Urs Schaltegger

• PhD
• Professor at University of Geneva

The Early Triassic is a key interval to understand biotic and environmental recovery after the major disturbance of the planetary system at the Permo-Triassic Boundary (PTB). The collapse of biodiversity and the dramatic change of the global carbon cycle are thought to be the result intrusions of mafic melts of the Siberian Large lgneous Province (...

The highest precision and accuracy in U–Pb geochronology is achieved using isotope dilution thermal ionisation mass spectrometry (ID-TIMS), a technique which owes its reliability to precise Pb and U isotope ratio analysis, a largely unified framework of lab protocols, and common isotopic tracers with accurately determined compositions. However, whi...

The incremental construction of plutons characterises magmatic activity in arc settings, where new continental crust is produced. This polyphasic growth entails interactions with one or more crustal components, which modulate the geochemical and isotopic compositions of the newly formed crust. However, the early stages of magmatism are not always p...

The “Likhall” bed is a rare case of a single-age zircon population from a carbonate rock, which in this case is contextualised with remarkable biotic and environmental changes and with meteorite bombardment of Earth after an asteroid breakup in space. Published high-precision chemical abrasion isotope dilution thermal ionisation mass spectrometry (...

Paleomagnetic records of middle Neoproterozoic (820 to 780 Ma) rocks display high amplitude directional variations that lead to large discrepancies in paleogeographic reconstructions. Hypotheses to explain these data include rapid true polar wander (TPW), a geomagnetic field geometry that deviates from a predominantly axial dipole field, a hyper‐re...

U-Pb geochronology by isotope dilution−thermal ionization mass spectrometry (ID-TIMS) has the potential to be the most precise and accurate of the deep time chronometers, especially when applied to high-U minerals such as zircon. Continued analytical improvements have made this technique capable of regularly achieving better than 0.1% precision and...

The southern Rocky Mountains in Colorado and northern New Mexico hosted intracontinental magmatism that developed during a tectonic transition from shortening (Laramide orogeny, ca. 75 to 40 Ma) through extension and rifting. We present a novel approach that uses stochastic weighted bootstrap simulations of a large set of new and historical geochro...

Reconstructing the tempo and emplacement mechanisms of large igneous provinces (LIPs) and establishing potential links to environmental change and biological crises requires detailed and targeted high- precision geochronology. Contact metamorphism during LIP intrusive magmatism can release large volumes of thermogenic gas, so determining the timing...

The 'Likhall' zircon bed is a rare case of a single-age zircon population from a carbonate rock, which in this case is contextualised with remarkable biotic and environmental changes as well as meteorite bombardment of Earth after an asteroid breakup in space. Published chemical-abrasion, high-precision isotope-dilution, thermal ionization mass spe...

The Transvaal Supergroup, on the Kaapvaal Craton in South Africa, is widely accepted as one of the best-preserved sedimentary archives to constrain planetary-scale environmental changes during the late Archean and early Proterozoic, yet the sedimentation age for certain stratigraphic intervals remains poorly constrained. To improve the temporal con...

The zircon-rich ‘Likhall’ bed found in the Middle Ordovician (Darriwilian) ‘Täljsten‘ interval, Sweden, is a rare phenomenon of a single zircon U-Pb age population preserved in a carbonate rock ( ‘crypto-tephra’ [1]). It is contextualised with biodiversification during the ‘main phase’ of the Great Ordovician Biodiversification Event (GOBE [2]) and...

The timing and duration of ore-forming processes are amongst the key parameters required in the study of mineral systems. After more than a century of technical developments, innovations and investigation, the U–Pb system arguably is the most mature radioisotopic system in our possession to conduct absolute dating of a wide range of minerals across...

Anomalous mercury (Hg) contents recorded near the Permian-Triassic boundary (PTB) are often linked to Siberian Traps Large Igneous Province (STLIP) volcanism and the Permian-Triassic boundary mass extinction (PTBME). However, mounting evidence indicates that the relation between STLIP volcanism and Hg “anomalies” is not straightforward. This study...

The nucleation, growth and demise of carbonate platforms in foreland basins are controlled by intrinsic and extrinsic factors 1) net carbonate production, 2) orogen-fed terrigenous input and 3) changes in accommodation. Variations in subsidence rate ahead of the orogenic front mainly reflect the flexure of the foreland lithosphere due to loading by...

Large volume rhyolitic ignimbrite volcanism is a significant contributor to the evolving crust. The introduction of high-silica material into the upper crust, differentiation within the middle crust, and partial melting in the lower crust contributes to geochemical and isotopic evolution of the crust. Developing accurate models for the genetic evol...

