Origin of natural sulfur-metal chimney in the Tangyin hydrothermal field,Okinawa Trough:constraints from rare earth element and sulfur isotopic compositions

For the first time,we present the rare earth element (REE)and sulfur isotopic composition of hydrothermal precipitates recovered from the Tangyin hydrothermal field (THF),Okinawa Trough at a water depth of 1206 m.The natural sulfur samples exhibit the lowest ∑REE concentrations (∑REE= 0.65×10^-6-4.580×10^-6)followed by metal sulfides (∑REE=1.71×10^-6-11.63×10^-6).By contrast,the natural sulfur-sediment samples have maximum ∑REE concentrations (∑REE=1 1.54×10^-6-33.06×10^-6), significantly lower than those of the volcanic and sediment samples.Nevertheless,the δEu,δCe,(La/Yb)N, La/Sm,(Gd/Yb)N and normalized patterns of the natural sulfur and metal sulfide show the most similarity to the sediment.Most hydrothermal precipitate samples are characterized by enrichments of LREE (LREE/HREE=10.09-24.53)arid slightly negative Eu anomalies or no anomaly (δEu=0.48-0.99),which are different from the hydrothermal fluid from sediment-free mid-oceanic ridges and back-are basins,but identical to the sulfides from the Jade hydrothermal field.The lower temperature and more oxidizing conditions produced by the mixing between seawater and hydrothermal fluids further attenuate the leaching ability of hydrothermal fluid,inducing lower REE concentrations for natural sulfur compared with metal sulfide;meanwhile,the negative Eu anomaly is also weakened or almost absent.The sulfur isotopic compositions of the natural sulfur (δ^34S=3.20‰-5.01‰,mean 4.23 ‰)and metal sulfide samples (δ34S=0.82‰-0.89‰,mean 0.85‰)reveal that the sulfur of the chimney is sourced from magmatic degassing.

Langerhans cell histiocytosis presenting as an isolated brain tumour:A case report

Langerhans cell histiocytosis(LCH)is a rare proliferative histiocyte disorder.It can affect any organ or system,especially the bone,skin,lung,and central nervous system(CNS).In the CNS,the hypothalamic-pituitary is predominantly affected,whereas the brain parenchyma is rarely affected.LCH occurring in the brain parenchyma can be easily confused with glioblastoma or brain metastases.Thus,multimodal imaging is useful for the differential diagnosis of these intracerebral lesions and detection of lesions in the other organs.CASE SUMMARY A 47-year-old man presented with a headache for one week and sudden syncope.Brain computed tomography(CT)and magnetic resonance imaging showed an irregularly shaped nodule with heterogeneous enhancement.On^(18)F-fluorodeoxyglucose(^(18)F-FDG)positron emission tomography/CT,a nodule with^(18)F-FDG uptake and multiple cysts in the upper lobes of both lungs were noted,which was also confirmed by high-resolution CT.Thus,the patient underwent surgical resection of the brain lesion for further examination.Postoperative pathology confirmed LCH.The patient received chemotherapy after surgery.No recurrence was observed in the brain at the 12-mo follow-up.CONCLUSION Multimodal imaging is useful for evaluating the systemic condition of LCH,developing treatment plans,and designing post-treatment strategies.