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A study of high-grade metamorphic rocks by a combined ion microprobe and bulk mineral analysis with diffusion modeling revealed the significant influence exerted by interdiffusion in stabilizing the nature of arrangement of stable isotopes in gradually cooling rocks. Assessment of multiple fractionations in rocks is essential in predicting the nature of retrogression in the rocks.

Significant zonation in major, minor, trace, and volatile elements has been documented in naturally glassy olivine-hosted melt inclusions from the Siqueiros Fracture Zone and the Galapagos Islands. Components with a higher concentration in the host olivine than in the melt (e.g., MgO, FeO, [Cr.sub.2][O.sub.3], and MnO) are depleted at the edges of the zoned melt inclusions relative to their centers, whereas except for CaO, [H.sub.2]O, and F, components with a lower concentration in the host olivine than in the melt (e.g., [Al.sub.2][O.sub.3], Si[O.sub.2], [Na.sub.2]O, [K.sub.2]O, Ti[O.sub.2], S, and Cl) are enriched near the melt inclusion edges. This zonation is due to formation of an olivine-depleted boundary layer in the adjacent melt in response to cooling and crystallization of olivine on the walls of the melt inclusions, concurrent with diffusive propagation of the boundary layer toward the inclusion center. Concentration profiles of some components in the melt inclusions exhibit multicomponent diffusion effects such as uphill diffusion (CaO, FeO) or slowing of the diffusion of typically rapidly diffusing components ([Na.sub.2]O, [K.sub.2]O) by coupling to slow diffusing components such as Si[O.sub.2] and [Al.sub.2][O.sub.3]. Concentrations of [H.sub.2]O and F decrease toward the edges of some of the Siqueiros melt inclusions, suggesting either that these components have been lost from the inclusions into the host olivine late in their cooling histories and/or that these components are exhibiting multicomponent diffusion effects. A model has been developed of the time-dependent evolution of MgO concentration profiles in melt inclusions due to simultaneous depletion of MgO at the inclusion walls due to olivine growth and diffusion of MgO in the melt inclusions in response to this depletion. Observed concentration profiles were fit to this model to constrain their thermal histories. Cooling rates determined by a single-stage linear cooling model are 150-13,000°C [h.sup.-1] from the liquidus down to ~ 1,000°C, consistent with previously determined cooling rates for basaltic glasses; compositional trends with melt inclusion size observed in the Siqueiros melt inclusions are described well by this simple single-stage linear cooling model. Despite the overall success of the modeling of MgO concentration profiles using a single-stage cooling history, MgO concentration profiles in some melt inclusions are better fit by a two-stage cooling history with a slower-cooling first stage followed by a faster-cooling second stage; the inferred total duration of cooling from the liquidus down to ~ 1,000°C ranges from 40 s to just over 1 h. Based on our observations and models, compositions of zoned melt inclusions (even if measured at the centers of the inclusions) will typically have been diffusively fractionated relative to the initially trapped melt; for such inclusions, the initial composition cannot be simply reconstructed based on olivine-addition calculations, so caution should be exercised in application of such reconstructions to correct for post-entrapment crystallization of olivine on inclusion walls. Off-center analyses of a melt inclusion can also give results significantly fractionated relative to simple olivine crystallization. All melt inclusions from the Siqueiros and Galapagos sample suites exhibit zoning profiles, and this feature may be nearly universal in glassy, olivine-hosted inclusions. If so, zoning profiles in melt inclusions could be widely useful to constrain late-stage syneruptive processes and as natural diffusion experiments. Keywords Melt inclusions * Chemical zonation * Diffusion * Geospeedometry, Introduction It is often implicitly assumed that glassy melt inclusions in phenocrysts are homogeneous and thus that analyses from near the center of an inclusion are representative of the inclusion [...]

The elevation history of Earth's surface is key to understanding the geodynamic processes responsible for the rise of plateaus. We investigate the timing of Colorado Plateau uplift by estimating depositional temperatures of Tertiary lake sediments that blanket the plateau interior and adjacent lowlands using carbonate clumped isotope paleothermometry (a measure of the temperature-dependent enrichment of [sup.13]C-[sup.18]O bonds in carbonates). Comparison of modern and ancient samples deposited near sea level provides an opportunity to quantify the influence of climate and therefore assess the contribution of changes in elevation to the variations of surface temperature on the plateau. Analysis of modern lake calcite from 350 to 3300 m elevation in the southwestern United States reveals a lake water carbonate temperature (LCT) lapse rate of 4.2 [+ or -] 0.6[degrees]C/km. Analysis of Miocene deposits from 88 to 1900 m elevation in the Colorado River drainage suggests that the ancient LCT lapse rate was 4.1 [+ or -] 0.7[degrees]C/km, and temperatures were 7.7 [+ or -] 2.0[degrees]C warmer at any one elevation than predicted by the modern trend. The inferred cooling is plausible in light of Pliocene temperature estimates off the coast of California, and the consistency of lapse rates through time supports the interpretation that there has been little or no elevation change for any of the samples since 6 Ma. Together with previous paleorelief estimates from apatite (U-Th)/He data from the Grand Canyon, our results suggest most or all of the plateau's lithospheric buoyancy was acquired ~80-60 Ma and do not support explanations that ascribe most plateau uplift to Oligocene or younger disposal of either the Farallon or North American mantle lithosphere. Citation: Huntington, K. W., B. P. Wernicke, and J. M. Eiler (2010), Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry, Tectonics, 29, TC3005, doi: 10.1029/2009TC002449.

