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Sea surface temperature data from coastal observation stations: quality control and semidiurnal characteristics
Hua YANG, Qingqing GAO, Huifeng JI, Peidong HE, Tianmao ZHU
Sea surface temperature (SST) data obtained from coastal stations in Jiangsu, China during 2010–2014 are quality controlled before analysis of their characteristic semidiurnal and seasonal cycles, including the correlation with the variation of the tide. Quality control of data includes the validation of extreme values and checking of hourly values based on temporally adjacent data points, with 0.15°C/h considered a suitable threshold for detecting abnormal values. The diurnal variation amplitude of the SST data is greater in spring and summer than in autumn and winter. The diurnal variation of SST has bimodal structure on most days, i.e., SST has a significant semidiurnal cycle. Moreover, the semidiurnal cycle of SST is negatively correlated with the tidal data from March to August, but positively correlated with the tidal data from October to January. Little correlation is detected in the remaining months because of the weak coastal–offshore SST gradients. The quality control and understanding of coastal SST data are particularly relevant with regard to the validation of indirect measurements such as satellite-derived data.
key words: sea surface temperature, data quality control, semidiurnal cycle, tidal movement, coastal observations
Source and nature of ore-forming fluids of the Edmond hydrothermal field, Central Indian Ridge: evidence from He-Arisotope composition and fluid inclusion study
Yejian WANG, Xiqiu HAN, Zhongyan QIU
doi: 10.1007/s13131-016-0963-1
To understand the source and nature of the ore-forming fluids of the Edmond hydrothermal field on the Central Indian Ridge, we studied the He-Ar isotope composition and fluid inclusions of the hydrothermal precipitates. Our results show that the sulfide samples contain noble gases He, Ne, Kr, and Xe with their abundances in between those of air-saturated water (ASW) and mid-ocean ridge basalt (MORB). The3He/4He ratio varies from 1.3 to 8.7 Ra (n=10, average: 5.1 Ra), whereas the40Ar/36Ar ratio is from 285.3 to 314.7 (n=10, average: 294.8). These results suggest that the He was derived from a mixture of MORB with variable amounts of seawater, but the Ar in the ore-forming fluids trapped in the sulfides is predominantly derived from seawater. The fluid inclusions of barite have a wide range of homogenization temperatures and salinities varying from 163°C to 260°C and 2.6 wt% to 8.5 wt% NaCl equiv., respectively. It is suggested that the ore-forming fluids were produced by phase separation, which agreed with the present-day vent fluid study.
key words: fluid inclusion, helium and argon isotopes, phase separation, massive sulfides, Central Indian Ridge

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