Lake 34.0°N; 97.2°E; 4540 m asl) on the semi-arid northeastern Tibetan Plateau were analysed to identify post-glacial vegetation and environmental changes, and to investigate the responses of lake ecosystems to such changes. Based on the pollen record, five major vegetation and climate changes could be identified: (1) A shift from alpine desert to alpine steppe indicates a change from cold, dry conditions to warmer and more moist conditions at 14.8 cal. ka BP, (2) alpine steppe with tundra elements points to conditions of higher effective moisture and a stepwise warming climate at 13.6 cal. ka BP, (3) the appearance of high-alpine meadow vegetation indicates a further change towards increased moisture, but with colder temperatures, at 7.0 cal. ka BP, (4) the reoccurrence of alpine steppe with desert elements suggests a return to a significantly colder and drier phase at 6.3 cal. ka BP, and (5) the establishment of alpine steppe-meadow vegetation indicates a change back to relatively moist conditions at 2.2 cal. ka BP. To place the reconstructed climate inferences from the NE Tibetan Plateau into the context of Holocene moisture evolution across the Tibetan Plateau, I applied a five-scale moisture index and average link clustering to all available continuous pollen and non-pollen palaeoclimate records from the Tibetan Plateau, in an attempt to detect coherent regional and temporal patterns of moisture evolution on the Plateau. However, no common temporal or spatial pattern of moisture evolution during the Holocene could be detected, which can be assigned to the complex responses of different proxies to environmental changes in an already very heterogeneous mountain landscape, where minor differences in elevation can result in marked variations in microenvironments. Focusing on the past 200 years, I analysed the sedimentary records (LC6 Lake 29.5°N, 94.3°E, 4132 m asl; and Wuxu Lake 29.9°N, 101.1°E, 3705 m asl) from the southeastern Tibetan Plateau. I found that despite presumed significant temperature increases over that period, pollen and diatom records from the SE Tibetan Plateau reveal only very subtle changes throughout their profiles. The compositional species turnover investigated over the last 200 years appears relatively low in comparison to the species reorganisations during the Holocene. The results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem. Forest clearances and reforestation have not caused forest decline in our study area, but a conversion of natural forests to semi-natural secondary forests. The results from the numerical proxy comparison of the two sets of two pairs of Tibetan lakes indicate that the use of different proxies and the work with palaeo-ecological records from different lake types can cause deviant stories of inferred change. Irrespective of the timescale (Holocene or last 200 years) or region (SE or NE Tibetan Plateau) analysed, the agreement in terms of the direction, timing, and magnitude of change between the corresponding terrestrial data sets is generally better than the match between the corresponding lacustrine data sets, suggesting that lacustrine proxies may partly be influenced by in-lake or local catchment processes whereas the terrestrial proxy reflects a more regional climatic signal. The current disaccord on coherent temporal and spatial climate patterns on the Tibetan Plateau can partly be ascribed to the complexity of proxy response and lake systems on the Tibetan Plateau. Therefore, a multi-proxy, multi-site approach is important in order to gain a reliable climate interpretation for the complex mountain landscape of the Tibetan Plateau.
The East African Plateau provides a spectacular example of geodynamic plateau uplift, active continental rifting, and associated climatic forcing. It is an integral part of the East African Rift System and has an average elevation of approximately 1,000 m. Its location coincides with a negative Bouguer gravity anomaly with a semi-circular shape, closely related to a mantle plume, which influences the Cenozoic crustal development since its impingement in Eocene-Oligocene time. The uplift of the East African Plateau, preceding volcanism, and rifting formed an important orographic barrier and tectonically controlled environment, which is profoundly influenced by climate driven processes. Its location within the equatorial realm supports recently proposed hypotheses, that topographic changes in this region must be considered as the dominant forcing factor influencing atmospheric circulation patterns and rainfall distribution. The uplift of this region has therefore often been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While the far-reaching influence of the plateau uplift is widely accepted, the timing and the magnitude of the uplift are ambiguous and are still subject to ongoing discussion. This dilemma stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift. In order to quantify the amount of plateau uplift and to find evidence for the existence of significant relief along the East African Plateau prior to rifting, I analyzed and modeled one of the longest terrestrial lava flows; the 300-km-long Yatta phonolite flow in Kenya. This lava flow is 13.5 Ma old and originated in the region that now corresponds to the eastern rift shoulders. The phonolitic flow utilized an old riverbed that once drained the eastern flank of the plateau. Due to differential erosion this lava flow now forms a positive relief above the parallel-flowing Athi River, which is mimicking the course of the paleo-river. My approach is a lava-flow modeling, based on an improved composition and temperature dependent method to parameterize the flow of an arbitrary lava in a rectangular-shaped channel. The essential growth pattern is described by a one-dimensional model, in which Newtonian rheological flow advance is governed by the development of viscosity and/or velocity in the internal parts of the lava-flow front. Comparing assessments of different magma compositions reveal that length-dominated, channelized lava flows are characterized by high effusion rates, rapid emplacement under approximately isothermal conditions, and laminar flow. By integrating the Yatta lava flow dimensions and the covered paleo-topography (slope angle) into the model, I was able to determine the pre-rift topography of the East African Plateau. The modeling results yield a pre-rift slope of at least 0.2°, suggesting that the lava flow must have originated at a minimum elevation of 1,400 m. Hence, high topography in the region of the present-day Kenya Rift must have existed by at least 13.5 Ma. This inferred mid-Miocene uplift coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa. Accordingly, the combination of my results regarding the Yatta lava flow emplacement history, its location, and its morphologic character, validates it as a suitable “paleo-tiltmeter” and has thus to be considered as an important topographic and volcanic feature for the topographic evolution in East Africa.
