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Iddingsitization is an aqueous alteration that is known to take place in meteorites and continental basalts providing a potential habitat for microbial life. However, little is known about the exact mode by which this reaction occurs in the hadal seafloor and its implication for the deep subsurface biosphere. A comprehensive investigation of hadal basalts from the southern Mariana Trench (SMT) conducted with microscopic examinations shows that iddingsite occurs as augite‐hosted veins, rims, and mineral grains formed completely in place of augite within the SMT basalts. Carbon geochemistry indicates that organic matter with homogenous δ13C values between –27.8‰ and –27.2‰ might be biogenically accumulated in the SMT basalts. Furthermore, the close spatial relationships between carbonaceous matter (CM) and goethite in iddingsite point to microbial attachment to iddingsite minerals. Thus, iddingsitization might have fueled H2‐utilizing microorganisms inhabiting the hadal oceanic crust, thereby leading to the formation of CM, as implied by oxygen isotopic compositions revealing low alteration temperatures (32–83°C) favorable for microbial growth. In all, microbial biosignatures associated with iddingsite in the SMT basalts are highlighted, and these results could pave the way for deciphering the deep subsurface biosphere at hadal zones. [ABSTRACT FROM AUTHOR]

Carbonate‐associated sulfate (CAS) δ34S values (δ34SCAS) are generally assumed to reflect S isotopic composition of paleo‐seawater and have been extensively used to reconstruct secular variations in seawater sulfate concentrations during the geological past. However, it has often been documented that δ34SCAS records are incompatible with seawater sulfur isotopes (20.9 ± 0.1%, 2σ) determined from other archives, such as sulfate evaporites and barite (both of which may also display inconsistencies). A possible explanation for this discrepancy is that δ34SCAS values can be easily altered by atmospheric sulfate and sulfide re‐oxidation. However, the specific influence of biological factors (vital effects, common in biogenic carbonates) on CAS S isotopic composition remains unresolved, particularly at microscale levels. To elucidate these effects on δ34SCAS, S isotopic profiles were analyzed across two skeletal transects of two modern deep‐sea corals (gorgonia) using a novel secondary‐ion mass spectrometry method. Strong S isotopic fractionation was observed in calcitic skeletons from the most 34S‐depleted center (δ34S = ∼19‰), increasing outward to a relatively constant 22.5‰ in gorgonia sp. coral and 21.6‰ in bamboo coral, suggesting that vital effects are much larger than previous estimated (∼±1‰ fractionation from seawater). Oxygen isotopic and Mg, S, O elemental compositions, and Raman spectral and crystal morphological features indicate that processes such as pH control, Rayleigh fractionation, and organic effects are precluded as causes of such fractionation. Instead, vital effects associated with kinetic processes related to surface entrapment seem plausible as controls on S isotopic fractionations in the coral. This novel method is significant for gaining insights into vital effects, assessing the reliability of biogenic carbonates as high‐resolution environmental archives of S isotopes, and understanding the fundamental mechanisms governing biomineralization. Plain Language Summary: The δ34S values of carbonate‐associated sulfate (CAS) serve as crucial indicators of past environmental conditions, providing insights into historical variations in seawater sulfate and atmospheric oxygen levels. It is commonly assumed that δ34SCAS closely reflects seawater sulfate, except for severely altered samples. However, analysis of S isotopic profiles across two skeletal transects of modern calcitic deep‐sea corals (gorgonia sp. coral and bamboo coral) using a newly developed in situ method based on secondary‐ion mass spectrometry, reveals significant isotopic fractionation. The most 34S‐depleted center (δ34S = ∼19‰) increases outward to a relatively constant value of 22.5‰ for gorgonia sp. coral and 21.6‰ for bamboo coral. These findings suggest that vital effects play a notable role in δ34SCAS fractionation, challenging the previous consensus of ∼±1‰. Further investigation, incorporating multiple indices and skeletal δ18O, indicates that vital effects associated with kinetic processes related to surface entrapment contribute to this fractionation. These insights shed light on the processes driving S–O isotopic fractionation in biogenic carbonates, bolstering their utility in reconstructing paleo‐oceanographic conditions. Key Points: Development of in situ carbonate S isotopic analysis using secondary‐ion mass spectrometryCommonly observed anomalous low δ34S and δ18O values in the axial skeleton of deep‐sea gorgonia coralsContribution of kinetic‐associated vital effects to significant Carbonate‐associated sulfate sulfur isotopic fractionation, supported by multiple geochemical indices [ABSTRACT FROM AUTHOR]

Nowadays, photopolymerization has spanned across all academic and industrial applications due to its appealing features such as energy saving, environmentally‐friendly polymerization conditions, high monomer conversions, rapid polymerization kinetics and so on. Photoinitiator (PI), as a crucial component of the photoinitiating system (PIS) are capable of interacting with light efficiently, enabling to generate initiating species in mono or multicomponent systems. In this work, 13 phenothiazine‐based oxime esters (OXEs) (never reported before) were synthesized and their photoinitiation abilities for the free radical photopolymerization (FRP) of acrylates were examined upon irradiation with LED@405 nm. Parallel to their photochemical reactivities, their abilities to initiate thermal polymerization processes were also investigated. Finally, these OXEs exhibited excellent photo/thermal initiation performances, demonstrating their dual initiation properties. Phenothiazine‐based oxime esters can be used as PIs in 3D printing as well as thermal initiator in the manufacturing of carbon fiber composites. [ABSTRACT FROM AUTHOR]

[Objective] To investigate the hadal sediments main type, geochemical characteristics and formation in the Challenger Deep of the southern Mariana Trench, [Methods] the mineralogical and geochemical analysis were uesd to study the sediments and altered basalt from north slope (overlying plate) and axis to the south slope (subduction plate) at the Challenger Deep of the Mariana Trench. [Results and Conclusions] The hadal sediments can be divided into four types: red deep-sea clay, siliceous sediments, micromanganese-rich sediments, and calcareous sediments. The red deep-sea clay is the most common type of hadal sediment, which contribute the most to subducted sediments. Major and trace element geochemical characteristics are similar to those of altered basalt of the oceanic crust, which imply that red clay is mainly derived from the basalt alteration of the subducted and overlying plates, rather than the volcanic and terrestrial inputs. Moreover, intensified organic matter diagenesis has an important influence on the geochemical properties of the hadal sediments, which is the main reason the Challenger Deep sediments have lower rare earth elements and enrich more micromanganese nodules than the adjacent deep-sea sediments. [ABSTRACT FROM AUTHOR]