The increasing demand for wood, pasture, and palm oil drives deforestation and stands as the largest threats to rainforests. Whilst many consequences of deforestation are well understood, the effects on coastal ecosystems remain less clear. This issue is very apparent in Malaysian Borneo where the lack of historical deforestation data makes characterising baseline environmental conditions challenging. Building upon a previous study testing the suitability of coral Ba/Ca records as proxies for riverine sediment, we extend these records to the late nineteenth century, revealing a significant mid-20th-century surge in riverine barium levels, and a gradual lag within records consistent with distance from the river. We argue this increase is associated with the onset of industrial deforestation supported by historical logging records as well as land use data. Ba/Ca records provide unequivocal evidence for the temporal onset and magnitude of the impact of deforestation raising baseline sediment discharge in the nearshore waters.

The use of detrital minerals to reconstruct sedimentary provenance is subject to a range of biases, which may reduce the value of the geological information they retain. With the advent of in situ Rb-Sr geochronology, rapid analyses of a representative (>100) number of grains can now be performed on radiogenic Sr-bearing minerals to provide more comprehensive knowledge of source-to-sink processes through more diversified mineral analysis. Here, we test the in situ Rb-Sr technique on detrital white mica and biotite from basin margin and axis samples in a simple rift basin (Perth Basin, Australia) for which previously published detrital zircon U-Pb and Hf isotopic data exist. For the basin margin adjacent to Archean basement, which has unimodal detrital zircon ages at c. 2600 Ma, two mica samples reveal a dominant age mode at c. 500 Ma, reflecting thermal resetting in the craton proximal to the Gondwanan orogenic front, and a subordinate portion of Archean mica detritus that can be interpreted as having been distally sourced (>100 km away). Similarly, a basin axis sample yielded minor c. 1200 Ma apparent mica ages, representing distal sources from the Albany-Fraser-Wilkes Orogen, and c. 500 Ma grains that are likely a resetting product. Whilst obscured in the detrital zircon record, mica samples allow quantification of the relative contributions of distal and proximal sources to the basin. Finally, detrital biotite that was (partially) altered to chlorite yielded partially to fully reset ages between c. 500 and 130 Ma, the latter linked to heating from the c. 137-130 Ma Bunbury Basalt. Ultimately, the use of in situ Rb-Sr geochronology from detrital micas reveal previously unrecognized provenance and tectonic information that is critical to understanding the true complexity of ancient geological histories, but which remains obscured in standard detrital zircon U-Pb geochronology.

Determining the maximum temperature or burial depth where liquid hydrocarbon is preserved (i.e., oil preservation window) is a critical scientific problem. However, large discrepancy remains in the documented oil preservation window (e.g., 150-175 degrees C versus >240 degrees C), significantly influencing our understanding of the distribution of oil in deep earth. In this study, complete diagenesis and fluid inclusion records of oil charging and cracking were discovered in a Permian carbonate reservoir from the eastern Sichuan Basin (South China). Reconstructions of the diagenesis and petroleum evolution history reveal dynamic temperature-pressure controls on oil stability. Specifically, oil can be cracked to form methane-dominated gas after heating at <= 192 degrees C (sigma = 4) and in a hydrostatic pressure regime for similar to 20 m.y. Extreme overpressure formed postdating oil cracking due to intense calcite cementation, which resulted in isolated system and favored generation and accumulation of abnormally high pressure (up to 199 MPa) hydrocarbon fluids. The new oil preservation window can be applied to normal pressure or weak overpressure reservoirs, predicting the distribution of liquid hydrocarbon in deep earth.

