Hydrothermal Activity Research Articles

Hypothesis for Molecular Evolution in the Pre-Cellular Stage of the Origin of Life.

Life was originated from inorganic world and had experienced a long period of evolution in about 3.8 billion years. The time for emergence of the pioneer creations on Earth is debatable nowadays, and how the scenario for the prebiotic molecular interactions is still mysterious. Before the spreading of cellular organisms, chemical evolution was perhaps prevailing for millions of years, in which inorganic biosynthesis was ultimately replaced by biochemical reactions. Understanding the major molecular players and their interactions toward cellular life is fundamental for current medical science and extraterrestrial life exploration. In this review, we propose a road map for the primordial molecular evolution in early Earth, which probably occurred adjacent to hydrothermal vents with a strong gradient of organic molecules, temperature, and metal contents. Natural selection of the macromolecules with strong secondary structures and catalytic centers is associated with decreasing of overall entropy of the biopolymers. Our review may shed lights into the important selection of gene-coding RNA with secondary structures from large amounts of random biopolymers and formation of ancient ribosomes with biological machines supporting the basic life processes. Integration of the free environmental ribosomes by the early cellular life as symbiotic molecular machines is probably the earliest symbiosis on Earth.

Comparative population genomics unveils congruent secondary suture zone in Southwest Pacific Hydrothermal Vents.

How the interplay of biotic and abiotic factors shapes current genetic diversity at the community level remains an open question, particularly in the deep sea. Comparative phylogeography of multiple species can reveal the influence of past climatic events, geographic barriers, and species life history traits on spatial patterns of genetic structure across lineages. To shed light on the factors that shape community-level genetic variation and to improve our understanding of deep-sea biogeographic patterns, we conducted a comparative population genomics study on seven hydrothermal vent species co-distributed in the Back-Arc Basins (BABs) of the Southwest Pacific region. Using ddRAD-seq, we compared the range-wide distribution of genomic diversity across species and discovered a shared phylogeographic break. Demogenetic inference revealed shared histories of lineage divergence and a secondary contact. Low levels of asymmetric gene flow probably occurred in most species between the Woodlark and North Fiji basins, but the exact location of contact zones varied from species to species. For two species, we found individuals from the two lineages co-occurring in sympatry in Woodlark Basin. Although species exhibit congruent patterns of spatial structure (Eastern vs Western sites), they also show variation in the degree of divergence among lineages across the suture zone. Our results also show heterogeneous gene flow across the genome, indicating possible partial reproductive isolation between lineages and early speciation. Our comparative study highlights the pivotal role of historical and contemporary factors, underscoring the need for a comprehensive approach-especially in addressing knowledge gaps on the life history traits of deep-sea species.

Unveiling the life of archaea in sediments: Diversity, metabolic potentials, and ecological roles

AbstractThe domain Archaea was initially characterized as extremophiles upon its proposal. Recent significant discoveries have redrawn our views of archaeal biology, encompassing the identification of mesophilic archaeal groups, the expansion of archaeal diversity and metabolic capabilities, and the elucidation of evolutionary relationships among archaea, bacteria, and eukaryotes. Archaea are ubiquitous and constitute a substantial fraction of the microbial biomass within sediments. Therefore, comprehending their ecological roles is paramount for understanding their contributions to global geochemical cycles. In this review, we summarize the diversity of archaea across various sediment ecosystems, from terrestrial inland to deep‐sea environments, utilizing representative genomes supported by the Genome Taxonomy Database, which encompasses habitats such as hot springs, salt lakes, freshwater lakes, rivers, mangroves, estuaries, coastal regions, seafloor sediments, cold seeps, and hydrothermal vents. Furthermore, we integrate analyses of representative genomes with recent studies to highlight the metabolic potentials, novel enzymatic functions, and significant discoveries related to the carbon, nitrogen, and sulfur cycles across different archaeal lineages. Finally, we discuss recent research hotspots and achievements in archaeal studies, while projecting future exploration directions. The expanding diversity and metabolic capacities of archaea have broadened our perspective on the tree of life and underscored their critical impacts on ecosystems.