The effects of prograde thermal metamorphism on carbon isotope ratios were re-analyzed by resolving the errors in the calculations involved in the distillation of carbon dioxide from residual graphite through the Rayleigh equation. The corrections require that the fluids with residual hydrocarbons and graphite should have a high C/C ratio and that the reaction rate among the hydrocarbon and graphite residuals and the fluids must be rapid under equilibrate conditions. These enable the Rayleigh distillation reactions to proceed to low residual carbon values and therefore, approximate optimum value diagnostic of biogenic carbon.

Small amounts of water (tens to hundreds of parts per million) can have a profound effect on the properties of mantle peridotites, including viscosities, conductivities, and melting temperatures. Measuring the water content of nominally anhydrous minerals (NAMs) has provided insight into the amounts of water contained within mantle rocks. However, converting from NAM water contents to the activity of H2O is non-trivial. Equilibria involving amphibole can be used to determine values of the activity of H2O (aH2O) at the time of mineral equilibration. This approach yields low values of the activity of H2O (<0.3) for four peridotite xenoliths from Southeastern Australia. These four xenoliths also record values of oxygen fugacity (fO2) that range from −0.2 to −1.2 log units below the fayalitemagnetite-quartz buffer. All these values of fO2 are inconsistent with the presence of a CH4-rich fluid (too oxidizing), and the lowest value of oxygen fugacity, as recorded by one sample, is inconsistent with the presence of a CO2-rich fluid. [ABSTRACT FROM AUTHOR]

Simple Summary: This study indicates that volcanic activity has a long-term impact on biological growth. The synthesis of chlorophyll a by Anabaena pseudoichthyoides was most efficient in the presence of increasing concentrations of volcanic ash leachate. Analysis of the major and trace elements in the solution before and after cultivation shows that the volcanic ash soaking solution has a higher nutrient content compared to granite. This increased nutrient content is a key factor promoting microbial growth. The findings suggest that volcanic ash significantly influences microorganisms, with lasting effects that can persist for tens of thousands to hundreds of thousands of years. The impact of volcanic activity on microorganisms has always been a hot topic of discussion during geological history. Further studies are needed on the effects of volcanic activity on microbial growth in shale and the differences in nutrients provided by volcanic ash and other weathered rocks. This study's results indicated that TOC contents at the bottom of the shale layer are 1.93–4.44% and 3.0% on average. The TOC contents at the top of the layer are 3.38–5.13% and 4.0% on average. It indicated that TOC contents at the bottom of the shale layer are smaller than the TOC contents at the top of the layer, suggesting that volcanic activity posed a long-term effect on biological growth. Seven different leachate concentrations were set in this experiment as follows: 1/10, 1/100, 1/500, 1/1000, 1/1500, 1/2000, and 1/2500. The results showed that the growth status of Pseudourostyla crassipes was affected by the addition of leachates with different concentrations compared to the control group. Additionally, the synthesis of chlorophyll a by Anabaena pseudoichthyoides was the most efficient with the 1/10 volcanic ash leachate. Through the analysis of major and trace elements in the solution before labeland after cultivation, the main elemental content of Ca2+, Mg2+, Na+, and K+ decreased by 3.8~87.24%, 75.96~92.70%, 86.56~95.67%, and 5.42~20.52% in the solution after microbial growth respectively. The trace elements B, Ba, Zn, and Fe decreased by 27.54~94.39%, 20~82.03%, 70.45~98.29%, and 99%. It was found that the B, Ba, Fe, and Zn elements decreased significantly. The nutrients from volcanic ash are the main factor promoting microbial growth. It can be indicated that the volcanic ash soaking solution has a higher content of nutrients when compared to the solubility of nutrients in volcanic ash compared to that of granite. A higher content of nutrients promotes microbial growth. The calculation results indicate that a volcanic eruption with a quantity of several 1010 m3 has a significant impact on microorganisms, lasting from tens of thousands to hundreds of thousands of years. [ABSTRACT FROM AUTHOR]

In situ X-ray diffraction and Raman spectroscopy of a synthetic whitlockite, Ca9Mg(PO3OH) (PO4)6, have been conducted at high pressures or high temperatures. The results show that whitlockite is stable up to ~15 GPa at ambient temperature and undergoes a thermally induced dehydrogenation to merrillite above 973 K at ambient pressure. The obtained pressure-volume data were fitted using a third-order Birch-Murnaghan equation of state, yielding an isothermal bulk modulus of K0 = 79(4) GPa with a pressure derivative of K 0 ′ = 4.3(6). When K 0 ′ was fixed at 4, the refined isothermal bulk modulus was 81(1) GPa. The volumetric thermal expansion coefficient (αV) is 4.05(8) × 10-5 K−1, and the axial thermal expansion coefficients (αa and αc) are 1.07(5) × 10−5 K−1 and 1.91(6) × 10−5 K−1. Both compressibility and thermal expansion show an axial anisotropy. The effects of pressure and temperature on the Raman spectra of whitlockite have been quantitatively analyzed. The isothermal and isobaric mode Grüneisen parameters and the intrinsic anharmonic mode parameters of whitlockite were derived. Some amounts of OH−-bearing whitlockite may be preserved in meteorites if whitlockite undergoes a low-temperature process. [ABSTRACT FROM AUTHOR]

