Observation of Two New Excited Ξb0 States Decaying to Λb0 K-π+

Two narrow resonant states are observed in the Λb0K-π+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Λb0K-π+ system indicates that these are excited Ξb0 baryons. The masses of the Ξb(6327)0 and Ξb(6333)0 states are m[Ξb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Ξb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Δm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Λb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Γ[Ξb(6327)0]<2.20(2.56) and Γ[Ξb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Ξb0 resonances

Search for dark photons produced in 13 TeV pppp collisions

Searches are performed for both promptlike and long-lived dark photons, A 0 , produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using A 0 → μ þ μ − decays and a data sample corresponding to an integrated luminosity of 1 . 6 fb − 1 collected with the LHCb detector. The promptlike A 0 search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived A 0 search is restricted to the low-mass region 214 <m ð A 0 Þ < 350 MeV. No evidence for a signal is found, and 90% confidence level exclusion limits are placed on the γ – A 0 kinetic-mixing strength. The constraints placed on promptlike dark photons are the most stringent to date for the mass range 10 . 6 <m ð A 0 Þ < 70 GeV, and are comparable to the best existing limits for m ð A 0 Þ < 0 . 5 GeV. The search for long-lived dark photons is the first to achieve sensitivity using a displaced-vertex signature

Endoskarn and Cu-Zn mineralization at the Empire mine, Idaho, USA

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The Magmatic-Hydrothermal Transition - Evidence from Quartz Phenocryst Textures and Endoskarn Abundance in Cu-Zn Skarns at the Empire Mine, Idaho, USA'

Information about the magmatic to hydrothermal transition is preserved in late-stage features of quartz phenocrysts and endoskarn alteration in some Cu-Zn skarn deposits such as the Empire Mine in Idaho. Important features include: (1) quartz phenocrysts with strong resorption textures such as vermicular zones of igneous groundmass cutting primary quartz cathodoluminescence banding, (2) anomalous amounts of endoskarn (more than 50% of mineralized rock), (3) high F activities as evidenced by fluorite as an accessory mineral in igneous rocks, in alteration assemblages, and in fluid inclusions and by high F in hydroxyl sites in igneous biotite and amphibole, and (4) direct association of Zn, which normally is deposited distally at low temperature, with Cu in proximal locations and in endoskarn. These features are explained by the following model: (1) F lowers the solidus temperature of the magma, thus changing the timing, temperature, and duration of hydrothermal fluid exsolution. (2) Upon magmatic vapor saturation the F-rich hydrothermal fluids form bubbles that adhere to quartz phenocrysts and chemically corrode/tunnel into the quartz forming vermicular resorption textures. (3) F-rich hydrothermal fluids also promote the formation of endoskarn; silicic rocks are attacked by F-rich fluids in the same sense that carbonate wall rocks are dissolved by weakly to moderately acidic hydrothermal fluids. (4) Low fluid exsolution temperature facilitated by high F activity promotes high Zn/Cu ratios in proximal locations due to the solubility of Zn relative to Cu at lower temperatures. This model may be applicable at other localities such as the world-class Cu-Zn skarn Antamina mine, as well as some tin and rapakivi granites. © Elsevier B.V. All rights reserved

The magmatic-hydrothermal transition-evidence from quartz phenocryst textures and endoskarn abundance in Cu-Zn skarns at the Empire Mine, Idaho, USA

Information about the magmatic to hydrothermal transition is preserved in late-stage features of quartz phenocrysts and endoskarn alteration in some Cu-Zn skarn deposits such as the Empire Mine in Idaho. Important features include: (1) quartz phenocrysts with strong resorption textures such as vermicular zones of igneous groundmass cutting primary quartz cathodoluminescence banding, (2) anomalous amounts of endoskarn (more than 50% of mineralized rock), (3) high F activities as evidenced by fluorite as an accessory mineral in igneous rocks, in alteration assemblages, and in fluid inclusions and by high F in hydroxyl sites in igneous biotite and amphibole, and (4) direct association of Zn, which normally is deposited distally at low temperature, with Cu in proximal locations and in endoskarn. These features are explained by the following model: (1) F lowers the solidus temperature of the magma, thus changing the timing, temperature, and duration of hydrothermal fluid exsolution. (2) Upon magmatic vapor saturation the F-rich hydrothermal fluids form bubbles that adhere to quartz phenocrysts and chemically corrode/tunnel into the quartz forming vermicular resorption textures. (3) F-rich hydrothermal fluids also promote the formation of endoskarn; silicic rocks are attacked by F-rich fluids in the same sense that carbonate wall rocks are dissolved by weakly to moderately acidic hydrothermal fluids. (4) Low fluid exsolution temperature facilitated by high F activity promotes high Zn/Cu ratios in proximal locations due to the solubility of Zn relative to Cu at lower temperatures. This model may be applicable at other localities such as the world-class Cu-Zn skarn Antamina mine, as well as some tin and rapakivi granites

The Empire Cu-Zn Mine, Idaho: Exploration implications of unusual skarn features related to high fluorine activity

