Hydrothermal Activity Research Articles

Флюидный режим образования вторичных доломитов в палеозойских карбонатных коллекторах Хасырейского месторождения (вал Гамбурцева)

The search for hydrocarbon deposits in the sediments of the Lower Paleozoic complex of the Timan-Pechora oil and gas province, which are associated with the main prospects for increasing reserves, is a relevant topic for research. It is necessary to understand the formation processes of carbonate reservoirs within the complex under consideration to develop a strategy for predicting the structure of the complex reservoirs. Obtaining data on the parameters of the fluid regime of the formation of secondary dolomites in the Paleozoic carbonate reservoirs of the Khasyrey field (Gamburtsev swell) was the aim of the study. We studied primary fluid inclusions in dolomite and anhydrite cements filling vuggy voids in reservoir rocks. We showed that the inclusions contained up to 10 vol. % of the gas phase, which was represented by methane and water vapor. The liquid phase was characterized by a substantially chloride-calcium composition, the salinity is 13.5–23.5 wt. % NaCl-eq. These data might indicate the formation of cavities and cements of secondary dolomites from moderate-temperature solutions of high salinity, which were formed as a result of mixing sedimentation (primary marine) waters and brines of hydrothermal vents. The products of evaporite dissolution in the presence of hydrocarbons and sulfate reduction processes were the most likely source and supplier of the fluids, both the formation of leaching caverns in the rock and the cements performing them. Fluids could enter the upper floors of the section from hydrothermal sources in the basement zones and lower horizons of the sedimentary cover through a system of faults and cracks during tectonic activation.

Oxidation of sulfur, hydrogen, and iron by metabolically versatile Hydrogenovibrio from deep sea hydrothermal vents.

Chemolithoautotrophic Hydrogenovibrio are ubiquitous and abundant at hydrothermal vents. They can oxidize sulfur, hydrogen or iron, but none are known to use all three energy sources. This ability though would be advantageous in vents hallmarked by highly dynamic environmental conditions. We isolated three Hydrogenovibrio strains from vents along the Indian Ridge, which grow on all three electron donors. We present transcriptomic data from strains grown on iron, hydrogen or thiosulfate with respective oxidation and autotrophic CO2 fixation rates, RubisCO activity, SEM, and EDX. Maximum estimates of one strain's oxidation potential were 10, 24, and 952mmol for iron, hydrogen and thiosulfate oxidation and 0.3, 1, and 84mmol CO2 fixation, respectively, per vent per hour indicating their relevance for element cycling in-situ. Several genes were up- or downregulated depending on the inorganic electron donor provided. Although no known genes of iron-oxidation were detected, upregulated transcripts suggested iron-acquisition and so far unknown iron-oxidation-pathways.

Landscape of the metaplasmidome of deep-sea hydrothermal vents located at Arctic Mid-Ocean Ridges in the Norwegian-Greenland Sea: ecological insights from comparative analysis of plasmid identification tools.

Plasmids are one of the key drivers of microbial adaptation and evolution. However, their diversity and role in adaptation, especially in extreme environments, remains largely unexplored. In this study, we aimed to identify, characterize, and compare plasmid sequences originating from samples collected from deep-sea hydrothermal vents located in Arctic Mid-Ocean Ridges. To achieve this, we employed, and benchmarked three recently developed plasmid identification tools-PlasX, GeNomad, and PLASMe-on metagenomic data from this unique ecosystem. To date, this is the first direct comparison of these computational methods in the context of data from extreme environments. Upon recovery of plasmid contigs, we performed a multiapproach analysis, focusing on identifying taxonomic and functional biases within datasets originating from each tool. Next, we implemented a majority voting system to identify high-confidence plasmid contigs, enhancing the reliability of our findings. By analysing the consensus plasmid sequences, we gained insights into their diversity, ecological roles, and adaptive significance. Within the high-confidence sequences, we identified a high abundance of Pseudomonadota and Campylobacterota, as well as multiple toxin-antitoxin systems. Our findings ensure a deeper understanding of how plasmids contribute to shaping microbial communities living under extreme conditions of hydrothermal vents, potentially uncovering novel adaptive mechanisms.

