J. W. Valley

• PhD
• Professor at University of Wisconsin–Madison

The Willsboro-Lewis wollastonite district occurs along the margin of the 1.15 Ga Marcy anorthosite massif in the Adirondack Highlands (New York), and records mineralogical and isotopic evidence for formation in the anorthosite’s low-pressure metamorphic contact aureole. Wollastonite – garnet – pyroxene gneisses in the ~25 km long, 1.5 km thick skar...

Montana hosts the largest sapphire deposits in the US, but the genesis of and connection among the various secondary and primary sapphire occurrences remains cryptic. In situ SIMS measurements of oxygen isotopes in sapphires and zircon inclusions in sapphires provide an opportunity to study the isotope and trace element geochemistry in order to und...

Detrital zircons from the Jack Hills are the dominant source of Hadean (pre-4000 Ma) terrestrial material available for study today. Values of δ¹⁸O in many of these zircons (6.0 to 7.5‰) are above the mantle-equilibrated value. For two decades, these mildly elevated values have been the primary evidence that protoliths of the zircon-forming magmas...

Determining the mechanisms by which the earliest continental crust was generated and reworked is important for constraining the evolution of Earth’s geodynamic, surface, and atmospheric conditions. However, the details of early plate tectonic settings often remain obscured by the intervening ~4 Ga of crustal recycling. Covariations of U, Nb, Sc, an...

Explosive silicic eruptions pose a significant threat to society, yet the development and destabilization of the underlying silicic magmatic systems are still controversial. Zircons provide simultaneous information on the trace element composition and age of silicic magmatic systems, while melt inclusions in quartz and plagioclase yield important c...

Methane has been widely regarded as an important source of greenhouse gas that modulated Earth’s paleoclimate. Notably, it has been proposed that a massive release of methane via clathrate destabilization may have played a critical role during and/or in the immediate aftermath of the Marinoan deglaciation. One key piece of supporting evidence for t...

Rationale The use of secondary ion mass spectrometry (SIMS) to perform micrometer‐scale in situ carbon isotope (δ ¹³ C) analyses of shells of marine microfossils called planktic foraminifers holds promise to explore calcification and ecological processes. The potential of this technique, however, cannot be realized without comparison to traditional...

The ability to precisely constrain the physical-chemical conditions of serpentinization, such as temperature and fluid source, is limited by the accuracy of calibrations for oxygen isotope fractionation between serpentine and water – i.e., 1000 lnα(serpentine-water) – which disagree by up to 20 ‰ when extrapolated to T < 200 °C. In this study, we p...

Simultaneous analysis of carbon and nitrogen isotope ratios by SIMS was applied for the first‐time to a natural diamond from the Kelsey Lake kimberlite, State Line Distinct, Colorado (UWD‐1). This in situ procedure is faster, reduces sample size for analysis, and measures both isotope ratios from a single ~ 10 μm diameter pit, a critical advantage...

Upper Jurassic Fulmar Formation sandstones from the Fulmar Field in the Central North Sea are buried to 3.2 km and 128 °C but contain only 3.7 ± 1.7% (1σ) quartz cement, substantially less than volumes predicted by models based on temperature-related quartz precipitation kinetics. Oxygen isotope microanalysis of quartz overgrowths suggests that onl...

The Ediacaran Shuram excursion (SE) records a global decrease in carbonate carbon isotope (δ¹³Ccarb) values from +6‰ down to ca. –10‰, representing the largest δ¹³Ccarb negative anomaly in Earth history. While the SE is widely recorded in the upper Doushantuo Formation of South China, it shows highly variable δ¹³Ccarb profiles among correlative sec...

Infiltration-driven metamorphism has produced the widespread development of forsterite in the siliceous dolomites of the Alta, Utah contact aureole. SIMS (secondary ion mass spectrometry) δ¹⁸O analyses show that in most of the middle to outer forsterite zone samples, forsterite, calcite and dolomite are homogenous in δ¹⁸O at the grain-scale, but fo...

Knowledge of oxygen diffusion in garnet is crucial for a correct interpretation of oxygen isotope signatures in natural samples. A series of experiments was undertaken to determine the diffusivity of oxygen in garnet, which remains poorly constrained. The first suite included high-pressure (HP), nominally dry experiments performed in piston-cylinde...