Silicon nanowires (SiNWs) are extensively studied in the scientific community due to their remarkable electrical and optical properties. In our previous studies, we have demonstrated that cylindrical−shaped SiNWs sustain longitudinal plasmon resonances (LPRs) and transverse plasmon resonances (TPRs). In this work, we will present the results of our investigation on conical SiNWs with different lengths and demonstrate that the NW size plays a role on the spectral response. We selected two groups of SiNWs with approximately 300 nm and 750 nm in length with different lengths and diameters. We investigated the optical properties of the SiNWs at a high energy and spatial resolution by using transmission electron microscopy and in situ electron energy loss spectroscopy. In the UV region of the spectrum investigated here, the experimental evidence suggests the presence of LPRs and a clear presence of TPRs. We found that, as the NW length increases, the LPR fundamental mode shifts towards higher energies, while the diameter seems to affect the TPR, shifting it to lower energy levels when the diameter increases. These SiNWs can play a role in the development of low−dimensional devices for applications in nano−electronics and nano−photonics. [ABSTRACT FROM AUTHOR]

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 interacted at low temperature with liquid water before burial and melting, implying that the surface of Earth cooled quickly after core and Moon formation and that habitable conditions for life existed within 250 Myr of the formation of Earth, over 800 Myr before the oldest generally accepted microfossils. These conclusions are based on oxygen isotope analyses of zircon domains with well-defined growth zoning and nearly concordant U-Pb ages within zircon grains with low magnetic susceptibility, which are further inferred to be unaltered by various tests. However, no studies of Jack Hills zircons have directly correlated oxygen isotope ratios and radiation damage, which facilitates alteration in zircon. Several previous studies have selected zircons that show radiation-damaged, discordant, and/or hydrous domains and have shown that such altered material is not reliable as a record of igneous composition. In contrast, this study targeted zircons that are interpreted as not altered and demonstrates the importance of testing zircons for radiation damage and alteration as part of any geochemical study, regardless of age. This study expands on existing data and presents the first comprehensive evaluation of δ18O, OH/O, CL imaging, U-Pb concordance, and radiation-damage state within Jack Hills zircons. A total of 115 Hadean zircon grains in this study have water contents similar to nominally anhydrous standard reference zircons and are interpreted as pristine. Raman band broadening correlated with δ18O reveals low levels of radiation damage, indicating significant annealing. The present-day effective doses (Deff) are uniformly less than the first percolation point [dose where damage domains, that are isolated at lower damage state, overlap to form a continuous pathway through the crystal, ~2 × 1015 α-decays/mg (Ewing et al. 2003)] and most zircons have Deff <1 × 1015 α-decays/mg. Modeling of representative α-recoil damage and annealing histories indicates that most zircons in this study have remained below the Deff of the first percolation point throughout their history. The δ18O values for these primary zircons include many that are higher than would be equilibrated with the mantle at magmatic temperatures and average 6.32 ± 1.3‰ in the Hadean and 6.26 ± 1.6‰ in the Archean. There is no correlation in our suite of unaltered Hadean zircons between δ18O and OH/O, Deff, age, or U-Pb age concordance. These carefully documented Hadean-age zircons have low amounts of radiation damage in water-poor domains sampled by δ18O analysis. The mildly elevated δ18O values are a primary magmatic geochemical signature. These results strengthen the conclusion that mildly elevated-δ18O magmas existed during the Hadean, supporting the hypothesis that oceans and a habitable Earth existed before 4300 Ma. [ABSTRACT FROM AUTHOR]

Part VIII of the evolutionary system of mineralogy focuses on 1220 metamorphic mineral species, which correspond to 755 root mineral kinds associated with varied metamorphic rock types, most of which likely formed prior to the Phanerozoic Eon. A catalog of the mineral modes of 2785 metamorphic rocks from around the world reveals that 94 mineral kinds often occur as major phases. Of these common metamorphic minerals, 66 are silicates, 14 are oxides or hydroxides, 8 are carbonates or phosphates, 4 are sulfides, and 2 are polymorphs of carbon. Collectively, these 94 minerals incorporate 23 different essential chemical elements. Patterns of coexistence among these 94 minerals, as revealed by network analysis and Louvain community detection, point to six major communities of metamorphic phases, three of which correspond to different pressure-temperature (P-T) regimes of metamorphosed siliceous igneous and sedimentary rocks, while three represent thermally altered carbonate and calc-silicate lithologies. Metamorphic rocks display characteristics of an evolving chemical system, with significant increases in mineral diversity and chemical complexity through billions of years of Earth history. Earth's first metamorphic minerals formed in thermally altered xenoliths and contact zones (hornfels and sanidinite facies) associated with early Hadean igneous activity (>4.5 Ga). The appearance of new Hadean lithologies, including clay-rich sediments, arkosic sandstones, and carbonates, provided additional protoliths for thermal metamorphism prior to 4.0 Ga. Orogenesis and erosion exposed extensive regional metamorphic terrains, with lithologies corresponding to the Barrovian sequence of index mineral metamorphic zones appearing by the Mesoarchean Era (>2.8 Ga). More recently, rapid subduction and rebound of crustal wedges, coupled with a shallowing geothermal gradient, has produced distinctive suites of blueschist, eclogite, and ultrahigh-pressure metamorphic suites (<1.0 Ga). The evolution of metamorphic minerals thus exemplifies changes in physical and chemical processes in Earth's crust and upper mantle. [ABSTRACT FROM AUTHOR]