Mercury isotope fractionation and mercury source analysis in coal

Understanding the sources of mercury (Hg) in coal is crucial for understanding the natural Hg cycle in the Earth's system, as coal is a natural Hg reservoir. We conducted analyses on the mass-dependent fractionation (MDF), reported as δ202Hg, and mass-independent fractionation (MIF), reported as Δ199Hg, of Hg isotopes among individual Hg species and total Hg (THg) in Chinese coal samples. This data, supplemented by a review of prior research, allowed us to discern the varying trend of THg isotope fractionation with coal THg content. The Hg isotopic composition among identified Hg species in coal manifests notable disparities, with species exhibiting higher thermal stability tending to have heavier δ202Hg values, whereas HgS species typically display the most negative Δ199Hg values. The sources of Hg in coal are predominantly attributed to Hg accumulation from the original plant material and subsequent input from hydrothermal activity. Hg infiltrates peat swamps via vegetation debris, thus acquiring a negative Δ199Hg isotopic signature. Large-scale lithospheric Hg recycling via plate tectonics facilitates the transfer of Hg with a positive Δ199Hg from marine reservoirs to the deep crust. The later-stage hydrothermal input of Hg with a positive Δ199Hg enhances coal Hg content. This process has resulted in an upward trend of Δ199Hg values corresponding with the increase in coal THg content, ultimately leading to near-zero Δ199Hg in high-Hg coals. Coal Hg reservoirs are affected by large-scale natural Hg cycling, which involves the exchange of Hg between continents and seas.

Multi-million-year magmatic and hydrothermal activity is key to the formation of supergiant to behemothian porphyry copper deposits

Understanding the primary controls on mineral deposit formation and size is essential for sourcing the metals required by our ever-growing economy. The tonnage of porphyry copper deposits ranges five orders of magnitude but the key mechanisms and processes that modulate the size of these deposits remain enigmatic. Here, we investigate the behemothian deposits of the Chuquicamata Intrusive Complex (CIC) in northern Chile employing high-precision U–Pb and Re–Os geochronology. We resolve a complex long-lived magmatic-hydrothermal activity that lasted over 3.3 Myr. High-precision zircon petrochronology data indicate two distinct porphyry emplacement episodes, separated by 0.5 Myr, with the younger generation closely tied to the main intervals of hydrothermal mineralization. High-precision Re–Os molybdenite dates reveal a prolonged hydrothermal mineralization interval (> 2.5 Myr) that progressively migrated southwards within the CIC and continued after the end of the (apparent) magmatic activity. We show that the rate of copper precipitation varies little in nature (0.025–0.10 Mt/kyr) and is independent of the size of the deposit. Consistent with evidence from smaller deposits, our findings provide unprecedented evidence that copper endowment in porphyry copper deposits positively correlates with the timescales of magmatic and hydrothermal activity. Supergiant to behemothian deposits require multi-million-year magmatic-hydrothermal activity, linking the largest porphyry copper systems to a simple metric – the duration of magmatic-hydrothermal activity.

Identifying the genesis of hydrothermal activities in the Xiangcheng fault belt, southwestern China: Evidence from hydrochemistry and stable isotopes