Protein biochemistry and engineering drive the development of a carbonic anhydrase-based carbon dioxide sequestration strategy.

The sequestration of carbon dioxide using carbonic anhydrase (CA) is one of the most effective methods for mitigating global warming. The burning of fossil fuels releases large quantities of flue gas; because of its high temperature and of the alkaline conditions required for CaCO3 precipitation in the mineralization process, thermo-alkali-stable CAs are needed. In this context, Manyumwa etal. conducted a biochemical characterization of three CAs derived from thermophilic bacteria. They then employed a rational design approach to enhance the specific activity and stability of the enzyme from the hydrothermal vent species Persephonella sp. KM09-Lau-8.

Giant pit craters on the modern seafloor above magma-induced hydrothermal vent complexes of Scotia Sea, offshore Antarctica

Massive injection of 13C depleted carbon to the ocean and atmosphere coincided with major environmental upheaval multiple times in the geological record. For several events, the source of carbon has been attributed to explosive venting of gas produced when magmatic sills intruded organic-rich sediment. The concept mostly derives from studies of a few ancient sedimentary basins with numerous hydrothermal vent complexes (HTVCs) where craters appear to have formed across large areas of the seafloor at the same time, but good examples remain rare in strata younger than the Early Eocene. We present geophysical data documenting at least 150 large (km-scale) craters on the modern seafloor across ∼148,000 km2 of Scan Basin in the southern Scotia Sea, a remote region offshore Antarctica. Seismic and bathymetric information reveals the craters relate to vertical fluid pipes extending above dome-shaped forced folds and saucer-shaped igneous sills. Presumably, magmatic intrusions deform overlying sediment and produce thermogenic gas, where buoyant hydrothermal fluids migrate upwards from sill flanks through V-shaped gas chimneys to the seafloor. Fluid expulsion, driven by excess pore pressure, enhances vertical conduits and creates collapse structures on the seafloor. Age estimates for sill emplacement and crater formation come from correlations of seismic reflectors with bore hole data collected on IODP Expedition 382. Sills intruded into sediment at least two times, first about 12–13 Ma (Middle Miocene), which occurred with deep intrusions of stacked composite sills, and once about 0.9 Ma and associated with volcanism along Discovery Bank, which may have reactivated previous fluid venting. Crater reactivation has occurred since 0.9 Ma, although probably episodically. Importantly, at present-day, numerous craters related to sills and fluid pipes populate the seafloor above a young sedimentary basin, and the ocean and atmosphere are receiving massive quantities of 13C depleted carbon. The two phenomena are unrelated but, with changes in global climate and sedimentation, the craters could be filled simultaneously and give an impression in the rock record of rapid and coeval formation coincident with carbon emission. Interpretations of ancient HTVCs and their significance to global carbon cycling needs revision with consideration of modern seafloor regions with HTVCs, notably Scan Basin.

Perturbations in Microbial Communities at Hydrothermal Vents of Panarea Island (Aeolian Islands, Italy).

Marine hydrothermal ecosystems represent extreme environments connected to submarine volcanic areas characterized by vents, having high temperatures and particular chemical compositions. The hydrothermal marine system of Panarea, located in one of the seven small islands belonging to the Aeolian Archipelago (southern Tyrrhenian Sea), is characterized by a range of vents exhibiting diverse physical and chemical conditions. We aimed to analyze the microbial community of a peculiar hot spring belonging to the Panarea hydrothermal field, known as "Black Point" (BP), in two separate sampling expeditions (May and August). Our results demonstrated that the chemical-physical variations within this hydrothermal vent, such as temperature fluctuations, mineral content, and hydrothermal fluid dynamics, play a role in shaping the structure and diversity of microbial communities. The differences between the two sampling expeditions suggest that seasonal changes, i.e., in temperature, pH, and redox potential (Eh), could drive microbial community shifts over time.

Volcanic aerosols captured by plants: A study of nanoparticles and their chemical composition.