Paleocene–Eocene phosphorite beds from three major outcrops of the Maknassy-Mezzouna basin (Central-Tunisia) were geochemically investigated to improve local stratigraphy, determine their ages, and attempt to constrain ocean circulation. 87Sr/86Sr ratios of phosphate materials from the Chouabine Formation display a large variation even within the s...

Anomalous mercury (Hg) contents recorded near the Permian-Triassic boundary (PTB) are often linked to Siberian Traps Large Igneous Province (STLIP) volcanism and the Permian-Triassic boundary mass extinction (PTBME). However, mounting evidence indicates that the relation between STLIP volcanism and Hg “anomalies” is not straightforward. This study...

Anomalous mercury (Hg) contents recorded near the Permian-Triassic boundary (PTB) are often linked to Siberian Traps Large Igneous Province (STLIP) volcanism and the Permian-Triassic boundary mass extinction (PTBME). However, mounting evidence indicates that the relation between STLIP volcanism and Hg “anomalies” is not straightforward. This study...

Large volumes of mafic igneous rocks are commonly emplaced during Large Igneous Province (LIP) eruptions, and these mafic rocks are often contemporaneous with periods of environmental disturbances, such as global ocean anoxia, and as a result, mass extinctions. The Paraná-Etendeka LIP is no exception, and has been previously correlated with, and in...

n-situ 40Ar/39Ar petrochronology to study the mechanisms of argon diffusion in white mica. Clémentine Antoine1, Richard Alan Spikings1, André Navin Paul1, Urs Schaltegger1 1 Département des Sciences de la Terre et de l’Environnement, Université de Genève, rue des Maraîchers 13, CH-1205 Genève. Staircase topologies in 40Ar/39Ar degassing spectra...

The Variscan orogeny was responsible for the formation of a significant volume of igneous basement throughout present-day Europe. Detailed understanding of these rocks has, however, been obfuscated by significant overprinting during younger geologic events. In order to better understand the formation of this basement, we present U–Pb dates, trace e...

Twelve apatite samples have been tested as secondary ion mass spectrometry (SIMS) reference materials. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analysis shows that the SLAP, NUAN and GR40 apatite gems are internally homogeneous, with most trace element mass fractions having 2 standard deviations (2s) ≤ 2.0%. BR2, BR5,...

The Great Oxidation Episode represents a long-term major shift in atmospheric and water-column redox conditions. Its onset is marked by the loss of mass-independently fractionated sulfur from the marine sedimentary units and its end coincides with the collapse of the positive carbonate excursion known as the Lomagundi-Jatuli Episode. With such time...

The Paleoproterozoic is characterized by major changes in Earth’s surficial environments, which are currently preserved in multiple sedimentary sequences around the world (e.g. occurrence of widespread glaciations, the Great Oxidation Event, milestones in the evolution of life, etc.). Precise absolute time constraints are of paramount importance fo...

The extrusive component of the Karoo Large Igneous Province, the Drakensberg Continental Flood basalts of South Africa and Lesotho, is mainly composed of altered tholeiitic basalts without uraniferous mineral phases that are suitable for high-precision dating (e.g. baddeleyite or zircon), and thus dating is restricted to ⁴⁰Ar/³⁹Ar groundmass and pl...

Amphibole- and clinopyroxene-bearing monzodiorites were emplaced at 340 Ma (CA-ID-TIMS zircon age), suggesting the formation of hydrous and dry magmas closely related in space and time in the NE Bohemian Massif. Hafnium and oxygen isotopes of zircon in less evolved rocks (<55 wt% SiO2) are similar between Amp and Cpx monzodiorites (εHf = −3.3 ± 0.5...

The Great Oxygenation Event (GOE) is a drastic change of the atmosphere's composition occurring at the end of the Archean. This major transition is currently constrained within ~200 Ma depending the basin and is traceable by the disappearance of the mass-independent fractionation of sulfur preserved in sedimentary rocks. Constraining the duration a...

The Kuruman Formation is a well-developed and preserved Paleoproterozoic banded iron formation (BIF) as a part of the thick Transvaal Supergroup, located in the Griqualand West Basin, South Africa. It is among the youngest BIF before the irreversible loss of mass-independent fractionation of sulfur in the Kaapvaal Craton, that defines the Great Oxi...

The Precambrian comprises the vast majority of Earth’s history. Preserved archives contain essential information about the first few billion years for planetary evolution of our planet. Despite covering a large part of the history of our planet, these outcrops are not so abundant due to erosion and frequently occur in disparate areas. In this study...