The instrumental bias (here expressed as bias*, the difference relative to San Carlos Olivine, SC-Ol) of oxygen isotopes in secondary ion mass spectrometry (SIMS) analyses of olivine and pyroxene were investigated. Seventeen olivine (Fo0–100), nine orthopyroxene (En70–100Wo0–3), and three clinopyroxene (En28-49Wo45–50) reference materials (RMs) wer...

Significance There is a common consensus that lode gold deposits mostly precipitated from metamorphic fluids via fluid boiling and/or fluid–rock interaction, but whether magmatic hydrothermal fluids and the mixing of such fluids with an external component have played a vital role in the formation of lode gold deposits remains elusive. We use garnet...

The nature of Earth's earliest crust and crustal processes remain unresolved questions in Precambrian geology. While some hypotheses suggest that plate tectonics began in the Hadean, others suggest that the Hadean was characterized by long‐lived protocrust and an absence of significant plate tectonic processes. Recently proposed trace‐element proxi...

Significance The permanent disappearance of mass-independent sulfur isotope fractionation (S-MIF) from the sedimentary record has become a widely accepted proxy for atmospheric oxygenation. This framework, however, neglects inheritance from oxidative weathering of pre-existing S-MIF–bearing sedimentary sulfide minerals (i.e., crustal memory), which...

We addressed fundamental questions about the lithology, age, structure, and thermal evolution of the deep crust of the retroarc hinterland of the North American Cordilleran orogen through systematic investigation of zircons from Cretaceous plutons in the Snake Range and Kern Mountains of east-central Nevada. Geochronological (U-Pb) and geochemical...

Biominerals that accrete shell or skeleton are commonly used as windows to past geochemical environments. Using biominerals as paleoproxies depends on the assumption that biominerals faithfully and predictably record environmental parameters, yet little has been done from a mineralogical perspective to understand how various environmental shifts im...

Tellurium-rich (Te) adularia-sericite epithermal Au-Ag deposits are an important current and future source of precious and critical metals. However, the source and evolution of ore-forming fluids in these deposits are masked by traditional bulk analysis of quartz oxygen isotope ratios that homogenize fine-scale textures and growth zones. To advance...

The study of serpentinites and ophicarbonates from ophiolitic terrains provides a three-dimensional perspective on the hydration and carbonation processes affecting modern oceanic lithosphere. The Chenaillet ophiolite (western Alps) is interpreted as a fragment of an oceanic core complex that resembles a modern slow spreading center, and it was wea...

The southern Coast Mountain batholith was episodically active from Jurassic to Eocene time and experienced four distinct high magmatic flux events during that period. Similar episodicity has been recognized in arcs worldwide, yet the mechanism(s) driving such punctuated magmatic behavior are debated. This study uses zircon Hf and O isotopes, with w...

We present >500 zircon δ18O and Lu-Hf isotope analyses on previously dated zircons to explore the interplay between spatial and temporal magmatic signals in Zealandia Cordillera. Our data cover ~8500 km2 of middle and lower crust in the Median Batholith (Fiordland segment of Zealandia Cordillera) where Mesozoic arc magmatism along the paleo-Pacific...

The Ediacaran Period (ca. 635-539 Ma) witnessed the earliest paleontological evidence for macroscopic life (i.e., Ediacara biota) and geochemical observations of the largest carbon cycle J o u r n a l P r e-p r o o f Journal Pre-proof anomaly in Earth history (i.e., Shuram Excursion, SE). Numerous hypotheses have been proposed for the origins of th...

This study addresses the question of how and where arc magmas obtain their chemical and isotopic characteristics. The Wooley Creek batholith and Slinkard pluton are a tilted, mid-to upper-crustal part of a vertically extensive, late-Jurassic, arc-related magmatic system in the Klamath Mountains, northern California. The main stage of the system is...

This study addresses the question of how and where arc magmas obtain their chemical and isotopic characteristics. The Wooley Creek batholith and Slinkard pluton are a tilted, mid- to upper-crustal part of a vertically extensive, late-Jurassic, arc-related magmatic system in the Klamath Mountains, northern California. The main stage of the system is...

The largest carbon isotope (δ13C) negative anomaly recorded in marine carbonates in Earth history — the Ediacaran Shuram Excursion (SE) — preserves values down to ca. –10‰ on a global scale. Despite the intensive geochemical and theoretical work published in the past decade, its origin and the degree to which its geochemical signature has been diag...