The Longhua deposit is a vein-type Ni-Co deposit in South China, known for its ultrahigh grades of Ni (6.48 %) and Co (0.44 %), which has attracted considerable attention. However, the classification of the deposit remains disputed, presenting challenges for comprehensive metallogenic studies. This study primarily investigates the mineral characteristics and fluid evolution of the deposit, which is characterized by the following features: (1) It hosts a Ni-Co-As-Ag-Bi assemblage within steeply dipping quartz-calcite veins; (2) It contains Ni-Co-Fe arsenides, sulfarsenides, sulfides and native Bi with special fern-like and spherical textures; (3) The ore minerals precipitate from the stage of arsenide (monoarsenide -> diarsenide -> triarsenide), to sulfarsenide, and ultimately to sulfide, aligning with the elemental sequence of Ni -> Co -> Fe in each stage and overall transition from As to S; (4) The ore-forming fluids are characterized by medium-to-low temperatures (230-90 degrees C) and are enriched in CH4. Together, these findings indicate that the deposit could be classified as a five-element (Ni-Co-As-Ag-Bi) hydro-thermal vein deposit. The reduction of the ore-forming fluid, attributed to the oxygen fugacity buffering effect of CH4-organic carbon derived from the thermal decomposition of the host black shales, probably plays a significant role in generating the mineral sequence. The final sulfide stage formed at a higher oxygen fugacity, likely due to the consumption of the black shales, which reduced the overall reducing capacity. The Longhua deposit is the first five-element hydrothermal vein deposit in China, and provides an excellent example for investigating the complete formation processes.

The initial silicate melt related to magmatic Ni-Cu deposits located in orogenic settings in China (e.g., East Tianshan orogenic belt, East Kunlun orogenic belt) had a high fO2 that progressively decreased with continued magmatic evolution. It is still unknown if the sulfide melt that separated from the silicate melt inherited this high fO2, or even whether oxygen fugacity in sulfide plays an important role in the mineralization processes. In this work we undertook new in situ Fe, Cu, and Ni isotopic analyses of base metal sulfides from the Xiarihamu magmatic sulfide deposit (East Kunlun orogenic belt), and combined this new data with previously published Fe and Cu isotopic results from orogenic and cratonic magmatic sulfide deposits to assess changes in fO2 in sulfide during sulfide melt evolution, and the role of these processes in metal enrichment. In the Xiarihamu deposit, pentlandite has a Fe/Ni ratio similar to high-temperature pentlandite (Fe4.95Ni4.08S7.96) found in the upper disseminated ores which host high-temperature maucherite inclusions. These findings indicate a high formation temperature for the sulfide in the upper disseminated ores. Atomic % Fe in pyrrhotite suggests that fO2 increased during the transition from disseminated mineralized ultramafic rocks (47.2-50.7), through net-textured + massive mineralized ultramafic rocks (47.1-48.1), to disseminated mineralized gabbros (46.9-47.3). Early crystallized, high temperature sulfides in disseminated ores do not display high oxygen fugacity characteristics (high Fe3+/Sigma Fe), whereas in the silicate melt, fO2 continued to decrease with progressed evolution. Orogenic magmatic sulfide deposits show consistent, uniquely lighter delta 56Fe and delta 65Cu in disseminated ores relative to the same sulfides from massive ores. This cannot be explained by crustal contamination and sulfide melt fractionation based on Fe and Cu isotopes. Uncoupled delta 62Ni (insensitive to fO2 variations) and delta 56Fe, as well as heavy delta 56Fe and Co enrichment in late crystallized pentlandite (low temperature and high Fe3+/Sigma Fe) from the Xiarihamu and Kalatongke deposits (located in different orogenic belts), suggests that an increase in oxygen fugacity and related Fe3+/Sigma Fe ratios exert control on Co mineralization. Iron, Cu and Ni isotopes in sulfide can be used as indicators of Fe3+/Sigma Fe ratios in magmatic sulfide deposits in an orogenic environment, and changes in the Fe3+/Sigma Fe ratio play a critical role in Co enrichment.

