Volcanic Initiation of the Eocene Heart Mountain Slide, Wyoming, USA

The Eocene Heart Mountain slide of northwest Wyoming covers an area of as much as 5000 km2 and includes allochthonous Paleozoic carbonate and Eocene volcanic rocks with a run-out distance of as much as 85 km. Recent geochronologic data indicated that the emplacement of the slide event occurred at ∼48.9 Ma, using laser ablation inductively coupled plasmamass spectrometry (LA-ICPMS) extracted fromU-Pb zircon ages frombasal layer and injectite carbonate ultracataclasite (CUC). We now refine that age with U-Pb results from a lamprophyre diatreme that is temporally and spatially related to the CUC injectites. The ages for the lamprophyre zircons are 48.97 ± 0.36 Ma (LA-ICPMS) and 49.19 ± 0.02 Ma (chemical abrasion isotope dilution thermal ionization mass spectrometry). Thus, the lamprophyre and CUC zircons are identical in age, and we interpret that the zircons in the CUC were derived from the lamprophyre during slide emplacement. Moreover, the intrusion of the lamprophyre diatreme provided the trigger mechanism for the Heart Mountain slide. Additional structural data are presented for a variety of calcite twinning strains, results from anisotropy of magnetic susceptibility for the lamprophyre and CUC injectites and alternating-field demagnetization on the lamprophyre, to help constrain slide dynamics. These data indicate that White Mountain experienced a rotation about a vertical axis and minimum of 35° of counterclockwise motion during emplacement

Imposing a unilateral carbon constraint on European energy-intensive industries and its impact on their international competitiveness - data & analysis

This paper investigates the implications of EU climate change policy for energy intensive industries. Specifically, it calculates, for a range of energy-intensive processes and products, the product price increases that would be required to maintain unit profits at present levels, based on likely values of allowance prices in the European Union Emissions Trading Scheme up to 2020. For most of the energy- and carbon-intensive products considered here, an allowance price of €20 per tonne of carbon dioxide would require price increases of between 0.1 to 5% to maintain profits, assuming full pass-through of the allowance price along the value chain. Doubling the allowance price to €40/tonne would double the required increase. The activities that risk being most challenged by the carbon constraint appear to be container glass production using virgin inputs, primary aluminium production, primary steel production based on the basic oxygen furnace process, and some basic chemicals production. However, the analysis has also shown that for many of these cases alternative production processes exist, based on recycled inputs, for example. The cement sector, although very energy- and carbon-intensive, is relatively little exposed to international competition. Indeed, the paper also investigates in how far it would be possible for the affected activities to pass through cost increases to their clients, by analysing their exposure to domestic and international competition. It concludes that the sectors analysed are typically relatively highly concentrated (sometimes even at the world level) and form parts of vertically integrated and locally-clustered value chains. This tends to increase market entry and exit barriers and, thus, to reduce the risk of large output losses and delocalisation.climate change, competitiveness, energy-intensive industries, emissions trading

Imposing a unilateral carbon constraint on European energy-intensive industries and its impact on their international competitiveness - data & analysis

We examine the implications of EU climate policy for energy intensive industries by calculating, for a range of energy-intensive processes and products, the product price increases that would be required to maintain unit profits at present levels, based on likely values of allowance prices in the European Union Emissions Trading Scheme up to 2020. We also investigate in how far it would be possible for the affected activities to pass through cost increases to their clients, by analysing their exposure to domestic and international competition. It concludes that the sectors analysed are typically relatively highly concentrated (sometimes even at the world level) and form parts of vertically integrated and locally-clustered value chains. This tends to increase market entry and exit barriers and, thus, to reduce the risk of large output losses and delocalisation.climate change, competitiveness, energy-intensive industries, emissions trading, bergmann, schmitz, hayden, gerday, kosonen

Final Inversion of the Midcontinent Rift During the Rigolet Phase of the Grenvillian Orogeny

