@article{DrewesMoreirasKorup2018, author = {Drewes, Julia and Moreiras, Stella and Korup, Oliver}, title = {Permafrost activity and atmospheric warming in the Argentinian Andes}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {323}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2018.09.005}, pages = {13 -- 24}, year = {2018}, abstract = {Rock glaciers are permafrost or glacial landforms of debris and ice that deform under the influence of gravity. Recent estimates hold that, in the semiarid Chilean Andes for example, active rock glaciers store more water than glaciers. However, little is known about how many rock glaciers might decay because of global warming and how much this decay might contribute to water and sediment release. We investigated an inventory of >6500 rock glaciers in the Argentinian Andes, spanning the climatic gradient from the Desert Andes to cold-temperate Tierra del Fuego. We used active rock glaciers as a diagnostic of permafrost, assuming that the toes mark the 0 degrees C isotherm in climate scenarios for the twenty-first century and their impact on freezing conditions near the rock glacier toes. We find that, under future worst case warming, up to 95\% of rock glaciers in the southern Desert Andes and in the Central Andes will rest in areas above 0 degrees C and that this freezing level might move up more than twice as much (similar to 500 m) as during the entire Holocene (similar to 200 m). Many active rock glaciers are already well below the current freezing level and exemplify how local controls may confound regional prognoses. A Bayesian Multifactor Analysis of Variance further shows that only in the Central Andes are the toes of active rock glaciers credibly higher than those of inactive ones. Elsewhere in the Andes, active and inactive rock glaciers occupy indistinguishable elevation bands, regardless of aspect, the formation mechanism, or shape of rock glaciers. The state of rock glacier activity predicts differences in elevations of toes to 140 m at best so that regional inference of the distribution of discontinuous permafrost from rock-glacier toes cannot be more accurate than this in the Argentinian Andes. We conclude that the Central Andes-where rock glaciers are largest, cover the most area, and have a greater density than glaciers-is likely to experience the most widespread disturbance to the thermal regime of the twenty-first century. (C) 2018 Elsevier B.V. All rights reserved.}, language = {en} } @misc{HollEtteKnoblochetal.2009, author = {Holl, Frank and Ette, Ottmar and Knobloch, Eberhard and Rodr{\´i}guez, Jos{\´e} {\´A}ngel and Durisch Acosta, Christian and Astuhuam{\´a}n Gonzales, C{\´e}sar W. and Covarrubias, Jos{\´e} Enrique and K{\"u}gelgen, Helga von and P{\´e}rez Brignoli, Hector and Kraft, Tobias and Einert, Katharina}, title = {HiN : Alexander von Humboldt im Netz = Humboldt und Hispano-Amerika : Vergangenheit, Gegenwart und Zukunft (Vol. 1)}, volume = {X}, number = {19}, editor = {Ette, Ottmar and Knobloch, Eberhard}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1617-5239}, doi = {10.25932/publishup-3187}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42917}, pages = {155}, year = {2009}, abstract = {Inhalt: - Frank Holl: Vorwort / Prefacio - Ottmar Ette: Entre mundos - v{\´i}as de Alexander von Humboldt hacia la conciencia universal - Eberhard Knobloch: Alexander von Humboldts Weltbild - Jos{\´e} {\´A}ngel Rodr{\´i}guez: El culto a Humboldt en Venezuela - Christian Durisch Acosta: Die Humboldt-Rezeption in Ecuador - ein kulturgeschichtlicher Beitrag zum ecuadorianischen Nationsbildungsprozess - C{\´e}sar W. Astuhuam{\´a}n Gonz{\´a}les: Incas, J{\´i}varos y la obra de Humboldt Vues des Cordill{\`e}res - Jos{\´e} Enrique Covarrubias: La recepci{\´o}n de la figura y obra de Humboldt en M{\´e}xico 1821-2000 - Helga von K{\"u}gelgen: Klassizismus und vergleichendes Sehen in den Vues des Cordill{\`e}res - Hector P{\´e}rez Brignoli: Alexander von Humboldt en Centroam{\´e}rica y en el R{\´i}o de la Plata - Tobias Kraft und Katharina Einert: Das ganze Werk in einem Netz? Bibliographie online verf{\"u}gbarer Alexander-von-Humboldt-Digitalisate}, language = {mul} } @phdthesis{Ibarra2021, author = {Ibarra, Federico}, title = {The thermal and rheological state of the Central Andes and its relationship to active deformation processes}, doi = {10.25932/publishup-50622}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-506226}, school = {Universit{\"a}t Potsdam}, pages = {xvi, 149}, year = {2021}, abstract = {The Central Andes region in South America is characterized by a complex and heterogeneous deformation system. Recorded seismic activity and mapped neotectonic structures indicate that most of the intraplate deformation is