Zircon U-Pb dating is a powerful and widely used geochronologic technique to constrain the timing and rates of magmatic and high and lower-grade metamorphic processes, as well as sediment provenance. Zircon trace element (TE) compositions also record magmatic and metamorphic processes during zircon growth. In this study, zircon laser ablation split...

Detrital chromites are commonly reported within Archean metasedimentary rocks, but have thus far garnered little attention for use in provenance studies. Systematic variations of Cr-Fe spinel mineral chemistry with changing tectonic setting has resulted in the extensive use of chromite as a petrogenetic indicator, and so detrital chromites represen...

The 119 Ma Dinkey Dome pluton in the central Sierra Nevada Batholith is a peraluminous granite and contains magmatic garnet and zircon that are complexly zoned with respect to oxygen isotope ratios. Intracrystalline SIMS analysis tests the relative importance of magmatic differentiation processes vs. partial melting of metasedimentary rocks. Wherea...

U–Pb ages, trace element content and oxygen isotope ratios of single zircons from five plagiogranite intrusions of the Troodos ophiolite were measured to determine their crystallization age and assess the importance of fractional crystallization versus crustal anatexis in their petrogenesis. The results indicate that oceanic magmatism in Troodos to...

The Colorado Plateau has undergone as much as 1.8 km of uplift over the past 80 Ma, but never underwent the pervasive deformation common in the neighboring tectonic provinces of the western USA. To understand the source, timing and distribution of mantle hydration, and its role in plateau uplift, garnets from four eclogite xenoliths of the Moses Ro...

Three tourmaline reference materials sourced from the Harvard Mineralogical and Geological Museum (schorl 112566, dravite 108796 and elbaite 98144), which are already widely used for the calibration of in situ boron isotope measurements, are characterised here for their oxygen and lithium isotope compositions. Homogeneity tests by secondary ion mas...

The ability to constrain the petrogenesis of multiple serpentine generations recorded at the microscale is crucial for estimating the extent and conditions of modern versus fossil serpentinisation in ophiolites. To address matrix bias effects during oxygen isotope analysis by SIMS, we present the first investigation analysing antigorite in the comp...

High Spatial-resolution Assessment of Diagenesis and Primary Isotopic Variability in Maastrichtian Molluscan Carbonates from Antarctica - Benjamin Linzmeier, Thomas Tobin, Peter Ward, Ian Orland, Daniella Assing, Kouki Kitajima, Phillip Gopon, Brian Huber, Shanan Peters, John Valley

Application of SIMS and APT to Understand Scale Dependent U-Pb Isotope Behavior in Zircon - Tyler Blum, John Valley, Baptiste Gault, Leigh Stephenson

Earth's hydrological cycle was profoundly perturbed by massive carbon emissions during an ancient (56 Ma) global warming event referred to as the Paleocene‐Eocene thermal maximum (PETM). One approach to gaining valuable insight into the response of the hydrological cycle is to construct sea‐surface salinity (SSS) records that can be used to gauge c...

Ediacaran-aged (635–541 million years ago) marine sediments contain a large negative carbon isotope (δ13C) excursion, in which carbonate δ13C values reach −12‰ (VPDB). Known as the ‘Shuram’ excursion, many workers have interpreted this δ13C record as an unprecedented perturbation to the global carbon cycle, leading to speculation about a causal con...

Recent work suggests that the C- and O-isotope composition of laminated soil carbonate rinds can provide high-resolution (100s yr/sample) information about hydrologic processes and vegetation over tens of thousands of years. However, while this archive can potentially provide quantitative reconstructions, most interpretations have thus far been qua...

Carbonate carbon isotope (δ¹³Ccarb) chemostratigraphy is a valuable tool in Precambrian stratigraphic correlation. The effectiveness of this tool rests on the assumption that δ¹³Ccarb data record global seawater signals. However, in some cases δ¹³Ccarb data may exhibit rapid and noisy stratigraphic variations that appear to have been influenced by...

We present quantitative petrographic data, high spatial resolution oxygen isotope analyses of quartz cement, basin modelling and a kinetic model for quartz precipitation for two Paleocene-Eocene Wilcox Group sandstones from Texas and two Jurassic Fulmar Formation sandstones from the Central North Sea. At each location, one sandstone has been buried...

Oxygen isotope analyses of diagenetic cements can provide detailed evidence of sedimentary burial processes and conditions, as the δ18O values of precipitating minerals reflect contemporaneous local δ18Owater and temperature conditions. Uncertainties in the timing and rates of pore water δ18O evolution in sedimentary basins can complicate interpret...