Regional faults are beneficial structures for the formation of hydrothermal activities and have thus become target areas for geothermal resource utilization. Numerous hydrothermal activities have been reported along the Xiangcheng fault belt, particularly concentrating in the Batang, Xiangcheng and Shangri-La areas. In this study, hydrochemistry and stable isotopes were used to identify the genesis of hydrothermal activities in the Xiangcheng fault belt. The pH values of the geothermal water in these regions gradually decreases in this order, while the total dissolved solids gradually increase. The δD and δ18O values indicate the geothermal waters are mainly originated from snowmelt water and meteoric water. The recharge elevation of geothermal waters in Batang, Xiangcheng, and Shangri-La was 4415–4904 m, 4585–5038 m, and 3673–3969 m, respectively. Most geothermal waters belong to the hydrochemical type HCO3-Na, however some Batang geothermal water is of the SO4·HCO3-Na type, influenced by deep geothermal gas, and some Shangri-La geothermal water is of HCO3-Ca·Na type, influenced by shallow cold water and dissolution of carbonate rocks. Correlations of major ions suggest that HCO3-Na type geothermal waters are determined by the dissolution of paragonite, K-feldspar and albite as well as positive ion exchange. According to Na-K-Mg triangle diagram and mineral saturation indices, the geothermal waters do not reach full equilibrium and are mixed with shallow cold. Geothermometers, including cationic and SiO2, and geochemical thermodynamic calculations indicate that the deep and shallow reservoir temperatures are 200–240 °C and 169–193 °C for the Batang area, 194–201 °C and 119–131 °C for the Xiangcheng area, and 156–178 °C and 100–109 °C for the Shangri-La area. Conceptual models of the genesis of hydrothermal activities in the Batang, Xiangcheng, and Shangri-La areas were constructed, respectively. CaCO3 scaling is dominated in the study area. The hydrothermal activities of Batang and Xiangcheng areas with enriched deep materials and high reservoir temperatures are beneficial for rare-alkali metal (e.g., Li). The findings of this study provide a scientific basis for the development and utilization of geothermal resources in the high-temperature hydrothermal activity areas of western Sichuan.

The Carboniferous Wuzunbulake orogenic gold deposit in South Tianshan Orogen (NW China): Sericite Rb[sbnd]Sr geochronology, pyrite geochemistry, and metallogeny

The Kumishi area is located in the eastern part of the South Tianshan Orogen, which hosts several gold deposits and has substantial gold discovery potential. The timing of gold mineralization at Kumishi, however, has been poorly constrained owing to the absence of suitable dating minerals. Hydrothermal activity at Wuzunbulake is divided into the pre-ore stage 1 pyrite-quartz, syn-ore stage 2 quartz(-sulfide) and post-ore stage 3 quartz-calcite alteration/mineralization. Three types of pyrite have been recognized, i.e., Py1 (stage 1), Py2 (stage 2), and PyWR (from wallrock). Our in-situ RbSr dating on stage 2 sericite yielded an isochron age of 351.0 ± 17.4 Ma, indicating Early Carboniferous gold mineralization. Py1 and Py2 have δ34SΣS = 8.28–15.97 ‰ (avg. 12.88 ‰) and 6.92–8.70 ‰ (avg. 7.67 ‰), respectively, indicating that the sulfur in Py1 was metamorphic fluid sourced, while that of Py2 may have a mixed metamorphic fluid and wallrock source (0.84–3.27 ‰; avg. 2.31 ‰). For Py1, its contents of Au, As, Ag, Bi, Co, Cu, Mn, Ni, Pb, Sb, Tl are the lowest. Py2 has significantly higher Au-As-Ag, slightly higher Co-Cu-Ni-Sb-Tl, but lower Bi-Mn-Pb contents than those in PyWR. Considering also the sulfur isotope features, we considered that Py1 was primarily originated from the initial ore-forming fluid, and Py2 was derived from both the ore fluid and PyWR, with the former being more important and represents the source of gold. Based on that Py2 was formed by metasomatism on the PyWR margin and the element spatial coupling characteristics shown in EPMA geochemical maps, we inferred that the Au enrichment and precipitation are associated with fluid-rock reactions. The initial ore fluid is likely featured by the enrichments in Au, As, Ag, Co, Cu, Ni, Sb, Tl, and depletions in Bi, Mn, and Pb. The Wuzunbulake is best classified as an orogenic gold deposit based on its tectonic background, wallrock alteration style, and the ore-fluid source and characteristics.