located along the margins of the orogen, in the transitions to the foreland and the forearc. Furthermore, the actively deforming provinces of the foreland exhibit distinct deformation styles that vary along strike, as well as characteristic distributions of seismicity with depth. The style of deformation transitions from thin-skinned in the north to thick-skinned in the south, and the thickness of the seismogenic layer increases to the south. Based on geological/geophysical observations and numerical modelling, the most commonly invoked causes for the observed heterogeneity are the variations in sediment thickness and composition, the presence of inherited structures, and changes in the dip of the subducting Nazca plate. However, there are still no comprehensive investigations on the relationship between the lithospheric composition of the Central Andes, its rheological state and the observed deformation processes. The central aim of this dissertation is therefore to explore the link between the nature of the lithosphere in the region and the location of active deformation. The study of the lithospheric composition by means of independent-data integration establishes a strong base to assess the thermal and rheological state of the Central Andes and its adjacent lowlands, which alternatively provide new foundations to understand the complex deformation of the region. In this line, the general workflow of the dissertation consists in the construction of a 3D data-derived and gravity-constrained density model of the Central Andean lithosphere, followed by the simulation of the steady-state conductive thermal field and the calculation of strength distribution. Additionally, the dynamic response of the orogen-foreland system to intraplate compression is evaluated by means of 3D geodynamic modelling. The results of the modelling approach suggest that the inherited heterogeneous composition of the lithosphere controls the present-day thermal and rheological state of the Central Andes, which in turn influence the location and depth of active deformation processes. Most of the seismic activity and neo--tectonic structures are spatially correlated to regions of modelled high strength gradients, in the transition from the felsic, hot and weak orogenic lithosphere to the more mafic, cooler and stronger lithosphere beneath the forearc and the foreland. Moreover, the results of the dynamic simulation show a strong localization of deviatoric strain rate second invariants in the same region suggesting that shortening is accommodated at the transition zones between weak and strong domains. The vertical distribution of seismic activity appears to be influenced by the rheological state of the lithosphere as well. The depth at which the frequency distribution of hypocenters starts to decrease in the different morphotectonic units correlates with the position of the modelled brittle-ductile transitions; accordingly, a fraction of the seismic activity is located within the ductile part of the crust. An exhaustive analysis shows that practically all the seismicity in the region is restricted above the 600°C isotherm, in coincidence with the upper temperature limit for brittle behavior of olivine. Therefore, the occurrence of earthquakes below the modelled brittle-ductile could be explained by the presence of strong residual mafic rocks from past tectonic events. Another potential cause of deep earthquakes is the existence of inherited shear zones in which brittle behavior is favored through a decrease in the friction coefficient. This hypothesis is particularly suitable for the broken foreland provinces of the Santa Barbara System and the Pampean Ranges, where geological studies indicate successive reactivation of structures through time. Particularly in the Santa Barbara System, the results indicate that both mafic rocks and a reduction in friction are required to account for the observed deep seismic events.}, language = {en} } @article{Kalczewiak2020, author = {Kalczewiak, Mariusz}, title = {Yiddish Buenos Aires and the struggle to leave the margins}, series = {East European Jewish affairs}, volume = {50}, journal = {East European Jewish affairs}, number = {1-2}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1350-1674}, doi = {10.1080/13501674.2020.1774275}, pages = {115 -- 133}, year = {2020}, abstract = {Yiddish culture developed in Argentina within the context of a self-perception that figured Buenos Aires as a marginal and peripheral locale on the global Yiddish map. Against this backdrop, Argentine Yiddish culturalists argued for the strengthening of local Yiddish culture with a goal of elevating Buenos Aires's status within the international hierarchies of Yiddish culture. Buenos Aires indeed emerged in the 1920s as a producer of Yiddish cultural contents, maintained networks of international cultural contacts with other Yiddish centers, financially supported Eastern European Yiddish establishments, and hoped that these contacts would allow for solving Buenos Aires reputation problems. The pre-World War II preoccupation with the status of Buenos Aires as a center of Yiddish culture provided a basis upon which post-Holocaust discourse of Argentine Jewish responsibility for the maintenance of Yiddish culture was constructed.