Polymetallic enrichment layers are commonly found at the base of the Lower Cambrian and extensively distributed across the Upper Yangtze Platform, yet their genetic models remain controversial. This study systematically collected samples from a typical section in the southeastern Chongqing region for mineral, organic, and inorganic analyses. It investigates the relationship between the abundance of various trace metal elements and organic matter at the base of the Niutitang Formation, as well as the vertical distribution characteristics of organic carbon isotopes and organic matter features. The results indicate that the Niutitang Formation shale exhibits a distinct three-part structure from bottom to top. Various metal elements are enriched in the lower interval, showing a close correlation between the abundance of polymetallic elements and the carbon isotopes of shale organic matter. The middle interval contains the highest TOC value and the lowest Ti/Al ratio, while the upper interval shows a significant decrease in organic matter abundance, with a clear positive correlation between the excess silicon content and Ti/Al ratio. Additionally, the mixing effect of deep-sea upwelling is the primary control on the formation of polymetallic enrichment layers in the lower interval, followed by the adsorption of organic matter under anoxic conditions. The sedimentary environment of the upper interval of the Niutitang Formation trends toward oxidation, with paleoclimate shifting toward colder and drier conditions, exhibiting aeolian sedimentary features that are unfavorable for the enrichment of trace metal elements. Consequently, upwelling is a key factor in the enrichment and mineralization of trace metal elements at the base of the Lower Cambrian in the Upper Yangtze region. [ABSTRACT FROM AUTHOR]

Diagenetic spheroids are rounded mineralised structures in sedimentary rocks that span several orders of size dimensions. These objects include rosettes spanning tens of micrometres; millimetre-sized granules; and centimetre- to metre-scale botryoids, nodules, and concretions. Connections between diagenetic spheroids and chemically oscillating reactions (COR) have been established based on chemical and pattern similarities. Nevertheless, it is unknown if there are variations in their occurrences throughout geological time, especially during periods of global environmental change. This is because COR are pattern-forming reactions where carboxylic acids are decarboxylated by strong oxidants like sulphuric acid, bromate, or iodate. The hypothesis is that there should be a greater number of diagenetic spheroids at periods of increased atmospheric and oceanic oxygenation levels. Hence, this work presents the first compilation of occurrences of diagenetic spheroids between 0.541 and 1.8 billion years ago (Ga). The compiled patterned objects are those with concentric laminations and radially aligned crystals, which are patterns akin to equidistant circularly concentric waves that radially diffuse in COR. Another characteristic of diagenetic spheroids, similar to that found in botryoidal minerals, is the destructive interference that forms circular twins; this is identical to the COR pattern formed when circular waves meet. The timeline of Proterozoic diagenetic spheroids produced in this work reveals a significant increase in occurrences across the Ediacaran, which is attributed to an increased environmental oxidation state. During this interval, seawater is known to have become richer in sulphate and iodate, which create ideal conditions for the abiotic and diagenetic oxidation of biomass. Therefore, increased occurrences of diagenetic spheroids in the Neoproterozoic possibly represent sedimentological evidence for abiotic decarboxylation reactions and widespread COR in productive environments. The distribution of diagenetic spheroids observed during the Proterozoic may also be more broadly applicable to other epochs of Earth's history. [ABSTRACT FROM AUTHOR]

Simple Summary: In this contribution, we show that, at a natural abundance, the nitrogen, carbon, and sulfur isotopic compositions of uterus cancerous and healthy tissues are different due to various metabolic pathways. These differences indicate that the isotopic composition might be a potential diagnostic and prognostic biomarker. We have tried to correlate the isotopic composition of tissues with that of serum, which would give us access to noninvasive biomarkers. In this respect, the obtained bulk isotopic compositions do not show any systematic correlation between the cancerous tissue and serum. Their application as biomarkers would probably require a position-specific isotopic analysis. Objectives: The metabolic pathway of cancerous tissue differs from healthy tissue, leading to the unique isotopic composition of stable isotopes at their natural abundance. We have studied if these changes can be developed into diagnostic or prognostic tools in the case of endometrial cancer. Methods: Measurements of stable isotope ratios were performed using isotope ratio mass spectrometry for nitrogen, carbon, and sulfur isotopic assessment. Uterine tissue and serum samples were collected from patients and the control group. Results: At a natural abundance, the isotopic compositions of all three of the studied elements of uterus cancerous and healthy tissues are different. However, no correlation of the isotopic composition of the tissues with that of serum was found. Conclusions: Differences in the isotopic composition of the tissues might be a potential prognostic tool. However, the lack of a correlation between the differences in the isotopic composition of the tissues and serum seems to exclude their application as diagnostic biomarkers, which, however, might be possible if a position-specific isotopic analysis is performed. [ABSTRACT FROM AUTHOR]

