Olivier Bachmann

Olivier Bachmann
ETH Zurich | ETH Zürich · Department of Earth Sciences

PhD

About

297
Publications
97,324
Reads
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11,328
Citations
Citations since 2017
140 Research Items
7613 Citations
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201720182019202020212022202305001,0001,500
Introduction
Olivier Bachmann currently works at the Department of Earth Sciences, ETH Zurich. Olivier does research in Geology, Mineralogy and Petrology.

Publications

Publications (297)
Article
Full-text available
Many volcanoes show transitions between explosive and effusive eruptive styles both through the history of the volcano as a whole and occasionally within the course of a single eruption. These differing eruptive styles have vastly different implications for hazard assessments in surrounding regions and so understanding such changes is important. He...
Article
Full-text available
Rapid industrialization has led to a dramatic increase in air pollution. In China, the factors driving the abundance and composition of smog, particularly fine particulate matter, remain poorly understood, and short-term air pollution data are available from few air quality monitoring networks. Using laser ablation-inductively coupled plasma-mass s...
Article
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The concentration of pre-eruptive volatiles is a key parameter that controls the eruptive behaviour of volcanoes. Among these, water is the most abundant volatile and has a major influence on magma chamber dynamics and a primary role in driving eruptions. While accurately quantifying the pre-eruptive dissolved water concentration of magmas is a cru...
Article
Many volcanoes have the ability to impact human infrastructure with explosive activity and understanding the processes of magma generation and conditions of storage in these systems remains a priority. The Sete Cidades volcano on the island of São Miguel, Azores archipelago is exactly such a volcano lying only 12 km from the island’s capital city o...
Article
The origins of felsic low-δ18O melts (< +5.5 ‰) are usually attributed to assimilation of high-temperature hydrothermally altered (HTHA) rocks. Very few alkaline (silica undersaturated and/or peralkaline) examples are known. Here, we classify the Miocene Fataga Group in Gran Canaria, a silica-undersaturated to mildly saturated alkaline volcanic seq...
Article
Full-text available
Fluid exsolution in magmas is a process that, in many silicic upper crustal reservoirs, starts at relatively low crystallinities (near liquidus), and precedes the precipitation of many ore bodies, including pegmatites. As any magmatic system approaches its solidus, the amount of the exsolved fluid phase increases and becomes progressively dominant...
Article
Volcano sector collapses are catastrophic events that can mobilize huge volumes of material and cause changes in the magmatic plumbing system, leading to variations in growth rate and/or composition. Dating pre-historic volcanic debris avalanche deposits is challenging. Geological materials directly recording avalanche formation and amenable to rad...
Article
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Since the onset of plate tectonics, continents have evolved through a balance between crustal growth, reworking, and recycling at convergent plate margins. The term “reworking” involves the re-insertion of crustal material into pre-existing crustal volumes, while crustal growth and recycling respectively represent gains from and losses to the mantl...
Article
The Ordovician rocks of Sierra Las Planchadas are an exceptionally preserved natural example of a plutonic-volcanic connection. Located in northwestern Argentina, the Las Planchadas Formation consists of a monzogranitic batholith that displays a window into the source of large subvolcanic rhyolitic rocks, cryptodomes and volcanic feeder-dykes. Mafi...
Article
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The chemical composition of gases emitted by active volcanoes reflects both magma degassing and shallower processes, such as fluid-rock hydrothermal interaction and mixing with atmospheric-derived fluids. Untangling the magmatic fluid endmember within surface gas emission is therefore challenging, even with the use of well-known magma degassing tra...
Article
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Inter‐session excess variance of U/Pb and Pb/Pb ratios in LA‐ICP‐MS zircon dating is the largest contributor to systematic errors, which in turn limit the accuracy of age determinations. Quantifying long‐term excess variance of reference materials allows for the estimation of excess variance in samples, but such compilations are not available in th...
Article
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This contribution provides in-situ LA-ICP-MS U-Pb ages and trace element determinations of zircons from dacitic to rhyolitic lavas, ignimbrites and intrusions in the Southern Rocky Mountain Volcanic Field (SRMVF) in Colorado, USA. The data record a period of intense magmatic activity in the Oligocene-early Miocene (∼37-22 Ma) which gave rise to som...