We present high-precision isotope dilution-thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon data from the Carboniferous Punteglias granodiorite from the Central Alpine basement in the Aar massif in Switzerland. These analyses yield complex age spectra consisting of both concordant and normally discordant dates, which form a linear array i...

The emplacement of Large Igneous Provinces (LIPs) is commonly correlated with global climate change, and environmental and biological crises. To establish this complex causative link, chemical proxies from marine sedimentary sections must be temporally tied to LIP activity through high-precision geochronology. The temporal link is often ambiguous,...

In the Cadomian orogenic belt a package of glacigenic sedimentary deposits have been recently described in the Armorican Massif (Normandy, France). The Granville Tillite Member, the middle part of the upper Granville Formation, is late Ediacaran in age. Maximum depositional ages of the pre- and syn-glacial sedimentary deposits obtained by LA-ICP-MS...

Correlation of geographically disparate sedimentary sections is of fundamental importance to most stratigraphic studies. First order approaches to achieve a correlation is by comparing lithostratigraphy, backed up by a comparison of geochemical features and ultimately verifying the temporal consistency.The precise and accurate U-Pb dating of access...

To improve the temporal correlation between changing environmental settings in the Paleoproterozoic and the Great Oxidation Event (GOE) at ca. ~2.4 Ga, we performed a detrital zircon study on six samples from glacial deposits of the Makganyene Formation, Griqualand West Basin, South Africa. It is hypothesized that these diamictites are the remnants...

The Miocene Climatic Optimum (MCO) represents a global warm period (approximately 17–14.7 Ma) interrupting a long-term period of Cenozoic cooling. In order to elucidate if bauxitization took place in southeastern European mid-latitude areas during the MCO, we studied a section of undated massive karst bauxite (Crveni Klanac, CK) in central Dalmatia...

Age determination of minerals using the U-Pb technique is widely used to quantify time in Earth's history. A number of geochronology laboratories produce the highest precision U-Pb dates employing the EARTHTIME 202Pb-205Pb-233U-235U tracer solution for isotope dilution, and the EARTHTIME ET100 and ET2000 solutions for system calibration and laborat...

We present a refined approach for acquiring sulfur (S) isotope compositions (³³S/³²S, ³⁴S/³²S) in apatite by secondary ion mass spectrometry (SIMS), including the characterisation of new reference materials. In order to test the method, we analyzed potential apatite reference samples for their S isotope ratios via three different bulk methods. The...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

This comment addresses the incorrect treatment and presentation of data from laser ablation ICP-MS U–Pb age determinations of two samples of the Třebíč Pluton. This results in inaccurate ages and error assessment, invalidating the age interpretations of the authors. To corroborate our arguments, new high-precision chemical abrasion ID-TIMS data are...

Zircon occasionally crystallizes in evolved melt pockets in mafic large igneous province (LIP) magmas, and in these cases, it is used to provide high-precision age constraints on LIP events. The precision and accuracy of high-precision ages from LIPs are crucially important, because they may be implicated in mass extinctions. However, why zircon cr...

To better constrain the age and duration of the magmatism associated with the Karoo large igneous province (LIP), we present new U-Pb ID-TIMS dates and εHf values from baddeleyite and zircon grains from Karoo basin mafic sills and from felsic samples from the Lebombo and Mwenezi monoclines, together with an ⁴⁰Ar/³⁹Ar age database of Karoo rocks tha...

Mts. Kalnik and Požeška gora volcaniclastic sequences hold valuable information concerning the Miocene syn-rift evolution of the North Croatian Basin, and the evolution of the Carpathian-Pannonian Region and the Central Paratethys. We present volcanological, high-precision geochronological, and compositional data of volcanic glass to constrain thei...

Precise U–Pb zircon dating using the chemical abrasion – isotope dilution – thermal ionization mass spectrometry (CA-ID-TIMS) method constrains the age of the Central Sudetic Ophiolite (CSO) in the Variscan Belt of Europe. A felsic gabbro from the Ślęża Massif contains zircon xenocrysts dated at 404.8 ± 0.3 Ma and younger crystals dated at 402.6 ±...

The Devonian Frasnian–Famennian (F–F) boundary marks one of the five main extinction intervals of the Phanerozoic Aeon. This time was characterized by two pulses of oceanic anoxia, named the Lower and Upper Kellwasser events, during which massive marine biodiversity losses occurred. This paper presents high-resolution magnetic susceptibility, X-ray...