}, language = {en} } @phdthesis{Kooten2023, author = {Kooten, Willemijn Sarah Maria Theresia van}, title = {Structural inheritance of the Salta Rift basin and its control on exhumation patterns of the Eastern Cordillera between 23 and 24°S}, doi = {10.25932/publishup-61798}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-617983}, school = {Universit{\"a}t Potsdam}, pages = {XIX, 188}, year = {2023}, abstract = {The deformation style of mountain belts is greatly influenced by the upper plate architecture created during preceding deformation phases. The Mesozoic Salta Rift extensional phase has created a dominant structural and lithological framework that controls Cenozoic deformation and exhumation patterns in the Central Andes. Studying the nature of these pre-existing anisotropies is a key to understanding the spatiotemporal distribution of exhumation and its controlling factors. The Eastern Cordillera in particular, has a structural grain that is in part controlled by Salta Rift structures and their orientation relative to Andean shortening. As a result, there are areas in which Andean deformation prevails and areas where the influence of the Salta Rift is the main control on deformation patterns. Between 23 and 24°S, lithological and structural heterogeneities imposed by the Lomas de Olmedo sub-basin (Salta Rift basin) affect the development of the Eastern Cordillera fold-and-thrust belt. The inverted northern margin of the sub-basin now forms the southern boundary of the intermontane Cianzo basin. The former western margin of the sub-basin is located at the confluence of the Subandean Zone, the Santa Barbara System and the Eastern Cordillera. Here, the Salta Rift basin architecture is responsible for the distribution of these morphotectonic provinces. In this study we use a multi-method approach consisting of low-temperature (U-Th-Sm)/He and apatite fission track thermochronology, detrital geochronology, structural and sedimentological analyses to investigate the Mesozoic structural inheritance of the Lomas de Olmedo sub-basin and Cenozoic exhumation patterns. Characterization of the extension-related Tacur{\´u} Group as an intermediate succession between Paleozoic basement and the syn-rift infill of the Lomas de Olmedo sub-basin reveals a Jurassic maximum depositional age. Zircon (U-Th-Sm)/He cooling ages record a pre-Cretaceous onset of exhumation for the rift shoulders in the northern part of the sub-basin, whereas the western shoulder shows a more recent onset (140-115 Ma). Variations in the sedimentary thickness of syn- and post-rift strata document the evolution of accommodation space in the sub-basin. While the thickness of syn-rift strata increases rapidly toward the northern basin margin, the post-rift strata thickness decreases toward the margin and forms a condensed section on the rift shoulder. Inversion of Salta Rift structures commenced between the late Oligocene and Miocene (24-15 Ma) in the ranges surrounding the Cianzo basin. The eastern and western limbs of the Cianzo syncline, located in the hanging wall of the basin-bounding Hornocal fault, show diachronous exhumation. At the same time, western fault blocks of Tilcara Range, south of the Cianzo basin, began exhuming in the late Oligocene to early Miocene (26-16 Ma). Eastward propagation to the frontal thrust and to the Paleozoic strata east of the Tilcara Range occurred in the middle Miocene (22-10 Ma) and the late Miocene-early Pliocene (10-4 Ma), respectively.}, language = {en} } @phdthesis{Meessen2019, author = {Meeßen, Christian}, title = {The thermal and rheological state of the Northern Argentinian foreland basins}, doi = {10.25932/publishup-43994}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439945}, school = {Universit{\"a}t Potsdam}, pages = {xviii, 151}, year = {2019}, abstract = {The foreland of the Andes in South America is characterised by distinct along strike changes in surface deformational styles. These styles are classified into two end-members, the thin-skinned and the thick-skinned style. The superficial expression of thin-skinned deformation is a succession of narrowly spaced hills and valleys, that form laterally continuous ranges on the foreland facing side of