Nanoparticles (NPs) exhibit high reactivity and mobility in the environment, and a significant capacity to penetrate living organisms, potentially leading to harmful effects. Volcanoes are the second major source of natural NPs emitted into the atmosphere, with an estimated flux of 342 Tg/year. Few studies have focused on their fate. Thanks to technological advances in single-particle inductively coupled plasma mass spectrometry (spICP-MS), this trend is starting to reverse. La Soufrière volcano in Guadeloupe, chosen as a case study, exhibits increasing hydrothermal activity since its last eruption in 1530. This study aims to characterize NPs produced during volcanic activity by analysing ancient ash deposits, as well as those formed during periods of volcanic inactivity by examining condensates near fumaroles, as ultrafine particles are primarily generated through gas condensation. In this study, plants are utilized as samplers for NPs produced by fumarole activity. The use of a ICP-MS time-of-flight in single particle mode (spICP-ToF-MS), combined with data processing techniques such as hierarchical agglomerative clustering, enables the detailed characterization of NPs by determining their multi-element composition, concentration, and mass distribution. The results demonstrate that plants can effectively serve as samplers, even under the extreme environmental conditions present at the volcano's summit. However, differences in their efficiency at trapping particles on leaf surfaces can be attributed to varying physical characteristics of the plants. The spICP-ToF-MS analysis identified three types of multi-elemental NPs (NP-Al+Si, NP-Al+Fe, NP-Ti+Al) and three mono-elemental NPs (NP-Al, NP-Si, NP-Fe). Additionally, NPs containing trace elements were detected exclusively in undiluted Sphagnum pore water, where one tri-elemental NP (Sr-Ce-La), one bi-elemental NP (CeLa), and nine mono-elemental NP families (Cr, Cu, Zn, Sr, Y, Zr, Ba, La, Ce) were identified. Elements with potential negative effects on biota such as Cu, Zn, and Cr were also highlighted. Furthermore, the composition of the total of NPs (excluding families) is compared with elemental ratios from materials of different origins (volcanic, detrital, atmospheric) to validate their volcanic source.

High genomic connectivity within Anatoma at hydrothermal vents along the Central and Southeast Indian Ridge

Hydrothermal vents are ecosystems inhabited by a highly specialized fauna. To date, more than 30 gastropod species have been recorded from vent fields along the Central and Southeast Indian Ridge and all of them are assumed to be vent-endemic. During the INDEX project, 701 representatives of the genus Anatoma (Mollusca: Vetigastropoda) were sampled from six abyssal hydrothermal vent fields. Traditional morphology and COI barcoding of Hoffman et al. (Eur J Taxon 826:135–162, 2022) were combined with 2b-RAD sequencing to investigate the anatomid community structure and connectivity between the different vent fields. Consequently, 2b-RAD sequencing supported the primary species hypothesis (based on morphology) for 125 individuals of the recently described taxa A. discapex, A. declivis, A. laevapex and A. paucisculpta. We assigned 22 additional specimens to species with 2b-RAD sequencing and updated the community analyses that confirmed the pattern of expanding populations. Population structure and FST values indicated high connectivity along the six sampled vent fields for the three most abundant species. High levels of gene flow are suggested, pointing to high dispersal potential of the target species along the study area. However, low levels of heterozygosity revealed a small gene pool and therefore an increased vulnerability towards environmental change. Our results demonstrate that 2b-RAD sequencing, in combination with other molecular methods, can accurately characterise macrobenthic mollusc communities. Sequencing technology is an essential tool for ongoing monitoring. Furthermore, we highlight that the inferred molecular and ecological patterns provide valuable insights into hydrothermal vent ecosystems, which are crucial for the successful conservation of these ecosystems.