In addition to copper, gold, and molybdenum, porphyry deposits are important reservoirs of critical metals such as rhenium, selenium, tellurium, and platinum group elements (PGEs). However, enrichment of cobalt (Co) has received little attention. Several studies have shown that Co enrichment does occur in porphyry deposits, however, the source(s) of Co and the mechanism(s) responsible for its enrichment in the high-temperature hydrothermal systems that ultimately form Co-rich porphyry deposits, are poorly understood. In order to address this knowledge gap, we investigated the Jinchang porphyry deposit in Northeast China which is one of the most Co-enriched porphyry deposits worldwide. In-situ elemental and Fe-S isotopic analysis, as well as electron backscatter diffraction, have been conducted on two types of pyrite (Py1 and Py2). Py1 exhibits a core-mantlerim structure, with Co enrichment in the core (Avg. 4.5 wt%) and rim (Avg. 7.5 wt%). Py2 displays a distinct core-rim structure, with Co enrichment only in the rim (Avg. 8.4 wt%). The early Co-rich fluid led to the formation of the Co-rich Py1 core. As pyrite continued to grow, Co in the fluid was depleted, leading to the formation of the Co-poor Py1 mantle and Py2 core. The most significant changes in S56Fe values and Co contents were observed between the Py2 core and Py2 rim (S56Fe: X0.94 %o, Co: X10.67 wt%). This significant variation was generated by the re-injection of Co-rich fluids, which led to the coupled dissolution-reprecipitation of pyrite, leading to the formation of the Co-rich Py1 rim and Py2 rim. Each injection of Co-rich fluid not only formed a Corich zone in pyrite, but also precipitated Co-bearing minerals, such as siegenite and cobaltite. The magmatic S34S isotope signature of pyrite and chalcopyrite (1.5-5.3 %o) rules out the possibility that Co originated from a sedimentary source. Due to the low Co content in felsic magmas, the repeated injections of Co-rich mafic magma are the only plausible source for the formation of such Co-rich fluids. Besides other possible causes, the heavy S56Fefluid values derived from mafic magmas suggest the addition of serpentinized oceanic crust slab during subduction, which directly contributed to the formation of mafic magmas. Multiple injections of mafic magma can significantly enhance the Co content in ore-forming fluids, which may be a critical prerequisite for Co enrichment in porphyry deposits worldwide. Early high-temperature and highsalinity fluids create an environment highly favourable to Co enrichment. As temperatures decrease, Co begins to precipitate, and breccia pipes, which experience rapid temperature drops due to fracturing, become favourable areas for Co deposition. The main precipitation stage of Co pre-dates the main stage of porphyry CuAu ore formation, which might be the reason that Co enrichment in porphyry deposits normally goes undetected.

Stable calcium (Ca) and iron (Fe) isotopes could provide a new way to investigate granite petrogenesis, and their isotope fractionation mechanisms in felsic magmas have been increasingly understood through continuous efforts in recent years. However, comprehensive Ca and Fe isotope fractionation during highly fractionated magmas is still unclear. This study presents Ca and Fe isotope data for some fractionated granites from Southern Myanmar. The S56/54Fe values of the less fractionated Eocene granites range from 0.11 f 0.03 %o to 0.23 f 0.04 %o. The highly fractionated Late Cretaceous and Paleocene granites clearly exhibit 0.15 %o and 0.42 %o variations in S56/54Fe values, respectively. These S56/54Fe values are negatively correlated with those of Fe2O3T, TiO2 contents and (La/Yb)N ratios, suggesting that more evolved melts are enriched in heavy Fe isotopes, primarily as a result of fractional crystallization of Fe-rich minerals enriched in light Fe isotopes (e.g., biotite and ilmenite). Some Late Cretaceous granites with low Nb/Ta and Zr/Hf ratios display relatively low S56/54Fe values, which may be modified by exsolved fluids enriched in light Fe isotopes. Moreover, the S44/40Ca values of the Late Cretaceous, Paleocene, and Eocene granites range from 0.71 f 0.07 %o to 0.90 f 0.06 %o, 0.62 f 0.08 %o to 0.89 f 0.06 %o, and 0.66 f 0.06 %o to 0.75 f 0.05 %o, respectively. Most of the studied granites have relatively consistent Ca isotopic compositions with those of the continental crust. Combined with high S44/40Ca values (up to 0.90 %o), the studied granites have a weakly negative correlation between S44/40Ca values and Eu/Eu* ratios. This evidence suggests that fractional crystallization of plagioclase with light Ca isotopes may also be a reason for Ca isotope fractionation during felsic magma differentiation, in addition to crustal magma sources and crustal contamination. Additionally, a Late Cretaceous granite with a high (Dy/Yb)N ratio has the lowest S44/40Ca value (0.52 f 0.06 %o), possibly reflecting the presence of residual garnet in the source. The affirmation of significant Ca and Fe isotope fractionation in highly evolved melts strengthens the utility of Fe and Ca isotopes as tracers of magma differentiation.

