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Oxygen isotopes are useful for tracing interactions between magmas, crustal rocks and surface‐derived waters. We use them here to consider links between voluminous silicic magmatism and large‐scale hydrothermal circulation in New Zealand's central Taupō Volcanic Zone (TVZ). We present >350 measurements of plagioclase, quartz, hornblende and groundmass glass δ18O values from 40 eruptions from three discrete magmatic systems: Ōkataina and Taupō calderas, and the smaller Northeast Dome system. For each mineral, mean δ18O values vary by ∼1‰ (δ18Oplag = +6.7–7.8‰, δ18Oqtz = +7.7–+8.7‰, δ18Ohbl = +5.4–+6.4‰, δ18Oglass = +7.1–+8.0‰), and inter‐mineral fractionations mostly reflect high‐temperature equilibria. Outliers (e.g., ∼+6‰ or >+10‰ plagioclase) represent contaminants incorporated on short‐enough timescales to preserve disequilibrium (∼102 yrs for plagioclase). Melt δ18O values calculated from phenocrysts are ∼+7.3–+8.0‰. Where multiple magmas were involved in the same eruption their δ18Omelt values are indistinguishable, implying that their parental mushes were isotopically well‐mixed. However, small (≤0.5‰) but consistent δ18Omelt value gradients occur over millennial timescales at Ōkataina and Taupō, with short‐term ∼0.4–0.5‰ decreases in δ18Omelt values over successive post‐caldera eruptions correlating with increases in 87Sr/86Sr. These changes reflect tens of percent assimilation of a mixture of hydrothermally altered silicic plutonic material and higher‐87Sr/86Sr greywacke. These examples represent the first evidence for assimilation of altered crust into TVZ magmas. The subtle and short‐lived isotopic signals of these interactions are only recognized through the high temporal resolution of the TVZ eruptive record and complementary radiogenic isotope data. Similar interactions may have been obscured in other nominally high‐ or normal‐δ18O magmatic systems. Plain Language Summary Heat coming from large sub‐volcanic magma systems drives convection of surface‐derived waters through the upper few kilometers of Earth's crust, forming hydrothermal systems. The nature and depth of the interface between hydrothermal systems and their underlying magmatic heat sources are often not well constrained. High temperature alteration of rocks by surface‐derived waters lowers rock oxygen isotope (18O/16O) ratios, which can thus be used to track infiltration of water into the crust. We measured the 18O/16O ratios of minerals from the products of 40 young eruptions from the highly active Taupō Volcanic Zone, New Zealand, to assess whether the erupted magmas had melted and incorporated rocks that were altered in this way. At both Taupō and Ōkataina volcanoes, we observe periods of subtle (but statistically significant) progressive lowering of magma 18O/16O ratios over successive eruptions, suggesting that their magmatic systems at times overlapped and interacted with overlying hydrothermal systems. At both volcanoes, these reductions occurred as the magmatic system was rebuilt to shallow levels in the crust following very large (caldera‐forming) eruptions. The subtle and short‐lived signals of these interactions are only recognized here because of the unusually high eruption frequencies of Taupō and Ōkataina volcanoes. Key Points Large silicic mushes in the Taupō Volcanic Zone are isotopically well‐mixed with respect to oxygen but show subtle temporal δ18O variations Temporal trends in melt δ18O values reflect transient interactions with altered and unaltered assimilants after caldera collapses Muted (sub‐permil) melt δ18O value variability reflects limited isotopic contrasts between magmas and country rocks in this setting

The transfer of fluid and trace elements from the slab to the mantle wedge cannot be adequately explained by simple models of slab devolatilization. The eclogite-facies mélange belt of northern New Caledonia represents previously subducted oceanic crust and contains a significant proportion of talc and chlorite schists associated with serpentinite. These rocks host large quantities of H 2 O and CO 2 and may transport volatiles to deep levels in subduction zones. The bulk-rock and stable isotope compositions of talc and chlorite schist and serpentinite indicate that the serpentinite was formed by seawater alteration of oceanic lithosphere prior to subduction, whereas the talc and chlorite schists were formed by fluid-induced metasomatism of a mélange of mafic, ultramafic and metasedimentary rocks during subduction. In subduction zones, dehydration of talc and chlorite schists should occur at sub-arc depths and at significantly higher temperatures (∼ 800°C) than other lithologies (400–650°C). Fluids released under these conditions could carry high trace-element contents and may trigger partial melting of adjacent pelitic and mafic rocks, and hence may be vital for transferring volatile and trace elements to the source regions of arc magmas. In contrast, these hybrid rocks are unlikely to undergo significant decarbonation during subduction and so may be important for recycling carbon into the deep mantle.