the orogen. Each of the hills is defined by a reverse fault that roots in a basal d{\´e}collement surface within the sedimentary cover, and acted as thrusting ramp to stack the sedimentary pile. Thick-skinned deformation is morphologically characterised by spatially disparate, basement-cored mountain ranges. These mountain ranges are uplifted along reactivated high-angle crustal-scale discontinuities, such as suture zones between different tectonic terranes. Amongst proposed causes for the observed variation are variations in the dip angle of the Nazca plate, variation in sediment thickness, lithospheric thickening, volcanism or compositional differences. The proposed mechanisms are predominantly based on geological observations or numerical thermomechanical modelling, but there has been no attempt to understand the mechanisms from a point of data-integrative 3D modelling. The aim of this dissertation is therefore to understand how lithospheric structure controls the deformational behaviour. The integration of independent data into a consistent model of the lithosphere allows to obtain additional evidence that helps to understand the causes for the different deformational styles. Northern Argentina encompasses the transition from the thin-skinned fold-and-thrust belt in Bolivia, to the thick-skinned Sierras Pampeanas province, which makes this area a well suited location for such a study. The general workflow followed in this study first involves data-constrained structural- and density-modelling in order to obtain a model of the study area. This model was then used to predict the steady-state thermal field, which was then used to assess the present-day rheological state in northern Argentina. The structural configuration of the lithosphere in northern Argentina was determined by means of data-integrative, 3D density modelling verified by Bouguer gravity. The model delineates the first-order density contrasts in the lithosphere in the uppermost 200 km, and discriminates bodies for the sediments, the crystalline crust, the lithospheric mantle and the subducting Nazca plate. To obtain the intra-crustal density structure, an automated inversion approach was developed and applied to a starting structural model that assumed a homogeneously dense crust. The resulting final structural model indicates that the crustal structure can be represented by an upper crust with a density of 2800 kg/m³, and a lower crust of 3100 kg/m³. The Transbrazilian Lineament, which separates the Pampia terrane from the R{\´i}o de la Plata craton, is expressed as a zone of low average crustal densities. In an excursion, we demonstrate in another study, that the gravity inversion method developed to obtain intra-crustal density structures, is also applicable to obtain density variations in the uppermost lithospheric mantle. Densities in such sub-crustal depths are difficult to constrain from seismic tomographic models due to smearing of crustal velocities. With the application to the uppermost lithospheric mantle in the north Atlantic, we demonstrate in Tan et al. (2018) that lateral density trends of at least 125\,km width are robustly recovered by the inversion method, thereby providing an important tool for the delineation of subcrustal density trends. Due to the genetic link between subduction, orogenesis and retroarc foreland basins the question rises whether the steady-state assumption is valid in such a dynamic setting. To answer this question, I analysed (i) the impact of subduction on the conductive thermal field of the overlying continental plate, (ii) the differences between the transient and steady-state thermal fields of a geodynamic coupled model. Both studies indicate that the assumption of a thermal steady-state is applicable in most parts of the study area. Within the orogenic wedge, where the assumption cannot be applied, I estimated the transient thermal field based on the results of the conducted analyses. Accordingly, the structural model that had been obtained in the first step, could be used to obtain a 3D conductive steady-state thermal field. The rheological assessment based on this thermal field indicates that the lithosphere of the thin-skinned Subandean ranges is characterised by a relatively strong crust and a weak mantle. Contrarily, the adjacent foreland basin consists of a fully coupled, very strong lithosphere. Thus, shortening in northern Argentina can only be accommodated within the weak lithosphere of the orogen and the Subandean ranges. The analysis suggests that the d{\´e}collements of the fold-and-thrust belt are the shallow continuation of shear zones that reside in the ductile sections of the orogenic crust. Furthermore, the localisation of the faults that provide strain transfer