Unveiling ophiuroid biodiversity across North Atlantic habitats via an integrative perspective

The depths of the North Atlantic Ocean host a species-rich fauna providing heterogeneous habitats from thermal vent fields to cold-water coral reefs. With the increasing threat of destruction of deep-sea habitats due to human impacts, such as demersal fishing and the beginning of deep-sea mining, an analysis of the diversity and distribution of species is crucial for conservation efforts. Brittle stars occur in high biomasses, contributing to the biodiversity of the seafloor. Specimens were collected during several scientific expeditions to gain a more detailed insight into the brittle star diversity in the North Atlantic Ocean. An integrative approach to identify the species with DNA barcoding (mtCOI) in combination with morphological studies revealed 24 species. Most species have been previously identified in the North Atlantic, but sequences for 13 species are newly added to public repositories. Additionally, the MALDI-TOF-MS proteomic analysis was successfully applied for 197 specimens with known COI barcodes. Results are congruent with other molecular species delimitations demonstrating the functionality of proteomics for the identification of brittle stars. This dataset significantly expands our understanding of the taxonomic and genetic diversity of brittle stars and contributes to publicly available data. It emphasizes the importance of considering habitat heterogeneity for large scale patterns of biodiversity.

Surface complexation of rare earth elements on goethite in sea-floor hydrothermal environment: Insight from first principles simulations

Deep-sea mud shows tremendous resource potential for rare earth elements (REEs) and its formation is closely associated with sea-floor hydrothermal activities. Iron (oxyhydr)oxides link the sources and sinks of REEs in sea-floor hydrothermal systems. However, the complexation mechanisms of REEs on iron (oxyhydr)oxides have not been well understood yet. In this study, by using the first principles molecular dynamics technique, we first calculated the pKa’s of surface groups on goethite (110) surface at elevated temperatures relevant to sea-floor hydrothermal systems and then evaluated the complexation structures and free energies of REEs on goethite (110) and (010) surfaces using the method of constraint by taking Sc3+, Y3+, and La3+ as model REE cations. The results show that REE complexation occurs in mildly acidic to neutral conditions. The most thermodynamically stable complexes of REEs are bidentate complexes on two neighboring FeOH sites on goethite (110) surface and tridentate complexes on two neighboring FeOH sites plus one Fe2OH site on goethite (010) surface. Sc3+ complexes match the goethite lattice and can be incorporated into the lattice. The stabilities of REE complexes increase with the distance from hydrothermal vents. Complexation of Y3+ is less favored on goethite compared to other REEs whereas Sc3+ prefers complexation on goethite (010) surface and La3+ exhibits similar stabilities on both (010) and (110) surfaces. The derived atomic level complexation mechanisms would be helpful for the interpretation of experimental data and the prediction of REEs’ behavior in the sea-floor. The findings presented here provide valuable insights into REEs fractionation and enrichment in deep-sea muds.

The Role of Mafic Intrusions in Producing Alkaline Vent Fluids at the Lost City Hydrothermal Field: Evidence from Stable Potassium Isotopes

The alkaline, H2-rich vent fluids of the Lost City Hydrothermal Field (LCHF) have generally been attributed to serpentinization of tectonically uplifted mantle peridotite. However, elevated concentrations of highly incompatible and fluid mobile trace alkali metals, Rb and Cs, indicate reaction with relatively unaltered mafic components (Seyfried et al., 2015). Here, we present high-precision stable-K isotope analyses of LCHF vent fluids, which provide new constraints on source-rock lithology and support more quantitative estimates of fluid:rock ratio, providing a new constraint on heat and mass transfer processes. We find that δ41K values of LCHF vent fluids (0.03–0.07 ‰) are distinct from local seawater (0.13 ± 0.02 ‰). In combination with near-seawater concentrations of K (10.4 ± 0.1 mmol/kg), these data are incompatible with hydrothermal alteration of peridotite alone, which is highly depleted in K. Instead, K-isotope and concentration data are consistent with hydrothermal alteration of mafic rocks (e.g., gabbro or diabase) at a fluid:rock ratio of 6–26, a range that agrees well with Rb, Cs, and 87Sr/86Sr-based estimates of fluid:rock ratio, updated here to reflect derivation from mafic source rocks.Geochemical modeling of hydrothermal fluid-rock reactions indicates that LCHF vent fluids can be effectively reproduced by a two-stage reaction in which seawater initially reacts at 200–300 °C with mafic rocks at in a fluid:rock ratio of ∼ 10 —as constrained by the above isotopic and trace-element systematics— and subsequently reacts with peridotite at a fluid:rock ratio of ∼ 30 at roughly the same temperature, pressure conditions. We also note that LCHF vent fluids are ∼ 2 % depleted in Cl compared to seawater, which may reflect admixture of a vapor component derived from ongoing phase separation at higher (> 450 °C) temperatures. We thus propose that the LCHF represents waning-stage hydrothermal activity initiated by a discrete off-axis mafic intrusion that has subsequently cooled to intermediate temperatures conducive to olivine hydrolysis and production of alkaline vent fluids. In this interpretation, alkaline H2-rich vent fields occupy a narrow thermal window in the expected evolution of hydrothermal activity associated with episodic off-axis mafic intrusions into tectonically exposed ultramafic host rocks and are thus likely to be rare on the modern seafloor.