The past climate in central Asia, and especially on the Tibetan Plateau (TP), is of great importance for an understanding of global climate processes and for predicting the future climate. As a major influence on the climate in this region, the Asian Summer Monsoon (ASM) and its evolutionary history are of vital importance for accurate predictions. However, neither the evolutionary pattern of the summer monsoon nor the driving mechanisms behind it are yet clearly understood. For this research, I first synthesized previously published Late Glacial to Holocene climatic records from monsoonal central Asia in order to extract the general climate signals and the associated summer monsoon intensities. New climate and vegetation sequences were then established using improved quantitative methods, focusing on fossil pollen records recovered from Tibetan lakes and also incorporating new modern datasets. The pollen-vegetation and vegetation-climate relationships on the TP were also evaluated in order to achieve a better understanding of fossil pollen records. The synthesis of previously published moisture-related palaeoclimate records in monsoonal central Asia revealed generally different temporal patterns for the two monsoonal subsystems, i.e. the Indian Summer Monsoon (ISM) and East Asian Summer Monsoon (EASM). The ISM appears to have experienced maximum wet conditions during the early Holocene, while many records from the area affected by the EASM indicate relatively dry conditions at that time, particularly in north-central China where the maximum moisture levels occurred during the middle Holocene. A detailed consideration of possible driving factors affecting the summer monsoon, including summer solar insolation and sea surface temperatures, revealed that the ISM was primarily driven by variations in northern hemisphere solar insolation, and that the EASM may have been constrained by the ISM resulting in asynchronous patterns of evolution for these two subsystems. This hypothesis is further supported by modern monsoon indices estimated using the NCEP/NCAR Reanalysis data from the last 50 years, which indicate a significant negative correlation between the two summer monsoon subsystems. By analogy with the early Holocene, intensification of the ISM during coming decades could lead to increased aridification elsewhere as a result of the asynchronous nature of the monsoon subsystems, as can already be observed in the meteorological data from the last 15 years. A quantitative climate reconstruction using fossil pollen records was achieved through analysis of sediment core recovered from Lake Donggi Cona (in the north-eastern part of the TP) which has been dated back to the Last Glacial Maximum (LGM). A new data-set of modern pollen collected from large lakes in arid to semi-arid regions of central Asia is also presented herein. The concept of "pollen source area" was introduced to modern climate calibration based on pollen from large lakes, and was applied to the fossil pollen sequence from Lake Donggi Cona. Extremely dry conditions were found to have dominated the LGM, and a subsequent gradually increasing trend in moisture during the Late Glacial period was terminated by an abrupt reversion to a dry phase that lasted for about 1000 years and coincided with the first Heinrich Event of the northern Atlantic region. Subsequent periods corresponding to the warm Bølling-Allerød period and the Younger Dryas cold event were followed by moist conditions during the early Holocene, with annual precipitation of up to about 400 mm. A slightly drier trend after 9 cal ka BP was then followed by a second wet phase during the middle Holocene that lasted until 4.5 cal ka BP. Relatively steady conditions with only slight fluctuations then dominated the late Holocene, resulting in the present climatic conditions. In order to investigate the relationship between vegetation and climate, temporal variations in the possible driving factors for vegetation change on the northern TP were examined using a high resolution late Holocene pollen record from Lake Kusai. Moving-window Redundancy Analyses (RDAs) were used to evaluate the correlations between pollen assemblages and individual sedimentary proxies. These analyses have revealed frequent fluctuations in the relative abundances of alpine steppe and alpine desert components, and in particular a decrease in the total vegetation cover at around 1500 cal a BP. The climate was found to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, after the 1500 cal a BP threshold in vegetation cover was crossed the vegetation appears to have been affected more by extreme events such as dust storms or fluvial erosion than by the general climatic trends. In addition, pollen spectra over the last 600 years have been revealed by Procrustes analysis to be significantly different from those recovered from older samples, which is attributed to an increased human impact that resulted in unprecedented changes to the composition of the vegetation. Theoretical models that have been developed and widely applied to the European area (i.e. the Extended R-Value (ERV) model and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model) have been applied to the high alpine TP ecosystems in order to investigate the pollen-vegetation relationships, as well as for quantitative reconstructions of vegetation abundance. The modern pollen–vegetation relationships for four common pollen species on the TP have been investigated using Poaceae as the reference taxa. The ERV Submodel 2 yielded relatively high PPEs for the steppe and desert taxa (Artemisia Chenopodiaceae), and low PPEs for the Cyperaceae that are characteristic of the alpine Kobresia meadows. The plant abundances on the central and north-eastern TP were quantified by applying these PPEs to four post-Late Glacial fossil pollen sequences. The reconstructed vegetation assemblages for the four pollen sequences always yielded smaller compositional species turnovers than suggested by the pollen spectra, indicating that the strength of the previously-reported vegetation changes may therefore have been overestimated. In summary, the key findings of this thesis are that (a) the two ASM subsystems show asynchronous patterns during both the Holocene and modern time periods, (b) fossil pollen records from large lakes reflect regional signals for which the pollen source areas need to be taken into account, (c) climate is not always the main driver for vegetation change, and (d) previously reported vegetation changes on the TP may have been overestimated because they ignored inter-species variations in pollen productivity.