between the deeper ductile crust and the shallower d{\´e}collement is strongly influenced by crustal weak zones such as foliation. In contrast to the northern foreland, the lithosphere of the thick-skinned Sierras Pampeanas is fully coupled and characterised by a strong crust and mantle. The high overall strength prevents the generation of crustal-scale faults by tectonic stresses. Even inherited crustal-scale discontinuities, such as sutures, cannot sufficiently reduce the strength of the lithosphere in order to be reactivated. Therefore, magmatism that had been identified to be a precursor of basement uplift in the Sierras Pampeanas, is the key factor that leads to the broken foreland of this province. Due to thermal weakening, and potentially lubrication of the inherited discontinuities, the lithosphere is locally weakened such that tectonic stresses can uplift the basement blocks. This hypothesis explains both the spatially disparate character of the broken foreland, as well as the observed temporal delay between volcanism and basement block uplift. This dissertation provides for the first time a data-driven 3D model that is consistent with geophysical data and geological observations, and that is able to causally link the thermo-rheological structure of the lithosphere to the observed variation of surface deformation styles in the retroarc foreland of northern Argentina.}, language = {en} } @article{NavazoOyhenartDahintenetal.2020, author = {Navazo, B{\´a}rbara and Oyhenart, Evelia and Dahinten, Silvia and Mumm, Rebekka and Scheffler, Christiane}, title = {Decrease of external skeletal robustness (Frame Index) between two cohorts of school children living in Puerto Madryn, Argentina at the beginning of the 21st century}, series = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger}, volume = {77}, journal = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger}, number = {5}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0003-5548}, doi = {10.1127/anthranz/2020/1182}, pages = {405 -- 413}, year = {2020}, abstract = {Background: It has been shown that modern life style with reduced physical activity can lead to lower bone accumulation. Also a decline trend in external skeletal robustness in children and young adolescents, measured by the Frame Index (FI), seems to have a parallel trend with the increase in overweight and obesity. Based on these findings we estimate that likely, the FI should be changed after a decade in the Argentinean population as well as in others population of the world. Thereby, the aim of the present study was to describe, using the FI, the pattern of external skeletal robustness in school children aged 6-14 years from two cohorts of Argentina (Puerto Madryn, Chubut) and to compare them with the European reference (Czech Republic, Germany, Poland and Russia). Methods: Elbow breadth and height of Puerto Madryn school children were collected in two cross-sectional studies conducted between 2001-2006 (cohort 1 = C1) and 2014-2016 (cohort 2 = C2). Percentiles (P) values, for males and females, from C1 and C2 were calculated combining the LMSmethod and its extension. A t-test has been used to compare, by age and sex, the FI values between the Argentinean cohorts and the European reference (ER). Then, in order to know the percentage of the variation of the percentiles values between cohorts, as well as with ER, percent differences between means (PDM\%) were employed. Results: FI from Argentinean cohorts differed significantly from ER. Even more, C2 was not only smaller than ER, but also than C1. In males, C1-C2 showed significant differences at 6-8, 11 and 12 years and in females at all ages. Then, respect to ER each Argentinean cohort showed significant differences in males of C1 at 6, 12-14 years and in females at 6 and 11-14 years; and of C2, in both sexes, from 6 to 14 years. The PDM\% values for elbow breadth of male were negative in ER-C1 in all percentiles analyzed; in ER-C2 positive (P3 and P50) and negative (P97) and C1-C2 recorded positive values. In females, elbow breadth showed negative values for ER-C1 (P50 and P97), and positive for the remaining values. Finally, height registered, in both sexes, negative values in ER-C1 (except P97 in females), ER-C2 and C1-C2. Conclusions: After ten years of the first study carried on in Puerto Madryn, school children show a negative trend in the external skeletal robustness. Additionally, the children of both Argentinean cohorts have lower values compared to the European reference, and mainly the actual cohort. This situation would be explained, in part, by the progressive increase over time of overweight and obesity as consequence, among others, of the change in the quantity and/or quality of the food that children have access to and with the physical activity they do at school and outside.