@phdthesis{Brinkmann2022,
  author    = {Brinkmann, Pia},
  title     = {Laserinduzierte Breakdownspektroskopie zur qualitativen und quantitativen Bestimmung von Elementgehalten in geologischen Proben mittels multivariater Analysemethoden am Beispiel von Kupfer und ausgew{\"a}hlten Seltenen Erden},
  doi       = {10.25932/publishup-57212},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-572128},
  school      = {Universit{\"a}t Potsdam},
  pages     = {148},
  year      = {2022},
  abstract  = {Ein schonender Umgang mit den Ressourcen und der Umwelt ist wesentlicher Bestandteil des modernen Bergbaus sowie der zuk{\"u}nftigen Versorgung unserer Gesellschaft mit essentiellen Rohstoffen. Die vorliegende Arbeit besch{\"a}ftigt sich mit der Entwicklung analytischer Strategien, die durch eine exakte und schnelle Vor-Ort-Analyse den technisch-praktischen Anforderungen des Bergbauprozesses gerecht werden und somit zu einer gezielten und nachhaltigen Nutzung von Rohstofflagerst{\"a}tten beitragen. Die Analysen basieren auf den spektroskopischen Daten, die mittels der laserinduzierten Breakdownspektroskopie (LIBS) erhalten und mittels multivariater Datenanalyse ausgewertet werden. Die LIB-Spektroskopie ist eine vielversprechende Technik f{\"u}r diese Aufgabe. Ihre Attraktivit{\"a}t machen insbesondere die M{\"o}glichkeiten aus, Feldproben vor Ort ohne Probennahme oder ‑vorbereitung messen zu k{\"o}nnen, aber auch die Detektierbarkeit s{\"a}mtlicher Elemente des Periodensystems und die Unabh{\"a}ngigkeit vom Aggregatzustand. In Kombination mit multivariater Datenanalyse kann eine schnelle Datenverarbeitung erfolgen, die Aussagen zur qualitativen Elementzusammensetzung der untersuchten Proben erlaubt. Mit dem Ziel die Verteilung der Elementgehalte in einer Lagerst{\"a}tte zu ermitteln, werden in dieser Arbeit Kalibrierungs- und Quantifizierungsstrategien evaluiert. F{\"u}r die Charakterisierung von Matrixeffekten und zur Klassifizierung von Mineralen werden explorative Datenanalysemethoden angewendet. Die spektroskopischen Untersuchungen erfolgen an B{\"o}den und Gesteinen sowie an Mineralen, die Kupfer oder Seltene Erdelemente beinhalten und aus verschiedenen Lagerst{\"a}tten bzw. von unterschiedlichen Agrarfl{\"a}chen stammen. F{\"u}r die Entwicklung einer Kalibrierungsstrategie wurden sowohl synthetische als auch Feldproben von zwei verschiedenen Agrarfl{\"a}chen mittels LIBS analysiert. Anhand der Beispielanalyten Calcium, Eisen und Magnesium erfolgte die auf uni- und multivariaten Methoden beruhende Evaluierung verschiedener Kalibrierungsmethoden. Grundlagen der Quantifizierungsstrategien sind die multivariaten Analysemethoden der partiellen Regression der kleinsten Quadrate (PLSR, von engl.: partial least squares regression) und der Intervall PLSR (iPLSR, von engl.: interval PLSR), die das gesamte detektierte Spektrum oder Teilspektren in der Analyse ber{\"u}cksichtigen. Der Untersuchung liegen synthetische sowie Feldproben von Kupfermineralen zugrunde als auch solche die Seltene Erdelemente beinhalten. Die Proben stammen aus verschiedenen Lagerst{\"a}tten und weisen unterschiedliche Begleitmatrices auf. Mittels der explorativen Datenanalyse erfolgte die Charakterisierung dieser Begleitmatrices. Die daf{\"u}r angewendete Hauptkomponentenanalyse gruppiert Daten anhand von Unterschieden und Regelm{\"a}ßigkeiten. Dies erlaubt Aussagen {\"u}ber Gemeinsamkeiten und Unterschiede der untersuchten Proben im Bezug auf ihre Herkunft, chemische Zusammensetzung oder lokal bedingte Auspr{\"a}gungen. Abschließend erfolgte die Klassifizierung kupferhaltiger Minerale auf Basis der nicht-negativen Tensorfaktorisierung. Diese Methode wurde mit dem Ziel verwendet, unbekannte Proben aufgrund ihrer Eigenschaften in Klassen einzuteilen. Die Verkn{\"u}pfung von LIBS und multivariater Datenanalyse bietet die M{\"o}glichkeit durch eine Analyse vor Ort auf eine Probennahme und die entsprechende Laboranalytik weitestgehend zu verzichten und kann somit zum Umweltschutz sowie einer Schonung der nat{\"u}rlichen Ressourcen bei der Prospektion und Exploration von neuen Erzg{\"a}ngen und Lagerst{\"a}tten beitragen. Die Verteilung von Elementgehalten der untersuchten Gebiete erm{\"o}glicht zudem einen gezielten Abbau und damit eine effiziente Nutzung der mineralischen Rohstoffe.},