The Empire Cu-Zn skarn deposit is unusual because of the proximal position of Zn mineralization, abundance of endoskarn, and the extremely vermicular texture of quartz phenocrysts in the related intrusive rocks. Cu-Zn skarn occurs at the contact between Upper Mississippian White Knob limestone and the granite porphyry phase of the Mackay Stock which consists, from early to late, of quartz monzodiorite, granophyre, granite porphyry, porphyritic granite, and many dikes. The late phases have high F and also extremely vermicular quartz phenocrysts. Endoskarn is more abundant than exoskarn. The earliest alteration of the intrusive rocks consists of disseminated diopsidic pyroxene (Di64Hd36 to Di88Hd12), actinolite, and titanite. This assemblage was cut by early scapolite (Me18 to Me35, mostly Me18-26) and/or green pyroxene (Di14Hd80 to Di20Hd77) veinlets, with or without wollastonite halos. These early veins were then cut by main-stage endoskarn veins that typically have a garnet + minor pyroxene inner zone, a wollastonite and/or pyroxene ± Ca-rich plagioclase (An56 to An89) envelope, and a halo containing disseminated, fine-grained alteration minerals of the same assemblage as the envelope. Some veins contain only the envelope assemblage and are interpreted to represent the alteration front. The inner zone locally contains vesuvianite. Where many veins intersect, endoskarn is massive. Pyroxene is zoned around fluid conduits; the distal pyroxene is Fe rich (hedenbergitic) whereas the proximal pyroxene is Fe poor (diopsidic). The garnet changes in the opposite way, being Fe poor-Al rich (grossularitic) in locations distal to the fluid conduits, and Fe rich (andraditic) in proximal locations. In contrast, in the exoskarn, all pyroxene is diopsidic and garnet is andraditic. Weak, retrograde alteration composed of quartz + calcite + chlorite with minor fluorite, talc, and epidote overprinted both endoskarn and exoskarn. Magnetite precipitated after garnet-pyroxene in both endoskarn and exoskarn. Sphalerite precipitated together with chalcopyrite in proximal locations and is associated with retrograde alteration. Other ore minerals include minor molybdenite, bornite, pyrite, galena, arsenopyrite, native Au, as well as supergene minerals such as chrysocolla, malachite, azurite, native Cu, and limonite. Fluid xenoliths from pyroxene in early endoskarn veinlets homogenize at >600°C. Massive endoskarn and exoskarn replacing limestone inclusions in granite porphyry formed at 500° to >700°C, whereas the highest temperature inclusions, >700°C, occur in narrow garnet + minor pyroxene veins. Fluid inclusions in exoskarn replacing wall rock have homogenization temperatures of 500° to 650°C. Retrograde alteration and Cu-Zn mineralization occurred at 250° to 300°C. Fluid inclusions in prograde minerals contain daughter minerals, whereas fluid inclusions in retrograde minerals do not, indicating a decrease in salinity with time. Late-stage fluids have low eutectic temperatures, indicating the possible presence of KCl, NaCl, FeCl2, CaCl2, MgCl2, K2CO3, and/or Na2CO3. Formation of the unusually abundant endoskarn, the proximal position of Zn mineralization, and the extremely vermicular texture of quartz phenocrysts are all believed to have been promoted by the high F content of the magmatic fluid. These features may serve as exploration indicators of associated high F mineralization such as buried porphyry Mo deposits

Tectonic setting and petrogenesis of the Celebi granitoid, (Kirikkale-Turkey) and comparison with world skarn granitoids

WOS: 000178679500003Many studies have shown systematic correlations between the composition of plutons worldwide and the metal content of associated skarns. This is the first report of similar correlations between the composition of Celebi granitoid and skarns of the Celebi district in Central Anatolia, Turkey. The Celebi district is well known for its polymetallic Fe-Wand Cu vein ores. These are hosted by calcic skarn zones. Both exoskarns (pyroxene-gamet) and endoskarns (epidote-pyroxene) occur in the district formed mainly along the granitoid contacts and along the fractures within the marble. Based on mineralogy, petrology and geochemistry, two different igneous rocks were recognized in the Celebi granitoid, referred to as leucocratic (felsic) and mesocratic (intermediate) Celebi granitoid. The leucocratic Celebi occurs as dominant rock type, and is classified as granite. The mesocratic Celebi is not widespread and is classified as adamellite, tomalite, quartz monzonite and quartz monzodiorite. The mesocratic Celebi has I-type characteristics, and have subalkaline, calc-alkaline and metaluminous characteristics like most worldwide skarn granitoids. A post-collisional tectonic setting is proposed on the basis of field evidence, the relative timing of intrusions with respect to metamorphic and obducted ophiolitic rocks and trace element geochemistry. The high abundance of La and Ce and the enrichment of V in mafic components suggest that Celebi granitoids are formed by partial melting of mantle rocks, but have been contaminated by interaction with continental crust involving possible magma mixing processes (i.e. mixing of coexisting felsic and mafic magmas). In the district, the mesocratic type and mafic microgranular enclaves (MME) mainly within leucocratic type represent a mafic underplating magma that was mixed with and/or injected into felsic magma of the leucocratic type. The present study shows that Fe mineralization is associated with mesocratic Celebi type, whereas W mineralization is associated with leucocratic type. Mesocratic Celebi granitoid is significantly different from the worldwide average of plutons associated with Fe skarns. In particular, MgO vs. SiO2, FeOt+CaO+Na2O/K2O vs. SiO2, Fe2O3/Fe2O3+FeO vs. SiO2 and V vs. Ni vary from typical values (are lower than values typical for plutons associated with Fe skarns) for plutons associated with Fe skarns. Instead, it resembles the geochemical characteristics of plutons associated with worldwide Cu and possibly An skarns. This suggests new exploration possibilities for copper and gold in the Celebi district. (C) 2002 Elsevier Science B.V. All rights reserved