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U--Pb ages have been measured on secondary dolomite and silica cements in Cambrian sandstone at the base of an 840 mthick sub-horizontally bedded sedimentary sequence beneath the Bruce nuclear site in southern Ontario to document the history of fluid movement. Results show an average U--Pb age of 320 [+ or -] 10 Ma. The initial common Pb end member is slightly, but distinctly, enriched in [.sup.206]Pb compared with that in older and younger calcite cements elsewhere within the sedimentary section. Combined with previous hydro-geochemical and fluid inclusion studies of the same rocks, the age is interpreted to record episodic migration of a saturated hydrothermal brine. Previously dated calcite cement in sub-horizontal fractures about 500 m higher in the stratigraphic section near the base of the Silurian sequence records similar U--Pb ages of 318 [+ or -] 10 Ma by laser ablation inductively coupled plasma mass spectrometry and 313 [+ or -] 1 Ma by isotope dilution thermal ionization mass spectrometry. We suggest that the subhorizontal fractures were generated by slumping that resulted from dissolution of underlying evaporite deposits. These ages overlap with the peak of plutonism in the Alleghanian mountains, which were being uplifted contemporaneously 500 km to the southeast. The results suggest the transport of hydrothermal brine from areas of crustal melting through the deep Cambrian sandstone aquifer, while at higher crustal levels meteoric water was also driven over equally large distances by hydraulic gradients from the Alleghanian mountains. Key words: U--Pb dating, hydrochronology, dolomitization, hydrothermal fluids, deep geological repository, Alleghanian, southern Ontario carbonate platform. Des ages U--Pb ont ete mesures sur des ciments de dolomite secondaire et de silice dans du gres cambrien a la base d'une sequence sedimentaire litee subhorizontale de 840 m d'epaisseur sous le site nucleaire de Bruce, dans le sud de l'Ontario, afin d'en documenter l'histoire d'ecoulement des fluides. Les resultats montrent un age U--Pb moyen de 320 [+ or -] 10 Ma. Le pole du Pb elementaire initial est legerement, mais clairement enrichi en [.sup.206]Pb par rapport a ceux de ciments de calcite plus anciens et plus jeunes ailleurs dans le profil sedimentaire. Combine aux resultats d'etudes hydrogeochimiques et d'inclusions fluides anterieures des memes roches, cet age est interprete comme refletant la migration episodique d'une saumure hydrothermale saturee. Du ciment de calcite deja date provenant de fractures subhorizontales quelque 500 m plus haut dans la coupe stratigraphique, pres de la base de la sequence silurienne, a produit des ages U--Pb semblables de 318 [+ or -] 10 Ma par spectrometrie de masse a plasma inductif avec ablation au laser et de 313 [+ or -] 1 Ma par spectrometrie de masse a thermoionisation avec dilution isotopique. Nous proposons que les fractures subhorizontales ont ete produites par le glissement qui a resulte de la dissolution de depots d'evaporites sous-jacents. Ces ages chevauchent la pointe du plutonisme dans les montagnes Alleghaniennes, qui etaient simultanement soulevees 500 km plus au sud-est. Les resultats suggerent un transport de saumure hydrothermale de zones de fusion crustale a travers l'aquifere de gres cambrien profond alors que, a moins grandes profondeurs dans la croute, de l'eau meteorique se deplacait aussi sur des distances aussi grandes sous l'effet de gradients hydrauliques associes aux montagnes Alleghaniennes. [Traduit par la Redaction] Mots-cles : datation U--Pb, hydrochronologie, dolomitisation, fluides hydrothermaux, depot geologique en profondeur, Alleghanien, plateforme carbonatee du sud de l'Ontario., Introduction Ages of secondary carbonate minerals in veins and vugs record the past movement of fluids, which can respond to subtle or distant tectonic processes that may have affected otherwise [...]

A record of fluid flow has been documented within a Paleozoic carbonate platform sequence by U--Pb dating of calcite in veins and vugs from rock core sampled througha shallowly dipping sequenceof sedimentary rocks beneath the Bruce nuclear site, Ontario, Canada. Secondary calcite from >650 m deep Ordovician carbonate rocks yields a Silurian age of 434 [+ or -] 5 Ma possibly related to infiltration of seawater from overlying evaporitic basins as well as hydrothermal solutions that infiltrated from below. In contrast, near-surface Devonian rocks mostly give vein infill ages over the range of 80-100 Ma with evidence for younger infill down to 50 Ma. Vein calcite samples previously dated from surface outcrops of Ordovician carbonate exposed up to 500 km to the east yielded similar U--Pb ages. Coincidence of near-surface vein calcite ages indicates widespread vein emplacement synchronous with a change in direction of motion of the North American plate as well as possible erosional unroofing following passage of the region over the Great Meteor hotspot approximately 125 Myr ago. Deeper carbonate formations have remained apparently impermeable to post-Paleozoic disturbance despite these perturbations. Key words: U--Pb calcite dating, hydrochronology, deep geological repository, southern Ontario carbonate platform, Great Meteor hotspot. Un registre de l'ecoulement des fluides a ete obtenu d'une sequence paleozoique de plateforme carbonatee par la datation U--Pb de calcite dans des veines et cavites dans des carottes prelevees d'une sequence de roches sedimentaires de faible pendage sous le site nucleaire de Bruce (Ontario, Canada). De la calcite secondaire provenant de roches carbonatees ordoviciennes de plus de 650 m de profondeur produit un age silurien de 434 [+ or -] 5 Ma possiblement relie a l'infiltration d'eau de mer issue de bassins evaporitiques sus-jacents, ainsi qu'a des solutions hydrothermales infiltrees depuis le bas. En comparaison, des roches devoniennes situees presde la surface produisent des ages de remplissagede veines dans une fourchettede 80 Ma a 100Maet des indices de remplissage plus recent allant jusqu'a 50 Ma. Des echantillons de calcite de veine deja dates tires d'affleurements de carbonates ordoviciens exposes jusqu'a 500 km a l'est donnent des ages U--Pb semblables. La coincidence des ages de calcite de veines situees pres de la surface indique une mise en place synchrone de veines a grande echelle accompagnant un changement de la direction de deplacement de la plaque nord-americaine, ainsi qu'une possible exposition par erosion suivant le passage de la region au-dessusdu point chauddu Grand Meteore vers 125 Ma.Endepit deces perturbations, des formations carbonatees plus profondes sont demeurees apparemment impermeables aux modifications post-paleozoiques. [Traduit par la Redaction] Mots-cles : datation U--Pb sur calcite, hydrochronologie, depot de dechets nucleaires, plateforme carbonatee du sud de l'Ontario, point chaud du Grand Meteor., Introduction Permanent secure storage of nuclear waste from power generation represents a major societal challenge. Because radioactive material must be confined over a time scale of several million years this [...]