Article
Precise age determinations of volcanic deposits from the Late Pleistocene and Holocene are fundamental for hazard assessment. Retrieving accurate radiogenic ages typically relies on analysing specific minerals (such as zircon or sanidine), which are in many cases lacking in the deposits. We present a new 230Th‐238U disequilibrium dating method by L...
Conference Paper
Most volcanoes, across tectonic settings, can show both explosive and effusive eruptions, either as separated eruptive events or within the same eruptive episode. Such differences in eruptive style have significant implications for depositional morphology and hazards associated with the eruptions. In many cases, chemically nearly identical magmas m...
Article
Lithium and hydrogen are volatile elements which diffuse rapidly in crystals and melt, making them powerful geochemical tools to reconstruct geological processes that take place on short time scales, such as syn- and post-eruptive degassing. Although the dynamics of hydrogen are fairly well understood to better constrain such processes, the assessm...
Article
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Mafic and ultramafic plutonic rocks are often considered to be crystal cumulates (i.e., they are melt-depleted), but such a classification is much more contentious for intermediate to silicic granitoids (e.g., tonalite, granodiorite, granite, and syenite). Whether or not a given plutonic rock has lost melt to feed shallower subvolcanic intrusive bo...
Article
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The magmatic-hydrothermal transition is key in controlling the fate of many economically important elements due to the change in partitioning when melt and magmatic fluid coexist. Despite its increasing economic importance, the behavior of lithium (Li) in such environments remains poorly known. We illustrate how compositionally unusual biotites fro...
Article
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As ascending magmas undergo cooling and crystallization, water and fluid-mobile elements (e.g., Li, B, C, F, S, Cl) become increasingly enriched in the residual melt until fluid saturation is reached. The consequential exsolution of a fluid phase dominated by H2O (magmatic volatile phase or MVP) is predicted to occur early in the evolution of long-...
Article
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Somma-Vesuvius is one of the most iconic active volcanoes with historic and archeological records of numerous hazardous eruptions. Petrologic studies of eruptive products provide insights into the evolution of the magma reservoir before eruption. Here, we quantify the duration of shallow crustal storage and document the evolution of phonolitic magm...
Article
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The location, volume and physical states of magma reservoirs are primary controls on the eruptive behavior of volcanic systems. Fundamental to understanding and monitoring these systems is the ability to identify reservoir size and physical properties, in particular melt fraction which plays an important role in the rheology and stability of a magm...
Article
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Lithium is an economically important element that is increasingly extracted from brines accumulated in continental basins. While a number of studies have identified silicic magmatic rocks as the ultimate source of dissolved brine lithium, the processes by which Li is mobilized remain poorly constrained. Here we focus on the potential of low-tempera...
Conference Paper
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The formation of the Pannonian basin by major lithospheric extension during the early to mid-Miocene was accompanied by intensive volcanic activity. Among it, explosive volcanism fed by silicic (dacite to rhyolite) magmas is considered to have been the largest (accumulated tephra volume exceeded 4000 km3) in Europe in the last 20 Myr. Zircon U-Pb g...
Conference Paper
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The Mid-Miocene volcanism in the northern Pannonian basin has a peculiar nature. The first volcanic products (metaluminous andesite to peraluminous dacite-rhyodacite) are unique since the dacites and rhyodacites contain almandine garnet, which rarely occurs in volcanic rocks. The primary almandine crystals have a moderate Ca content (CaO=4.5–8.1 wt...
Article
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The oldest geological materials on Earth are Hadean (>4 Ga) detrital zircon grains. Their chemistry and apparently low Ti-in-zircon temperatures (≤700 °C) are considered to be inconsistent with crystallization in a magma of the tonalite-trondhjemite-granodiorite (TTG) suite, although these are the dominant Archean (4.0–2.5 Ga) silicic rocks. Using...
Article
Granitoids are a major component of the continental crust. They play a pivotal role in its evolution, either by adding new material (continental growth), or by reworking older continental crust. These two roles correspond to two main ways of forming granitic magmas, either by partial melting of pre-existing crustal rocks yielding granitic melts dir...
Article
Granitic melts may form either directly, by melting of pre-existing crustal rocks, or by fractionation of mafic to intermediate magmas, typically mantle-derived. Each model is applicable to different portions of the Earth at different times. Whenever there is an important flux of mafic magmas from the mantle, differentiation of basaltic magmas domi...