}, language = {en} } @phdthesis{Pingel2015, author = {Pingel, Heiko}, title = {Mountain-range uplift \& climate-system interactions in the Southern Central Andes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-82301}, school = {Universit{\"a}t Potsdam}, pages = {xii, 178}, year = {2015}, abstract = {Zwei h{\"a}ufig diskutierte Aspekte der sp{\"a}tk{\"a}nozoischen Gebirgsbildung der Anden sind der Zeitpunkt sowie die Art und Weise der Heraushebung des Puna-Plateaus und seiner Randgebiete innerhalb der Ostkordillere und die damit verbundenen klimatischen {\"A}nderungen in NW Argentinien. Die Ostkordillere trennt die Bereiche des endorheischen, ariden Plateaus von semiariden und extern entw{\"a}sserten intermontanen Becken sowie dem humiden Andenvorland im Osten. Diese Unterschiede verdeutlichen die Bedeutung der {\"o}stlichen Flanken der Anden als orografische Barrieren gegen{\"u}ber feuchten Luftmassen aus dem Osten und spiegelt sich auch in ausgepr{\"a}gten Relief- und Topografiegradienten, der Niederschlagsverteilung, und der Effizienz von Oberfl{\"a}chenprozessen wider. Obwohl das {\"u}bergeordnete Deformationsmuster in diesem Teil der Anden eine ostw{\"a}rts gerichtete Wanderung der Deformationsprozesse im Gebirge indiziert, gibt es hier keine klar definierte Deformationsfront. Hebungsvorg{\"a}nge und die damit im Zusammenhang stehenden Sedimentprozesse setzen r{\"a}umlich und zeitlich sehr unterschiedlich ein. Zudem gestalten periodisch wiederkehrende Deformationsereignisse innerhalb intermontaner Becken und diachrone Hebungsvorg{\"a}nge, durch Reaktivierung {\"a}lterer Sockelstrukturen im Vorland, eine detaillierte Auswertung der r{\"a}umlich-zeitlichen Hebungsmuster zus{\"a}tzlich schwierig. Die vorliegende Arbeit konzentriert sich haupts{\"a}chlich auf die tektonische Entwicklung der Ostkordillere im Nordwesten Argentiniens, die Ablagerungsgeschichte ihrer intermontanen Sedimentbecken und die topografische Entwicklung der Ostflanke des andinen Puna-Plateaus. Im Allgemeinen sind sich die Sedimentbecken der Ostkordillere und der angrenzenden Provinzen, den Sierras Pampeanas und der Santa B{\´a}rbara Region, den durch St{\"o}rungen begrenzten und mit Sedimenten verf{\"u}llten Becken der hochandinen Plateauregion sehr {\"a}hnlich. Deutliche Unterschiede zur Puna bestehen aber dennoch, denn wiederholte Deformations-, Erosions- und Sedimentationsprozesse haben in den intermontanen Becken zu einer vielf{\"a}ltigen Stratigrafie, {\"U}berlagerungsprozessen und einer durch tektonische Prozesse und klimatischen Wandel charakterisierten Landschaft beigetragen. Je nach Erhaltungsgrad k{\"o}nnen in einigen F{\"a}llen Spuren dieser sediment{\"a}ren und tektonischen Entwicklung bis in die Zeit zur{\"u}ckreichen, als diese Bereiche des Gebirges noch Teil eines zusammenh{\"a}ngenden und unverformten Vorlandbeckens waren. Im Nordwesten Argentiniens enthalten k{\"a}nozoische Sedimente zahlreiche datierbare und geochemisch korrelierbare Vulkanaschen, die nicht nur als wichtige Leithorizonte zur Entschl{\"u}sselung tektonischer und sediment{\"a}rer Ereignisse dienen. Die vulkanischen Gl{\"a}ser dieser Aschen archivieren außerdem Wasserstoff-Isotopenverh{\"a}ltnisse fr{\"u}herer Oberfl{\"a}chenwasser, mit deren Hilfe - im Vergleich mit den Isotopenverh{\"a}ltnissen rezenter meteorischer W{\"a}sser - die r{\"a}umliche und zeitliche Entstehung orografischer Barrieren und tektonisch erzwungene Klima- und Umweltver{\"a}nderungen verfolgt werden k{\"o}nnen. Uran-Blei-Datierungen an Zirkonen aus den vulkanischen Aschelagen und die Rekonstruktion sediment{\"a}rer Pal{\"a}otransportrichtungen im intermontanen Humahuaca-Becken in der Ostkordillere (23.5° S) deuten an, dass das heutige Becken bis vor etwa 4.2 Ma Bestandteil eines gr{\"o}ßtenteils uneingeschr{\"a}nkten Ablagerungsbereichs war, der sich bis ins Vorland erstreckt haben muss. Deformation und Hebung {\"o}stlich des heutigen Beckens sorgten dabei f{\"u}r eine fortschreitende Entkopplung des Entw{\"a}sserungsnetzes vom Vorland und eine Umlenkung der Flussl{\"a}ufe nach S{\"u}den. In der Folge erzwang die weitere Hebung der Gebirgsbl{\"o}cke das Abregnen {\"o}stlicher Luftmassen in immer {\"o}stlicher gelegene Bereiche. Zudem k{\"o}nnen periodische Schwankungen der hydrologischen Verbindung des Beckens mit dem Vorland im Zusammenhang mit der Ablagerung und Erosion m{\"a}chtiger Beckenf{\"u}llungen identifiziert werden. Systematische Beziehungen zwischen Verwerfungen, regionalen Diskontinuit{\"a}ten und verstellten Terrassenfl{\"a}chen verweisen außerdem auf ein generelles Muster beckeninterner Deformation, vermutlich als Folge umfangreicher Beckenerosion und damit