  language  = {de}
}
@phdthesis{Raschke2023,
  author    = {Raschke, Stefanie},
  title     = {Characterization of selenium and copper in cell systems of the neurovascular unit},
  doi       = {10.25932/publishup-60366},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-603666},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XIV, 184, v},
  year      = {2023},
  abstract  = {The trace elements, selenium (Se) and copper (Cu) play an important role in maintaining normal brain function. Since they have essential functions as cofactors of enzymes or structural components of proteins, an optimal supply as well as a well-defined homeostatic regulation are crucial. Disturbances in trace element homeostasis affect the health status and contribute to the incidence and severity of various diseases. The brain in particular is vulnerable to oxidative stress due to its extensive oxygen consumption and high energy turnover, among other factors. As components of a number of antioxidant enzymes, both elements are involved in redox homeostasis. However, high concentrations are also associated with the occurrence of oxidative stress, which can induce cellular damage. Especially high Cu concentrations in some brain areas are associated with the development and progression of neurodegenerative diseases such as Alzheimer's disease (AD). In contrast, reduced Se levels were measured in brains of AD patients. The opposing behavior of Cu and Se renders the study of these two trace elements as well as the interactions between them being particularly relevant and addressed in this work.},
  language  = {en}
}
@phdthesis{Stoltnow2023,
  author    = {Stoltnow, Malte},
  title     = {Magmatic-hydrothermal processes along the porphyry to epithermal transition},
  doi       = {10.25932/publishup-61140},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-611402},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxviii, 132},
  year      = {2023},
  abstract  = {Magmatic-hydrothermal systems form a variety of ore deposits at different proximities to upper-crustal hydrous magma chambers, ranging from greisenization in the roof zone of the intrusion, porphyry mineralization at intermediate depths to epithermal vein deposits near the surface. The physical transport processes and chemical precipitation mechanisms vary between deposit types and are often still debated. The majority of magmatic-hydrothermal ore deposits are located along the Pacific Ring of Fire, whose eastern part is characterized by the Mesozoic to Cenozoic orogenic belts of the western North and South Americas, namely the American Cordillera. Major magmatic-hydrothermal ore deposits along the American Cordillera include (i) porphyry Cu(-Mo-Au) deposits (along the western cordilleras of Mexico, the western U.S., Canada, Chile, Peru, and Argentina); (ii) Climax- (and sub-) type Mo deposits (Colorado Mineral Belt and northern New Mexico); and (iii) porphyry and IS-type epithermal Sn(-W-Ag) deposits of the Central Andean Tin Belt (Bolivia, Peru and northern Argentina). The individual studies presented in this thesis primarily focus on the formation of different styles of mineralization located at different proximities to the intrusion in magmatic-hydrothermal systems along the American Cordillera. This includes (i) two individual geochemical studies on the Sweet Home Mine in the Colorado Mineral Belt (potential endmember of peripheral Climax-type mineralization); (ii) one numerical modeling study setup in a generic porphyry Cu-environment; and (iii) a numerical modeling study on the Central Andean Tin Belt-type Pirquitas Mine in NW Argentina. Microthermometric data of fluid inclusions trapped in greisen quartz and fluorite from the Sweet Home Mine (Detroit City Portal) suggest that the early-stage mineralization precipitated from low- to medium-salinity (1.5-11.5 wt.