Since 1998 the serious public health problem in South East Asia of counterfeit artesunate, containing no or subtherapeutic amounts of the active antimalarial ingredient, has led to deaths from untreated malaria, reduced confidence in this vital drug, large economic losses for the legitimate manufacturers, and concerns that artemisinin resistance might be engendered. With evidence of a deteriorating situation, a group of police, criminal analysts, chemists, palynologists, and health workers collaborated to determine the source of these counterfeits under the auspices of the International Criminal Police Organization (INTERPOL) and the Western Pacific World Health Organization Regional Office. A total of 391 samples of genuine and counterfeit artesunate collected in Vietnam (75), Cambodia (48), Lao PDR (115), Myanmar (Burma) (137) and the Thai/Myanmar border (16), were available for analysis. Sixteen different fake hologram types were identified. High-performance liquid chromatography and/or mass spectrometry confirmed that all specimens thought to be counterfeit (195/391, 49.9%) on the basis of packaging contained no or small quantities of artesunate (up to 12 mg per tablet as opposed to approximately 50 mg per genuine tablet). Chemical analysis demonstrated a wide diversity of wrong active ingredients, including banned pharmaceuticals, such as metamizole, and safrole, a carcinogen, and raw material for manufacture of methylenedioxymethamphetamine ('ecstasy'). Evidence from chemical, mineralogical, biological, and packaging analysis suggested that at least some of the counterfeits were manufactured in southeast People's Republic of China. This evidence prompted the Chinese Government to act quickly against the criminal traders with arrests and seizures. An international multi-disciplinary group obtained evidence that some of the counterfeit artesunate was manufactured in China, and this prompted a criminal investigation. International cross-disciplinary collaborations may be appropriate in the investigation of other serious counterfeit medicine public health problems elsewhere, but strengthening of international collaborations and forensic and drug regulatory authority capacity will be required.

Background Plasmodium falciparum malaria remains a major public health problem. A vital component of malaria control rests on the availability of good quality artemisinin-derivative based combination therapy (ACT) at the correct dose. However, there are increasing reports of poor quality anti-malarials in Africa. Methods Seven collections of artemisinin derivative monotherapies, ACT and halofantrine anti-malarials of suspicious quality were collected in 2002/10 in eleven African countries and in Asia en route to Africa. Packaging, chemical composition (high performance liquid chromatography, direct ionization mass spectrometry, X-ray diffractometry, stable isotope analysis) and botanical investigations were performed. Results Counterfeit artesunate containing chloroquine, counterfeit dihydroartemisinin (DHA) containing paracetamol (acetaminophen), counterfeit DHA-piperaquine containing sildenafil, counterfeit artemether-lumefantrine containing pyrimethamine, counterfeit halofantrine containing artemisinin, and substandard/counterfeit or degraded artesunate and artesunate+amodiaquine in eight countries are described. Pollen analysis was consistent with manufacture of counterfeits in eastern Asia. These data do not allow estimation of the frequency of poor quality anti-malarials in Africa. Conclusions Criminals are producing diverse harmful anti-malarial counterfeits with important public health consequences. The presence of artesunate monotherapy, substandard and/or degraded and counterfeit medicines containing sub-therapeutic amounts of unexpected anti-malarials will engender drug resistance. With the threatening spread of artemisinin resistance to Africa, much greater investment is required to ensure the quality of ACTs and removal of artemisinin monotherapies. The International Health Regulations may need to be invoked to counter these serious public health problems.

In November 2007 we conducted a water column and seafloor mapping study of the submarine volcanoes of the Aeolian Arc in the southern Tyrrhenian Sea aboard the R/V Urania. On 26 conductivity‐temperature‐depth casts and tows we measured temperature, conductivity, pressure, and light scattering and also collected discrete samples for helium isotopes, methane, and pH. The 3He/4He isotope ratio, an unambiguous indicator of hydrothermal input, showed a clear excess above background at 6 of the 10 submarine volcanoes surveyed. Marsili seamount had the highest anomaly, where the 3He/4He ratio reached a δ3He value of 23% at 610 m depth compared with background values of ∼5%. Smaller but distinct δ3He anomalies occurred over Palinuro, Enarete, Eolo, Sisifo, and Secca del Capo. Although hydrothermal emissions are known to occur offshore of some Aeolian subaerial volcanoes, and hydrothermal deposits have been sampled throughout the arc, our results are the first to confirm active discharge on Marsili, Enarete, Eolo, Sisifo, and Secca del Capo. Samples collected over Lametini, Filicudi North, Alicudi North, and Alcione had δ3He near the regional background values, suggesting either absence of, or very weak, hydrothermal activity on these seamounts. Hydrocasts between the volcanoes revealed a consistent δ3He maximum between 11% and 13% at 2000 m depth throughout the SE Tyrrhenian Sea. The volcanoes of the Aeolian arc and the Marsili back arc, all <1000 m deep, cannot contribute directly to this maximum. This deep 3He excess may be a remnant of tritium decay or may have been produced by an unknown deep hydrothermal source.