Dryland vulnerability : typical patterns and dynamics in support of vulnerability reduction efforts
(2011)
The pronounced constraints on ecosystem functioning and human livelihoods in drylands are frequently exacerbated by natural and socio-economic stresses, including weather extremes and inequitable trade conditions. Therefore, a better understanding of the relation between these stresses and the socio-ecological systems is important for advancing dryland development. The concept of vulnerability as applied in this dissertation describes this relation as encompassing the exposure to climate, market and other stresses as well as the sensitivity of the systems to these stresses and their capacity to adapt. With regard to the interest in improving environmental and living conditions in drylands, this dissertation aims at a meaningful generalisation of heterogeneous vulnerability situations. A pattern recognition approach based on clustering revealed typical vulnerability-creating mechanisms at global and local scales. One study presents the first analysis of dryland vulnerability with global coverage at a sub-national resolution. The cluster analysis resulted in seven typical patterns of vulnerability according to quantitative indication of poverty, water stress, soil degradation, natural agro-constraints and isolation. Independent case studies served to validate the identified patterns and to prove the transferability of vulnerability-reducing approaches. Due to their worldwide coverage, the global results allow the evaluation of a specific system’s vulnerability in its wider context, even in poorly-documented areas. Moreover, climate vulnerability of smallholders was investigated with regard to their food security in the Peruvian Altiplano. Four typical groups of households were identified in this local dryland context using indicators for harvest failure risk, agricultural resources, education and non-agricultural income. An elaborate validation relying on independently acquired information demonstrated the clear correlation between weather-related damages and the identified clusters. It also showed that household-specific causes of vulnerability were consistent with the mechanisms implied by the corresponding patterns. The synthesis of the local study provides valuable insights into the tailoring of interventions that reflect the heterogeneity within the social group of smallholders. The conditions necessary to identify typical vulnerability patterns were summarised in five methodological steps. They aim to motivate and to facilitate the application of the selected pattern recognition approach in future vulnerability analyses. The five steps outline the elicitation of relevant cause-effect hypotheses and the quantitative indication of mechanisms as well as an evaluation of robustness, a validation and a ranking of the identified patterns. The precise definition of the hypotheses is essential to appropriately quantify the basic processes as well as to consistently interpret, validate and rank the clusters. In particular, the five steps reflect scale-dependent opportunities, such as the outcome-oriented aspect of validation in the local study. Furthermore, the clusters identified in Northeast Brazil were assessed in the light of important endogenous processes in the smallholder systems which dominate this region. In order to capture these processes, a qualitative dynamic model was developed using generalised rules of labour allocation, yield extraction, budget constitution and the dynamics of natural and technological resources. The model resulted in a cyclic trajectory encompassing four states with differing degree of criticality. The joint assessment revealed aggravating conditions in major parts of the study region due to the overuse of natural resources and the potential for impoverishment. The changes in vulnerability-creating mechanisms identified in Northeast Brazil are well-suited to informing local adjustments to large-scale intervention programmes, such as “Avança Brasil”. Overall, the categorisation of a limited number of typical patterns and dynamics presents an efficient approach to improving our understanding of dryland vulnerability. Appropriate decision-making for sustainable dryland development through vulnerability reduction can be significantly enhanced by pattern-specific entry points combined with insights into changing hotspots of vulnerability and the transferability of successful adaptation strategies.