Article
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The growth and evolution of crustal-scale magmatic systems play a key role in the generation of the continental crust, the largest eruptions on Earth, and the formation of metal resources vital to our society. However, such systems are rarely exposed on the Earth’s surface, limiting our knowledge about the magmatic processes occurring throughout th...
Article
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Thirty-two trace elements were examined in the tree rings of downy oak to evaluate the pollution levels close to a cement plant isolated in a rural context and an industrial area where multiple sources of air pollution are or were present. Tree cores were collected from trees growing 1 km from both the cement plant and the industrial area that are...
Article
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Most volcanoes erupt both effusively and explosively, with explosive behaviour being responsible for most human fatalities. Eruption style is thought to be strongly controlled by fast conduit processes, limiting our ability for prediction. Here we address a critical question in the quest to develop timely forecasting of eruptive behaviour: are ther...
Article
U‐Th disequilibrium dating uses the ratio of the intermediate 230Th daughter isotope to the 238U parent isotope to date zircon crystallisation for volcanic and plutonic rocks in Pleistocene–Holocene deposits. It is frequently used to constrain the duration and rate of magma recharge in volcanic systems. While ≤ 350 ka zircon is not in secular equil...
Article
Here we document how the different growth features and intracrystalline distributions of both major and trace cations in clinopyroxene phenocrysts are important recorders of the intricate magma dynamics at Vulcano Island (Aeolian Arc, Italy). The compositions of clinopyroxene phenocrysts from products erupted over the last ~54 ka cluster at differe...
Article
Radiogenic 40Ca is preferentially concentrated in the continental crust through the decay of radioactive 40K and may have the potential to be used as a tracer for Ca fluxes to the ocean through time. Numerous published flux estimates suggest that rivers are the dominant source of Ca to the oceans. This conflicts, however, with conclusions drawn fro...
Article
Silicic calderas globally tend to record a cyclic magmatic, structural, and eruptive evolutionary progression. Some calderas are polycyclic, involving multiple catastrophic collapses in the same approximate location. Here we discuss five examples from well-studied, geologically-young and active magmatic systems: The Kos-Nisyros Volcanic Complex (Gr...
Article
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Ciomadul is the youngest volcano in eastern-central Europe. Although its last eruption occurred at ca. 30 ka, there are independent indications for a high-crystallinity magma reservoir persisting beneath the volcano until present. In order to further test the hypothesis of long-lived melt presence and to better constrain the nature and timescales a...
Article
Full-text available
Geophysical and petrological probes are key to understanding the structure and the thermochemical state of active magmatic systems. Recent advances in laboratory analyses, field investigations and numerical methods have allowed increasingly complex data-constraint models with new insights into magma plumbing systems and melt evolution. However, the...
Article
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Dense, glassy pyroclasts found in products of explosive eruptions are commonly employed to investigate volcanic conduit processes through measurement of their volatile inventories. This approach rests upon the tacit assumption that the obsidian clasts are juvenile, that is, genetically related to the erupting magma. Pyroclastic deposits within the...
Book
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This community roadmap presents an integrative approach including the most urgent infrastructure requests for the future development of geosciences in Switzerland. It recommends to strengthen the multidisciplinary nature of the geosciences by putting all activities under the roof of the Integrated Swiss Geosciences supported by four specific resear...
Article
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Changes from effusive to explosive behavior are common during single eruptive events. However, in many cases these shifts are recorded between distinct eruptions, separated by periods of volcanic repose. In the quiescent periods, magma chamber processes are likely to play a major role in controlling the style of the next eruption, by modifying the...
Article
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The Aso-4 caldera-forming event (86.4 ± 1.1 ka, VEI-8) is the second largest volcanic eruption Earth experienced in the past 100 ka. The ignimbrite sheets produced during this event are some of the first ever described compositionally zoned pyroclastic flow deposits exhibiting clear compositional, mineralogical and thermal gradients with stratigrap...
Article
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We present a novel approach to use zircon as a correlation tool as well as a monitor for magma reservoir processes in silicic volcanic systems. Fingerprinting eruption products based on trace element content and U-Pb dates of zircon offers a promising, previously underestimated tephra correlation perspective, particularly in cases where the main mi...