Formation of a Large Cold Groundwater Mantle Helium Anomaly and High Temperature Geothermal Resources in Response to Bimodal Magmatism Near Roosevelt Hot Springs and Utah FORGE, Milford Valley, Southwest Utah

AbstractA large mantle helium anomaly and separate domains of high heat flow are the predominant manifestations of bimodal magmatic activity in the Milford valley. The mantle helium anomaly (1.9–2.6 R/Ra) covers 270 km2 and is subdivided into two separated domains: a cold shallow groundwater regime and high temperature hydrothermal activity. The zone of anomalous heat flow covers >100 km2 and is also subdivided into two adjacent domains, comprising hydrothermal activity at Roosevelt Hot Springs (RHS) (3–7 W/m2) and conductive heat flow (100–180 mW/m2). While the transfer of heat and mantle helium at RHS are coupled, heat and helium transfer are decoupled in the adjacent cold groundwater regime to the west. Both the mantle helium and geothermal anomalies are attributed to recent mafic‐felsic magmatic intrusions of >400 km3, however, the absence of volcanic eruptions <500,000 years indicates magmas stall before rising to shallow crustal level <10 km depth. Deep level magmatism produces a felsic composition melt, which is inferred to be responsible for the widespread and near uniform range of diluted mantle helium values. A thick and impermeable mass of crystalline granitic basement rock at the mid‐crustal level divides the ascent of mantle helium into separate flow paths. It may also impede the rise of buoyant magma trapping thermal energy that facilitates partial melting, slow cooling, and development of a thick thermal aureole. Partitioning of convective and conductive thermal regimes and independent flow paths supplying deeply derived helium characterize the development of a large long‐lived magma‐related geothermal system.

Fish-inspired tracking of underwater turbulent plumes

Autonomous ocean-exploring vehicles have begun to take advantage of onboard sensor measurements of water properties such as salinity and temperature to locate oceanic features in real time. Such targeted sampling strategies enable more rapid study of ocean environments by actively steering towards areas of high scientific value. Inspired by the ability of aquatic animals to navigate via flow sensing, this work investigates hydrodynamic cues for accomplishing targeted sampling using a palm-sized robotic swimmer. As proof-of-concept analogy for tracking hydrothermal vent plumes in the ocean, the robot is tasked with locating the center of turbulent jet flows in a 13,000-liter water tank using data from onboard pressure sensors. To learn a navigation strategy, we first implemented RL on a simulated version of the robot navigating in proximity to turbulent jets. After training, the RL algorithm discovered an effective strategy for locating the jets by following transverse velocity gradients sensed by pressure sensors located on opposite sides of the robot. When implemented on the physical robot, this gradient following strategy enabled the robot to successfully locate the turbulent plumes at more than twice the rate of random searching. Additionally, we found that navigation performance improved as the distance between the pressure sensors increased, which can inform the design of distributed flow sensors in ocean robots. Our results demonstrate the effectiveness and limits of flow-based navigation for autonomously locating hydrodynamic features of interest.