Despite being a prominent continental-scale feature, the late Mesoproterozoic North American Midcontinent Rift did not result in the break-up of Laurentia, and subsequently underwent structural inversion. The timing of inversion is critical for constraining far-field effects of orogenesis and processes associated with the rift\u27s failure. The Keweenaw fault in northern Michigan (USA) is a major thrust structure associated with rift inversion; it places ca. 1093 Ma rift volcanic rocks atop the post-rift Jacobsville Formation, which is folded in its footwall. Previous detrital zircon (DZ) U-Pb geochronology conducted by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) assigned a ca. 950 Ma maximum age to the Jacobsville Formation and led researchers to interpret its deposition and deformation as postdating the ca. 1090–980 Ma Grenvillian Orogeny. In this study, we reproduced similar DZ dates using LA-ICP-MS and then dated 19 of the youngest DZ grains using high-precision chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS). The youngest DZ dated by CA-ID-TIMS at 992.51 ± 0.64 Ma (2σ) redefines the maximum depositional age of the Jacobsville Formation and overlaps with a U-Pb LA-ICP-MS date of 985.5 ± 35.8 Ma (2σ) for late-kinematic calcite veins within the brecciated Keweenaw fault zone. Collectively, these data are interpreted to constrain deposition of the Jacobsville Formation and final rift inversion to have occurred during the 1010–980 Ma Rigolet Phase of the Grenvillian Orogeny, following an earlier phase of Ottawan inversion. Far-field deformation propagated \u3e500 km into the continental interior during the Ottawan and Rigolet phases of the Grenvillian Orogeny

A Structural Comparison of Ordered and Non-Ordered Ion Doped Silicate Bioactive Glasses

One of the key benefits of sol-gel-derived glasses is the presence of a mesoporous structure and the resulting increase in surface area. This enhancement in textural properties has a significant e ect on the physicochemical properties of the materials. In this context the aim of this study was to investigate how sol-gel synthesis parameters can influence the textural and structural properties of mesoporous silicate glasses. We report the synthesis and characterization of metal ion doped sol-gel derived glasses with di erent dopants in the presence or absence of a surfactant (Pluronic P123) used as structure-directing templating agent. Characterization was done by several methods. Using a structure directing agent led to larger surface areas and highly ordered mesoporous structures. The chemical structure of the non-ordered glasses was modified to a larger extent than the one of the ordered glasses due to increased incorporation of dopant ions into the glass network. The results will help to further understand how the properties of sol-gel glasses can be controlled by incorporation of metal dopants, in conjunction with control over the textural properties, and will be important to optimize the properties of sol-gel glasses for specific applications, e.g., drug delivery, bone regeneration, wound healing, and antibacterial materials.European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 643050, project “HyMedPoly

Zircon Chemistry in a Gabbro Pluton at House Mountain, Idaho

An Eocene (ca 45 million year old) gabbro pluton near House Mountain in southwest Idaho provides an opportunity to explore how the conditions of crystallization are recorded in zircon chemistry. Zircon is a zirconium silicate mineral present in trace amounts in magmas, which is capable of incorporating large, highly charged elements (e.g. transition metals, actinides, lanthanides) that do not easily substitute into other minerals. Variations in these elements can be used to track magma evolution. For example, the titanium concentration is related to the temperature at which zircon crystallizes from the magma; rare earth elements (REE) and the relative proportion of europium (Eu-anomaly) can be used to track the degree of crystallization of the magma. Trace elements (TE) were measured in situ on 25 micron spots in zoned zircon crystals using laser ablation inductively coupled plasma mass spectrometry. Two samples from the pluton, an equigranular gabbro and a felsic granophyre, were analyzed. The zircons from the gabbro record cooling temperatures, and evolution from a primitive, mafic magma to one enriched in TE with a stronger Eu-anomaly. Residual felsic melt segregated from crystallized minerals and concentrated in the granophyre records evolved compositions in the final stage of crystallization

Reconstructing the Geologic History of the House Mountain Metamorphic Complex (Southern Idaho) Through Zircon Age and Geochemical Analysis

Zircons from quartzo-feldspathic gneiss within the Precambrian (\u3e725 Ma) siliciclastics of the House Mountain Metamorphic Complex of southwestern Idaho were studied to determine its origin and evolution. Cathodoluminescence imaging of internal zoning due to growth and recrystallization of zircon, along with laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) analysis of these zircons, reveal a complex history of metamorphism at House Mountain. Primary igneous crystallization in the orthogneiss occurred near 130 Ma. Convoluted regions of the zircons have ages ranging from 130 to 85 Ma. These younger ages are hypothesized to be related to lead loss and new crystal growth during and after a series of metamorphic recrystallization and melt infiltration events. Uranium and rare earth element (REE) concentrations illustrate a trend of removal of incompatible trace elements from the zircon lattice during recrystallization. Changes in REE concentrations and pattern suggest late zircon growth in the presence of garnet. Further work is being done on garnets from the study rock to verify partitioning of heavy rare earth elements (HREE) between zircon and garnets. The igneous and metamorphic history extracted from this gneiss is supported by independent metamorphic zircon and titanite ages from adjacent siliciclastics rocks and amphibolite sills