The complete consumption of the oceanic domain of a tectonic plate by subduction into the upper mantle results in continent subduction, although continental crust is typically of lower density than the upper mantle. Thus, the sites of former oceanic domains (named suture zones) are generally decorated with stratigraphic sequences deposited along continental passive margins that were metamorphosed under low-grade, high-pressure conditions, i.e., low temperature/depth ratios (< 15°C/km) with respect to geothermal gradients in tectonically stable regions. Throughout the Mesozoic and Cenozoic (i.e., since ca. 250 Ma), the Mediterranean realm was shaped by the closure of the Tethyan Ocean, which likely consisted in numerous oceanic domains and microcontinents. However, the exact number and position of Tethyan oceans and continents (i.e., the Tethyan palaeogeography) remains debated. This is particularly the case of Western and Central Anatolia, where a continental fragment was accreted to the southern composite margin of the Eurasia sometime between the Late Cretaceous and the early Cenozoic. The most frontal part of this microcontinent experienced subduction-related metamorphism around 85-80 Ma, and collision-related metamorphism affected more external parts around 35 Ma. This unsually-long period between subduction- and collision-related metamorphisms (ca. 50 Ma) in units ascribed to the same continental edge constitutes a crucial issue to address in order to unravel how Anatolia was assembled. The Afyon Zone is a tectono-sedimentary unit exposed south and structurally below the front high-pressure belt. It is composed of a Mesozoic sedimentary sequence deposited on top of a Precambrian to Palaeozoic continental substratum, which can be traced from Northwestern to southern Central Anatolia, along a possible Tethyan suture. Whereas the Afyon Zone was defined as a low-pressure metamorphic unit, high-pressure minerals (mainly Fe-Mg-carpholite in metasediments) were recently reported from its central part. These findings shattered previous conceptions on the tectono-metamorphic evolution of the Afyon Zone in particular, and of the entire region in general, and shed light on the necessity to revise the regional extent of subduction-related metamorphism by re-inspecting the petrology of poorly-studied metasediments. In this purpose, I re-evaluated the metamorphic evolution of the entire Afyon Zone starting from field observations. Low-grade, high-pressure mineral assemblages (Fe-Mg-carpholite and glaucophane) are reported throughout the unit. Well-preserved carpholite-chloritoid assemblages are useful to improve our understanding of mineral relations and transitions in the FeO-MgO-Al2O3-SiO2-H2O system during rocks’ travel down to depth (prograde metamorphism). Inspection of petrographic textures, minute variations in mineral composition and Mg-Fe distribution among carpholite-chloritoid assemblages documents multistage mineral growth, accompanied by a progressive enrichment in Mg, and strong element partitioning. Using an updated database of mineral thermodynamic properties, I modelled the pressure and temperature conditions that are consistent with textural and chemical observations. Carpholite-bearing assemblages in the Afyon Zone account for a temperature increase from 280 to 380°C between 0.9 and 1.1 GPa (equivalent to a depth of 30-35 km). In order to further constrain regional geodynamics, first radiometric ages were determined in close association with pressure-temperature estimates for the Afyon Zone, as well as two other tectono-sedimentary units from the same continental passive margin (the Ören and Kurudere-Nebiler Units from SW Anatolia). For age determination, I employed 40Ar-39Ar geochronology on white mica in carpholite-bearing rocks. For thermobarometry, a multi-equilibrium approach was used based on quartz-chlorite-mica and quartz-chlorite-chloritoid associations formed at the expense of carpholite-bearing assemblages, i.e., during the exhumation from the subduction zone. This combination allows deciphering the significance of the calculated radiometric ages in terms of metamorphic conditions. Results show that the Afyon Zone and the Ören Unit represent a latest Cretaceous high-pressure metamorphic belt, and the Kurudere-Nebiler Unit was affected by subduction-related metamorphism around 45 Ma and cooled down after collision-related metamorphism around 26 Ma. The results provided in the present thesis and from the literature allow better understanding continental amalgamation in Western Anatolia. It is shown that at least two distinct oceanic branches, whereas only one was previously considered, have closed during continuous north-dipping subduction between 92 and 45 Ma. Between 85-80 and 70-65 Ma, a narrow continental domain (including the Afyon Zone) was buried into a subduction zone within the northern oceanic strand. Parts of the subducted continent crust were exhumed while the upper oceanic plate was transported southwards. Subduction of underlying lithosphere persisted, leading to the closure of the southern oceanic branch and to subduct the front of a second continental domain (including the Kurudere-Nebiler Unit). This followed by a continental collisional stage characterized by the cease of subduction, crustal thicknening and the detachment of the subducting oceanic slab from the accreted continent lithosphere. The present study supports that in the late Mesozoic the East Mediterranean realm had a complex tectonic configuration similar to present Southeast Asia or the Caribbean, with multiple, coexisting oceanic basins, microcontinents and subduction zones.