Production of abiotic or biogenic hydrocarbons on rock particles in the presence of H2O and carbon compounds

Abiotic H2 and hydrocarbons are found in fluids discharged from ultramafic-hosted hydrothermal vents. Beneath the hydrothermal vents, abiotic H2 and hydrocarbons can be formed by serpentinization reactions and Fischer–Tropsch-type hydrocarbon-forming reactions, respectively, over ultramafic rocks. However, the source rocks that form abiotic H2 and hydrocarbons may extend to broader subsurface rocks. Here, we show that various rock constituents (solid acids) play a catalytic role in the formation of H and OH radicals via H2O dissociation, as well as in the formation of diverse hydrocarbons via the synthesis reactions of H radicals and inorganic carbons or by H radical-induced dissociation of organic carbons. The mechanisms and characteristics of these formation processes were explored through a series of reactor-based laboratory experiments. Four types of solid acid-containing rocks were mixed with H2O and a carbon source and reacted at different temperatures and pressures for different reaction periods. The product gases were analyzed via GC/MS. Twenty-nine hydrocarbons up to C11, predominantly including CH4 and aromatic hydrocarbons, were identified when CO2 (inorganic carbon source) and basalt particles were used; in contrast, 42 hydrocarbons up to C11, predominantly including CH4 and aliphatic hydrocarbons, were identified when soybean oil (organic carbon source) and basalt particles were used. The results of this study imply that abiotic H2 and diverse hydrocarbons are produced in the subsurface of Earth regardless of the presence of living organisms and suggest that solid acid-containing rocks near hot springs or volcanic areas can promote CO2 conversion into CH4 with the aid of H radicals supplied from H2O dissociation over the rocks.

Global Sn Isotope Compositions of Cassiterite Identify the Magmatic–Hydrothermal Evolution of Tin Ore Systems

Published Sn isotope data along with 150 new analyses of cassiterite and four granite analyses constrain two major tin isotope fractionation steps associated with (1) separation of tin from the magma/orthomagmatic transitional environment and (2) hydrothermal activity. A distinct Sn isotope difference across deposit type, geological host rocks, and time of ore deposit formation demonstrates that the difference in the mean δ124Sn value represents the operation of a unified process. The lower Sn isotope values present in both residual igneous rocks and pegmatite suggest that heavier Sn isotopes were extracted from the system during orthomagmatic fluid separation, likely by F ligands with Sn. Rayleigh distillation models this first F ligand-induced fractionation. The subsequent development of the hydrothermal system is characterized by heavier Sn isotope composition proximal to the intrusion, which persists in spite of Sn isotope fractionating towards isotopically lighter Sn during hydrothermal evolution.

Morphology and phylogenetic position of two novel Dysteria species (Ciliophora: Cyrtophoria) from deep-sea hydrothermal vents on the Central Indian Ridge, Indian Ocean

This study reports the discovery of two novel ciliate species – Dysteria brevicauda sp. nov. and Dysteria parasemilunaris sp. nov. – inhabiting unique environments in recently explored hydrothermal vent fields at the Onnuri and Onbada vents (1978 m and 2523 m depths, respectively) along the Central Indian Ridge in the Indian Ocean. The species were identified using a combination of morphological and molecular approaches. The morphology of D. brevicauda sp. nov. (65–110 × 20–30 μm) is characterized by a protruding dorso-anterior part, a short tail-like structure, converging outer two right kineties at the posterior end, and two frontoventral kineties with a few gaps in the anterior part. D. parasemilunaris sp. nov. (50–70 × 25–35 μm) can be recognized by its elongated oval shape with a dorsoapical collar-like protrusion, a terminally positioned stout podite, and five right kineties, including two frontoventral kineties. D. parasemilunaris sp. nov., which inhabits both the Onnuri and Onbada vents, is morphologically almost identical to Dysteria sp. collected from another hydrothermal vent, Clam Acres, in 1985. Thus, these are considered conspecific species. Phylogenetic analysis based on SSU rDNA sequences places the two new species within Dysteria Group III and V clades, respectively. D. brevicauda sp. nov. is positioned between Spirodysteria kahli (97.3% similarity) and D. subtropica (97.1% similarity). Meanwhile, D. parasemilunaris sp. nov. forms a cluster with D. semilunaris (95.3% similarity) and branches off from D. lanceolata (94.3% similarity). These findings contribute to the understanding of ciliate biodiversity in deep-sea hydrothermal vents. http:zoobank.org/urn:lsid:zoobank.org:pub:FE45985A-C0C1-4BAC-9471-3CC5D6180FEC.