On Earth, impact structures are rare in intertropical zones. Here we evaluate the 35-40 km diameter Velingara depression in Senegal as a candidate impact structure. The depression has a topographic relief of only 50 m and is essentially buried under modern sediments. For the first time, potential-field ground observations and a microstructural survey of detrital zircons for shock features were conducted at Velingara. A 15 mGal gravity low in a 10 km diameter central anomaly was found, while significant (100 nT) amplitude magnetic field anomalies were observed in the depression. Forward modeling was used to explain the crustal sources of the anomalies, arguing in favor of the presence of a buried impact structure. An electron backscatter diffraction survey of circa 5,000 detrital zircons from a sample of modern alluvium identified a single granular zircon; orientation data for the grain does not record the former presence of reidite, but does closely resemble grains with highly dispersed neoblast orientations that have only been reported from impact settings. Age determination by LA-ICP-MS indicates the unusual granular zircon recorded an age of ca. 550 Ma. Results of the geophysical data and zircon microstructural survey reported here are consistent with, but do not yet prove, an impact origin hypothesis for the Velingara structure. The difference in amplitude between the diameter of the depression, and that of the gravity anomaly remains puzzling. Several impact scenarios are considered, which include the subsequent evolution via surface processes of a 10-km crater into a larger depression, or a large-scale (d = 40 km) complex impact crater with a peculiar geophysical anomaly limited to its central region.

Copper and iron isotopic signatures in sulfide and silicate minerals are important genetic indicators in magmatic sulfide deposits. Kalatongke is a large‐scale magmatic Cu‐Ni sulfide deposit in the Central Asian Orogenic Belt, and one that experienced multiple stages of magmatism and contamination. It is an ideal deposit in which to study Cu‐Fe isotopic fractionation during multiple stages of magmatism and sulfide mineralization processes. The Kalatongke sulfide orebodies are hosted by three small mafic intrusions in which pyroxene and sulfides (pyrrhotite, pentlandite, and chalcopyrite) are the most common Fe‐rich minerals, and chalcopyrite is the dominant Cu‐rich mineral. Sulfide liquid and silicate melt ▵56FeSul‐Sil (0.03–0.19‰) and ▵65CuCcp‐Sil (−0.78–0.74‰) values are indicative of non‐equilibrium fractionation. Most of the Cu isotope compositions in the sulfide ores at Kalatongke can be modeled as subduction‐ metasomatized, oxidized mantle source‐derived silicate melt (initial δ57Fe = 0.15‰, δ65Cu = −0.07‰) that underwent lower crustal contamination, and then reacted with silicate melt, having an R factor of 100–1,000. Rapid silicate melt and sulfide liquid Fe isotope exchange and re‐equilibration between chalcopyrite and pyrrhotite in the massive ores is reflected in the similarity of their δ56Fe values. Sulfide in disseminated ores shows a range of Fe isotope ratios, influenced by the proportions of monosulfide solid solution (MSS) and intermediate solid solution (ISS) formed. Copper isotopes can be utilized to characterize crustal contamination and silicate melt‐sulfide liquid interaction, while the Fe isotope ratios of sulfide minerals record sulfide liquid segregation and evolution in magmatic sulfide deposits.

In situ garnet Lu‐Hf geochronology has the potential to revolutionise the chronology of petrological and tectonic processes, yet there is a paucity of well‐characterised reference materials to account for laser‐induced matrix‐dependant elemental fractionation. Here, we characterise two reference garnets GWA‐1 (Lu ~ 7.0 μg g−1) and GWA‐2 (Lu ~ 8.5 μg g−1) for in situ garnet Lu‐Hf geochronology. Isochron ages from isotope dilution Lu‐Hf analyses yield crystallisation ages of 1267.0 ± 3.0 Ma with initial 176Hf/177Hfi of 0.281415 ± 0.000012 (GWA‐1), and 934.7 ± 1.4 Ma with 176Hf/177Hfi of 0.281386 ± 0.000013 (GWA‐2). In situ Lu‐Hf analyses yield inverse isochron ages up to 10% older than the known crystallisation age due to matrix effects between garnet and reference glass (NIST SRM 610) under different instrument tuning conditions. This apparent age offset is reproducible for both materials within the same session and can be readily corrected to obtain accurate ages. Our results demonstrate that GWA‐1 and GWA‐2 are robust reference materials that can be used to correct for matrix‐analytical effects and also to assess the accuracy of in situ Lu‐Hf garnet analyses across a range of commonly encountered garnet compositions.