verbundenen {\"A}nderungen im tektonischen Spannungsfeld der Region. Einige dieser Beobachtungen k{\"o}nnen anhand ver{\"a}nderter Wasserstoff-Isotopenkonzentrationen vulkanischer Gl{\"a}ser aus der k{\"a}nozoischen Stratigrafie untermauert werden. Die δDg-Werte zeigen zwei wesentliche Trends, die einerseits in Verbindung mit Oberfl{\"a}chenhebung innerhalb des Einzugsgebiets zwischen 6.0 und 3.5 Ma stehen und andererseits mit dem Einsetzen semiarider Bedingungen durch Erreichen eines Schwellenwertes der Topografie der {\"o}stlich gelegenen Gebirgsz{\"u}ge nach 3.5 Ma erkl{\"a}rt werden k{\"o}nnen. Tektonisch bedingte Unterbrechung der Sedimentzufuhr aus westlich gelegenen Liefergebieten um 4.2 Ma und die folgende Hinterland-Aridifizierung deuten weiterhin auf die M{\"o}glichkeit hin, dass diese Prozesse die Folge eines lateralen Wachstums des Puna-Plateaus sind. Diese Aridifizierung im Bereich der Puna resultierte in einem ineffizienten, endorheischen Entw{\"a}sserungssystem, das dazu beigetragen hat, das Plateau vor Einschneidung und externer Entw{\"a}sserung zu bewahren und Reliefgegens{\"a}tze aufgrund fortgesetzter Beckensedimentation reduzierte. Die diachrone Natur der Hebungen und Beckenbildungen sowie deren Auswirkungen auf das Flusssystem im angrenzenden Vorland wird sowohl durch detaillierte Analysen der Sedimentherkunft und Transportrichtungen als auch Uran-Blei-Datierungen im Lerma- und Met{\´a}n-Becken (25° S) weiterhin unterstrichen. Das wird besonders deutlich am Beispiel der isolierten Hebung der Sierra de Met{\´a}n vor etwa 10 Ma, die mehr als 50 km von der aktiven orogenen Front im Westen entfernt liegt. Ab 5 Ma sind typische Lithologien der Puna nicht mehr in den Vorlandsedimenten nachweisbar, welches die weitere Hebung innerhalb der Ostkordillere und die hydrologische Isolation des Angastaco-Beckens in dieser Region dokumentiert. Im Sp{\"a}tplioz{\"a}n und Quart{\"a}r ist die Deformation letztlich {\"u}ber das gesamte Vorland verteilt und bis heute aktiv. Um die Beziehungen zwischen tektonisch kontrollierten Ver{\"a}nderungen der Topografie und deren Einfluss auf atmosph{\"a}rische Prozesse besser zu verstehen, werden in dieser Arbeit weitere altersspezifische Wasserstoff-Isotopendaten vulkanischer Gl{\"a}ser aus dem zerbrochenen Vorland, dem Angastaco-Becken in der {\"U}bergangsregion zwischen Ostkordillere und Punarand und anderer intermontaner Becken weiter s{\"u}dlich vorgestellt. Die Resultate dokumentieren {\"a}hnliche H{\"o}henlagen der untersuchten Regionen bis ca. 7 Ma, gefolgt von Hebungsprozessen im Bereich des Angastaco-Beckens. Ein Vergleich mit Isotopendaten vom benachbarten Puna-Plateau hilft abrupte δDg-Schwankungen in den intermontanen Daten zu erkl{\"a}ren und untermauert die Existenz wiederkehrender Phasen verst{\"a}rkt konvektiver Wetterlagen im Plioz{\"a}n, {\"a}hnlich heutigen Bedingungen. In dieser Arbeit werden gel{\"a}ndeorientierte und geochemische Methoden kombiniert, um Erkenntnisse {\"u}ber die Abl{\"a}ufe von topografiebildenden Deformations- und Hebungsprozessen zu gewinnen und Wechselwirkungen mit der daraus resultierenden Niederschlagsverteilung, Erosion und Sedimentation innerhalb tektonisch aktiver Gebirge zu erforschen. Diese Erkenntnisse sind f{\"u}r ein besseres Verst{\"a}ndnis von Subduktionsgebirgen essentiell, besonders hinsichtlich des Deformationsstils und der zeitlich-r{\"a}umlichen Beziehungen bei der Hebung und Sedimentbeckenbildung. Diese Arbeit weist dar{\"u}berhinaus auf die Bedeutung stabiler Isotopensysteme zur Beantwortung pal{\"a}oaltimetrischer Fragestellungen und zur Erforschung von Pal{\"a}oumweltbedingungen hin und liefert wichtige Erkenntnisse f{\"u}r einen kritischen Umgang mit solchen Daten in anderen Regionen.}, language = {en} } @article{RibackiTrumbullLopezDeLuchietal.2022, author = {Ribacki, Enrico and Trumbull, Robert B. and Lopez De Luchi, Monica Graciela and Altenberger, Uwe}, title = {The chemical and B-Isotope composition of Tourmaline from intra-granitic Pegmatites in the Las Chacras-Potrerillos Batholith, Argentina}, series = {The Canadian mineralogist : journal of the Mineralogical Association of Canada}, volume = {60}, journal = {The Canadian mineralogist : journal of the Mineralogical Association of Canada}, number = {1}, publisher = {Association of Canada}, address = {Ottawa}, issn = {0008-4476}, doi = {10.3749/canmin.2100036}, pages = {49 -- 66}, year = {2022}, abstract = {The Devonian Las Chacras-Potrerillos batholith comprises six nested monzonitic to granitic intrusions with metaluminous to weakly peraluminous composition and a Sr-Nd isotopic signature indicating a dominantly juvenile mantle-derived source. The chemically most evolved units in the southern batholith contain a large number of