Deep-sea anemones (Cnidaria, Actiniaria) from off the northeastern coast of Brazil: new records and description of Stephanauge prima sp. nov.

Deep-sea anemones (order Actiniaria) are a diverse group of cnidarians found in basically all marine habitats, from soft sediments to hydrothermal vents and cold seeps. From the waters of Brazil, in the Southern Atlantic Ocean, the deep actinian fauna has been described to encompass 14 sea anemones species, belonging to three families: Hormathiidae, Amphianthidae and Actinoscyphiidae. Here we analyze material trawled from the Potiguar Basin, off the northeast coast of Brazil. We provide new occurrence records for Chondrophellia coronata (Verrill, 1883), Actinoscyphia saginata (Verrill, 1882), Amphianthus bathybium Hertwig, 1882, and Amphianthus michaelsarsi Carlgren, 1934. We also describe a new Amphianthidae species, Stephanauge prima sp. nov. This increases the total number of deep actinians found in Brazil to 17 and provides context for discussing the representativeness of these families and the potential richness of Actiniaria in deep Brazilian waters.

Evolution of a seafloor massive sulfide deposit on axial volcanic ridges: a case study of the Duanqiao hydrothermal field, Southwest Indian Ridge

The mineralization process below the surface of the seafloor in a hydrothermal field has an important influence on the distribution and enrichment of elements. The Duanqiao hydrothermal field (DHF) is located on the new axial volcanic ridge of the ultraslow-spreading Southwest Indian Ridge. Owing to the limited surface sulfide samples, the metallogenic processes occurring below the seafloor surface such as the element enrichment mechanism and the temporal evolution of the sulfide deposits remain unclear. In this study, we conducted mineral texture, geochemical, 230Th/U dating, and laser ablation inductively coupled plasma mass spectrometer analyses of a drill core containing shallow sulfide deposits to study their evolution process. The results revealed that pyrite is enriched in Mn, Co, As, Mo, Ag, Cd, Sb, Tl, and Pb, chalcopyrite is characterized by high concentrations of Se, Sn, In, As, Ag and Pb, and sphalerite is enriched in Co, Ga, Ge, As, Ag, Cd, Sb, and Pb. The 230Th/U dating data suggested five different mineralization periods during 4,552–2,297 years. Apart from the top and bottom, the core exhibited obvious characteristics of gradual accumulation of mineralization. Results revealed that the variations in the elemental contents of different layers and different types of pyrite were controlled by the interaction of seawater and hydrothermal fluids within the sulfide mound over five different mineralization periods. Compared with other hydrothermal fields on other mid-ocean ridges, DHF pyrite is generally enriched in Zn, Pb, As, Ag, Cd, Mo, and Sb, which might reflect shallow subsurface mixing during different periods of hydrothermal activity.

The Source and Significance of Silicon in the Late Permian Dalong Formation, Northeastern Sichuan Basin

The Late Permian was a critical interval in geological history, during which dramatic changes occurred in the Earth’s surface system, and a set of black rock series rich in organic matter and silicon, the Dalong Formation, was deposited in the northeastern Sichuan Basin. We conducted a detailed sedimentological and petrological investigation integrated with (major and trace) element contents in the deep-water sequence of the Xibeixiang and Jianfeng sections. It demonstrates the source of silicon, tectonic background, and sedimentary environment of the Dalong Formation, and explores the influence of hydrothermal activities on organic matter enrichment. The results show that the upper part of the Dalong Formation contained more radiolarians in the Xibeixiang section compared to the Jianfeng section. Hydrothermal proxies such as Eu/Eu*, Al-Fe-Mn diagram, Al/(Al + Fe + Mn), and LuN/LaN suggest a biotic origin for the chert in the Dalong Formation in the Xibeixiang and Jianfeng sections, while the Xibeixiang section was slightly affected by hydrothermal activities. The La-Th-Sc diagram and the La/Sc and Ti/Zr crossplots point to a continental island arc and active continental margin origins for the Xibeixiang and Jianfeng sections. Combined with previous research, the silicon of the Dalong Formation in the northeastern Sichuan Basin is mainly derived from biological sources. The Xibeixiang section was affected by a small amount of hydrothermal fluid due to its proximity to the Paleo-Tethys Ocean and continental island arcs. Furthermore, the enrichment of organic matter was predominantly driven by high productivity, with minimal impact from hydrothermal activities. These insights hold significant research value and practical implications for shale gas exploration in the Sichuan Basin.