The Reef Deposit is an anomalous AuCu occurrence in the Paleoproterozoic terranes of northern Wisconsin, better known as host to significant CuZn volcanogenic massive sulfide (VMS) deposits. Previous work using lead isotopes and fluid inclusions has identified a protracted development of the mineralization from initial formation as the root zone ve...

The Paleocene-Eocene thermal maximum (PETM) was an extraordinary pulse of global warming that left an indelible mark on the Earth approximately 56 Ma ago. This warming event is associated with an addition of large amounts of 13 C-depleted carbon into the atmosphere-ocean system, but the magnitude of the negative carbon isotope excursion (CIE) signa...

Carbonate carbon isotopes have been used widely to study Precambrian paleoclimate, paleoceanography, and chemostratigraphic correlation. This is particularly true in the study of Precambrian climatic change, oceanic and atmospheric redox conditions, and stratigraphic correlation, because few Precambrian fossils provide diagnostic information about...

Corundum (Crn), including sapphire, occurs in emery pods surrounded by marble on the island of Naxos, Greece. The emery formed from bauxite deposited in karst that was metamorphosed to 400 to 700 °C at 20‐15 Ma. Many of these rocks initially appeared well suited for refractory accessory mineral (RAM) thermometry, which uses oxygen isotope fractiona...

Diagenetic minerals preserve records of burial processes that overprint records of seawater chemistry and impact reservoir porosity. The Mississippian-Devonian aged Bakken Formation in the Williston Basin is a reservoir rock of economic importance whose productivity is affected by diagenetic carbonates, particularly dolomite-ankerite-series carbona...

The globally-recorded Ediacaran Shuram Excursion (SE) represents the largest carbonate carbon isotope (δ13Ccarb) negative anomaly in Earth’s history. Typically, the SE is characterized by δ13Ccarb values that plunge to a nadir of ca. −10‰ over a short stratigraphic interval and then rise steadily in the overlying tens or hundreds of meters before r...

The Marinoan glaciation (a.k.a. the Snowball Earth) represents a profound paleoclimatic anomaly in deep time. However, the detailed mechanism of its termination remains largely unknown. It was hypothesized that massive releases of methane via clathrate destabilization at ~635 Ma may have played a role in terminating the glaciation. A key piece of s...

A Nanoscale Record of Impact-Induced Pb Mobility in Lunar Zircon - Volume 25 Supplement - Tyler B. Blum, David A. Reinhard, Matthew A. Coble, Michael J. Spicuzza, Yimeng Chen, Aaron J. Cavosie, Lutz Nasdala, Chutimun Chanmuang N., Ty J. Prosa, David J. Larson, John W. Valley

Skarn garnets in the Mineral King roof pendant of the south–central Sierra Nevada within Sequoia National Park, California, USA reveal variable fluid chemistry with a significant component of meteoric water during metasomatism in the Early Cretaceous Sierra Nevada Batholith. We focus on andradite garnet associated with Pb–Zn mineralization in the W...

Oxygen isotopes were analyzed in human teeth dating to approximately 1250 BC from a Bronze Age battlefield along the Tollense River in northwestern Germany. Tooth enamel was sectioned, prepared, and analyzed using Secondary Ion Mass Spectrometry (SIMS) and Confocal Laser Fluorescence Microscopy (CLFM). The results of the study indicate that diagene...

Volume 16 of Reviews in Mineralogy inroduces to high-temperature stable isotope geochemistry and should provide an entry into the pertinent literature, as well as some understanding of the basic concepts and potential applications. The first three chapters focus on the theory and experimental data base for equilibrium, disequilibrium, and kinetics...

Volume 43 of Reviews in Mineralogy and Geochemistry follows the 1986 Reviews in Mineralogy (Vol. 16) in approach but reflects significant changes in the field of Stable Isotope Geochemistry. In terms of new technology, new sub-disciplines, and numbers of researchers, the field has changed more in the past decade than in any other since that of its...

ABSTRACT A basic outline is established here for the dolomitization history of the mixed carbonate-clastic facies that comprise the middle Bakken tight-oil reservoir of the Williston Basin (Late Devonian – Early Mississippian). A mineralogical dataset compiled from sources in the public domain reveals a strong correspondence between the clay and do...