Preprint
Full-text available
Geophysical and petrological probes are key to understanding the structure and the thermochemical state of active magmatic systems. Recent advances in laboratory analyses, field investigations and numerical methods have allowed increasingly complex data-constraint models with new insights into magma plumbing systems and melt evolution. However, the...
Article
Sedimentological and zircon U–Pb–Hf isotopic analyses of the Carboniferous strata in the Bainaimiao arc belt (BAB) provide provenance information for the northern margin of the North China Craton (NCC). The late Carboniferous strata in the eastern BAB were dominantly shallow marine carbonate-clastic deposits. Detrital zircon data show that: (1) san...
Article
The purpose of this review study is to reappraise in a more comprehensive form the thermodynamic principles behind the partitioning of trace elements between clinopyroxene and melt. The original corollary is that the partitioning energetics controlling the crystal-melt exchange are described by two distinct but complementary contributions: ΔGpartit...
Article
Most explosive, silicic volcanoes spend thousands of years in repose between eruptive events. The timing of the switch from repose to eruption is key to interpreting monitoring signals and improving the safety of people living close to active volcanoes. We addressed this question using a novel technique based on lithium isotopic (δ7Li) and elementa...
Article
Full-text available
Estimating the quantity of CO2 diffusively emitted from the Earth’s surface has important implications for volcanic surveillance and global atmospheric CO2 budgets. However, the identification and quantification of non-hydrothermal contributions to CO2 release can be ambiguous. Here, we describe a multi-parametric approach employed at the Nisyros c...
Article
Full-text available
Water-rich silicic magmas are capable of erupting effusively and explosively, and this drastic change in eruptive styles, termed effusive-explosive transition, has important implications in managing volcanic hazards. Some volcanoes exhibit effusive-explosive transitions during the same eruptive event, while others show this behavior between differe...
Article
Large quartz pebbles erupted with the Escorial ignimbrite provide insight into the late-magmatic evolution of the shallow, cooling magmatic-hydrothermal system below the Cerro Escorial volcano of the Southern Central Volcanic Zone in the Argentine Andes. The ignimbrite is of relatively small volume, crystal-rich, dacitic in composition, and not par...
Article
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Silicic magmas play an important role in the formation of continental crust and are responsible for some of the most hazardous volcanic eruptions on the planet. Low-δ¹⁸O silicic magmas (δ¹⁸O < 5.5 ‰) have been a petrological conundrum as they require significant incorporation of rocks that were hydrothermally altered by meteoric water at high water...
Article
Orogenic crustal thickening leads to increased continental elevation and runoff into the oceans, but there are fundamental uncertainties in the temporal patterns of thickening through Earth history. U‐Pb age and trace element data in detrital zircons from Antarctica are consistent with recent global analyses suggesting two dominant peaks in average...
Article
Most arc volcanoes erupt intermediate to silicic magmas that have sufficient volatile contents to behave explosively. Despite this explosive potential, low-energy effusive eruptions of such viscous water-rich magmas are common occurrences. Hence, predicting the style of the next eruption, with its obvious importance on hazard mitigation, remains on...
Article
Pre- to syn-eruptive fluids released by the magmatic system forming the non-welded rhyolitic Kos Plateau Tuff ignimbrite, Greece, were characterized using fluid inclusions entrapped in quartz from granitic clasts entrained from the roof or walls of the feeding magma reservoir. This fluid was initially of intermediate density and relatively low sali...
Article
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Quantifying the relative contributions of crustal versus mantle-derived melt is important for understanding how silicic magmas are generated, stored, and interact with country rock in trans-crustal magmatic systems. Low-δ18O rhyolitic ignimbrites and lavas erupted during Miocene volcanic activity in the central Snake River Plain (14-6 Ma) have been...
Article
Full-text available
Granitoids of the tonalite–trondhjemite–granodiorite (TTG) series dominate Earth’s earliest continental crust. The geochemical diversity of TTGs is ascribed to several possible geodynamic settings of magma formation, from low-pressure differentiation of oceanic plateaus to high-pressure melting of mafic crust at convergent plate margins. These inte...
Article
Lake City Caldera (22.93 ± 0.02 Ma) is the youngest of 25 Tertiary calderas within the Southern Rocky Mountain Volcanic Field (SRMVF) and offers an opportunity to study the relationship between plutonic rocks and their volcanic equivalents. Extreme topographical relief of the area reveals the three-dimensional exposure of a complex, high-K calc-alk...