Rare amphibolite in the New Jersey Highlands containing plagioclase megacrysts ≤13 cm long forms bodies 0.5 to 2 m thick that preserve a penetrative metamorphic fabric and have sharp, conformable contacts against Mesoproterozoic country rocks. The megacrystic amphibolites were emplaced as thin dikes along extensional faults between 1160 and 1130 Ma. Amphibolites contain weakly zoned, subhedral andesine megacrysts (An29–44) in a matrix of plagioclase (An18–38), magnesio-hastingsite, biotite, diopside, Fe-Ti oxides, and apatite. The whole-rock major oxide composition of the megacrystic amphibolite matrix has high TiO2 (2.07 wt.% ± 2.0%), Al2O3 (17.03 wt.% ± 0.87%), and Fe2O3t (12.84 wt.% ± 3.2%) that represents an Al-Fe-rich mafic magma type that is characteristic of anorthosite associations globally. The whole-rock, rare earth element (REE) composition of the megacrystic amphibolite matrix is characterized by enrichments in light rare earth elements (LREEs) (La/YbN = 1.73–10.69) relative to middle (MREEs) and heavy (HREEs) rare earth elements (Gd/YbN = 1.30–1.85), and most samples have small positive Eu anomalies (Eu/Eu* = 0.95–1.25). The megacrystic amphibolite matrix is also enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs) (e.g., Ba/Nb = 24–22). Megacrystic amphibolites formed through partial melting of subduction-modified lithospheric mantle that fractionated olivine and plagioclase, producing a high-Al-Fe mafic magma. Plagioclase megacrysts formed through extraction of a plagioclase-rich crystal-liquid mush from anorthosite that mixed with mafic magma and collected in the upper part of the mid-crustal magma (depth of ~20 km based on Al-in-hornblende geobarometry) chamber through flotation. Periodic tapping of this mixed source by extensional fractures led to emplacement of the amphibolites as dikes and may have interrupted the extensive fractionation and plagioclase separation necessary to form voluminous anorthosite intrusions. [ABSTRACT FROM AUTHOR]

Recent discoveries of potential ice particles and ice-cemented regolith on extraterrestrial bodies like the Moon and Mars have opened new opportunities for developing technologies to extract water, facilitating future space missions and activities on these extraterrestrial body surfaces. This study explores the potential for water extraction from regolith through an experiment designed to test water recuperation from regolith simulant under varying gravitational conditions. The resultant water vapor extracted from the regolith is re-condensed on a substrate surface and collected in liquid form. Three types of substrates, hydrophobic, hydrophilic, and grooved, are explored. The system's functionality was assessed during a parabolic flight campaign simulating three distinct gravity levels: microgravity, lunar gravity, and Martian gravity. Our findings reveal that the hydrophobic surface demonstrates the highest efficiency due to drop-wise condensation, and lower gravity levels result in increased water condensation on the substrates. The experiments aimed to understand the performance of specific substrates under lunar, Martian, and microgravity conditions, providing an approach for in-situ water recovery, which is crucial for establishing economically sustainable water supplies for future missions. To enhance clarity and readability, in this paper, "H2O" will be referred to as "water". [ABSTRACT FROM AUTHOR]

The Chemical Vapor Transport (CVT) Reaction is an important and efficient method of synthesizing pyrite crystals. CVT-grown pyrites have been comprehensively investigated for physical properties and elemental chemical compositions. However, the isotopic compositions have not been investigated. In this study, four series of pyrite crystals (PY3, PY4, PY5, and PY6) were synthesized using the CVT method, with PY5 undoped and the others doped with nickel. The synthesized crystals were characterized qualitatively with confocal laser Raman microspectroscopy and quantitatively by EMPA, LA-ICP-MS, SIMS, and IRMS. The synthetic products are irregular polycrystalline aggregates or cubic and octahedral monocrystals, with characteristic Raman bands at ~344 cm−1, ~380 cm−1/377 cm−1, ~427 cm−1/430 cm−1, and S/Fe weight and atomic ratios of 1.15–1.17 and 2.01–2.04, respectively, indicative of pyrite. The pyrites contain traces of inevitable impurities such as Si and Br. The nickel contents of Ni-doped pyrites are heterogeneous, 39–27 300 ppm for PY3, 24–21 700 ppm for PY4, and 57–2610 ppm for PY6. By comparison, the δ34S values obtained by SIMS are relatively homogeneous (PY3 = 17.3 ± 0.9‰, PY4 = 17.7 ± 0.8‰, PY5 = 17.9 ± 0.8‰, PY6 = 17.7 ± 0.6‰, ±2SD), and are consistent with IRMS δ34S values (17.8 ± 0.2‰ for PY3, 18.3 ± 0.9‰ for PY4, 18.2 ± 0.3‰ for PY5, 18.1 ± 0.1‰ for PY6, ±2SD). The homogeneity of 34S/32S suggests that CVT has the potential to synthesize reference materials for the determination of sulfur isotopic composition of pyrite using in situ techniques. Additionally, we also investigated the matrix effects of nickel in pyrite on the measurement of 34S/32S by SIMS, and a preliminary equation of Δ34S (‰) = −0.59 × Ni (wt%)0.27 (R2 = 0.3), where Δ34S is the discrepancy between in situ and bulk δ34S values, was derived for calibration. [ABSTRACT FROM AUTHOR]