The southeast Tyrrhenian Sea off the western coast of southern Italy is one of the two areas of the Mediterranean basin where active subduction and associated volcanism occur. Rollback of westward-dipping Ionian oceanic lithosphere has created a small back-arc basin and the Aeolian Arc with seven subaerial volcanoes: Stromboli, Panarea, Vulcano, Lipari, Salina, Filicudi, and Alicudi volcanic-islands (Figure 1). At least eight submarine volcanoes in the area have been explored to a limited degree. For several decades, the submarine centers in the arc and back-arc have been the target of geophysical, volcanological, and mineral exploration (e.g., Dekov and Savelli, 2004). Deep-sea dredging has collected evidence of hydrothermal activity at many of the submarine centers. CTD recordings in the water column, coupled with helium isotopic measurements, identified significant chemical signals at Palinuro, Enarete, Eolo, Marsili, Sisifo, and Secca del Capo that may result from hydrothermal venting (Lupton et al., 2011).

Massive sulfide samples have been recovered from Brothers and Rumble II West volcanoes of the southern Kermadec frontal arc, northeast of New Zealand. Both are caldera-forming volcanoes with Brothers largely dacitic and Rumble II West basaltic to basaltic-andesite in composition. The sulfide samples are considered to be pieces of chimneys from near the base of the caldera walls and are dominated by Cu-Fe-Ba ± Pb (chalcopyrite-pyrite-barite ± galena) and to a lesser extent, Zn-Fe-Ba ± Pb (sphalerite-pyrite-barite ± galena) mineralization. Gold is present in the samples up to 6.1 ppm. Paragenetic relationships suggest that the two hydrothermal systems have heated up and later cooled down. Oxidation of the sulfides is common and suggests that parts of the deposits are relatively old. Fluid inclusion microthermometric data show salinities fall predominantly in the range 3.0 to 3.4 wt% NaCl equivalent, similar to seawater values (3.2 wt%). About 15% of the Brothers salinity data range to both lower (2.2 wt%) and higher (3.9 wt%) than seawater values. Homogenization temperatures for type I inclusions in barite range between 175 and 322 °C for the Brothers samples, and between 205 and 268 °C for one Rumble II West sample. A dramatic decrease in temperature and/or change in the oxidation state of the hydrothermal fluid are considered the main mechanisms responsible for gold deposition at the Kermadec vent sites. This was achieved by mixing the hydrothermal fluid with ambient seawater within what are inferred to have been <300 °C \"white smoker\" chimneys, consistent with S isotope results. Fluid inclusion volatiles are dominated by H^sub 2^O (99.81-99.98 mol%) followed by CO^sub 2^ (0.03-0.17) and lesser amounts of N^sub 2^ (0.004-0.023), CH^sub 4^ (0.002-0.026) and trace COS and C^sub 2^-C^sub 3^ hydrocarbons. Fluid inclusions hosted by barite contain noticeably lesser amounts of gas than those within sulfides, consistent with mixing. The source of the relatively high concentrations of CH^sub 4^ is enigmatic, although may be related to the thermal degradation of organic-rich sediments intercalated within the volcanic pile. Addition of a pressure correction and the effect of dissolved gases show that the hydrothermal fluids did not boil at the chimney depths. However, the range of measured salinities in the Brothers field combined with slightly positive trends in fluid inclusion CO^sub 2^/CH^sub 4^ versus CO^sub 2^/N^sub 2^ plots suggest sub-seafloor phase separation may have occurred in the hydrothermal system prior to venting.[PUBLICATION ABSTRACT]