intra-granitic, pod-shaped tourmaline-bearing pegmatites. This study uses in situ chemical and boron isotopic analyses of tourmaline from nine of these pegmatites to discuss their relationship to the respective host intrusions and the implications of their B-isotope composition for the source and evolution of the magmas. The tourmalines reveal a diversity in element composition (e.g., FeO, MgO, TiO2, CaO, MnO, F) which distinguishes individual pegmatites from one another. However, all have a narrow 5 11 B range of -13.7 to -10.5\%0 (n = 100) which indicates a relatively uniform magmatic system and similar temperature conditions during tourmaline crystallization. The average delta(11) B value of -11.7\%0 is typical for S-type granites and is within the range reported for peraluminous granites. pegmatites, and metamorphic units of the Ordovician basement into which the Las Chacras-Potrerillos batholith intruded. The B-isotope evidence argues for a crustal boron source like that of the Ordovician basement, in contrast to the metaluminous to weakly peraluminous composition and juvenile initial Sr and Nd isotope ratios of the Las Chacras-Potrerillos batholith magmas. We propose that the boron was not derived from the magma source region but was incorporated from dehydration melting of elastic metasedimentary rocks higher up in the crustal column.}, language = {en} } @phdthesis{RuizMonroy2021, author = {Ruiz-Monroy, Ricardo}, title = {Organic geochemical characterization of the Yacoraite Formation (NW-Argentina)-paleoenvironment and petroleum potential}, doi = {10.25932/publishup-51869}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-518697}, school = {Universit{\"a}t Potsdam}, pages = {XVI, 161}, year = {2021}, abstract = {This dissertation was carried out as part of the international and interdisciplinary graduate school StRATEGy. This group has set itself the goal of investigating geological processes that take place on different temporal and spatial scales and have shaped the southern central Andes. This study focuses on claystones and carbonates of the Yacoraite Fm. that were deposited between Maastricht and Dan in the Cretaceous Salta Rift Basin. The former rift basin is located in northwest Argentina and is divided into the sub-basins Tres Cruces, Met{\´a}n-Aleman{\´i}a and Lomas de Olmedo. The overall motivation for this study was to gain new knowledge about the evolution of marine and lacustrine conditions during the Yacoraite Fm. Deposit in the Tres Cruces and Met{\´a}n-Aleman{\´i}a sub-basins. Other important aspects that were examined within the scope of this dissertation are the conversion of organic matter from Yacoraite Fm. into oil and its genetic relationship to selected oils produced and natural oil spills. The results of my study show that the Yacoraite Fm. began to be deposited under marine conditions and that a lacustrine environment developed by the end of the deposition in the Tres Cruces and Met{\´a}n-Aleman{\´i}a Basins. In general, the kerogen of Yacoraite Fm. consists mainly of the kerogen types II, III and II / III mixtures. Kerogen type III is mainly found in samples from the Yacoraite Fm., whose TOC values are low. Due to the adsorption of hydrocarbons on the mineral surfaces (mineral matrix effect), the content of type III kerogen with Rock-Eval pyrolysis in these samples could be overestimated. Investigations using organic petrography show that the organic particles of Yacoraite Fm. mainly consist of alginites and some vitrinite-like particles. The pyrolysis GC of the rock samples showed that the Yacoraite Fm. generates low-sulfur oils with a predominantly low-wax, paraffinic-naphthenic-aromatic composition and paraffinic wax-rich oils. Small proportions of paraffinic, low-wax oils and a gas condensate-generating facies are also predicted. Here, too, mineral matrix effects were taken into account, which can lead to a quantitative overestimation of the gas-forming character. The results of an additional 1D tank modeling carried out show that the beginning (10\% TR) of the oil genesis took place between ≈10 Ma and ≈4 Ma. Most of the oil (from ≈50\% to 65\%) was generated prior to the development of structural traps formed during the Plio-Pleistocene Diaguita deformation phase. Only ≈10\% of the total oil generated was formed and potentially trapped after the formation of structural traps. Important factors in the risk assessment of this petroleum system, which can determine the small amounts of generated and migrated oil, are the generally low TOC contents and the variable thickness of the Yacoraite Fm. Additional risks are associated with a low density of information about potentially existing reservoir structures and the quality of the overburden.}, language = {en} }