The sediments atop the sequence of ophiolite usually contain Fe(-Mn-Si)exhalites,chemical sediments that aremainlycomposedofamorphousFe-Mn oxy-hydroxides and chert/jasper.They were precipitated from hydrothermal fluids produced by deep leaching of basalt particularly during volcano activity or seafloor spreading.These hydrothermal Fe exhalites provide a good record for the depositional environment and the ocean environment as well.A well-preserved Phanerozoic Fe deposit,Motuosala Fe-Mn deposit,resulted from hydrothermal exhalation,was investigated for its trace element and Fe isotope geochemistry.The deposit is located in Xinjiang province,China and is hosted in a suit of Carboniferous volcano-sedimentary clastic rocks.The Fe deposit is mainly composed of massive hematite Fe oreand banded hematite-jasper ore.The hematite ore/band and jasper band were subjected to be analyzed.They are both composed mainly of Fe2O3 and Si O2,with very low contents of Al2O3 and Ti O2(<1%),indicating they werechemical precipitates with little detrital contamination.They both show slightly LREE depleted or near flat PAAS-normalised REE patterns,with positive Eu anomalies and Y anomolies,indicating that they were sourced from a mixture of high-temperature fluids and seawater.Compared to the hematite Fe ore/band,the jasper band shows higher EuSN/EuSN*but lower Y/Ho values.δ56Fe values for the hematite Fe ores are clustered around-0.3‰,similar to those for high-temperature fluids.The jasper samples show heavier Fe isotope compositions varying from-0.1‰to0.5‰,indicating that they were resulted from partial Fe precipitation.For all samples,δ56Fe values are related to Y/Ho and EuSN/EuSN*values.The results indicate that the hematite Fe ore and jasper were deposited in different environments.The jasper was deposited in a more anoxic condition with higher hydrothermal fluids/seawater ratio,probably when the hydrothermal activity was more intense;while the hematite Fe ore was deposited in a more oxic condition with lower hydrothermal fluids/seawater ratio,probably when the hydrothermal activity was weaker. The sediments atop the sequence of ophiolite usually contain Fe (-Mn-Si) exhalites, chemical sediments that aremainlycomposedofamorphousFe -Mnoxy-hydroxides and chert / jasper.They were precipitated from hydrothermal fluids produced by deep leaching of basalt especially during volcano activity or seafloor spreading. The hydrothermal Fe exhalites provide a good record for the depositional environment and the ocean environment as well. A well-preserved Phanerozoic Fe deposit, Motuosala Fe-Mn deposit, resulted from hydrothermal exhalation, was investigated for its trace element and Fe isotope geochemistry The deposit is located in Xinjiang province, China and is hosted by a suit of Carboniferous volcano-sedimentary clastic rocks.The Fe deposit is mainly composed of massive hematite Fe oreand banded hematite-jasper ore. The hematite ore / band and jasper band were Both are mainly composed of Fe2O3 and Si O2, with very low contents of Al2O3 and Ti O2 (<1%), indicating they werechemical precipitates with little detrital contamination. They both show slightly LREE depleted or near flat PAAS-normalized REE patterns, with positive Eu anomalies and Y anomolies, indicating that they were sourced from a mixture of high-temperature fluids and seawater. Compared to the hematite Fe ore / band, the jasper band shows higher EuSN / EuSN * but lower Y / Ho values. Δ56Fe values ​​for the hematite Feores are clustered around-0.3 ‰, similar to those for high-temperature fluids.The jasper samples show heavier Fe isotope compositions varying from-0.1 ‰ to 0.5 ‰, indicating that they were due from partial Fe precipitation. For all samples, δ56Fe values ​​are related to Y / Ho and EuSN / EuSN * values. The results indicate that the hematite Fe ore and jasper were deposited in different environments. jasper was deposited in a more anoxic condition with higher hydrothermal fluids / seawater ratio, probably when the hydrothermal activity was more intense; while the hematite ore was deposited in a more oxic condition with lower hydrothermal fluids / seawater ratio, probably when the hydrothermal activity was weaker.