Apatite Reference Materials for SIMS Microanalysis of Isotopes and Trace Elements

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, OL2, AFG2 and AFB1, which have U \u3e 63 μg g-1, 206Pb/204Pb \u3e 283, and homogeneous SIMS U-Pb data, have respective isotope dilution thermal ionisation mass spectrometry (ID-TIMS) ages of 2053.83 ± 0.21 Ma, 2040.34 ± 0.09 Ma, 868.87 ± 0.25 Ma, 478.71 ± 0.22 Ma and 473.25 ± 0.09 Ma. Minor U-Pb heterogeneity exists and accurate SIMS results require correction with the 3D Concordia-constrained common Pb composition. Among the studied samples, AFG2 and BR5 are the most homogeneous U-Pb reference materials. The SIMS sulfur isotopic compositions of eight of the apatites shows they are homogeneous, with 2s for both 103δ34S and 103δ33S \u3c 0.55‰. One apatite, BR96, has Δ33S = -0.36 ± 0.2‰. The apatite samples have ID-TIMS 87Sr/86Sr between 0.704214 ± 0.000030 and 0.723134 ± 0.000035

Constructing a Time Scale of Biotic Recovery Across the Cretaceous–Paleogene Boundary, Corral Bluffs, Denver Basin, Colorado, U.S.A.

The Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin in east-central Colorado preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. Poor exposure in much of the Denver Basin, however, makes it difficult to correlate between outcrops. To constrain fossil localities in coeval strata across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here, we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analyses identifying the K–Pg boundary in three sections and two independent, but nearly identical, 206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analyses have identified clear polarity reversal boundaries from chron C30n to chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery

The Temporal Evolution of Subduction Initiation in the Samail Ophiolite: High-Precision U–Pb Zircon Petrochronology of the Metamorphic Sole

High-precision dating of the metamorphic sole of ophiolites can provide insight into the tectonic evolution of ophiolites and subduction zone processes. To understand subduction initiation beneath a young, well-preserved and well-characterized ophiolite, we performed coupled zircon laser-ablation inductively coupled mass spectrometry trace element analyses and high-precision isotope dilution-thermal ionization mass spectrometry U–Pb dating on 25 samples from the metamorphic sole of the Samail ophiolite (Oman-United Arab Emirates). Zircon grains from amphibolite- to granulite-facies (0.8–1.3 GPa, ~700–900°C), garnet- and clinopyroxene-bearing amphibolite samples (n = 18) show systematic trends of decreasing heavy rare earth element slope (HREE; Yb/Dy) with decreasing Yb concentration, reflecting progressive depletion of the HREE during prograde garnet growth. For half of the garnet-clinopyroxene amphibolite samples, Ti-in-zircon temperatures increase, and U–Pb dates young with decreasing HREE slope, consistent with coupled zircon and garnet growth during prograde metamorphism. In the remaining samples, there is no apparent variation in Ti-in-zircon temperature with decreasing HREE slope, and the combined U–Pb and geochemical data suggest zircon crystallization along either the prograde to peak or prograde to initial retrograde portions of the metamorphic P–T–t path. The new data bracket the timing of prograde garnet and zircon growth in the highest grade rocks of the metamorphic sole between 96.698 ± 0.094 and 95.161 ± 0.064 Ma, in contrast with previously published geochronology suggesting prograde metamorphism at ~104 Ma. Garnet-free amphibolites and leucocratic pods from lower grade (but still upper amphibolite facies) portions of the sole are uniformly HREE enriched (Yb/Dy \u3e 5) and are ~0.5–1.3 Myr younger than the higher grade rocks from the same localities, constraining the temporal offset between the metamorphism and juxtaposition of the higher and lower grade units. Positive zircon εHf (+6.5 to +14.6) for all but one of the dated amphibolites are consistent with an oceanic basalt protolith for the sole. Our new data indicate that prograde sole metamorphism (96.7–95.2 Ma) immediately predated and overlapped growth of the overlying ophiolite crust (96.1–95.2 Ma). The ~600 ky offset between the onset of sole metamorphism in the northern portion of the ophiolite versus the start of ophiolite magmatism is an order of magnitude shorter than previously proposed (~8 Ma) and is consistent with either spontaneous subduction initiation or an abbreviated period of initial thrusting during induced subduction initiation. Taken together, the sole and ophiolite crust preserve a record of the first ~1.5 Myr of subduction. A gradient in the initiation of high-grade metamorphism from the northwest (96.7 Ma) to southeast (96.0–95.7 Ma) may record propagation of the nascent subduction zone and/or variations in subduction rate along the length of the ophiolite