Shallow-water carbonate rocks constitute a crucial component of large guyots, arising in distinct environments and harboring valuable insights into the evolutionary stages of seamount islands as well as the tectonic conditions of the underlying oceanic plate. Laser Ablation Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) was used to conduct in situ U–Pb isotope dating of carbonate minerals with low uranium content collected from Weijia Guyot. This dating approach yielded crucial evidence for the vertical development of the seamount. Our study indicates that shallow-water carbonate rocks in Weijia Guyot had a temporal range between 91 My and 137 My. The carbonate rocks underwent two growth phases, Hauterivian to Barremian and Cenomanian to Turonian, with a hiatus of approximately 20 My. Since the Hauterivian age, the shield volcano of Weijia Guyot is essentially complete, with its seamount top exposed at or near sea level and receiving its first stage of shallow-water carbonate sedimentation. Based on the dating of both shallow-water carbonate rocks and hawaiite within the Weijia Guyot, it is inferred that approximately 10 My elapsed from shield-building volcanism to late alkalic volcanism. During the Turonian age, the main reason for the second phase of shallow-water carbonate rocks in the seamounts was the regional tectonic uplift triggered by the drift of the Weijia Guyot along with the Pacific Plate toward the Society hotspot. [ABSTRACT FROM AUTHOR]

A series of Mo-polymetallic deposits have been developed in the Jiaodong Peninsula. Notably, these Mo-dominant deposits formed essentially during the same period as the well-known world-class Au deposits in this area, hinting at a potentially unique geological correlation between them. Therefore, conducting thorough research on Mo deposits in Jiaodong holds significant importance in exploring the area's controlling factors of Mesozoic metal endowments. To reveal the petrogenesis and metallogenic potentials of Mo-fertile and ore-barren granitoid, apatite grains from the Late Aptian Nansu granodiorite and Aishan monzogranite are investigated in this study. Detailed petrographical observations, combined with in situ analysis of electron probe micro-analyzer (EPMA) and Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), have been conducted on apatite grains from the Nansu and Aishan plutons. This comprehensive analysis, encompassing both major and trace elements as well as isotopic characteristics of apatite, aims to elucidate the metallogenic differences within the late Early Cretaceous granitoids of Jiaodong. The results reveal that the apatite grains across all samples belong to fluorapatites, suggesting their magmatic origin. Additionally, chondrite-normalized rare earth element (REE) patterns of apatites in ore-fertile and ore-barren granitoids exhibit a "right-leaning" trend, characterized by relative enrichments in light REEs and depletions in heavy REEs. Both the Nansu and Aishan plutons exhibit moderately negative Eu anomalies (with averages δEu values of 0.44 and 0.51, respectively), along with slightly positive Ce anomalies (averaging δCe values of 1.08 and 1.11, respectively). A negative correlation is observed between their δEu and δCe values, indicating that the parental magmas of ore-fertile and ore-barren granitoids were formed in a relatively oxidizing environment. The calculated apatite OH contents for the Nansu pluton range from 0.26 to 1.38, while those for the Aishan pluton vary between 0.24 and 1.51, indicating comparable melt H2O abundances. Consequently, the results suggest that neither the oxygen fugacities nor the water contents of the parental magma can account for the metallogenic differences between Nansu and Aishan plutons. The apatite in the Nansu pluton exhibits a higher Ce/Pb ratio and a relatively lower Th/U ratio, indicating the involvement of a greater volume of fluids in the magmatic evolution process of this ore-bearing granitoid. Apatite grains sourced from the Nansu and Aishan plutons exhibit εNd(t) values ranging from −16.63 to −17.61 (t = 115.7 Ma) and −17.86 to −20.86 (t = 116.8 Ma), respectively. These results suggest that their parental magmas primarily originated from the partial melting of Precambrian metamorphic basement rocks within the North China Craton, with a minor contribution from mantle-derived materials. Additionally, the presence of mafic microgranular enclaves in both the Nansu and Aishan plutons indicates that both have undergone magma mixing processes. The binary diagrams plotting the ratios of Ba/Th, Sr/Th, and U/Th against La/Sm demonstrate that apatite grains of ore-fertile granitoid exhibit a distinct trend towards sediment melting. This suggests the potential incorporation of sedimentary materials, particularly those rich in molybdenum, into the magmatic source of the Nansu pluton, ultimately leading to the occurrence of molybdenum mineralization. [ABSTRACT FROM AUTHOR]