The El Niño Southern Oscillation (ENSO) is a worldwide climate phenomenon impacting temperatures and precipitation regimes in Australia, Southeast Asia, and America. Previous studies have shown this climate phenomenon and the Indo–Australian monsoon to have a strong influence on Malaysian Borneo’s hydroclimate. In a context of climate change and increasingly strong extreme ENSO events, understanding the influence of ENSO on this region, as well as its evolution through time, is essential to better constrain the possible future impacts it will have on the Maritime Continent’s hydroclimate. To compensate for the limited availability of dependable instrumental data in the first half of the 20th century, we used coupled δ18O and Sr/Ca records from massive corals’ carbonate calcium skeletons to build a proxy for past hydroclimate: δ18Oseawater (δ18Osw). We first assessed our two 90 and 60-year-long δ18Osw records’ quality as proxies for hydroclimate by correlating them with different instrumental datasets before performing moving windowed correlations with the NINO3.4 index, an indicator of ENSO state. Results show variable agreement with local instrumental data depending on the distance from the river mouth, monsoon season, and instrumental dataset used. When correlated against the NINO3.4 index, our δ18Osw records showed a nonstationary increasing influence of ENSO from the 1980s and onwards on the local hydroclimate with correlation coefficients r > 0.8 using month groups towards the end of the year. Our findings highlight the differences in results depending on the chosen dataset, time scale, or period of the year, as well as the usefulness of these geochemical archives to better understand the impacts of climate phenomena across periods predating reliable instrumental data.

This study assesses the effect of chemical abrasion on in situ mass spectrometric isotopic and elemental analyses in zircon. Chemical abrasion improves the U–Pb systematics of SIMS (secondary ion mass spectrometry) analyses of reference zircons, while leaving other isotopic systems largely unchanged. SIMS 206Pb/238U ages of chemically abraded reference materials TEMORA-2, 91500, QGNG, and OG1 are precise to within 0.25 % to 0.4 % and are within uncertainty of chemically abraded TIMS (thermal ionization mass spectrometry) reference ages, while SIMS 206Pb/238U ages of untreated zircons are within uncertainty of TIMS reference ages where chemical abrasion was not used. Chemically abraded and untreated zircons appear to cross-calibrate within uncertainty using all but one possible permutation of reference materials, provided that the corresponding chemically abraded or untreated reference age is used for the appropriate material. In the case of reference zircons QGNG and OG1, which are slightly discordant, the SIMS U–Pb ages of chemically abraded and untreated material differ beyond their respective 95 % confidence intervals. SIMS U–Pb analysis of chemically abraded zircon with multiple growth stages is more difficult to interpret. Treated igneous rims on zircon crystals from the S-type Mount Painter Volcanics are much lower in common Pb than the rims on untreated zircon grains. However, the analyses of chemically abraded material show excess scatter. Chemical abrasion also changes the relative abundance of the ages of zircon cores inherited from the sedimentary protolith, presumably due to some populations being more likely to survive the chemical abrasion process than others. We consider these results from inherited S-type zircon cores to be indicative of results for detrital zircon grains from unmelted sediments. Trace element, δ18O, and εHf analyses were also performed on these zircons. None of these systems showed substantial changes as a result of chemical abrasion. The most discordant reference material, OG1, showed a loss of OH as a result of chemical abrasion, presumably due to dissolution of hydrous metamict domains or thermal dehydration during the annealing step of chemical abrasion. In no case did zircon gain fluorine due to exchange of lattice-bound substituted OH or other anions with fluorine during the HF partial dissolution phase of the chemical abrasion process. As the OG1, QGNG, and TEMORA-2 zircon samples are known to be compositionally inhomogeneous in trace element composition, spot-to-spot differences dominated the trace element results. Even the 91500 megacrystic zircon pieces exhibited substantial chip-to-chip variation. The light rare earth elements (LREEs) in chemically abraded OG1 and TEMORA-2 were lower than in the untreated samples. Ti concentration and phosphorus saturation ((Y + REE) / P) were generally unchanged in all samples.