Transition metals in alkaline Lost City vent fluids are sufficient for early-life metabolisms

Despite the importance of alkaline seafloor hydrothermal vents in broadening our understanding of deep-sea hydrothermal ecosystems, little is known about the mobility and concentrations of micronutrient transition metals in these environments. Here, we present new analyses of micronutrient transition metal concentrations in vent fluids from the iconic Lost City Hydrothermal Field (LCHF) and report concentrations of Fe = 2.9–18.3 µmol/kg, Zn = 1.30–5.86 µmol/kg, Cu = 0.43–5.06 µmol/kg, Ni = 86.4–556 nmol/kg, Mn = 8.3–274 nmol/kg, V = 25.9–127 nmol/kg, Mo = 24–94 nmol/kg, Co = 8.0–135 nmol/kg, W = 4.8–16 nmol/kg, and Cd = 1.7–4.5 nmol/kg. We additionally present results of a hydrothermal lherzolite alteration experiment conducted at 300 °C, 500 bar. Transition metal concentrations and major chemical parameters of experimental reaction fluids are broadly similar to LCHF vent fluids, indicating that transition metal concentrations in LCHF vent fluids, and alkaline hydrothermal fluids more generally, reflect metal solubility controlled by underlying rock-buffered hydrothermal reactions.Concentrations of Ni and Mo are especially noteworthy because of their recognized importance for biological methanogenesis (Ni) and nitrogen fixation (Mo). When compared with known biological thresholds, our findings indicate that Ni concentrations in LCHF vent fluids are sufficient to support the robust methane-metabolizing microbial communities observed in the immediate vicinity of LCHF vents and suggest that Ni availability influences the spatial distribution of LCHF methanogens. Furthermore, our laboratory hydrothermal experiments demonstrate that Mo concentrations of similar magnitude to those observed in LCHF vent fluids (and also modern seawater) can be obtained by hydrothermal alteration of ultramafic rocks with Mo-free (Na, Ca) Cl aqueous solution. Thus, we conclude that alkaline hydrothermal fluids were likely similarly enriched in Mo prior to oxidation of the Earth’s atmosphere and ocean, providing localized Mo-rich geochemical environments capable of supporting Mo-dependent nitrogen fixation at currently recognized threshold concentrations.

Orogenic Gold Deposits of Northern Transbaikalia, Russia: Geology, Age, Sources, and Genesis

The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (87Sr/86Sr, 143Nd/144Nd, Pb–Pb, and δ34S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.

Ages and geochemistry of garnet reveal multi-types of iron-copper mineralization in the Eastern Tianshan, NW China

The Aqishan-Yamansu Fe-Cu-Au metallogenic belt in the Eastern Tianshan, NW China, hosts numerous Fe and Fe-Cu deposits that may have different genetic models, such as volcanic-hosted and skarn/IOCG types. These variations in genetic models are attributed to whether the mineralization is associated with hydrothermal activity related to volcanic or intrusive rocks. This study primarily focuses on garnets formed during the early skarn alteration in the Shuanglong Fe-Cu and Shaquanzi Fe deposits within this belt. Garnets from the Shuanglong deposit can be divided into two types and exhibit general homogeneity, with SL-Grt1 being Fe-rich and subsequently replaced by the Fe-poor SL-Grt2. Garnets from the Shaquanzi deposit display complex zonation patterns, SQZ-Grt1 show core–oscillatory zoned rim and SQZ-Grt2 show core–mantle–oscillatory zoned rim. Laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of SL-Grt1 and SL-Grt2 produced lower intercept 206Pb/238U ages ranging from 318.0 ± 6.4 Ma to 303.7 ± 16.4 Ma, coinciding with the multi-stage granite occurrence. In contrast, SQZ-Grt1 and SQZ-Grt2 yielded ages between 328.0 ± 2.6 Ma and 320.4 ± 1.7 Ma, corresponding to the timing of the hosted rhyolite. SL-Grt1 show light rare earth element (LREE) enrichment, and low concentrations of high field strength elements (HFSE), such as V and Zr, and appears to have formed rapidly within an open system. Conversely, SL-Grt2 is characterized by heavy rare earth element (HREE) enrichment and elevated HFSE contents, which could be formed slowly in a closed system. The variable composition in the SQZ-Grt1 and SQZ-Grt2 record cyclical changes in fluid kinetics (vigorous fluid flow vs. fluid stagnation). The cyclical zones in SQZ-Grt2 with HREE and HFSE concentrations below the detection limit indicate multiple inputs of external seawater. The distinct characteristics between Shuanglong and Shaquanzi garnets may reflect the difference between the single magma intrusion and complex volcanic activity. Combining previously published chronological data, this study elucidates a transition from the Middle Carboniferous volcanic-hosted Fe deposits (335–320 Ma) to the Late Carboniferous intrusion-related skarn or IOCG type Fe-Cu deposits (310–300 Ma) in the Aqishan-Yamansu belt.