At Sams Creek, a gold-bearing, peralkaline granite porphyry dyke, which has a 7 km strike length and is up to 60 m in thickness, intrudes camptonite lamprophyre dykes and lower greenschist facies metapelites and quartzites of the Late Ordovician Wangapeka formation. The lamprophyre dykes occur as thin (< 3 m) slivers along the contacts of the granite dyke. δ^sup 18^O^sub magma^ values (+5 to +8[per thousand], VSMOW) of the A-type granite suggest derivation from a primitive source, with an insignificant mature crustal contribution. Hydrothermal gold-sulphide mineralisation is confined to the granite and adjacent lamprophyre; metapelite country rocks have only weak hydrothermal alteration. Three stages of hydrothermal alteration have been identified in the granite: Stage I alteration (high fO^sub 2^) consisting of magnetite-siderite±biotite; Stage II consisting of thin quartz-pyrite veinlets; and Stage III (low fO^sub 2^) consisting of sulphides, quartz and siderite veins, and pervasive silicification. The lamprophyre is altered to an ankerite-chlorite-sericite assemblage. Stage III sulphide veins are composed of arsenopyrite + pyrite ± galena ± sphalerite ± gold ± chalcopyrite ± pyrrhotite ± rutile ± graphite. Three phases of deformation have affected the area, and the mineralised veins and the granite and lamprophyre dykes have been deformed by two phases of folding, the youngest of which is Early Cretaceous. Locally preserved early-formed fluid inclusions are either carbonic, showing two- or three-phases at room temperature (liquid CO^sub 2^-CH^sub 4^ + liquid H^sub 2^O ± CO^sub 2^ vapour) or two-phase liquid-rich aqueous inclusions, some of which contain clathrates. Salinities of the aqueous inclusions are in the range of 1.4 to 7.6 wt% NaCl equiv. Final homogenisation temperatures (Th) of the carbonic inclusions indicate minimum trapping temperatures of 320 to 355°C, which are not too different from vein formation temperatures of 340-380°C estimated from quartz-albite stable isotope thermometry. δ^sup 18^O values of Stage II and III vein quartz range from +12 and +17[per thousand] and have a bimodal distribution (+14.5 and +16[per thousand]) with Stage II vein quartz accounting for the lower values. Siderite in Stage III veins have δ^sup 18^O (+12 to +16[per thousand]) and δ^sup 13^C values (-5[per thousand], relative to VPDB), unlike those from Wangapeka Formation metasediments (δ^sup 13^C^sub bulk carbon^ values of -24 to -19[per thousand]) and underlying Arthur Marble marine carbonates (δ^sup 18^O = +25[per thousand] and δ^sup 13^C = 0[per thousand]). Calculated δ^sup 18^O^sub water^ (+8 to +11[per thousand], at 340°C) and δ^sup 13^C^sub CO2^(-5[per thousand]) values from vein quartz and siderite are consistent with a magmatic hydrothermal source, but a metamorphic hydrothermal origin cannot be excluded. δ^sup 34^S values of sulphides range from +5 to +10[per thousand] (relative to CDT) and also have a bimodal distribution (modes at +6 and +9[per thousand], correlated with Stage II and Stage III mineralisation, respectively). The δ^sup 34^S values of pyrite from the Arthur Marble marine carbonates (range from +3 to +13[per thousand]) and Wangapeka Formation (range from -4 to +9.5[per thousand]) indicate that they are potential sources of sulphur for sulphides in the Sams Creek veins. Another possible source of the sulphur is the lithospheric mantle which has positive values up to +14[per thousand]. Ages of the granite, lamprophyre, alteration/mineralisation, and deformation in the region are not well constrained, which makes it difficult to identify sources of mineralisation with respect to timing. Our mineralogical and stable isotope data does not exclude a metamorphic source, but we consider that the source of the mineralisation can best be explained by a magmatic hydrothermal source. Assuming that the hydrothermal fluids were sourced from crystallisation of the Sams Creek granite or an underlying magma chamber, then the Sams Creek gold deposit appears to be a hybrid between those described as reduced granite Au-Bi deposits and alkaline intrusive-hosted Au-Mo-Cu deposits.[PUBLICATION ABSTRACT]

Since 1998 the serious public health problem in South East Asia of counterfeit artesunate, containing no or subtherapeutic amounts of the active antimalarial ingredient, has led to deaths from untreated malaria, reduced confidence in this vital drug, large economic losses for the legitimate manufacturers, and concerns that artemisinin resistance might be engendered. With evidence of a deteriorating situation, a group of police, criminal analysts, chemists, palynologists, and health workers collaborated to determine the source of these counterfeits under the auspices of the International Criminal Police Organization (INTERPOL) and the Western Pacific World Health Organization Regional Office. A total of 391 samples of genuine and counterfeit artesunate collected in Vietnam (75), Cambodia (48), Lao PDR (115), Myanmar (Burma) (137) and the Thai/Myanmar border (16), were available for analysis. Sixteen different fake hologram types were identified. High-performance liquid chromatography and/or mass spectrometry confirmed that all specimens thought to be counterfeit (195/391, 49.9%) on the basis of packaging contained no or small quantities of artesunate (up to 12 mg per tablet as opposed to ~ 50 mg per genuine tablet). Chemical analysis demonstrated a wide diversity of wrong active ingredients, including banned pharmaceuticals, such as metamizole, and safrole, a carcinogen, and raw material for manufacture of methylenedioxymethamphetamine ('ecstasy'). Evidence from chemical, mineralogical, biological, and packaging analysis suggested that at least some of the counterfeits were manufactured in southeast People's Republic of China. This evidence prompted the Chinese Government to act quickly against the criminal traders with arrests and seizures. An international multi-disciplinary group obtained evidence that some of the counterfeit artesunate was manufactured in China, and this prompted a criminal investigation. International cross-disciplinary collaborations may be appropriate in the investigation of other serious counterfeit medicine public health problems elsewhere, but strengthening of international collaborations and forensic and drug regulatory authority capacity will be required.