\% equiv. NaCl), CO2-bearing fluids at temperatures between 360 and 415°C and at depths of at least 3.5 km. Stable isotope and noble gas isotope data indicate that greisen formation and base metal mineralization at the Sweet Home Mine was related to fluids of different origins. Early magmatic fluids were the principal source for mantle-derived volatiles (CO2, H2S/SO2, noble gases), which subsequently mixed with significant amounts of heated meteoric water. Mixing of magmatic fluids with meteoric water is constrained by δ2Hw-δ18Ow relationships of fluid inclusions. The deep hydrothermal mineralization at the Sweet Home Mine shows features similar to deep hydrothermal vein mineralization at Climax-type Mo deposits or on their periphery. This suggests that fluid migration and the deposition of ore and gangue minerals in the Sweet Home Mine was triggered by a deep-seated magmatic intrusion. The second study on the Sweet Home Mine presents Re-Os molybdenite ages of 65.86±0.30 Ma from a Mo-mineralized major normal fault, namely the Contact Structure, and multimineral Rb-Sr isochron ages of 26.26±0.38 Ma and 25.3±3.0 Ma from gangue minerals in greisen assemblages. The age data imply that mineralization at the Sweet Home Mine formed in two separate events: Late Cretaceous (Laramide-related) and Oligocene (Rio Grande Rift-related). Thus, the age of Mo mineralization at the Sweet Home Mine clearly predates that of the Oligocene Climax-type deposits elsewhere in the Colorado Mineral Belt. The Re-Os and Rb-Sr ages also constrain the age of the latest deformation along the Contact Structure to between 62.77±0.50 Ma and 26.26±0.38 Ma, which was employed and/or crosscut by Late Cretaceous and Oligocene fluids. Along the Contact Structure Late Cretaceous molybdenite is spatially associated with Oligocene minerals in the same vein system, a feature that precludes molybdenite recrystallization or reprecipitation by Oligocene ore fluids. Ore precipitation in porphyry copper systems is generally characterized by metal zoning (Cu-Mo to Zn-Pb-Ag), which is suggested to be variably related to solubility decreases during fluid cooling, fluid-rock interactions, partitioning during fluid phase separation and mixing with external fluids. The numerical modeling study setup in a generic porphyry Cu-environment presents new advances of a numerical process model by considering published constraints on the temperature- and salinity-dependent solubility of Cu, Pb and Zn in the ore fluid. This study investigates the roles of vapor-brine separation, halite saturation, initial metal contents, fluid mixing, and remobilization as first-order controls of the physical hydrology on ore formation. The results show that the magmatic vapor and brine phases ascend with different residence times but as miscible fluid mixtures, with salinity increases generating metal-undersaturated bulk fluids. The release rates of magmatic fluids affect the location of the thermohaline fronts, leading to contrasting mechanisms for ore precipitation: higher rates result in halite saturation without significant metal zoning, lower rates produce zoned ore shells due to mixing with meteoric water. Varying metal contents can affect the order of the final metal precipitation sequence. Redissolution of precipitated metals results in zoned ore shell patterns in more peripheral locations and also decouples halite saturation from ore precipitation. The epithermal Pirquitas Sn-Ag-Pb-Zn mine in NW Argentina is hosted in a domain of metamorphosed sediments without geological evidence for volcanic activity within a distance of about 10 km from the deposit. However, recent geochemical studies of ore-stage fluid inclusions indicate a significant contribution of magmatic volatiles. This study tested different formation models by applying an existing numerical process model for porphyry-epithermal systems with a magmatic intrusion located either at a distance of about 10 km underneath the nearest active volcano or hidden underneath the deposit. The results show that the migration of the ore fluid over a 10-km distance results in metal precipitation by cooling before the deposit site is reached. In contrast, simulations with a hidden magmatic intrusion beneath the Pirquitas deposit are in line with field observations, which include mineralized hydrothermal breccias in the deposit area.},
  language  = {en}
}