Geobarometers are commonly used to determine the pressure (and hence depth) of magmatic bodies. For instance, at equilibrium, the concentration of dissolved volatiles in a vapor-saturated melt can be used as a barometer: this is the pressure of vapor-saturation P s a t v . Most determinations of P s a t v assume that melt and vapor contain only oxidized C-O-H species. However, sulfur is the third most abundant volatile element in magmas, and oxygen fugacity f O 2 exerts a strong influence on the speciation of the melt and vapor. To explore how S and f O 2 afect calculations of P s a t v , we model a Hawaiian tholeiite that contains both reduced and oxidized C-O-H-S species in the melt and vapor. We find that excluding reduced CO-H species in the system can result in significant underestimations of P s a t v under reducing conditions (ΔFMQ < 0). The efect of S on P s a t v is small except in the vicinity of the "sulfur solubility minimum" (SSmin; 0 < ΔFMQ < +2), where excluding S-bearing species can result in underestimates of P s a t v . The implications of these results depend on the volatile concentration of the system being investigated, its fO2, and the melt composition and temperature. Our results suggest there will be little impact on P s a t v calculated for mid-ocean ridge basalts because their f O 2 is above where reduced C-O-H species become important in the melt and vapor and yet below the SSmin. However, the f O 2 of ocean island and arc basalts are close enough to the SSmin and their S concentrations high enough to influence P s a t v . However, high-CO2 and high-H2O concentrations are predicted to reduce the efect of the SSmin. Hence, P s a t v calculated for shallowly trapped melt inclusions and matrix glass are more afected by the SSmin than deeply trapped melt inclusions. Lunar and martian magmas are typically more reduced than terrestrial magmas, and therefore accurate P s a t v calculations for them require the inclusion of reduced C-O-H species. [ABSTRACT FROM AUTHOR]

The equilibrium oxygen isotope fractionation factor is widely used in geological thermometry. However, under most natural conditions, the oxygen isotope exchange is rare to reach equilibrium. Especially for the complex water–rock interaction process, the contribution of the H2CO3 solution, CO32− solution, Ca(HCO3)2 solution, and CaCO3 solution to the equilibrium oxygen isotope fractionation factor of this process is poorly understood. In view of this predicament, these key parameters are obtained by ab initio calculations. The results showed that the contributions of different carbonate minerals and different aqueous solutions to the equilibrium oxygen isotope fractionation factor were different. Among all nine carbonate minerals (dolomite, calcite, aragonite, magnesite, siderite, otavite, smithsonite, ankerite, and strontianite), the minerals with the highest and lowest reduced partition function ratios (RPFR) were siderite and strontianite, respectively. At the same time, the RPFR of nitratine, which has the same structure as carbonate, was studied. The RPFRs of the three most widely distributed carbonates in nature (dolomite, calcite, and aragonite) were dolomite > calcite > aragonite. Among the H2CO3 solution, CO32− solution, Ca(HCO3)2 solution, and CaCO3 solution, the H2CO3 solution had the strongest ability to enrich 18O. In addition, the equilibrium oxygen isotope fractionation factors between aqueous solutions and gas phase species (CO2(g), H2O(g), and O2(g), etc.) were calculated systematically. The results showed that the oxygen isotope fractionation factors between solutions and gas phases were often inconsistent with the temperature change direction and that the kinetic effects played a key role. These theoretical parameters obtained in this study will provide key equilibrium oxygen isotope constraints for water-rock interaction processes. [ABSTRACT FROM AUTHOR]

A new approach is presented in this paper for the dynamic modeling of the chemical and isotopic evolution of C1–3 during the hydrocarbon generation process. Based on systematic data obtained from published papers for the pyrolysis of various hydrocarbon sources (type I kerogen/source rock, type II kerogen/source rock, type III kerogen/source rock, crude oil, and asphalt, etc.), the empirical evolution framework of the chemical and isotopic composition of C1–3 during the hydrocarbon generation process was built. Although the empirical framework was built only by fitting a large amount of pyrolysis data, the chemical and isotopic composition of C1–3 derived from the pyrolysis experiments all follow evolution laws, convincing us that it is applicable to the thermal evolution process of various hydrocarbon sources. Based on the simplified formula of the isotopic composition of mixed natural gas at different maturities (δ13Cmixed), δ13Cmixed = X × n i A × δ 13 C i A + Y × n i B × δ 13 C i B X × n i A + Y × n i B , it can be derived that the cumulative isotopic composition of alkane generated in a certain maturity interval can be expressed by the integral of the product of the instantaneous isotopic composition and instantaneous yield at a certain maturity point, and then divided by the cumulative yield of alkane generated in the corresponding maturity interval. Thus, the cumulative isotopic composition (A(X)), cumulative yield (B(X)), instantaneous isotope (C(X)), and instantaneous yield (D(x)) in the dynamic model, comply with the following formula during the maturity interval of (X0~X). A(X) = ∫ X 0 X C X × D X d x B (X) , where A(X) and B(X) can be obtained by the fitting of pyrolysis data, and D(x) can also be obtained from the derivation of B(X). The dynamic model was applied on the pyrolysis data of Pingliang Shale to illustrate the quantitative evolution of the cumulative yield, instantaneous yield, cumulative isotope, and instantaneous isotope of C1–3 with increasing maturity. The dynamic model can quantify the yield of methane, ethane, and propane, as well as δ13C1, δ13C2, and δ13C3, respectively, during the hydrocarbon generation process. This model is of great significance for evaluating the natural gas resources of hydrocarbon source rock of different maturities and for identifying the origin and evolutionary process of hydrocarbons by chemical and isotopic data. Moreover, this model provides an approach to study the dynamic evolution of the isotope series of C1–3 (including reversed isotopic series), which is promising for revealing the mechanism responsible for isotopic reversal when combined with post-generation studies. [ABSTRACT FROM AUTHOR]