Hydrothermal Methane Venting and Its Microbial Oxidation Along the Eastern Southwest Indian Ridge, 63.5°–68°E

AbstractMethane concentration and its stable carbon isotope ratio studies were carried out in deep waters of ultraslow‐spreading eastern Southwest Indian Ridge (eSWIR), 63.5°–68°E, to identify hydrothermal plumes and associated biogeochemical processes. High methane concentrations (1.0–37.8 nmol/kg) confirm the presence of 11 hydrothermal plumes along the ∼500 km long section of eSWIR. Among these 11 plumes, eight are reporting for the first time. Detailed investigations near 67.67°E; 26.61°S show the presence of three plumes at various depths and their dispersion >100 km along the ridge in east‐west directions. Stable carbon isotope ratios of these plumes show lighter and heavier isotope enrichment (−40‰ to −3‰). Lighter isotope enrichment may indicate that methane could be derived from a combination of abiotic and thermogenic sources and, heavier isotope enrichment is mainly because of microbial methane oxidation. We report strong evidence for the presence of an active hydrothermal field at 67.67°E; 26.61°S in the eSWIR for the first time.

Pacmanvirus isolated from the Lost City hydrothermal field extends the concept of transpoviron beyond the family Mimiviridae.

The microbial sampling of submarine hydrothermal vents remains challenging, with even fewer studies focused on viruses. Here we report the first isolation of a eukaryotic virus from the Lost City hydrothermal field, by co-culture with the laboratory host Acanthamoeba castellanii. This virus, named pacmanvirus lostcity, is closely related to previously isolated pacmanviruses (strains A23 and S19), clustering in a divergent clade within the long-established family Asfarviridae. Its icosahedral particles are 200nm in diameter, with an electron-dense core surrounded by an inner membrane. Its genome of 395 708bp (33% G + C) is predicted to encode 473 proteins. However, besides these standard properties, pacmanvirus lostcity was found associated with a new type of selfish genetic element, 7kb in length, whose architecture and gene content are reminiscent of those of transpovirons, hitherto specific to the family Mimiviridae. Like previously described transpovirons, this element propagates as an episome within its host virus particles and exhibits partial recombination with its genome. In addition, an unrelated 2kb long episome was also associated with pacmanvirus lostcity. Together, the transpoviron and the 2kb episome might participate to exchanges between pacmanviruses and other large DNA virus families. It remains to be elucidated if the presence of these mobile genetic elements is restricted to pacmanviruses or was simply overlooked in other members of the Asfarviridae.

Oscillation frequencies of long-period seismic events at Kusatsu–Shirane volcano, Japan, related to the volume of water vapour in a hydrothermal crack

SUMMARY Long-period (LP) seismic events at active volcanoes are characterized by damped harmonic oscillations, which are thought to be generated by resonances in fluid-filled cracks. LP source properties (crack geometry and fluid properties) are generally estimated by analytically calculating the ratios of spectral peaks in crack resonance frequencies and empirically calculating a quality (Q) factor. However, because this method is applicable only to LP events with more than four spectral peaks, we cannot use it to analyse LP events with fewer spectral peaks. To bridge this gap, we developed a new method to estimate source properties using the frequency (f), Q factor and seismic moment (M0) of the lowest spectral peak of an LP event. We assumed misty gas (water vapour containing small water droplets) as the fluid in the crack and analytically derived the geometrical relationships of the crack. M0 was estimated from observed amplitudes of the lowest spectral peaks at different stations using an assumed crack mechanism. We applied this method to LP events observed from 1989 to 1993 at Kusatsu–Shirane volcano, Japan. We found that the crack length was quite variable, but the crack width was almost constant at around 100 m during our study period. We also found a strong correlation between the inverse of f and the total mass of water in the crack, which can be explained theoretically using the acoustic properties of misty gas and crack geometrical relationships. The total mass of water is proportional to the volume of water vapour in the crack, and the water vapour has been interpreted to be derived from magmatic degassing at depth. The oscillation frequency of the LP event is thus a useful metric for monitoring magma degassing into the shallow hydrothermal system, which is an important constraint on the occurrence of phreatic eruptions. Because our simple approach is widely applicable to LP events, it can enable improved monitoring of hydrothermal activity and evaluation of the risk of phreatic eruptions.