Continental arc magmas supply the ore-forming element budget of most globally important porphyry-type ore deposits. However, the processes enabling certain arc segments to preferentially generate giant porphyry deposits remain highly debated. Here we evaluate the large-scale covariation of key ore-forming constituents in this setting by studying silicate melt inclusions in volcanic rocks from a fertile-to-barren segment of the Andean Southern Volcanic Zone (33-40 °S). We show that the north-to-south, fertile-to-barren gradient is characterized by a northward increase in S and Cl concentrations and a simultaneous decrease in Cu. Consequently, we suggest that the concentration of S and Cl rather than the concentration of ore metals regulates magmatic-hydrothermal ore fertility, and that the loss of volatiles prior to arrival in the upper crust impacts ore-forming potential more than magmatic sulfide saturation-related ore metal scavenging., (© 2022. The Author(s).)

The Hamburg meteorite fell on January 16, 2018, near Hamburg, Michigan, after a fireball event widely observed in the U.S. Midwest and in Ontario, Canada. Several fragments fell onto frozen surfaces of lakes and, thanks to weather radar data, were recovered days after the fall. The studied rock fragments show no or little signs of terrestrial weathering. Here, we present the initial results from an international consortium study to describe the fall, characterize the meteorite, and probe the collision history of Hamburg. About 1 kg of recovered meteorites was initially reported. Petrology, mineral chemistry, trace element and organic chemistry, and O and Cr isotopic compositions are characteristic of H4 chondrites. Cosmic ray exposure ages based on cosmogenic 3 He, 21 Ne, and 38 Ar are ~12 Ma, and roughly agree with each other. Noble gas data as well as the cosmogenic 10 Be concentration point to a small 40-60 cm diameter meteoroid. An 40 Ar- 39 Ar age of 4532 ± 24 Ma indicates no major impact event occurring later in its evolutionary history, consistent with data of other H4 chondrites. Microanalyses of phosphates with LA-ICPMS give an average Pb-Pb age of 4549 ± 36 Ma. This is in good agreement with the average SIMS Pb-Pb phosphate age of 4535.3 ± 9.5 Ma and U-Pb Concordia age of 4535 ± 10 Ma. The weighted average age of 4541.6 ± 9.5 Ma reflects the metamorphic phosphate crystallization age after parent body formation in the early solar system., (© 2020 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society (MET).)

Low-dimensional copper halides with high luminance have attracted increasing interest as heavy-metal-free light emitters. However, the optical mechanisms underpinning their excellent luminescence remain underexplored. Here, we report multiple self-trapped emissions in Cs 3 Cu 2 I 5 . Power-dependent photoluminescence spectra reveal the appearance of multiple self-trapped emission peaks with increasing excitation power, and this emission behavior is explored across a temperature range of 80-420 K. The zero-dimensional structure and soft crystal lattice contribute to the multiple self-trapped emissions in Cs 3 Cu 2 I 5 : this explains the origin of the broad emission and the luminescence mechanism in Cs 3 Cu 2 I 5 and will assist in improving our understanding of the optical properties of other metal halides. We incorporate the Cs 3 Cu 2 I 5 in light-emitting diodes that achieve a peak luminance of 140 cd/m 2 and an external quantum efficiency of 0.27%.

In the past three years, machine learning (ML) in combination with density functional theory (DFT) has enabled computational screening of compounds with the goal of accelerated materials discovery. Unfortunately, DFT+ML has, until now, either relied on knowledge of the atomic positions at DFT energy minima, which are a priori unknown, or been limited to chemical spaces of modest size. Here we report a strategy that we term learning-in-templates (LiT), wherein we first define a series of space group and stoichiometry templates corresponding to hypothesized compounds and, orthogonally, we allow any list of atoms to take on any template. The LiT approach is deployed in combination with previously established position-dependent representations and performs best with the representations that rely least on the atomic positions. Since the positions of the atoms in templates are known and do not change, LiT enables us to infer the properties of interest directly; additionally, LiT allows working with increased chemical spaces, since the same elements can take on a large number of templates. Only by using LiT were we able to span 5 × 10 6 double-perovskite compounds and achieve an acceleration factor of 700 compared to brute-force DFT, allowing us to predict never-before-screened compounds. Our findings motivated us to synthesize a new BaCu y Ta (1- y) S 3 perovskite, which we show using an electron probe microanalyzer has a 5:3 molar ratio of Cu to Ta and, using powder X-ray diffraction (XRD) analysis combined with a DFT-based XRD simulation and fitting, indicate a new phase having an I4/ m space group.