Since the early Paleozoic, numerous metallogenic events produced in the Sardinian massif a singular concentration of mineral deposits of various kinds. Among them, the Variscan metallogenic peak represents a late Paleozoic phase of diffuse ore formation linked to the tectonomagmatic evolution of the Variscan chain. Two main classes of ores may primarily be attributed to this peak: (1) mesothermal orogenic-type As-Au ± W ± Sb ores, only found in E Sardinia, and (2) intrusion-related Sn-W-Mo-F and base metals-bearing ores found in the whole Sardinian Batholith, but mainly occurring in central–south Sardinia. Both deposit classes formed diachronously during the Variscan post-compressional extension. The orogenic-type ores are related to regional-scale flows of mineralizing fluids, and the intrusion-related ores occur around fertile intrusions of different granite suites. Metallogenic reconstructions suggest almost entirely crustal processes of mineralization without a significant contribution from the mantle. We summarized these processes with a holistic approach and conceptualized the Sardinian Variscan Mineral System (SVMS), a crustal-scale physical system of ore mineralization in the Sardinian basement. The SVMS required suitable metal sources in the crust and diffuse crustal reworking triggered by heat that allowed (a) the redistribution of the original metal budget of the crust in magmas by partial melting and (b) the production of metal-bearing fluids by metamorphic dehydration. Heat transfer in the Sardinian Variscan crust involved shear heating in lithospheric shear zones and the role of mantle uplift as a thermal engine in an extensional tectonic setting. Lithospheric shear zones acted as effective pathways in focusing fluid flow through a large-scale plumbing system into regional-scale structural traps for ores. Pre-Variscan metal sources of metallogenic relevance may have been (1) the magmatic arc and magmatic arc-derived materials of Ordovician age, extensively documented in E Sardinia crust, and (2) an inferred Precambrian crystalline basement lying under the Phanerozoic crustal section, whose presence has been assumed from geophysical data and from petrological and geochemical characteristics of granite suites. At shallower crustal levels, important contributions of metals may have come from pre-Variscan ore sources, such as the Pb-Zn MVT Cambrian ores of SW Sardinia or the REE-bearing Upper Ordovician paleoplacers of E Sardinia. [ABSTRACT FROM AUTHOR]

The deeply buried Upper Ediacaran Qigebrak Formation dolostones in the Tarim Basin are promising future hydrocarbon exploration targets in China. However, the origin of these pervasive matrix dolomites is not well understood, which hampers further hydrocarbon exploration. In this study, petrographic, isotopic (C, O, and Sr), rare earth element (REE), and clumped isotope analyses were performed to unravel the mechanisms of early dolomitization. Petrographic investigations indicate that the Qigebrak Formation carbonates were completely replaced by three distinct types of dolomites: (1) dolomicrite (MD-1), (2) fabric-preserving dolomite (MD-2), and (3) fabric-destructive dolomite (MD-3). Despite different crystal textures, these three dolomite types have a narrow range of δ13C and 87Sr/86Sr values similar to those of coeval seawater. Furthermore, their seawater-normalized REE compositions display a seawater-like REE pattern with positive Ce anomalies. These findings suggest that the dolomitization fluids were seawater derived. From the clumped isotope temperature (TΔ47 ≈ 60 °C) and the δ18O water values of the dolomitization fluids, it can be inferred that the main mechanism for the formation of matrix dolomites was seepage-reflux dolomitization by mesosaline to penesaline seawater in the evaporative environment. MD-1 and MD-2 precipitated from mesosaline to penesaline seawater in slightly evaporated settings. MD-3 was likely formed via recrystallization of MD-1 and/or MD-2 at a greater depth. This study provides an insight into early dolomitization processes related to mesosaline to penesaline seawater, which may make the origins of dolomite reservoirs with similar geological backgrounds better understood. [ABSTRACT FROM AUTHOR]

Minerals of the apatite group commonly occur in granite pegmatites, and their ability to incorporate a wide range of trace elements makes them a good indicator of magma composition and magmatic–hydrothermal processes. Gem-quality purple apatite crystals from the Dara-e-Pech pegmatite field in Afghanistan have rarely been reported. Here, we investigated apatite crystals originated from this locality, using gemological testing, chemical analysis, and in situ U–Pb dating, with the purpose of identifying their origin, the constraints on the magma source in which the apatite crystals were formed, and the timing of the magmatic–hydrothermal activity. Our findings demonstrate that the purple apatite crystals were impure fluorapatite, characterized by heavy rare-earth element (HREE) enrichment, intermediate Eu anomalies, and non-CHARAC Y/Ho ratios. The results showed that these apatite crystals yielded a lower intercept age of 135.8 ± 6.9 Ma. We proposed that the pegmatitic apatite samples formed in a transitional magmatic–hydrothermal pegmatitic system with moderate fO2 in the Early Cretaceous (~135 Ma). Our study helps to constrain the magmatic–hydrothermal activities of the little-known Dara-e-Pech pegmatite field. [ABSTRACT FROM AUTHOR]