Banded iron formations (BIFs) archive the relationship between Earth's lithosphere, hydrosphere, and atmosphere through time. However, constraints on the origin of Earth's largest ore deposits, hosted by BIFs, are limited by the absence of direct geochronology. Without this temporal context, genetic models cannot be correlated with tectono-thermal and atmospheric drivers responsible for BIF upgrading through time. Utilizing in situ iron oxide U-Pb geochronology, we provide a direct timeline of events tracing development of all the giant BIF-hosted hematite deposits of the Hamersley Province (Pilbara Craton, Western Australia). Direct dating demonstrates that the major iron ore deposits in the region formed during 1.4 to 1.1 Ga. This is one billion to hundreds of millions of years later than previous age constraints based upon 1) the presence of hematite ore clasts in conglomerate beds deposited before ~1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at ~2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a ~2.2 to 2.0 Ga event, reflecting widespread, but now largely eroded iron mineralization occurring when the Pilbara and Kaapvaal cratons were proximal. No existing phosphate mineral dates overlap with obtained hematite dates and therefore cannot be related to hematite crystallization and ore formation. New geochronology conclusively links all major preserved hematite deposits to a far younger (1.4 to 1.1 Ga) formation period, correlated with the amalgamation of Australia following breakup of the Columbia supercontinent.

Despite their relatively rare occurrence, lepidolite-subtype pegmatites host abundant Li-Nb-Ta-Cs-Sn mineralization and represent a high-flux pegmatitic system with abnormally high F and Li activity. Characterization of highly fluxed melts and the impact of fluxes and exsolved fluids on fractionation of peraluminous melts have mainly been studied in experimental systems, with natural system correlations remaining poorly understood. Consequently, we conducted a systematic mineralogical study of a lepidolite-subtype pegmatite in the North Qinling orogenic belt, Central China. An abnormal "concave downward" fractionation trend for primary columbite-group minerals on the quadrilateral diagram is identified, and irregularly zoned columbite crystals coexist with F-rich minerals in one of the core zones have the highest Ta contents (normally 50.17-63.13 wt% Ta2O5) and Ta/(Nb + Ta) ratios (up to 0.65). Despite the consistently Ta-dominated B-site in the crystal lattice of microlite-group minerals, extreme compositional variations at the A- and Y-sites are observed. Compared with microlites in intermediate zones, the abrupt increase in U in microlite crystals in core zones and late units (up to 20.16 wt% UO2), is ascribed to the melt-fluid interaction with exsolved U-rich aqueous fluids. In addition, the fractional crystallization of F-bearing minerals resulted in a gradual decrease in F contents in microlite-group minerals from extremely F-rich (2.68-4.84 wt% F) in intermediate zones to low F species (mainly 0.82-1.71 wt% F) in core and late zones. Moreover, autometasomatism by a late fluxed melt and hydrothermal metasomatism by late aqueous fluids are identified in columbite- and microlite-group minerals. This work highlights that these non-typical fractionation behaviors related to the activity of fluxes (especially F) and the exsolution of aqueous fluids during the internal evolution of pegmatitic melts, are critical for the generation of lepidolitesubtype pegmatites. Fluorine was gradually enriched in the pegmatitic melt, and reached its highest level during crystallization of the (inner) intermediate and core zones. Non-equilibrium crystallization occurred throughout pegmatite evolution, and late units were most probably formed from aqueous fluid-enriched residual melts, rather than by hydrothermal replacement.

Lead isotopes are a powerful geochemical tracer and a popular tool applied across a broad range of scientific fields, e.g., earth sciences, archaeology, and forensic sciences. Here we present a Pb isotope dataset collected from 232 igneous samples, spanning a ca. 2.3 million km2 area in southeastern Australia, and over 3 billion years of Earth history. This contribution provides a range of isotopic maps showing the spatial variability of Pb isotopes (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), magma source U/Pb and Th/U, and model ages. The samples selected for this study encompass U- and Th-poor media (i.e., K-feldspar), and U- and Th-bearing sampling media (i.e., whole-rock), providing a temporally and spatially resolved image of U and Th distribution in the crust, and their influence on crustal Pb through radiogenic ingrowth. This dataset has the potential to benefit a wide variety of different disciplines and is an important resource for addressing earth science questions ranging from unravelling crustal differentiation and architecture, through tracing magma source U- and Th-enrichment, to mineral deposit genesis.