Detection of Harmful H2S Concentration Range, Health Classification, and Lifespan Prediction of CH4 Sensor Arrays in Marine Environments

Underwater methane (CH4) detection technology is of great significance to the leakage monitoring and location of marine natural gas transportation pipelines, the exploration of submarine hydrothermal activity, and the monitoring of submarine volcanic activity. In order to improve the safety of underwater CH4 detection mission, it is necessary to study the effect of hydrogen sulfide (H2S) in leaking CH4 gas on sensor performance and harmful influence, so as to evaluate the health status and life prediction of underwater CH4 sensor arrays. In the process of detecting CH4, the accuracy decreases when H2S is found in the ocean water. In this study, we proposed an explainable sorted-sparse (ESS) transformer model for concentration interval detection under industrial conditions. The time complexity was decreased to O (n logn) using an explainable sorted-sparse block. Additionally, we proposed the Ocean X generative pre-trained transformer (GPT) model to achieve the online monitoring of the health of the sensors. The ESS transformer model was embedded in the Ocean X GPT model. When the program satisfied the special instructions, it would jump between models, and the online-monitoring question-answering session would be completed. The accuracy of the online monitoring of system health is equal to that of the ESS transformer model. This Ocean-X-generated model can provide a lot of expert information about sensor array failures and electronic noses by text and speech alone. This model had an accuracy of 0.99, which was superior to related models, including transformer encoder (0.98) and convolutional neural networks (CNN) + support vector machine (SVM) (0.97). The Ocean X GPT model for offline question-and-answer tasks had a high mean accuracy (0.99), which was superior to the related models, including long short-term memory–auto encoder (LSTM–AE) (0.96) and GPT decoder (0.98).

Unusual spinel in the “Verde Prato” serpentinized peridotite

A petrographic study of “Verde Prato” (trade name of an ophiolitic serpentinised peridotite quarried in Tuscany) revealed, next to a relict Cr-spinel, another opaque ore mineral apparently containing ca.17 wt% SiO2. In order to unveil the origin of this anomalous composition, detailed SEM-EDS, μ-Raman spectroscopy and X-ray μ-diffraction investigations were undertaken, which provided useful but somehow contrasting indications. Therefore, in order to definitely unveil the nature of the unusual opaque mineral, a specific TEM study was undertaken. This showed the presence of submicroscopic euhedral Mn-Cr-Fe-spinels in a matrix of a 7 Å layer-silicate (Al-lizardite). Interesting, all the submicroscopic spinel grains were found to share the same crystallographic orientation, suggesting an origin from a single, larger, former crystal. This unusual type of alteration of the mantle spinel probably occurred on the ocean floor during the pervasive polyphase process of hydrothermal peridotite serpentinization. Overall, by mapping the different serpentinite microstructures and compositions, a polyphase serpentinization history consisting of at least eight different cycles has been suggested. Moreover, the spinel composition indicates that the alteration was accompanied by Mn-metasomatism, made possible by the close proximity of Mn-rich hydrothermal vents, such as “black smokers”.