The Valanginian Stage is marked by a period of global positive δ13C carbon cycle perturbation and biotic crises, which are collectively referred to as the Valanginian event (VE). Many attempts have been made to link the Paraná-Etendeka large igneous province volcanism with the VE. However, currently there is no conclusive proof to support this hypo...

The dynamics of the carbon cycle across different timescales is crucial for understanding past and present global climate changes. Following the Permian–Triassic boundary mass extinction (PTBME), the carbon cycle changed profoundly during the following 5.4 Myr, with magnitudes of changes comparable to those of the Precambrian. In pace with the succ...

The Early Jurassic (late Pliensbachian to early Toarcian) was a period marked by extinctions, climate fluctuations, and oceanic anoxia. Although the causes of the early Toarcian Oceanic Anoxia Event (OAE) have been fairly well studied, the events that lead to the Toarcian OAE, i.e. the events in the late Pliensbachian, have not been well constraine...

Astronomical forcing associated with Earth’s orbital and inclination parameters (Milankovitch forcing) exerts a major control on climate as recorded in the sedimentary rock record, but its influence in deep time is largely unknown. Banded iron formations, iron-rich marine sediments older than 1.8 billion years, offer unique insight into the early E...

The Variscan granites from the Western Erzgebirge were repeatedly dated by various methods, but no consensus has been reached about their exact intrusion ages. This study presents a multi-dating approach for the four largest intrusions from the Western Erzgebirge (Aue-Schwarzenberg, Bergen, Eibenstock, Kirchberg). We analysed several samples from e...

The role of accessory minerals in the incongruent release of Hf and Pb during continental weathering and its implications for the generation of distinct seawater isotope compositions is subject of debate. While it has been suggested that radiogenic Hf and Pb isotope signatures released during the dissolution of rocks are controlled by the relative...

The Adamello intrusive suite is a composite batholith in Northern Italy, with an estimated 2000 km 3 volume, assembled incrementally over a time span of 10 to 12 million years. The history of crystallization has been studied in detail through laser ablation ICP-MS and SIMS U-Pb geochronology of zircon, which records prolonged crystallization of eac...

The present sub-permil precision of single zircon chemical abrasion, isotope-dilution, thermal ionisation mass spectrometry (CA-ID-TIMS) UePb dates often reveals age dispersions that are outside of analytical uncertainty. Interpreting these complex age distributions requires the ability to distinguish between protracted crystallization of zircon ov...

The numerical age of the Jurassic–Cretaceous boundary has been controversial and difficult to determine. In this study, we present high-precision U–Pb geochronological data around the Jurassic–Cretaceous boundary in two distinct sections from different sedimentary basins: the Las Loicas, Neuquén Basin, Argentina, and the Mazatepec, Sierra Madre Ori...

Appendix S2. Measurement results from EPMA (n = 84 for each of the two zircon samples) at Universität Göttingen, Germany.

Appendix S3. Documentation of locations of EPMA (Universität Göttingen, Germany) linescans, and plots and histograms of mass fractions of HfO2, ThO2 and UO2.

Appendix S1. Details for ID‐TIMS analytical procedures in the laboratories.

Appendix S4. Measurement results from SHRIMP analyses (Curtin University, Perth, Australia) including additional Concordia plots and Th/U histograms.

This book chapter has been accepted for publication in: Huston, D. et al. Eds., Isotopes in economic geology, metallogenesis and exploration. SGA special volume. The knowledge of the timing and duration of ore-forming processes are perhaps one of the most desirable pieces of information that geologists require to draw a complete picture of the dep...

Magmatic arcs associated with subduction zones are the dominant active locus of continental crust formation, and evolve in space and time towards magmatic compositions comparable to that of continental crust. Accordingly, the secular evolution of magmatic arcs is crucial to the understanding of crust formation processes. In this paper we present th...

Here we document a detailed characterization of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U–Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean ²⁰⁶Pb/²³⁸U ages (95% confid...

Zircon is being found rather commonly in mafic rocks from large igneous provinces (LIP) despite their high crystalization temperatures and low zirconium contents, which apparently contradicts zircon saturation conditions. However, zircon in these rocks occur as tiny crystals in pockets of highly evolved melt that crystalize at much lower temperatur...

The age of the Jurassic/Cretaceous boundary has remained elusive for the past decades. In this study we evaluate how well the determined boundary age agrees between two distinct sections from different sedimentary basins, and whether we can constrain a globally valid Jurassic/Cretaceous boundary age. Here we present high-precision U-Pb zircon age d...