The Tabei uplift in the Tarim Basin is one of the deepest and most important petroleum-producing areas in China, with more than 3 billion t (21 billion bbl) of oil equivalent discovered in the Paleozoic carbonate reservoirs. Further petroleum exploration and development in the Tabei and neighboring areas will greatly bene fit from an in-depth understanding of the hydrocarbon charge and accumulation history of these deeply buried carbonate reservoirs. The molecular correlation of reservoir oils indicates that oils from major accumulations in the area share similar geochemical characteristics and were presumably derived from the same source rocks deposited in a marine environment. The Shunbei reservoir oil has the highest thermal maturity, followed by the Yuecan reservoir oil, whereas the Tahe reservoir oil has the lowest thermal maturity. Six generations of calcite cementation spanning over 130 m.y. have been delineated in calcite veins, with U-Pb ages ranging from ca. 446 Ma to ca. 316 Ma. The second and fifth generations of calcite cementation were accompanied by oil charge events, as indicated by the occurrence of bitumen and primary oil inclusions. Fluid inclusion analysis coupled with basin modeling results reveal that the Tabei area experienced two major oil charges, with the first charge occurring during the late Caledonian Orogeny, at 426 to 415 Ma, and the second charge during the middle-late Hercynian Orogeny, at 339 to 278 Ma. The Shunbei and Yuecan reservoirs contain well-preserved oils accumulated during the two charge events, whereas the Tahe reservoir oil has been partially biodegraded.

The Xiaoxi’nancha porphyry Au-Cu deposit is located in Yanbian, Jilin Province, NE China. Gold-Cu mineralization is mainly associated with chlorite-sericite alteration. The 40Ar/39Ar age of pre-mineralization hydrothermal biotite in potassic alteration defines a relatively well-defined cluster at 111 Ma to 114 Ma with a total fusion age of 112.0 ± 0.3 Ma. In-situ secondary-ion mass spectrometry U-Pb dating of hydrothermal titanite occurring with chalcopyrite yielded an intercept age of 109.0 ± 2.4 Ma. The similarity between the biotite and titanite formation ages suggests a mineralization age of 110 Ma. Chlorite, quartz and apatite coexist in equilibrium and are closely related to mineralization. The Al-in-chlorite geothermometer indicates a formation temperature of 236–351℃ (mean 309℃), and the quartz-apatite pair yielded an average formation temperature of 306℃. The in-situ δ34S compositions of sulfide have restricted and slightly positive values (pyrite 2.3 to 3.9‰, chalcopyrite 1.6 to 3.8‰ and molybdenite 2.3 to 3.7‰). The fluid δ18O values, calculated assuming quartz-fluid equilibrium, vary from 2.4 to 5.5‰ (average = 4.0‰). Therefore, the ore-forming hydrothermal fluids were of moderate-temperature with predominantly magmatic characteristics. Apatite exhibits distinct variations in structure and composition, and slight variations in oxygen isotopic composition. The areas in apatite with dark BSE textures are characterized by lower δ18O values, Cl contents and temperatures and higher F contents, consistent with the result of water–rock interaction rather than mixing with meteoric water. The water–rock interaction and its resulting cooling, can reduce the metal solubility, likely triggering mineralization at Xiaoxi’nancha.

Plate tectonics is the primary method for cycling of material between the mantle, crust, and surface reservoirs of our planet. Oxygen isotopes (18O/16O, δ18O) in zircon have been shown to track source components through subduction, primarily by detecting the presence of isotopically heavy supracrustal material. Isotopically light signatures are relatively rare, suggesting recycling of high-temperature hydrothermal sources is negligible. Here, we report light δ18O data from magmatic-arc rocks of the 511−500 Ma Stavely Belt in western Victoria, Australia. These rocks demonstrate a two-stage mixing history: (1) constant, highly radiogenic εHf with decreasing δ18O, indicating sub-mantle δ18O initial compositions, interpreted to represent a sub-arc mantle contaminated with low-δ18O slab melts and/or fluids; and (2) decreasing εHf with increasing δ18O, implying crustal contamination with country-rock turbidites. These new data suggest that high-temperature hydrothermal sources can be recycled through subduction zones and alter the composition of the sub-arc mantle. We demonstrate how slab tearing could have driven this process, its connection to the architecture of the Delamerian Orogen, and implications for circum-supercontinent margins.