Electrochemical survey of electroactive microbial populations in deep-sea hydrothermal fields

Electric discharge in deep-sea hydrothermal fields leads us to expect the existence of electroactive microbial ecosystems in the environments. Electrochemical properties such as electric field distribution on the seafloor and electrical conductivity of the rock can be useful indicators of searching electroactive microbial community in natural environments. We performed electric field measurements in deep-sea hydrothermal fields and collected rock samples by a remotely operative vehicle (ROV) operation. Several spots on the seafloor with strong electric fields were detected, which included both active hydrothermal vent areas and inactive sulfide deposits far from the vents. The electrical conductivity of the rock samples was correlated with the copper and iron sulfide content. Microbial community compositions of the rock samples were characterized by small subunit (SSU) rRNA gene amplicon sequencing analysis. The abundance of several microbial components, which are highly related to electroactive microorganisms such as Geobacteraceae and Thiomicrorhabdus, was affected by the electrical properties of rock samples. The results suggested that electrochemical properties on the seafloor would be related to the abundance of possible electroactive microbial populations, and that the electrochemical survey may be a powerful tool for exploring electroactive ecosystems.

Uranium mobility and enrichment during hydrocarbon generation and accumulation processes: A review

Black shale serve as a new uranium sources and provide reducing agents for uranium deposits through hydrocarbon generation. However, the systematically interplay between the black shale and the formation of uranium deposits is not obscure. This paper provides a comprehensive summary and critical assessment of the depositional control factors of uranium in black shales, the extent of uranium migration during hydrocarbon generation, the enrichment of uranium in oil/gas reservoirs, and the relationship between crude oil-natural gas leakage and uranium. The study show that U-riched constituents within black shale persist through mechanisms of adsorption, reduction, complexation, and absorption within matrices rich in phosphates, iron, carbonate minerals, and organic matter. The U in black shale originates from continental weathering, volcanic eruptions, and seabed hydrothermal activities. The average U concentration in black shale is determined by the U content in atmosphere, while its relative content is controlled by the degree of anoxia during the geological historical periods.. Black shale prior to the Late Neoproterozoic period exhibits minimal migration with hydrocarbon substances, whereas black shale post the Late Neoproterozoic period demonstrates migration, with a migration rate ranging approximately between 55 and 75 %. However, the migrated uranium does not accumulate in (ancient) reservoirs. The correlation between hydrocarbon substances and sandstone-type uranium deposit is attributed to the oxygen uptake by hydrocarbons or the thermochemical sulfate reduction (TSR). The study has fundamental significance for further understand the interaction mechanisms between uranium and hydrocarbon substances.

Significant correlations between heavy metals and prokaryotes in the Okinawa Trough hydrothermal sediments

Prokaryotes play crucial roles in hydrothermal vent ecosystems, yet their interactions with heavy metals are not well understood. This study explored the diversity of prokaryotic communities and their correlations with heavy metals and nutrient elements in hydrothermal sediments from Okinawa Trough. A total of 117 bacterial genera in 26 bacterial phyla and 10 archaeal classes in 3 archaeal phyla were identified, including dominant prokaryotic phyla Planctomycetes, Acidobacteria, Verrucomicrobia, and Euryarchaeota. Furthermore, Fe (39.61 mg/g), Mn (2.84 mg/g) and Ba (0.36 mg/g) were found to be the most abundant heavy metals in the Okinawa hydrothermal sediments. Notably, the concentrations of Zn, Ba, Mn, total organic carbon, and total nitrogen significantly increased, whereas the total sulfur concentration distinctively decreased at sampling sites farther from hydrothermal vents. These changes corresponded with reductions in prokaryotic abundance and diversity. Most heavy metals, including Mn, Fe, Co, Cu and As, presented significant positive correlations with a number of prokaryotic genera in the nearby sediment samples. In contrast, both positive and negative correlations with prokaryotes were observed in remote sediment. The keystone taxa include Magnetospirillum, GOUTA19, Lysobacter, Kaistobacter, Treponema, and Clostridium were detected through prokaryote interspecies interactions. The functional predictions revealed significant genes involved in carbon fixation, nitrogen/sulfur cycling, heat shock protein, and metal resistance pathways. Structural equation modeling confirmed that metal and nutrient elements directly influence the composition of prokaryotic communities, which in turn affects the relative abundance of functional genes.