Dominance of Sulfur-Oxidizing Bacteria, Thiomicrorhabdus, in the Waters Affected by a Shallow-Sea Hydrothermal Plume.

The shallow-sea hydrothermal vent at Guishan Islet, located off the coast of Taiwan, serves as a remarkable natural site for studying microbial ecology in extreme environments. In April 2019, we investigated the composition of prokaryotic picoplankton communities, their gene expression profiles, and the dissolved inorganic carbon uptake efficiency. Our results revealed that the chemolithotrophs Thiomicrorhabdus spp. contributed to the majority of primary production in the waters affected by the hydrothermal vent plume. The metatranscriptomic analysis aligned with the primary productivity measurements, indicating the significant gene upregulations associated with carboxysome-mediated carbon fixation in Thiomicrorhabdus. Synechococcus and Prochlorococcus served as the prokaryotic photoautotrophs for primary productivity in the waters with lower influence from hydrothermal vent emissions. Thiomicrorhabdus and picocyanobacteria jointly provided organic carbon for sustaining the shallow-sea hydrothermal vent ecosystem. In addition to the carbon fixation, the upregulation of genes involved in the SOX (sulfur-oxidizing) pathway, and the dissimilatory sulfate reduction indicated that energy generation and detoxification co-occurred in Thiomicrorhabdus. This study improved our understanding of the impacts of shallow-sea hydrothermal vents on the operation of marine ecosystems and biogeochemical cycles.

Discovery of indirect parasite life cycles at deep-sea hydrothermal vents

Discovery of indirect parasite life cycles at deep-sea hydrothermal vents

Continental Subduction and the Deep Carbon Cycle in Northern Tibet

AbstractDegassing of volatiles within convergent plate margins, investigated through systematic variations in gas geochemistry, provides crucial insights into the recycling process, the lithospheric structure, and the dynamics of plateau growth. To date, such processes in the India‐Asia continental collision zone remains poorly constrained in northern Tibet due to a dearth of detailed geochemical data on volatiles. Here, we report new data on chemical compositions and He–C isotopic ratios of hydrothermal volatiles in the northern plateau. CO2‐rich samples exhibit elevated 3He/4He ratios (0.11 RA–0.39 RA) compared to crustal values, as well as displaying heavy δ13C (−4.66–0.02‰) and high CO2/3He ratios ((36–9,400) × 109), indicating in summary the occurrence of carbonate in the mantle‐derived components. We have developed a coupled He–C isotope model incorporating depleted mantle (DM), recycled carbonate (RC), and crustal carbon endmember (CCE) reservoirs to explore quantitatively the nature of the hydrothermal volatiles emitted. The results of model calculations reveal an increasing proportion of RC together with a decreasing proportion of CCE from south to north that is accompanied by an increasing contribution from DM, all suggesting the presence of a carbonated mantle beneath northern Tibet. Degassing of helium from hydrothermal activities exhibits relatively high fluxes of total 3He (104–105 atoms/m2/s), indicating a tectonically active degassing of volatiles in the Tibetan Plateau under ongoing continental convergence between India and Asia. Systematic variations in He–C isotopes, mantle helium fluxes and RC/CEE proportions along hydrothermal activities spanning from the Himalayas to the Qaidam‐Gonghe basin are consistent with a dual continental subduction model acting beneath the whole Tibetan Plateau.